US 2015.0053616A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0053616 A1 Himeno et al. (43) Pub. Date: Feb. 26, 2015

(54) DEHYDRATION OF WATER CONTAINING Publication Classification SOURCE OF FORMALDEHYDE, ANDA METHOD FOR PRODUCING AN (51) Int. Cl. ETHYLENICALLY UNSATURATED CO2F I/44 (2006.01) CARBOXYLCESTER BOID 71/02 (2006.01) BOID 6/36 (2006.01) (71) Applicant: Lucite International UK Limited, (52) U.S. Cl. Southampton (GB) CPC ...... C02F I/448 (2013.01); B01D 61/362 (2013.01); B0ID 71/028 (2013.01); C02F (72) Inventors: Yoshiyuki Himeno, Hiroshima (JP); 2101/34 (2013.01) Ken Ooyachi, Hiroshima (JP); USPC ...... 210/640; 210/651 Masahide Kondo, Hiroshima (JP) (21) Appl. No.: 14/379,051 (57) ABSTRACT (22) PCT Fled: Feb. 18, 2013 Disclosed are methods for dehydrating a water containing source of formaldehyde in which water is separated from the (86) PCT NO.: PCT/UP2O13AOS4639 water containing source of formaldehyde using a Zeolite membrane. In certain aspects, the water containing source of S371 (c)(1), formaldehyde includes a separation enhancer having a rela (2) Date: Aug. 15, 2014 tive static permittivity ranging from 2.5 to 20, and the water containing source of formaldehyde may further include Related U.S. Application Data methanol. In certain aspects, (meth)acrylic acid alkyl ester (63) Continuation of application No. PCT/JP2012/054498, may be produced using the dehydrated source of formalde filed on Feb. 17, 2012. hyde. O - 16

17 18b. E} 8 E. 8as

15 //ZZZ 2) 2227 14 11 12 Patent Application Publication Feb. 26, 2015 Sheet 1 of 2 US 2015/005361.6 A1

FIG. 1

Patent Application Publication Feb. 26, 2015 Sheet 2 of 2 US 2015/005361.6 A1

FIG 2 25a

=•**************************?

******************************************••••••••~~~~-..-…-..-.-.-.-.-.-.

**********************************~~~~~~~~~~~~~~.…….……..….……–……….….….

?. »|-8-~~~~~~~~~~~~~~~~~ *.***************~~~~~~~~~&w.• &}|-*************--~~~~~~~~~~~~~~~~ US 2015/005361.6 A1 Feb. 26, 2015

DEHYDRATION OF WATER CONTAINING CITATION LIST SOURCE OF FORMALDEHYDE, AND A METHOD FOR PRODUCING AN Patent Literature ETHYLENICALLY UNSATURATED CARBOXYLCESTER O010 PTL 1 JP-A-2006-265123

TECHNICAL FIELD SUMMARY OF INVENTION 0001. The present invention relates to a method for dehy Technical Problem dration of water containing Source of formaldehyde, and a 0011. However, the method disclosed in PTL 1 had an method for producing (meth)acrylic acid alkyl ester. insufficient dehydration performance. BACKGROUND ART 0012. The present invention is made from the viewpoint of these problems, and it provides a method for dehydration of a 0002 Recently, a method for producing (meth)acrylic water containing source of formaldehyde having an excellent acid alkyl ester by reacting a carboxylic acid ester with form dehydration performance, and a method for producing (meth) aldehyde in the presence of a catalyst (vapor-phase conden acrylic acid alkyl ester using a dehydrated source of formal sation reaction) has been developed. For example, when dehyde obtained by dehydration of the water containing methyl propanoate is used as carboxylic acid ester, methyl source of formaldehyde. methacrylate is obtained as shown in the following formula (I). Solution to Problem CH, CH, COOCH+HCHO->CH CH 0013. According to a first aspect of the present invention, (CHOH) COOCH->CH C(CH)– there is provided a method for dehydration of a water con COOCH+HO (I) taining source of formaldehyde comprising the step of con 0003 Formaldehyde is used in the form of formalin in tacting the source of formaldehyde with a zeolite membrane many cases. Formalin is an aqueous solution containing in a manner effective to separate at least part of the water from formaldehyde, and generally contains methanol as a stabi the source of formaldehyde wherein the water containing lizer. Therefore, when formalin is used as a raw material of Source of formaldehyde comprises a separation enhancer (meth)acrylic acid alkyl ester, water is introduced into the having a relative static permittivity of between 2.5 and 20 at reaction system. When water is present in the reaction system, 20° C. and atmospheric pressure and wherein the water con inhibition of the reaction progression and deterioration of the taining source of formaldehyde further contains methanol. catalyst are more likely to occur. 0014 Preferably, the water is separated from the said 0004. A further reaction with an acetal is shown in the water containing source of formaldehyde by Zeolite mem following formula (II). brane pervaporation or Zeolite membrane vapor permeation, and more preferably, the water is separated by vapor perme ation. 0005. A theoretical example of formula (II) with a 0015 Typically, in the process of the invention, the water dimethoxymethane is shown in the following formula (III). enriched fluid is the permeate and the dehydrated source of formaldehyde is the retentate. However, it is possible for the CH, CH, COOR+CHOCHOCH->CH, C(: dehydrated source of formaldehyde to be the permeate and CH) COOR+2CH-OH (III) the water enriched fluid to be the retentate. 0006. The use of dimethoxymethane thus theoretically 0016. According to a further aspect of the present inven provides an anhydrous system which avoids the difficulty of tion there is provided a method for producing an ethylenically Subsequent water separation and/or Subsequent product unsaturated carboxylic ester, preferably, an C. Bethylenically hydrolysis. In addition, the use of dimethoxymethane avoids unsaturated carboxylic ester by contacting a source of form the use of free formaldehydebut nevertheless acts in a general aldehyde with a carboxylic acid ester in the presence of a sense as a source of formaldehyde. The absence of water and catalyst, wherein a dehydrated source of formaldehyde is free formaldehyde could greatly simplify the separation of obtained by contacting a water containing Source of formal methyl methacrylate from the product stream. dehyde with a zeolite membrane in a manner effective to 0007. However, in practice, formula (III) is problematic separate at least part of the water from the water containing because methanol dehydrates to dimethyl ether and water. In source of formaldehyde to produce the said dehydrated addition, dimethoxymethane decomposes under catalytic source of formaldehyde and the dehydrated source of form conditions to dimethylether and formaldehyde. Any water aldehyde is used as the said source of formaldehyde for the formed in these reactions can hydrolyse the ester feedstock or said method. product to its corresponding acid which may be undesirable. 0017 Aparticular preferred feature of the further aspect of 0008. In addition, the presence of water in the reaction the present invention is that the water containing source of mixture increases catalyst decay so that the presence of water formaldehyde contains a separation enhancer having a rela may be undesirable even in the production of ethylenically tive static permittivity of between 2.5 and 20, more preferably unsaturated carboxylic acids. and according to the first or further aspects of the present 0009. Therefore, when (meth)acrylic acid alkyl ester is invention the relative static permittivity is between 3 and 15, produced, there is a demand to reduce the amount of water and most preferably between 4 and 10, especially, between 4 which is introduced to the reaction system, and, for example and 8 at 20° C. and atmospheric pressure. a method of dehydration by distillation of an aqueous solution (0018. By “atmospheric pressure” herein is meant 101.325 of formaldehyde has been proposed (see PTL 1). kPa. US 2015/005361.6 A1 Feb. 26, 2015

0019. By “relative static permittivity” is meant the ratio of 0032 5. The method for dehydrating a water containing the electric field strength in a vacuum to that in a given Source of formaldehyde according to any one of 1 to 4. medium at a frequency of Zero, this is commonly known as wherein the separation enhancer is carboxylic acid ester. the dielectric constant. 0033 6. The method for dehydrating the water contain 0020. It has been found that the separation enhancer car ing source of formaldehyde according to claim 5, wherein the boxylic acid ester is particularly effective. The carboxylic carboxylic acid ester is selected from methyl methacrylate, acid ester is preferably methyl propanoate, methyl acrylate, methyl acrylate, methylpropanoate ethylethanoate or methyl methyl methacrylate, ethyl ethanoate or methyl ethanoate, ethanoate. more preferably, the carboxylic acid ester is methyl pro 0034 7. The method for dehydrating the water contain panoate or methyl ethanoate, and most preferably, the car ing source of formaldehyde according to claim 6, wherein the boxylic acid ester is methyl propanoate. carboxylic acid ester is methyl propanoate. 0021 A preferred feature of the further aspect of the 0035 8. The method for dehydrating the water contain present invention is that a water containing source of the ing source of formaldehyde according to any one of 1 to 7. separation enhancer is combined with the water containing wherein the Zeolite membrane is a Linde Type-A orchabazite Source of formaldehyde to produce a combined source and Zeolite membrane. wherein the combined source is dehydrated in accordance 0036 9. The method for dehydrating the water contain with the first or further aspect of the invention to provide the ing Source of formaldehyde according to 8, wherein the said dehydrated source of formaldehyde which contains a Zeolite membrane is a Linde Type-4A zeolite membrane. separation enhancer. Whether the water containing source of 0037 10. The method for dehydrating the water contain formaldehyde is combined or otherwise, it may be contacted ing source of formaldehyde according to any one of 1 to 9. with the Zeolite membrane in a batch process, a recycled batch wherein the concentration of water in the water containing process (i.e. repeated exposure of the same batch) or a con source of formaldehyde is at least 0.5% by mass based on tinuous process. In a continuous process, a series of Zeolite 100% by mass of the water containing source of formalde treatments with two or more membranes in series is also hyde. envisaged. 0038 11 A method for producing an ethylenically unsat 0022. In preferred embodiments, the water containing urated carboxylic ester, preferably, an O. Bethylenically Source of formaldehyde and, optionally, the water containing unsaturated carboxylic ester, comprising: contacting a dehy drated source of formaldehyde with a carboxylic acid ester in Source of the separation enhancer contains methanol. the presence of a catalyst, 0023. It will be appreciated from the foregoing that the 0039 wherein the dehydrated source of formaldehyde is separation enhancer is not methanol. Typically, the separation obtained by contacting a water containing Source of formal enhancer is not a C1-C5 alkyl alcohol, more typically, it is not dehyde with a zeolite membrane in a manner effective to an alkyl alcohol, most typically, it is not an alcohol. separate at least part of the water from the water containing 0024 Typically, the ethylenically unsaturated ester is source of formaldehyde to produce the said dehydrated selected from the list consisting of methyl methacrylate and source of formaldehyde. methyl acrylate. 0040 12 The method for producing an ethylenically 0025. The Zeolite membrane is preferably a Linde Type-A unsaturated carboxylic ester according to 11, wherein the Zeolite membrane, more preferably, a Linde type-4A zeolite water containing source of formaldehyde further comprises a membrane. separation enhancer having a relative static permittivity of 0026. The concentration of water in the water containing between 2.5 and 20 at 20° C. and atmospheric pressure. source of formaldehyde is preferably 0.5% by mass or more. 0041 13 The method for producing an ethylenically 0027 1) A method for dehydrating a water containing unsaturated carboxylic acid ester according to 12 compris Source of formaldehyde comprising: ing: combining a water containing source of the separation 0028 contacting the source of formaldehyde with a zeolite enhancer with the water containing source of formaldehyde membrane in a manner effective to separate at least part of the to produce a combined source, and dehydrating the combined water from the source of formaldehyde, wherein the water Source in accordance with the method for dehydrating the containing Source of formaldehyde comprises a separation water containing Source of formaldehyde according to 11 to enhancer having a relative static permittivity of between 2.5 provide a dehydrated source of formaldehyde which contains and 20 at 20° C. and atmospheric pressure and wherein the the separation enhancer. water containing source of formaldehyde further contains 0042. 14. The method for producing an ethylenically methanol. unsaturated carboxylic acid ester according to any one of 12 to 13, wherein the separation enhancer is carboxylic acid 0029 2. The method for dehydrating a water containing ester. Source of formaldehyde according to 1, wherein the manner 0043 15 The method for producing an ethylenically is selected from the group consisting of Zeolite membrane unsaturated carboxylic acid ester according to any one of 11 pervaporation or Zeolite membrane vapor permeation. to 14, wherein the water containing source of formaldehyde 0030) 3 The method for dehydrating a water containing further contains methanol. Source of formaldehyde according to 2, wherein water is 0044 16. The method for producing an ethylenically separated from the water containing source of formaldehyde unsaturated carboxylic acid ester according to any one of 13 by Zeolite membrane vapor permeation. to 15, wherein the water containing source of the separation 0031 (4) The method for dehydrating a water containing enhancer further contains methanol in addition to the separa Source of formaldehyde according to any one of 1 to 3. tion enhancer. wherein the separated water is a permeate and, a dehydrated 0045 17 The method for producing an ethylenically source of formaldehyde is a retentate. unsaturated carboxylic acid ester according to any one of 11 US 2015/005361.6 A1 Feb. 26, 2015

to 16, wherein the ethylenically unsaturated acid ester is instance, above 50%, a polymerization reaction of formalde selected from the group consisting of methyl methacrylate hyde may occur and stability tends to deteriorate. Accord and methyl acrylate. ingly, a preferred range for the content of formaldehyde is up to less than 20% by weight, more preferably, 5-18% by Advantageous Effects of Invention weight, most preferably, 5-15% by weight in the water con 0046. The present invention can provide a method for taining source of formaldehyde. When a combined water dehydration of the water containing source of formaldehyde containing source of formaldehyde and water containing having an excellent dehydration performance and a method Source of separation enhancer is used, the overall formalde for producing (meth)acrylic acid alkyl ester by using a dehy hyde level in the combined stream is preferably, 2 to 70% by drated source of formaldehyde obtained by such dehydration. mass with respect to 100% by mass of the water containing combined stream. Again, a preferred range for the content of BRIEF DESCRIPTION OF DRAWINGS formaldehyde is up to less than 20% by weight, more prefer ably, 3-18% by weight, most preferably, 5-15% by weight in 0047 FIG. 1 is a schematic configuration view showing the water containing combined stream. one example of a separation device where water is separated 0055. On the other hand, the content of organic solvent in from the water containing Source of formaldehyde. the combined water containing source of formaldehyde and 0048 FIG. 2 is a schematic configuration view showing a water containing source of separation enhancer other than further example of a separation device where water is sepa formaldehyde is preferably 5 to 90% by mass of 100% by rated from the water containing Source of formaldehyde. mass of combined water containing source of formaldehyde and water containing source of separation enhancer. When DESCRIPTION OF EMBODIMENTS the content of the organic solvent other than formaldehyde is 0049. The present invention will be described in detail lower than 5% by mass, the formaldehyde may not be suffi below. ciently stable. When the content of the organic solvent other 0050. A method for dehydration of the water containing than formaldehyde is higher than 90% by mass, the concen source of formaldehyde (hereinafter, simply referred to as tration of the raw material for producing (meth)acrylic acid “dehydration method”) of the present invention separates alkyl ester is lowered, and thus a sufficient yield tends not to water from water containing Source of formaldehyde by using be obtained. a Zeolite membrane. 0056. In the present invention, when water is separated 0051. In the invention, a water containing source of form from water containing source of formaldehyde using a Zeolite aldehyde is defined as a solution containing formaldehyde, membrane, separation enhancer is or is preferably added to water and an organic solvent other than formaldehyde. An the water containing source of formaldehyde. Thereby, the example of a dehydrated source of formaldehyde is a solution dehydration performance is increased. The separation where at least some water has been separated from the water enhancer may be in solution with an organic solvent such as containing source of formaldehyde. Generally herein, a methanol. In addition, the separation enhancer may be in “dehydrated source of formaldehyde' refers to a water con solution with water. Preferably, the separation enhancer is in taining Source of formaldehyde that has had at least some Solution with water and methanol. Accordingly, the separa water removed by the method of the present invention. tion enhancer may be added as a water containing, and 0052. The water containing source of formaldehyde con optionally, methanol containing, source of separation tains formaldehyde and water. Since formaldehyde is easily enhancer. Accordingly, the combined water containing polymerized, the water containing Source of formaldehyde Source of formaldehyde and separation enhancer may contain preferably contains an organic solvent other than formalde methanol as well as water. hyde, for preventing polymerization of formaldehyde in the 0057 The content of separation enhancer is preferably water containing Source of formaldehyde. The organic Sol 10% by mass or more, more preferably 20% by mass or more, vent other than formaldehyde is not specifically limited, and with respect to 100% by mass of water containing source of various organic solvents can be used. Typically, however, by formaldehyde. When the amount of separation enhancer is "organic solvents' mentioned herein is not meant the separa lower than 10% by mass, it is hard to obtain a sufficient tion enhancer described below. A preferred organic solvent is dehydration performance. The upper limit of the amount of methanol. However, generally, a preferred solvent is a com separation enhancer added is not specifically limited, but is pound with which the formaldehyde forms a weak or strong preferably 90% by mass or less, and more preferably 80% by complex which reduces the activity of formaldehyde towards mass or less. polymerization. 0058. The preferred separation enhancers are preferably 0053. The water containing source of formaldehyde is medium polarity solvents. available in the form of formalin. Commercially available 0059 Suitable separation enhancers may be selected from formalin contains methanol as a stabilizer. trifluoromethane, m-difluorobenzene, fluorobenzene, trifluo 0054 The content of formaldehyde is not specifically lim romethylbenzene, o-fluorotoluene, m-fluorotoluene, p-fluo ited, but is preferably 5 to 70% by mass with respect to 100% rotoluene, 1,3-bis(trifluoromethyl)benzene: methyl metha by mass of water containing source of formaldehyde. When noate, ethyl methanoate, methyl ethanoate, methyl acrylate, commercially available formalin is used as the water contain propyl methanoate, ethyl ethanoate, methylpropanoate, ethyl ing source of formaldehyde, the content of formaldehyde is acrylate, methyl trans-2-butenoate, methyl methacrylate, generally 37% by mass or more. When the content of form dimethyl malonate, butyl methanoate, isobutyl methanoate, aldehyde is low, for instance, below 5%, and the formalde propyl ethanoate, ethyl propanoate, methylbutanoate, ethyl hyde is used as a raw material in the reaction of producing 2-butenoate ethyl methacrylate, diethyl oxalate, dimethyl (meth)acrylic acid alkyl ester, a sufficient yield is not Succinate, ethylene glycol diacetate, pentyl methanoate, iso obtained. When the content of formaldehyde is high, for pentyl methanoate, butyl ethanoate, tert-butyl ethanoate, pro US 2015/005361.6 A1 Feb. 26, 2015 pyl propanoate, ethylbutanoate, methylpentanoate, ethylene static permittivity falling within the ranges defined above at glycol monoethylether acetate, cyclohexylmethanoate, butyl 20° C. and atmospheric pressure. acrylate, diethylmalonate, dimethylglutarate, 1.2.3,-propan 0061 The separation enhancer is preferably a carboxylic etriol-1,3-diacetate, pentyl ethanoate, butyl propanoate, pro acid ester represented by the following formula (IV). pyl butanoate, ethyl pentanoate, ethyl 3-methylbutanoate, R' COOR (IV) methyl hexanoate, benzyl methanoate, phenyl ethanoate, methylbenzoate, methyl salicylate, diethyl maleate, diethyl 10062) Informula (IV), R' is a hydrogenatom oran organic fumarate, methyl cyclohexanecarboxylate, cyclohexyl etha group, and the organic group is preferably an organic group noate, diisopropyl oxalate, diethyl Succinate, dimethyl adi having 1 to 4 carbon atoms. The organic group is a group pate, hexyl ethanoate, pentyl propanoate, isopentyl pro essentially having a carbonatom, and for example includes an panoate, butylbutanoate, propyl pentanoate, ethylhexanoate, alkyl group, or an alkoxy group. methyl heptanoate, ethyl benzoate, methyl 4-methylben I0063 R’ is an alkyl group, and the alkyl group is prefer Zoate, benzyl ethanoate, phenyl propanoate, ethyl salicylate, ably an alkyl group having 1 to 4 carbon atoms. methyl 2-methoxybenzoate, triacetin, cyclohexyl pro 0064 Specific examples of the carboxylic acid ester panoate, ethyl cyclohexanecarboxylate, diethyl glutarate, include methyl propanoate, methyl methacrylate, methyl heptyl ethanoate, pentylbutanoate, methyl octanoate, methyl acrylate, methyl ethanoate, or ethylethanoate. Of these, when 2-(acetyloxy)benzoate, dimethyl phthalate, 2-phenylethyl methyl propanoate or ethyl ethanoate is used as a separation ethanoate, benzyl propanoate, phenyl propanoate, propyl enhancer, a permeation fluxtends to be increased. In addition, benzoate, ethyl phenylacetate, cyclohexylbutanoate, diethyl methyl propanoate can be used as a raw material of a reaction adipate, octyl ethanoate, 2-methylheptyl ethanoate, pentyl which produces methyl methacrylate by reaction of formal pentanoate, ethyl trans-cinnamate, benzylbutanoate, phenyl dehyde and methyl propanoate, and therefore methyl pro pentanoate, butyl benzoate, pentyl hexanoate, propyl cin panoate is particularly preferable in the present invention. namate, diethyl phthalate, pentylbenzoate, pentyl salicylate, 0065. The water containing source of formaldehyde is 1-bornyl ethanoate, dibutyl tartrate, phenyl salicylate, hexyl Subjected to dehydration using a Zeolite membrane. benzoate, diethylnonanedioate, benzylbenzoate, benzyl sali 0066. The Zeolite membrane is a membrane having excel cylate, pentylcinnamate, diisobutyladipate, diethyl sebacate, lent separation, heat resistance, and chemical resistance prop phenyl 2-(acetyloxy)benzoate, tributyrin, dibutyl phthalate, erties. 2-naphthyl salicylate, dipentyl phthalate, dicyclohexyl adi 0067 Examples of the Zeolite membrane include a Linde pate, dibutyl sebacate, dihexyl phthalate, 1,2,3-propanetriyl Type-A (LTA) Zeolite membrane, a T-type (ERI-OFF) Zeolite hexanoate, butyl oleate, dioctyl phthalate, dioctyl sebacate; membrane, a X-type (FAU) Zeolite membrane, a Y-type 2-methyl-2-butanol. 2,2-dimethyl-1-propanol. 1-methylcy (FAU) Zeolite membrane, a mordenite (MOR) membrane, a clopentanol, 3-hexanol, 3-methyl-3-pentanol, 2-ethyl-1-bu ZSM-5 (MFI) Zeolite membrane, a BEA zeolite membrane, a tanol, o-cresol, cyclohexanemethanol, 2-methylcyclohex chabazite membrane (CHA), and a silicalite membrane. The anol, 2-heptanol, 3-heptanol, 4-heptanol, 3-methyl-2- structures of these Zeolites are described in "The Atlas of hexanol. 2.2-dimethyl-1-pentanol, 2.3-Xylenol. 2,4-Xylenol, Zeolite Framework Types", 6" revised edition, by Ch Baer 2.5-xylenol. 2,6-Xylenol, 3,4-xyleno, 3.5-xylenol, 1-phenyle locher, L. B McCusker and D H Olsen, Elsevier, ISBN 978 thanol, 2-octanol, 3-octanol, 4-octanol, 2-methyl-1-heptanol, 0-444-53064-6. Of these, a Linde Type-A zeolite membrane, 4-methyl-1-heptanol, 5-methyl-1-heptanol, 3-methyl-2-hep a T-type Zeolite membrane, a chabazite membrane (CHA), a tanol, 5-methyl-2-heptanol, 6-methyl-2-heptanol, 3-methyl X-type Zeolite membrane and a Y-type Zeolite membrane are 4-heptanol, 2-ethyl-1-hexano, 2,2-dimethyl-1-hexano, 2.2- preferable. From the viewpoint that water can be selectively dimethyl-1-hexanol. 1-phenyl-1-propanol. 2-phenyl-2- separated from the water containing Source of formaldehyde, propanol. 1-phenyl-2-propanol. 1-nonanol, 2-nonanol, a Linde Type-A zeolite and a chabazite (CHA) membrane 3-nonano. 1-naphthol, 2-naphthol. 1-phenyl-2-methyl-2-pro having high Al content is preferable. panol, thymol. 1-decanol, 2-decanol, 3-decanol. 2.2-dim 0068. In addition, the present invention provides advanta ethyl-1-octanol. 1-undecanol. 1-dodecanol. 1-tridecano, geously high flux rates. 1-tetradecanol; dimethyl ether, ethoxyacetylene, tetrahydro furan, diethyl ether, ethylene glycol dimethyl ether, tetrahy 0069 Generally, as a zeolite type, the higher the Alcon dropyran, 2-methyltetrahydrofuran, phenoxyacetylene, tent, the more the affinity to water is increased, and the more butoxyacetylene, diethylene glycol dimethyl ether, anisole, the dehydration performance tends to be improved. triethoxymethane, ethyl phenyl ether, 1,2-dimethoxyben 0070 The concentration of water in the water containing Zene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, trieth source of formaldehyde is typically 25% by mass or less, ylene glycol dimethyl ether, eucalyptol, tetraethylene glycol more typically, 20% by mass or less. When Linde Type-A Zeolite membrane is used as Zeolite membrane, from the dimethyl ether, 1-methoxynaphthalene; 1,4-cyclohexanedi viewpoint of water resistance thereof, a concentration of one, 2-octanone, 2-nonanone, di-tert-butyl ketone, 2,6-dim water in water containing source of formaldehyde is prefer ethyl-4-heptanone, 2-decanone, 2-undecanone, 7-tride ably 15% by mass or less, more preferably 10% by mass or canone, 9-heptadecanone, 10-nonadecanone; pentanal, 2.2- less. When a concentration of water in water containing dimethylpropanal and 1-heptanal; or selected from the above source of formaldehyde is more than 15% by mass, deterio list excluding C1-C5 alkyl alcohols; or selected from the ration of separation performance may occur due to the dete above list excluding alkyl alcohols; or selected from the rioration of the Linde Type-A zeolite membrane. However, if above list excluding alcohols. the concentration of water in the water containing source of 0060. In addition, the separation enhancer extends to mix formaldehyde is reduced, the permeation flux tends to be tures of two or more of the above listed solvents or mixtures reduced. Therefore, the concentration of water in the water of one or more of the above listed solvents with one or more containing Source of formaldehyde irrespective of membrane other solvents which mixtures in either case have relative is preferably 0.5% by mass or more, more preferably 2% by US 2015/005361.6 A1 Feb. 26, 2015

mass or more, and even more preferably 5% by mass or more 0079. As described above, in dehydration by a zeolite based on 100% by mass of the water containing source of membrane, a separation factor and a permeation flux tend to formaldehyde. be increased inaccordance with increase of a concentration of 0071. The amount of Zeolite is sufficient to dehydrate the water in the water containing Source of formaldehyde. Gen water containing source of formaldehyde by preferably at erally, a permeation flux tends to be increased in accordance least 10%, more preferably at least 20%, and most preferably with the rising of temperature of the water containing source. at least 30%. Typically, more than 50% of the total water 0080. In the present invention, the temperature of the presentis separated from the water containing source of form water containing source of formaldehyde during separation is aldehyde. preferably 0 to 200° C., more preferably, 30 to 180° C., and 0072 Generally, the higher the Si/A1 molar ratio in a Zeo most preferably 50 to 150° C. lite composition, the more the water separation performance I0081. One example of pervaporation will be specifically tends to decrease. In comparison with Linde Type-A zeolite described using FIG. 1. (Si/Als1.0), T-type Zeolite (Si/Al=3.6) and a mordenite (Si/ I0082 FIG. 1 shows a separator 10 for separating water Al=5.1) have a lower water separation performance. The from the water containing source of formaldehyde using a Si: Al molar ratio ranges for the Zeolite membrane are prefer Zeolite membrane by pervaporation. The separator 10 of the ably between 1:1 and 10:1, more preferably between 1:1 and example includes a vessel 11 storing an water containing 9:1. source of formaldehyde, a zeolite membrane 12 provided in the vessel 11, and a thermometer 13, a thermostatic bath 14 0073. The Linde Type-A zeolite membrane can beformed for maintaining the constant temperature of the water con by precipitating Linde Type-A Zeolite crystals on the Surface taining source of formaldehyde in the vessel 11, a vacuum of a porous Support. pump 15 for reducing pressure inside the decompression line 0074 Examples of the porous support include ceramics 16 and the Zeolite membrane 12, a decompression line 16 Such as alumina, silica, Zirconia, silicon nitride, and silicon connecting the Zeolite membrane 12 to vacuum pump 15, a carbide, metals such as aluminum and stainless steel, and first collection device 17 and a second collection device 18 polymers such as polyethylene, polypropylene, and polytet provided in the decompression line 16 and a vacuum gauge rafluoroethylene. From the viewpoint of the separation per 19. formance of the membrane, inorganic compounds such as 0083. In the Zeolite membrane 12, one end is sealed and ceramics or metals are preferable. The shape of the porous the other end is connected to the decompression line 16 Support is not specifically limited, but a tube shape is prefer through a plug 12a such as a stainless steel tube. able. I0084 Examples of the thermometer 13 include a thermo 0075. A method where a Linde Type-A zeolite crystal is couple, or the like. precipitated on the Surface of a porous Support includes a 0085. A first collection device 17 and second collection method in which a Linde Type-A zeolite seed crystal is device 18 collect components (permeation solution) sepa applied on the surface of the support, followed by precipita rated from the water containing source of formaldehyde. tion by a synthesis method such as a hydrothermal synthesis These devices include Dewar flasks 17a and 18a, which store method or a vapor phase method, in the presence of a silica a refrigerant for cooling components which permeate a Zeo raw material (for example, Sodium silicate, silica gel, silica lite membrane 12 in a vapor state and pass through the first Sol, silica powder, or the like) and/or an alumina raw material and the second collection devices 17 and 18, and trapping (for example, sodium aluminate, aluminum hydroxide, or the tubes 17b and 18b for trapping the component (permeation like). The Linde Type-A zeolite can be in the form of its Solution) in a cooled liquid state or Solid state. Examples of sodium salt in which form it is usually synthesized or can be the refrigerant include liquid nitrogen. ion exchanged with Solutions of metal ions, for examples, I0086 Specific examples of the pervaporation using a sepa chloride or nitrate salts, particularly potassium or calcium rator 10 shown in FIG. 1 will be described. A case using the ions or mixtures of these with sodium ions. Preferably part of Linde Type-A zeolite membranes as a zeolite membrane 12 is the Sodium ions are ion exchanged with calcium ions to described below. produce the structure known as Linde Type-5A zeolite. Most I0087 First, the water containing source of formaldehyde preferably the Linde Type-A zeolite is in the 100% sodium is stored in a vessel 11. The temperature of the water contain form known as Linde Type-4A zeolite. ing source of formaldehyde in the vessel 11 is maintained by 0076 X-type and Y-type Zeolites are preferably in their thermostatic bath 14 so as to be constant. The temperature of Sodium forms or acid forms, more preferably, the sodium the water containing source of formaldehyde is preferably 50 forms. to 150° C. In the specific examples below it is 60° C. 0077 Chabazite type Zeolites may be preferably in the I0088 Separately, liquid nitrogen is stored in Dewar flasks form of acid, sodium, potassium, calcium or strontium, more 17a and 18a. preferably sodium, potassium or calcium. A commercially I0089. Then, a vacuum pump 15 operates to reduce the available product can be used as the Linde Type-A zeolite pressure of an inner portion of a decompression line 16 and membrane. the Zeolite membrane 12. Then, water in the water containing 0078. As mentioned above, a method of separating water source of formaldehyde permeates the Zeolite membrane 12 from a water containing source of formaldehyde using a in the form of vapor. The water vapor permeating the Zeolite Zeolite membrane includes pervaporation, or vapor perme membrane 12 is cooled by liquid nitrogen filled in the Dewar ation. From the viewpoint that the size of the device can be flask 17a in a first collection device 17 and collected by a trap reduced, pervaporation is preferable, whereas from the view tube 17b. point that consumption of heatenergy can be lowered without 0090 The second collection device 18 need not be pro being associated with phase transition, vapor permeation is vided. However, when the second collection device 18 is preferable. provided, in a case where water vapor is not collected by the US 2015/005361.6 A1 Feb. 26, 2015

first collection device 17, the water vapor passing there especially methyl or H. n is an integerpreferably from 1 to 10, through can be collected by the second collection device 18, more preferably 1 to 5, and especially 1 to 3. and thus infiltration of water into the vacuum pump 15 can be 0100 However, other sources of formaldehyde may be Suppressed. used including trioxane or trioxane containing sources. 0091. In order to realize efficient membrane separation, it 0101 Therefore, a suitable source of formaldehyde is necessary to provide a concentration difference in the water includes any equilibrium composition which may provide a at the Supply side and at the permeation side in respect to the source of formaldehyde. Examples of such includebut are not Zeolite membrane. As a specific device for providing a con restricted to dimethoxymethane, trioxane, polyoxymethyl centration difference, one providing a pressure difference enes R-O-(CH-O), R wherein R' and/or R are which is as large as possible between the permeation and alkyl groups or hydrogen, i=1 to 100, paraformaldehyde, Supply sides, or one flowing gas other than water so as not to formalin (formaldehyde, methanol, water) and other equilib retain water on the permeation side, can be exemplified. rium compositions such as a mixture of formaldehyde, 0092. For providing as large a pressure difference as pos methanol and methyl propanoate. sible, the Supply side may be pressurized, or the permeation 0102 Typically, the polyoxymethylenes are higher for side may be depressurized. In consideration of ease and per mals or hemiformals of formaldehyde and methanol CH meability, the pressure of the supply side is preferably 50 to O—(CH, O), CH (“formal-i') or CH, O (CH, O) 800 kPa, the pressure of the permeation side is preferably 15.0 H (“hemiformal-i'), wherein i=1 to 100, preferably i=1 to kPa or lower, the pressure of the supply side is more prefer 5, and especially i=1 to 3, or other polyoxymethylenes with at ably atmospheric pressure to 500 kPa, and the pressure of the least one non methyl terminal group. Therefore, the source of permeation side is more preferably 5.0 kPa or lower. formaldehyde may also be a polyoxymethylene of formula 0093. As the gas other than water so as not to retain water R'-O-(CH2-O-).R, where R and R may be the in the permeation side, in consideration of inertness not react same or different groups and at least one is selected from a ing with water and ease of availability, nitrogen or argon is C-C alkyl group, for instance R-isobutyl and preferable. R’=methyl. 0094. According to the aforementioned method, water can 0103 Preferably, the term formalin is a mixture of form be separated from the water containing source of formalde aldehyde:methanol: water in the ratio 25 to 65%:0.01 to 25%: hyde. The separated water is collected in a trapping tube 17b 25 to 70% by weight. More preferably, the term formalin is a of the first collection device 17. On the other hand, the dehy mixture of formaldehyde:methanol: water in the ratio 30 to drated source of formaldehyde is stored in a vessel 11. 60%:0.03 to 20%:35 to 60% by weight. Most preferably, the 0095. The aforementioned method permeates water into a term formalin is a mixture of formaldehyde:methanol: water Zeolite membrane 12, and separates the water from the water in the ratio 35 to 55%:0.05 to 18%:42 to 53% by weight. containing source of formaldehyde, however, the present Preferably, the mixture comprising formaldehyde, methanol invention is not limited thereto. For example, when kinds of and methyl propanoate contains less than 50% water by the Zeolite membrane 12 are changed, components other than weight. More preferably, the mixture comprising formalde water can be made to permeate the Zeolite membrane 12 and hyde, methanol and methyl propanoate contains less than separate from the water containing source of formaldehyde. 20% water by weight. Most preferably, the mixture compris In this case, the dehydrated source of formaldehyde is col ing formaldehyde, methanol and methyl propanoate contains lected in the trapping tube 17b of the first collection device 17 0.1 to 15% water by weight. as the permeation Solution and water may be retained as the 0104 Typically, the water containing source of formalde retentate. hyde is a formaldehyde Solution comprising formaldehyde, 0096. The term “a source of formaldehyde' is that free water and, optionally, methanol. It should be appreciated that formaldehyde may either form in situ from the source under the Source of formaldehyde may not contain water, for reaction conditions or that the source may act as the equiva instance where it is in the form of trioxane or free formalde lent of free formaldehyde under reaction conditions, for hyde, but water may be added by mixing this stream with a example it may form the same reactive intermediate as form second water containing source of formaldehyde and/or with aldehyde so that the equivalent reaction takes place. For the a water containing Source of the separation enhancer, Such as avoidance of doubt the source may itself be free formalde wet methyl propanoate. hyde. 0105. The dehydrated source of formaldehyde obtained by 0097. A suitable source of formaldehyde may be a com the process of the present invention, either as permeate or as retentate from which water has been removed as permeate, pound of formula (V), may be advantageously used as a raw material for producing (meth)acrylic acid alkyl ester. (V) 0106. A method of producing (meth)acrylic acid alkyl RSX X ester will be described below as an example. $).C R 6 0107 (Meth)acrylic acid alkyl ester may be obtained by iii. pi reacting carboxylic acid ester and formaldehyde in the pres ence of a catalyst in a vapor-phase condensation reaction. Therefore, it is possible to use a dehydrated source of form 0.098 wherein R and R are preferably independently aldehyde obtained by the present invention as raw material for selected from C-C hydrocarbons or H. X is O., n is an the reaction. Since water is sufficiently removed from the integer from 1 to 100, and m is 1. dehydrated source of formaldehyde, the undesirable intro 0099 Rand Rare independently selected from C-C, duction of water into the reaction system can be reduced. alkyl, alkenyl or aryl as defined herein, or H. more preferably Therefore, Suppression of the progression of the reaction and C-C alkyl, or H. most preferably C-C alkyl or H, and deterioration of the catalyst does not easily occur. US 2015/005361.6 A1 Feb. 26, 2015

0108 Examples of the catalyst for this vapor-phase con 0.120. The dehydrated source of formaldehyde obtained by densation reaction include base catalysts, specifically a cata dehydrating methanol and the water containing source of lyst where alkali metals such as potassium, rubidium, and formaldehyde contains methanol. cesium are Supported on carriers such as silica, alumina, I0121 Therefore, when the methanol-containing dehy Zirconia, hafnia and combinations thereof. drated Solution is used or methyl propanoate produced by a 0109. A suitable molar ratio of carboxylic acid ester to liquid-phase homogeneous reaction is added to the dehy formaldehyde in the vapor-phase condensation reaction is 1:1 drated Solution, the vapor-phase condensation reaction can be to 20:1. performed in the presence of methanol without separate addi 0110. The reaction temperature of the vapor-phase con tion of methanol in a reaction system. densation reaction is preferably 250 to 400° C. and the reac 0.122 The reaction product obtained by vapor-phase con tion pressure is preferably 1x10 to 1x10 Pa. densation reaction contains water in addition to (meth)acrylic 0111 Advantageously, when the dehydrated source of acid alkyl ester which is the desired product. In vapor-phase formaldehyde contains formaldehyde and carboxylic acid condensation reaction, carboxylic acid ester is used in large ester, and when the molar ratio in the dehydrated source of excess in comparison with formaldehyde, and therefore the formaldehyde is within the aforementioned ratio for the reaction product contains unreacted carboxylic acid ester. vapor-phase condensation reaction, lower levels of or no car Moreover, when vapor-phase condensation reaction is per boxylic acid ester raw material need be added during the formed in the presence of the alcohol, the reaction product reaction. When the ratio of carboxylic acid ester in the dehy contains the alcohol. drated solution is too low or absent, carboxylic acid ester is I0123. Therefore, (meth)acrylic acid alkyl ester should be added separately to the dehydrated solution to achieve the separated from the reaction product. necessary level and the Solution is Subjected to the vapor 0.124. A method for separating (meth)acrylic acid alkyl phase condensation reaction. ester from the reaction product is not specifically limited, and 0112. As the carboxylic acid ester added to the dehydrated for example the (meth)acrylic acid alkyl ester may be sepa source of formaldehyde, the carboxylic acid ester mentioned rated by distilling the reaction product. in the dehydration method of water containing source of formaldehyde can be exemplified. The carboxylic acid ester 0.125. On the other hand, the residue after separating added to the dehydrated source of formaldehyde is preferably (meth)acrylic acid alkyl ester from the reaction product con the same as the carboxylic acid ester added to the water tains unreacted carboxylic acid ester and water. Therefore, containing source in the dehydration of the water containing when carboxylic acid ester and water are separated from the source of formaldehyde. residue, carboxylic acid ester is recovered and recycled as a 0113. As the carboxylic acid ester added to the dehydrated reactant in the production of (meth)acrylic acid alkyl ester. Source of formaldehyde, a commercially available product or 0.126 The residue of the reaction product above can be a synthetic compound may be used. used as carboxylic acid ester added to water containing Source 0114. The synthesis method of carboxylic acid ester is not of formaldehyde in the aforementioned dehydration method specifically limited, but a synthesis method will be described of the present invention. Accordingly, dehydration of water by an example of methyl propanoate. containing source of formaldehyde and separation of water 0115 Ethylene and methanol are reacted with carbon from unreacted carboxylic acid ester can be performed at the monoxide in the presence of a catalyst to obtain methyl pro same time. panoate (liquid-phase homogeneous reaction). I0127. The dehydrated source of formaldehyde produced 0116 Examples of the catalysts include a precious metal when the residue of reaction product is added to the water complex catalyst, specifically a complex catalyst or the like containing source of formaldehyde and dehydrated, contains coordinating phosphine or the like to precious metal. unreacted carboxylic acid ester in addition to formaldehyde. 0117. A reaction temperature of liquid-phase homoge Therefore, when the dehydrated source of formaldehyde is neous reaction is preferably 10 to 150° C. used as raw material of (meth)acrylic acid alkyl ester, unre 0118. A vapor-phase condensation reaction produces acted carboxylic acid ester is reused. water in addition to (meth)acrylic acid alkyl ester which is I0128. The residue of reaction product is added to the water objective Substance by reacting carboxylic acid ester and containing source of formaldehyde and dehydrated and the formaldehyde. The (meth)acrylic acid alkyl ester is hydro resultant solution containing dehydrated formaldehyde is lyzed by water producing the alcohol appropriate to the start used as a raw material of (meth)acrylic acid alkyl ester. ing ester. Therefore, vapor-phase condensation reaction is Thereby, the dehydration method of the present invention can preferably performed in the presence of the appropriate alco be incorporated into a portion of a method for producing hol for Suppressing hydrolysis of (meth)acrylic acid alkyl (meth)acrylic acid alkyl ester, whereby production costs can ester. be reduced. 0119 When as the carboxylic acid ester, methyl pro I0129. As described above, according to the dehydration panoate produced by the aforementioned liquid-phase homo method of the present invention, water can be highly effi geneous reaction is added to the dehydrated source of form ciently separated from the water containing Source of form aldehyde and Subjected to vapor-phase condensation aldehyde. In particular, when a separation enhancer is added reaction, methanol is used in excess, in comparison with and dehydrated, the dehydration performance is excellent. In ethylene, and therefore the resultant methyl propanoate con this case, if the permeate is enriched in water then the reten tains unreacted methanol. Since the vapor-phase condensa tate is enriched, with respect to the separation enhancer and tion reaction is preferably performed in the presence of alco water containing Source of formaldehyde, in formaldehyde hol, the unreacted methanol need not be separated from and separation enhancer or if the retentate is enriched in water methyl propanoate, and may be provided in the vapor-phase then the permeate is enriched informaldehyde and separation condensation reaction in addition to methyl propanoate. enhancer. It is preferred that the permeate is enriched in water. US 2015/005361.6 A1 Feb. 26, 2015

0130. The dehydrated source of formaldehyde obtained by following molar ratios: SiO/Al2O=112, OH /SiO-0.77. the dehydration method of the present invention is preferable Na+/(Na++K+)=0.77, and HO/(Na++K+)=20.75. as a raw material of (meth)acrylic acid alkyl ester. In particu 0.139. Then a porous tubular support whose surface is pro lar, it is preferable when methyl methacrylate is produced vided with seed crystals of the T-type Zeolite is immersed in from methyl propanoate. Further, when the dehydrated the above reaction mixture. The support consisted of “Mul Source of formaldehyde is used as a raw material, the intro lite', had a length of 10 cm, an external diameter of 1.2 cm, a duction of water into the reaction system can be reduced, and thickness of 1.5 mm, a pore diameter of 1.3 um and a porosity therefore, progress of reaction is not easily Suppressed and the of 40%. The average size of seed crystals is 100 um. The catalyst is not easily deteriorated. quantity of seed crystals on the porous support is 30 mg/cm. The hydrothermal synthesis is carried out for 24 hours at 100° EXAMPLES C., followed by rinsing for 12 hours and drying at 70° C. 0131 Hereinafter, specific description will be given in regard to the present invention by giving examples. However, Preparative Example 3 the invention is not limited to these. 0140 CHA-type Zeolite membranes were prepared gener Preparative Example 1 ally by hydrothermal synthesis via a secondary growth 0132) The Linde Type-4A zeolite membranes were pre method on the outer Surface of a porous C-alumina Support. pared generally in accordance with the examples of For the avoidance of doubt, by “CHA-type Zeolite' we mean EP1930067. Specifically, seed crystals to assist uniform to refer to a zeolite having a CHA structure as defined by the membrane formation were formed on the Support. Linde International Zeolite Association (IZA) and is a zeolite hav Type-4A Zeolite fine particles (seed crystals, particle size: ing the same structure as naturally-occurring Chabazite. 100 nm) were placed in water and stirred to yield a suspension 0141 First, seed crystals were attached to a porous C.-alu with a concentration of 0.5% by weight. mina Support to assist uniform membrane formation. 0133. The sealed body was used for this example. Specifi 0142. The following was prepared as a reaction mixture cally, a tubular porous body made of C-alumina and having for hydrothermal synthesis in the seeding process. In a mix opening sections at both ends was prepared. The porous body ture containing 12.8 g of 1 mol/L-NaOH acqueous solution had a mean pore size of 1.3 um, an outer diameter of 12 mm, and 75 g of water, 0.8g of aluminum hydroxide (containing an inner diameter of 9 mm and a length of 10 cm. A sealing 53.5 wt % of Al-O, obtained from Aldrich) was added and member was tightly fitted in one opening section of the dissolved with stirring to make a transparent solution. porous body, and a sealing member penetrated by an open air Thereto, 10.8 g of an aqueous N.N.N-trimethyl-1-adaman conduit was tightly fitted in the other opening section. tanammonium hydroxide (TMADAOH) solution (containing 0134. The sealed body was immersed in the aforemen 25 wt % of TMADAOH, obtained from Sachem Inc.) was tioned suspension. The entire porous body was immersed in added as an organic template, and 19.2 g of colloidal silica the Suspension, and the tip of the open air conduit was not (Snowtex-40, obtained from Nissan Chemicals Industries, immersed in the Suspension. The sealed body was immersed Ltd.) was further added. This mixture was stirred for 3 hours. in the suspension for 3 minutes. The sealed body was then ACHA-type Zeolite seed crystal of about 0.5um was synthe drawn out at a rate of about 0.2 cm/s. The porous body sized hydrothermally at 160° C. for 2 days. A dip-coating obtained by removing the sealing members and from the technique was used for seeding. Specifically, an inorganic sealed body was dried for 2 hours in a thermostatic bath at 25° porous Support was dipped vertically into a flask containing C., and then dried for 16 hours in a thermostatic bath at 70° C. an aqueous Suspension of the CHA-type Zeolite crystals at a to produce a seed crystal-attached porous body. concentration of 1% by weight for a predetermined time. It 0135 Sodium silicate, aluminum hydroxide and distilled was then dried at 100° C. for about 5 hours producing a seed water were mixed to yield a reaction solution. 1 part by mole crystal-attached porous body. of alumina (Al2O), 2 parts by mole of silicon dioxide (SiO2) and 2 parts by mole of sodium oxide (NaO) were added to 0143. The following was prepared as a reaction mixture 150 parts by mole of water to yield a reaction solution. The for membrane hydrothermal synthesis. In a mixture contain seed crystal-attached porous body was immersed in the reac ing 10.5 g of 1 mol/L-NaOH adueous solution, 7.0 g of 1 tion solution and held at 80° C. for 3 hours to form a zeolite mol/L-KOHaqueous solution and 100.0 g of water, 0.88 g of membrane on the Surface of the seed crystal-attached porous aluminum hydroxide (containing 53.5 wt % of Al2O, body. obtained from Aldrich) was added and dissolved with stirring to make a transparent solution. Thereto, 2.95g of an aqueous 0136. The obtained Zeolite membrane was then cleaned N.N.N-trimethyl-1-adamantanammonium hydroxide with a brush. Further, it was immersed for 16 hours in warm water at 40°C. A Linde Type-4A zeolite membrane was thus (TMADAOH) solution (containing 25 wt % of TMADAOH, obtained. obtained from Sachem Inc.) was added as an organic tem plate, and 10.5 g of colloidal silica (Snowtex-40, obtained Preparative Example 2 from Nissan Chemicals Industries, Ltd.) was further added. This mixture was stirred for 2 hours. The support attached 0.137 The T-type Zeolite membranes were prepared gen with the seed crystal was dipped in the vertical direction in a erally inaccordance with the examples of U.S. Pat. No. 6,387. Teflon (registered trademark) made inner cylinder containing 269. the reaction mixture above and after tightly closing the auto 0138 Amorphous silica is introduced with stirring into an clave, heated at 160° C. for 48 hours under self-generated aqueous Solution comprising sodium aluminate, sodium pressure. The system was allowed to cool, and the Support hydroxide and potassium hydroxide and allowed to age for 48 Zeolite membrane composite was taken out of the reaction hours. The composition of the Solution corresponds to the mixture, washed and thendried at 120° C. for 5 hours or more. US 2015/005361.6 A1 Feb. 26, 2015

The membrane samples were calcined to remove the template (3) Separation Factor at a rate of 0.1-0.5°C/min. Higher temperatures of 450-500° C. were applied for >20 h. 0153. In the same manner as in the concentration of water in permeate (2) above, the concentration of water in the feed 0144. The molar ratio SiO/Al2O, of the zeolite mem Solution was obtained and the separation factor was calcu brane was measured by SEM-EDX and found to be 17. lated from the following expression (VII). In the expression Example 1 (VII), “X” is concentration of water in the feed solution% by mass, and “Y” is concentration of water in the permeate % (0145 Formaldehyde (HCHO), water (HO), methanol by mass. (MeOH), and methyl propanoate (MeP) were mixed so that Separation factor={Y7(100-Y)}/{X7(100-X)} (VII) the mass ratio (HCHO:HO:MeOH:MeP) was 10:9:11:70, to prepare a sample (feed solution). Water was separated from the feed solution in accordance with the following methods Example 2 by using a separator 10 shown in FIG. 1. 0154 Water was separated again by using the Zeolite 0146 A Linde Type-4A zeolite membrane (manufactured membrane used in example 1 from the feed solution in the in a manner of preparative example 1 above, effective mem same manner as in example 1. Then, the separation perfor brane area: 2.64x10 m) as the zeolite membrane 12, and mance in the repetitive use of the Zeolite membrane was the thermocouples as a thermometer 13 were provided in the evaluated. The results are shown in Table 1. vessel 11. One end of the Zeolite membrane 12 was sealed, and the other end was connected with the decompression line Example 3 16 through the plug 12a made of stainless-steel, then, the Zeolite membrane 12 and the vacuum pump 15 were con 0155 Water was separated from the feed solution in the nected by the decompression line 16. Moreover, the first same manner as in example 1, except using an aqueous solu collection device 17, the second collection device 18, and the tion (feed solution) prepared so that the mass ratio in the vacuum gauge 19 were provided at the middle of the decom aqueous solution (HCHO:HO:MeOH:MeP) became 10:9: pression line 16. 41:40. Then, the separation performance of the Zeolite mem 0147 500 ml of previously prepared feed solution was brane was evaluated. The results are shown in Table 1. stored in the vessel 11. Then, the temperature of the feed solution in the vessel 11 was controlled at the thermostatic Example 4 bath 14 so that the temperature was 60° C. 0156 Water was separated from the feed solution in the 0148. The liquid nitrogen was stored in the Dewar flasks same manner as in example 1, except using an aqueous solu 17a and 18a respectively. tion (feed solution) prepared so that the mass ratio in the 014.9 Then, the vacuum pump 15 was operated for 30 aqueous solution (HCHO:HO:MeOH:MeP) became 10:9: minutes, and pressure inside the decompression line 16 and 61:20. Then, the separation performance of the Zeolite mem the Zeolite membrane 12 was reduced so that pressure on the brane was evaluated. The results are shown in Table 1. permeation side became 3.0 kPa or less. Vapor that permeated the Zeolite membrane 12 was cooled in the first collection Example 5 device 17 with the liquid nitrogen with which Dewar flask17a was filled, and the permeation liquid was collected in a trap 0157 Water was separated from the feed solution in the tube 17b. same manner as in example 1, except using a T-type Zeolite 0150. The separation performance of the Zeolite mem membrane (manufactured in a manner of preparative example brane was evaluated to obtain the permeation flux, the con 2, effective membrane area: 2.64x10 m) as the zeolite centrations of water in the collected permeate and the sepa membrane, and using an aqueous Solution (feed solution) ration factor in accordance with the following methods. The prepared so that the mass ratio in the aqueous Solution results are shown in Table 1. (HCHO:HO:MeOH:MeP) became 10:9:41:40. Then, the separation performance of the Zeolite membrane was evalu (1) Permeation Flux ated. The results are shown in Table 1. 0151. The mass of the permeate that was collected in the Example 6 trap tube 17b after separation was measured, and the perme ation flux was calculated from the following expression (VI). 0158 Water was separated from the feed solution in the In the expression (VI), “w” is weight of permeate kg), “A” is same manner as in example 1, except methyl ethanoate the effective membrane area of the zeolite membrane m). (MeAc) instead of the MeP, and using an aqueous solution and “t is the permeation timeh. This permeation flux is an (feed solution) prepared so that the mass ratio in the aqueous index that shows the weight of permeate per unit area of the solution (HCHO:HO:MeOH:MeAc) became 10:9:41:40. membrane, and per unit time. Then, the separation performance of the Zeolite membrane was evaluated. The results are shown in Table 1. Permeation flux (kg/m’-h=w/(Axt) (VI) Example 7 (2) Concentration of Water in Permeate 0159 Water was separated from the feed solution in the 0152 The concentration of water in the permeate was same manner as in example 1, except using methyl methacry obtained by using a gas-chromatograph (detector: TCD late (MMA) instead of the MeP, and using an aqueous solu (Thermal Conductivity Detector), separation column: pora tion (feed solution) prepared so that the mass ratio in the pako) at the column temperature of 170° C. aqueous solution (HCHO:HO:MeOH:MMA) became 10:9: US 2015/005361.6 A1 Feb. 26, 2015 10

41:40. Then, the separation performance of the Zeolite mem tion (feed solution) prepared by mixing HCHO, HO and brane was evaluated. The results are shown in Table 1. MeOH so that the mass ratio (HCHO:HO:MeOH) became 10:9:81. Then, the separation performance of the Zeolite Example 8 membrane was evaluated. The results are shown in Table 1. 0160 Water was separated from the feed solution in the same manner as in example 1, except using an aqueous solu Example 14 tion (feed solution) prepared so that the mass ratio in the aqueous solution (HCHO:HO:MeOH:MeP) became 11:0.6: 0166 Water was separated from the feed solution in the 12:76.4. Then, the separation performance of the Zeolite same manner as in example 1, except using an aqueous solu membrane was evaluated. The results are shown in Table 1. tion (feed solution) prepared by mixing HCHO, HO, MeOH Example 9 and MeP so that the mass ratio (HCHO:HO:MeOH:MeP) became 6: 9:15:70. Then, the separation performance of the 0161 Water was separated from the feed solution in the Zeolite membrane was evaluated. The results are shown in same manner as in example 1, except using an aqueous solu Table 1. tion (feed solution) prepared so that the mass ratio in the aqueous solution (HCHO:HO:MeOH:MeP) became 11:3: 12:74. Then, the separation performance of the Zeolite mem Example 15 brane was evaluated. The results are shown in Table 1. 0.167 Water was separated from the feed solution in the Example 10 same manner as in example 14, except using an aqueous solution (feed solution) prepared by mixing HCHO, H.O. 0162 Water was separated from the feed solution in the MeOH and 1-pentanol so that the mass ratio (HCHO:HO: same manner as in example 1, except using an aqueous solu MeOH:1-Pentanol) became 6:9:15:70. Then, the separation tion (feed solution) prepared so that the mass ratio in the performance of the Zeolite membrane was evaluated. The aqueous solution (HCHO:HO:MeOH:MeP) became 10:6: results are shown in Table 1. 11:73. Then, the separation performance of the Zeolite mem brane was evaluated. The results are shown in Table 1. Example 16 Example 11 0168 Water was separated from the feed solution in the 0163 Water was separated from the feed solution in the same manner as in example 14, except using an aqueous same manner as in example 1, except the temperature of the solution (feed solution) prepared by mixing HCHO, H.O. feed solution was adjusted to 50° C. Then, the separation MeOH and 1,4-butanediol so that the mass ratio (HCHO: performance of the Zeolite membrane was evaluated. The HO:MeOH:1,4-Butanediol) became 6: 9:15:70. Then, the results are shown in Table 1. separation performance of the Zeolite membrane was evalu Example 12 ated. The results are shown in Table 1. 0164. Water was separated from the feed solution in the Example 17 same manner as in example 1, except the temperature of the feed solution was adjusted to 40° C. Then, the separation 0169. Water was separated from the feed solution in the performance of the Zeolite membrane was evaluated. The same manner as in example 14, except using an aqueous results are shown in Table 1. solution (feed solution) prepared by mixing HCHO, H.O. MeOH and glycerol (1,2,3-trihydroxypropane) so that the Example 13 mass ratio (HCHO:HO:MeOH:Glycerol) became 0.165 Water was separated from the feed solution in the 6:9:15:70. Then, the separation performance of the Zeolite same manner as in example 1, except using an aqueous solu membrane was evaluated. The results are shown in Table 1. TABLE 1

Feed solution Concentration

Concentration Permeation of water in the Zeolite Temperature of water flux permeate Separation membrane C. Composition % by mass kg/m2 x h % by mass factor Example 1 Linde 60 HCHO/HO/MeOH/MeP = 9.0 2.61 99.98 4OOOO Type-4A 10,9,11.70 Example 2 Linde 60 HCHO/HO/MeOH/MeP = 9.0 2.46 99.97 31 OOO Type-4A 10,9,11.70 Example 3 Linde 60 HCHO/HO/MeOH/MeP = 9.0 1.75 99.93 1SOOO Type-4A 109,41.f40 Example 4 Linde 60 HCHO/HO/MeOH/MeP = 9.0 1.45 99.8 SOOO Type-4A 10.9, 61.20 Example 5 T-type 60 HCHO/HO/MeOH/MeP = 9.0 O.21 98.68 760 109,41.f40 Example 6 Linde 60 HCHO/HO/MeOH/MeAc = 9.0 1.3 99.91 12OOO Type-4A 109,41.f40 US 2015/005361.6 A1 Feb. 26, 2015 11

TABLE 1-continued

Feed solution Concentration

Concentration Permeation of water in the Zeolite Temperature of water flux permeate Separation membrane C. Composition % by mass kg/m2 x h % by mass factor Example 7 Linde 60 HCHO/HO/MeOH/MMA = 9.0 1.65 99.93 14OOO Type-4A 09:41.f40 Example 8 Linde 60 HCHO/HO/MeOH/MeP = O.6 O.33 88.57 1300 Type-4A 10.6.12.76.4 Example 9 Linde 60 HCHO/HO/MeOH/MeP = 3.0 1.35 99.37 S100 Type-4A 1,3,12.74 Example 10 Linde 60 HCHO/HO/MeOH/MeP = 6.O 1.94 99.67 47OO Type-4A Of 6.11.73 Example 11 Linde 50 HCHO/HO/MeOH/MeP = 9.0 2.24 99.93 1SOOO Type-4A O.9.11.70 Example 12 Linde 40 HCHO/HO/MeOH/MeP = 9.0 1.77 99.88 8100 Type-4A O.9.11.70 Example 13 Linde 60 HCHO/HO/MeOH = 9.0 O.92 99.45 1800 Type-4A O.9,81 Example 14 Linde 60 HCHO/HO/MeOH/MeP = 9.0 2.44 99.98 SO663 Type-4A 69,1570 Example 15 Linde 60 HCHO/HO/MeOH/1- 9.0 2.1 99.95 20090 Type-4A bentano = 69.1570 Example 16 Linde 60 HCHO/HO/MeOH1,4- 9.0 1.11 99.86 7131 Type-4A butenediol = 69,1570 Example 17 Linde 60 HCHO/HO/MeOH/glycerol = 9.0 O.93 99.89 908O Type-4A 69,1570

0170 As is apparent from Table 1, in examples 1 to 13, gas tight seal. The effective area of the exposed 36 mm mem water was able to be separated from the feed solution (an brane length was 1.36x10 m. aqueous solution of formaldehyde) efficiently, and the dehy 0.175. The apparatus was located in an air circulation oven dration performance was excellent. Particularly, the values (not shown). Thermally equilibrated feed solution was for the permeation flux and the separation factor in the pumped over the CHA-type Zeolite membrane at 1.5 ml/min examples 1 to 4, 6, 7, 11, 12, 14 and 15 in which dehydration and 110°C. (3 barg pressure) through the side arm 23. The was performed using the Linde Type-4A Zeolite membrane feed solution passed upwards over the Zeolite membrane Sur with containing the separation enhancer in the aqueous solu face before exiting through flanged outlet 25a. A vacuum of tion, were higher and the separation performance (dehydra 3.0. kPa was applied to the outlet 25b at the base of the tion performance) was improved compared to the example 13 stainless steel housing 21 to enable components passing in which dehydration was performed using the Linde Type through the walls of the membrane 20 (permeate) to be 4A Zeolite membrane without containing the separation removed out of the apparatus. Permeate liquid was collected enhancer in the aqueous solution. into a permeate collection vessel (not shown) and non-per 0171 Moreover, it is confirmed from the results of meate liquid was collected in a non-permeate collection ves examples 1 and 2 that the separation performance is main sel (not shown). Liquids in the collection vessels were tained excellently even though the Zeolite membrane is used sampled for analysis. The separation performance of the Zeo again. lite membrane was evaluated using analytical methods iden 0172. Therefore, it is especially preferable to apply the tical to those described in example 1. present invention to the process for the production of (meth) (0176) The feed to be dehydrated by the CHA-type Zeolite acrylic acid alkyl ester comprising reacting carboxylic acid membrane is given in Table 2. ester with formaldehyde in the presence of a catalyst, wherein a dehydrated Source of formaldehyde is used as a raw material TABLE 2 for the above reaction. Components in Feed Wt 9% Water 10.2 Example 18 Formaldehyde 4.9 Methanol 15.7 (0173 A feed solution having a HCHO/HO/MeOH/MeP Formal 1 O.23 mass ratio of 5:10:16:66 was fed continuously. Water was Isobutyraldehyde 0.27 Methacrolein O.21 separated from the feed solution in accordance with the fol Methyl propanoate 66.23 lowing method, using a separator as shown in FIG. 2. Methyl isobutyrate 0.77 0.174. A 400 mm CHA-type Zeolite membrane 20 (manu Methyl methacrylate 1.31 factured in a manner of preparative example 3 above.) was Others O.18 housed in a stainless steel housing 21. The top of the mem brane which is porous alpha-alumina Support was plugged 0177. The feed composition was fed continuously for 300 with a solid stainless steel cylinder 22 and sealed. The bottom hours and samples of the permeate and non-permeate liquid of the tube, below the side arm 23, was attached to a hollow were collected periodically for analysis. The water content of metal screw-threaded plug 24 and sealed to make a process the non-permeate was measured as 3.0%+/-0.1% throughout US 2015/005361.6 A1 Feb. 26, 2015

the 300 hours. The permeate contained 90% water and 10% 5. The method for dehydrating the water containing source methanol with all other components in Table 2 being below of formaldehyde according to claim 1, wherein the separation their detection limits (typically 10 ppm). enhancer is carboxylic acid ester. 0.178 The separation factor, for water with respect to 6. The method for dehydrating the water containing source organics between the feed and the permeate as defined in of formaldehyde according to claim 5, wherein the carboxylic (VII) is 79.2. acid ester is selected from methyl methacrylate, methyl acry 0179 The methanol and water in the permeate can easily late, methylpropanoate, ethyl ethanoate or methyl ethanoate. be separated by a conventional distillation. The level of water 7. The method for dehydrating the water containing source in the non-permeate can easily be reduced by increasing the of formaldehyde according to claim 6, wherein the carboxylic contact time and linear Velocity of the solution in contact with acid ester is methyl propanoate. the membrane. 8. The method for dehydrating the water containing source INDUSTRIALAVAILABILITY of formaldehyde according to claim 1, wherein the Zeolite membrane is a Linde Type-A or chabazite Zeolite membrane. 0180. The present invention can provide a method for 9. The method for dehydrating the water containing source dehydration of the water containing source of formaldehyde of formaldehyde according to claim 7, wherein the Zeolite having an excellent dehydration performance and a method membrane is a Linde Type-4A or chabazite Zeolite mem for producing (meth)acrylic acid alkyl ester by using a dehy brane. drated source of formaldehyde obtained by such dehydration. 10. The method for dehydrating the water containing REFERENCE SIGNS LIST Source of formaldehyde according to claim 1, the concentra tion of water in the water containing source of formaldehyde 0181 10: separator is at least 0.5% by mass based on 100% by mass of the water 0182) 11: vessel containing source of formaldehyde. 0183) 12: Zeolite membrane 11. A method for producing an ethylenically unsaturated 0184 12a: plug carboxylic ester comprising: 0185. 13: thermometer 0186 14: thermostatic bath contacting a dehydrated Source of formaldehyde with a 0187 15: vacuum pump carboxylic acid ester in the presence of a catalyst, 0188 16: decompression line wherein the dehydrated source of formaldehyde is (0189 17: first collection device obtained by contacting a water containing Source of 0.190) 18: second collection device formaldehyde with a Zeolite membrane and separating at (0191 17a, 18a: Dewar flask least part of the water from the water containing Source (0192 17b, 18b: trap tube of formaldehyde to produce the said dehydrated source 0.193) 19: Vacuum gauge of formaldehyde. (0194 20: CHA-type Zeolite membrane 12. The method for producing an ethylenically unsaturated 0.195 21: stainless steel housing carboxylic ester according to claim 11, wherein the water 0196) 22: stainless steel tube over porous C.-alumina Sup containing Source of formaldehyde further comprises a sepa port ration enhancer having a static permittivity of between 2.5 0197) 23: side arm and 20 at 20° C. and atmospheric pressure. 0198 24: screw-threaded plug (0199 25a, 25b: flanged outlets 13. The method for producing an ethylenically unsaturated 1. A method for dehydrating a water containing Source of carboxylic acid ester according to claim 12 comprising: formaldehyde comprising: combining a water containing Source of the separation contacting the water containing source of formaldehyde enhancer with the water containing source of formalde with a Zeolite membrane, and hyde to produce a combined source, and separating at least part of the water from the water contain dehydrating the combined source to provide a dehydrated ing source of formaldehyde to produce a dehydrated Source of formaldehyde which contains the separation source of formaldehyde, wherein: enhancer. the water containing source of formaldehyde comprises a separation enhancer having a static permittivity of 14. The method for producing an ethylenically unsaturated between 2.5 and 20 at 20° C. and atmospheric pressure carboxylic acid ester according to claim 12, wherein the and separation enhancer is carboxylic acid ester. the water containing source of formaldehyde comprises 15. The method for producing an ethylenically unsaturated methanol. carboxylic acid ester according to claim 11, wherein the water 2. The method for dehydrating the water containing source containing Source of formaldehyde further comprises metha of formaldehyde according to claim 1, wherein the separating nol. step consists of Zeolite membrane pervaporation or Zeolite 16. The method for producing an ethylenically unsaturated membrane vapor permeation. carboxylic acid ester according to claim 13, wherein the water 3. The method for dehydrating the water containing source containing source of the separation enhancer further com of formaldehyde according to claim 2, wherein water is sepa prises methanol in addition to the separation enhancer. rated from the water containing source of formaldehyde by Zeolite membrane vapor permeation. 17. The method for producing an ethylenically unsaturated 4. The method for dehydrating the water containing source carboxylic acid ester according to claim 11, wherein the of formaldehyde according to claim 1, wherein the separated ethylenically unsaturated acid ester is selected from the group water is a permeate and consisting of methyl methacrylate and methyl acrylate. the dehydrated source of formaldehyde is a retentate. k k k k k