Europaisches Patentamt 0 361 755 J) European Patent Office © Publication number: A2 Office europeen des brevets ® EUROPEAN PATENT APPLICATION © Application number: 89309487.0 © Int. CIA C07C 37/08 0 Date of filing: 19.09.89 © Priority: 30.09.88 JP 246658/88 © Applicant: MITSUI PETROCHEMICAL INDUSTRIES, LTD. © Date of publication of application: 2-5, Kasumigaseki 3-chome Chiyoda-ku 04.04.90 Bulletin 90/14 Tokyo 100(JP) © Designated Contracting States: @ Inventor: Fukuhara, Hiroshi AT BE CH DE ES FR GB GR IT LI LU NL SE c/o MITSUI PETROCHEMICAL INDUSTRIES LIMITED 3, Chigusakaigan Ichihara-shi Chiba(JP) Inventor: Matsunaga, Fujihisa c/o MITSUI PETROCHEMICAL INDUSTRIES LIMITED 3, Chigusakaigan Ichihara-shi Chiba(JP) © Representative: Myerscough, Philip Boyd et al J.A.Kemp & Co. 14, South Square Gray's Inn- London, WC1R 5EU(GB) © Phenol preparation process and propylene recovery therefrom. © Phenol is produced by (a) reacting benzene with propylene to synthesize cumene, (b) oxidizing the cumene of step (a) into cumene hydroperoxide, (c) acid cleaving cumene hydroperoxide into phenol and acetone, (d) hydrogenating the acetone of step (c) into isopropanoi and (e) dehydrating the isopropanol of step (d) into propylene. The propylene from step (e) is useful by itself or is recycled from the step (e) to step (a) of the phenol producing process. CM < in CO CO QL LU Xerox Copy Centre 1 EP 0 361 755 A2 2 Phenol Preparation Process and Propylene Recovery Therefrom BACKGROUND OF THE INVENTION duced is unbalanced relative to their commercial demands, one for less demand is produced largely in vain. This invention relates to the preparation of phe- As is known in the art, acetone is available in nol, and more particularly to a phenol preparing 5 surplus for these years. Thus the production of process which can recover propylene from the acetone by-product is now considered as a serious acetone by-product and recycle the recovered pro- drawback of the cumene process. Although ac- pylene as the starting material. etone has found the majority of its application as a It is well known in the art to react benzene with starting material for preparing methyl methacrylate, propylene to produce cumene, to oxidize cumene 70 the demand, for acetone is decreasing because of to produce cumene hydroperoxide, and to acid a switch of the starting material for preparing meth- cleavage cumene hydroperoxide into phenol and yl methacrylate to another. acetone. A conventional phenol preparing process Under the circumstances, there is a need for having these steps combined is generally known as the development of a phenol preparing process the cumene process. rs which is devoid of production of acetone and other It is also an old well-known technique to hy- by-products. Although several proposals have been drogenate acetone into isopropanol. This technique made, there is available no process capable of is still widely used at present for the assay of the preparing phenol in satisfactory yields. catalytic activity of a hydrogenating catalyst and In addition, impurities in propylene often cause other purposes. For example, the activity of Raney 20 a drawback during the preparing step of cumene nickel catalysts is often examined by comparing from benzene and propylene in the cumene pro- their acetone hydrogenating ability. Several ad- cess for the preparation of phenol. That is, pro- vanced processes have been proposed as dis- pylene for use in the cumene preparation is manu- closed in Japanese Patent Application Kokai Nos. factured generally using crude oil as the starting 12729/1987 and 77338/1987. 25 material. Crude oil, however, contains sulfur com- Nevertheless, insofar as the inventors know, it pounds and various heavy metals, and these impu- has never been proposed to produce isopropanol rities are sometimes carried in propylene as trace from the acetone by-product resulting from prep- contaminants, during its manufacturing process. For aration of phenol by the cumene process, and to example, carbonyl sulfide (COS) as a sulfur com- dehydrate the isopropanol into propylene. 30 pound or As as a heavy metal contaminant in There are known some analogous processes, propylene inhibits function of a catalyst (aluminum for example, to produce ethylene from ethanoi and chloride-HCI complex) for use in the cumene prep- to produce isobutylene from tert.-butanol. However, aration, thus disturbing normal progress of the these olefin producing processes cannot be applied cumene synthesis. Therefore, a strict purification of to the production of propylene from isopropanol for 35 . process is perproduced to avoid contamination the following reason. Since propylene is substan- propylene with these impurities. Types and quan- tially different in reactivity from ethylene or tity of these contaminants, however, vary depend- isobutylene, those skilled in the art cannot presume ing on not only the crude oil source but also the the dehydration of isopropanol from either the con- difference in the process conditions for the prep- ditions for synthesis of ethylene from ethanoi or the 40 aration of propylene from crude oil. Such irregular- conditions for synthesis of isobutylene from tert.- ity burdens the propylene purification process with butanol. exceptionally complex and severe steps. As to the reuse of the acetone which is by- In consequence, a process for the preparation produced in the cumene process, for example, by of propylene with highly stable purity containing no its conversion into propylene, no useful proposals 45 such impurities has been expected to be estab- have been made. lished, for the purpose of reducing the extreme The phenol preparing process generally known burden of steps in the propylene purification pro- as the cumene process is characterized by the cess. production of acetone by-product, which is ad- vantageous from some aspects, but disadvanta- 50 geous from other aspects. More particularly, it is an SUMMARY OF THE INVENTION advantage in that simultaneous production of two products in a single preparation unit is more effi- cient than individual production in separate units. In Therefore, an object of the invention is to pro- turn, if the proportion of phenol and acetone pro- vide a novel and improved process for preparing 3 =P 0 361 755 A2 phenol in commercially satisfactory yields without nol can be produced from benzene, oxygen, and producing by-products. hydrogen using a hydrocarbon having 3 carbon The outstanding problem of the cumene pro- atoms as an interlocking element. cess is the production of large amounts of acetone by-product, but not the low percent yield of phenol ; produced. To overcome the problem, the inventors DETAILED DESCRIPTION OF THE INVENTION have developed a process capable of converting the acetone by-product into propylene, that is, a process capable of obtaining propylene upon prep- In the practice of the invention, steps (a), (b), aration of phenol. By incorporating this process into 10 and (c) may be in accord with the conventional the phenol preparing process, the inventors have well-known cumene process. reached a process for preparing phenol without One typical example of the cumene process producing acetone by-product. will be described. Moreover, the propylene preparation obtained by dehydrating isopropanol which has been con- 75 verted from acetone by means of hydrogenation (a) Step of reacting benzene with propylene to does not contain any of the above-cited sulfur synthesize cumene compounds and heavy metals. Purity of the pro- pylene, therefore, is high enough to be used as the Benzene is reacted with propylene in the pres- raw material for cumene synthesis. Such a high 20 ence of a catalyst such as aluminum chloride com- purity renders possible reduction of the burden of plex. The aluminum chloride complex is prepared steps in the propylene purification process to a by causing aluminum chloride to absorb gaseous high degree and, in consequence, sharp industrial hydrogen chloride in a solvent such as cumene. rationalization of the cumene preparation process. The molar ratio of benzene to propylene is The above and other objects can be achieved 25 preferably in the range of from 1/1 to 10/1, more according to the present invention by cooperatively preferably from 1.2/1 to 6/1. The catalyst or alu- combining the following steps. minum chloride complex is preferably present in an According to a first aspect of the invention, amount of about 0.01 to 5% by weight, more there is provided a process for preparing phenol, preferably about 0.1 to 1% by weight of aluminum comprising the steps of: 30 chloride based on the reactants. For this reaction, (a) reacting benzene with propylene to syn- hydrogen chloride gas may be co-present in the thesize cumene, reaction system in order to stabilize the complex (b) oxidizing the cumene of step (a) to con- catalyst. vert it into cumene hydroperoxide, The alkylation to produce cumene preferably (c) acid cleaving cumene hydroperoxide into 35 takes place at a temperature of from 30 to 200° C, phenol and acetone, more preferably 60 to 160°C under a pressure of (d) hydrogenating the acetone of step (c) to from atmospheric pressure to 15 kg-f/cm2. The convert it into isopropanol, reaction may be carried out in a batchwise, con- (e) dehydrating the isopropanol of step (d) tinuous, or semi-batchwise manner. into propylene, and 40 The alkylation partially yields higher alkylated (f) recycling the propylene of step (e) to step by-products in addition to the end product or (a). cumene. The reaction mixture resulting from al- According to a second aspect of the invention, kylation is thus subject to distillation to separate there is provided a process for recovering pro- the mixture into unreacted benzene, cumene, and pylene from the acetone by-product produced 45 higher alkylated products.