Alkylation of Aromatic Substrates and Transalkylation Process

(19) & (11) EP 2 110 368 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 21.10.2009 Bulletin 2009/43 C07C 2/66 (2006.01) C07C 6/12 (2006.01) C07C 15/073 (2006.01) C07C 15/02 (2006.01) (21) Application number: 08290392.3 (22) Date of filing: 18.04.2008 (84) Designated Contracting States: (72) Inventor: Cary, Jean-Bernard AT BE BG CH CY CZ DE DK EE ES FI FR GB GR 76600 Le Havre (FR) HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR (74) Representative: Neel, Henry et al Designated Extension States: Total Petrochemicals Research Feluy AL BA MK RS Zone Industrielle C 7181 Seneffe (Feluy) (BE) (71) Applicant: Total Petrochemicals France 92047 Paris La Défense Cedex (FR) (54) Alkylation of aromatic substrates and transalkylation process (57) The present invention relates to a process for embodiment of the alkylation process the aromatic sub- the alkylation of an aromatic substrate and to a process strate is benzene and the alkylating agent in ethylene. In for the transalkylation of polyalkylated aromatic compo- an advantageous embodiment of the transalkylation nents, wherein the nitrogen containing compounds im- process the aromatic substrate is benzene and the poly- purities in the aromatic substrate feedstock and/or the alkylated aromatic component is diethylbenzene. alkylating agent feedstock are monitored in a range 15 wppb-35 wppm by dry colorimetry. In an advantageous EP 368 2 110 A1 Printed by Jouve, 75001 PARIS (FR) 1 EP 2 110 368 A1 2 Description verting essentially all olefinic compounds contained therein by hydrogenation; [Field of the invention] (c) contacting the thus treated aromatic-rich stream from (b) with an olefin-containing stream comprising [0001] The present invention relates to the alkylation 5 at least one olefin selected from the group consisting of aromatic substrates and related transalkylation proc- of ethylene, propylene, and butylene, wherein the ess. The alkylation of aromatic substrates such as ben- molar ratio of the olefin(s) to said aromatic hydrocar- zene to produce alkylated aromatics such as ethylben- bon is not less than 1 in the presence of a catalyst zene and diethylbenzene are known in the art. More pre- comprising zeolite beta, under alkylation conditions, cisely the invention relates to the monitoring of the nitro- 10 whereby mono and polyalkylated aromatics are gen containing compounds impurities in the aromatic formed; and substrate feedstock and/or in the alkylating agent feed- (d) separating said mono and polyalkylated aromat- stock. The transalkylation of polyalkylated aromatics ics formed in (c) from the remaining hydrocarbons. such as diethylbenzene with an aromatic substrate such as benzene to produce alkylated aromatics such as ethyl- 15 [0004] At col 6 lines 48-53 is mentioned that the olefins benzene is known in the art. The present invention also may be present in admixture with hydrogen, methane, relates to the monitoring of the nitrogen containing com- C2 to C4 paraffins, but it is usually preferable to remove pounds impurities in the aromatic substrate feedstock of dienes, acetylenes, sulfur compounds or basic nitrogen said transalkylation process. compounds (NH3 or amines) which may be present in 20 the olefin feedstock stream, to prevent rapid catalyst de- [Background of the invention] activation. [0005] US 6 617 482 describes a process for removing [0002] Alkylation and transalkylation processes using polar compounds from an aromatic feedstock which con- catalysts are often subject to catalyst regeneration and tains polar compounds and which is then used in an replacement requirements resulting from poisoning of 25 alkylation process. The process comprises contacting the catalyst by one or more impurities contained in the the feedstock in an adsorption zone at a temperature of hydrocarbon feedstock. In many cases, catalyst devel- less than or equal to 130°C with an adsorbent selective opments, e.g. to reduce coke-forming and other by-prod- for the adsorption of said polar compounds and compris- uct reactions, have progressed to the stage where poi- ing a molecular sieve having pores and/or surface cavi- soning by feedstock impurities is the primary reason that 30 ties with cross-sectional dimensions greater than 5.6 catalyst performance deteriorates which forces the cat- Angstroms. A treated feedstock substantially free of said alyst to be replaced or regenerated. Aromatics alkylation polar compounds is withdrawn from the adsorption zone processes employing molecular sieve catalysts can be and fed to an alkylation zone for contact under liquid conducted in either the vapor phase or the liquid phase. phase alkylation conditions with an alkylating agent in However, in view of the improved selectivity and de- 35 the presence of an alkylation catalyst. More particularly, creased capital and operating costs associated with liq- this prior art relates to a liquid phase aromatics alkylation uid phase operation, most commercial alkylation proc- process which includes subjecting the aromatic feed- esses now operate under at least partial liquid phase stock to a pretreatement step for the selective removal conditions. Unfortunately, one disadvantage of operating of polar contaminants that poison aromatic alkylation cat- under liquid phase conditions is that the molecular sieve 40 alysts. Such contaminants include nitrogen, sulfur, and catalysts tend to be more sensitive to the presence of oxygen containing compounds, particularly those that impurities in the feedstocks, particularly polar com- boil in the same ranges as benzene, toluene or xylenes. pounds such as nitrogen compounds. Such impurities [0006] US 2005 0143612 describes a process for the reduce the acid activity of the catalyst and hence de- production of alkyl aromatic compounds wherein aromat- crease the cycle time between required regenerations of 45 ic compounds which may be treated for removal of del- the catalyst. Various processes have been developed for eterious substances are reacted with olefin compounds, removal of such impurities prior to contact with the cat- which may also be treated for contaminant removal, in alyst. In the following prior arts there are description of the presence of acidic zeolite catalyst(s) to produce the said impurities as well as processes to remove these desired alkyl aromatic compound(s). The aromatic and impurities. 50 preferably also the olefin feeds are treated substantially [0003] US 6 002 057 describes a process for the alkyla- to remove contaminants, particularly the nitrogen com- tion of an aromatic hydrocarbon contained in a hydrocar- pounds contained therein, before they are brought to- bon stream comprising: gether for reaction in the presence of the zeolite catalyst (s). The feed pretreatment for removal of nitrogen com- (a) separating essentially all aromatics other than 55 pounds significantly improves the run length and life of said aromatic hydrocarbon from said hydrocarbon the acidic zeolite catalyst(s). A specific object of this prior stream, thereby forming an aromatic-rich stream; art is to provide methods and apparatus for treating an (b) treating said aromatic-rich stream of (a) by con- olefin or aromatic feedstock for removal of organic or 2 3 EP 2 110 368 A1 4 inorganic nitrogen compounds in preparation for a cata- sponse in time, many such apparatus can be used in lytic alkylation or transalkylation process. In accordance parallel and a measurement is launched e.g. every with said prior art, it has been found that nitrogen-con- minute or every ten seconds. Should the impurities are taining impurities in one or both feedstocks may neutral- found to be higher than a requested level the reactor ize the acidic active sites on the acidic zeolite catalyst 5 containing the catalyst can be temporarily by-passed. and thereby reduce catalyst activity and its ability to effect the desired reaction. Long-term accumulation of these [Brief summary of the invention] nitrogen-containing impurities on the catalyst gradually reduces catalyst activity to the point where plant perform- [0010] The present invention is a process for the ance becomes unacceptable, requiring that the plant be 10 alkylation of an aromatic substrate comprising: shutdown to reactivate, regenerate, or replace the catalyst. (a) providing an alkylation reaction zone containing [0007] US 7199275 relates to a process for alkylation an alkylation catalyst; of an aromatic hydrocarbon stream comprising impurities (b) introducing a feedstock comprising an aromatic in which said impurities are removed in a pretreatment 15 substrate and an alkylating agent into the inlet of said system having a first stage, a second stage located down- alkylation reaction zone and into contact with said stream of said first stage and a cycle length, said process alkylation catalyst; comprising the steps of: (c) operating said alkylation reaction zone at temperature and pressure conditions to cause alkylation (a) contacting the aromatic hydrocarbon stream with 20 of said aromatic substrate in the presence of said a first molecular sieve which is 13X in said first stage alkylation catalyst to produce an alkylation product of said pretreatment system, to remove at least a comprising a mixture of said aromatic substrate and portion of said impurities, to produce a partially treat- monoalkylated and polyalkylated aromatic compo- ed aromatic hydrocarbon stream; nents; (b) contacting said partially treated aromatic hydro- 25 (d) withdrawing the alkylation product from said carbon stream with a second molecular sieve which alkylation reaction zone; wherein is 4A in a second stage of said pretreatment system to remove substantially all of the remaining portion the nitrogen containing compounds impurities in the ar- of said impurities, and to produce a fully treated aromatic substrate or in the alkylating agent or both in the omatic hydrocarbon stream; and 30 aromatic substrate and in the alkylating agent are mon- (c) contacting said fully treated aromatic hydrocar- itored in a range 15 wppb-35 wppm by dry colorimetry.

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