Process for processing polyalkyl aromatic hydrocarbons

Abstract

The present invention relates to a process for treating a mixture containing polyalkylaromatic hydrocarbons for the purpose of a transalkylation process, which comprises a mild reduction with hydrogen in the presence of a suitable hydrogenation catalyst. The present invention also relates to a process for the transalkylation of polyalkylaromatic hydrocarbons comprising said treatment.

Description

Technical Field

[0001] The present invention relates to an improved process for treating polyalkyl aromatic hydrocarbons.

[0002] In particular, the present invention relates to a process for treating mixtures containing polyalkyl aromatic hydrocarbons derived from the alkylation of benzene or other aromatic compounds with an alcohol or an olefin (more specifically with an alcohol) in the presence of an acid catalyst (preferably an acid catalyst containing zeolite).

[0003] Methods for synthesizing alkyl aromatic hydrocarbons by alkylation of aromatic compounds in the presence of an acid catalyst are well known and are widely used industrially, for example, for obtaining styrene and phenol and subsequently, among other compounds, for producing basic organic intermediates such as ethylbenzene and cumene which are starting materials for obtaining polymers such as polystyrene and polycarbonate and alkyl derivatives of naphthalene. The process uses an olefin, an alcohol or a mixture thereof as the alkylating compound.

[0004] Although the selectivity of the alkylation reaction has been optimized, it is also known that at least a part of the aromatic reactants in the alkylation reaction undergoes two or more alkylation steps, usually producing undesired polyalkylated aromatic compounds. The undesired products are subsequently separated from the monoalkylated products and heavy by-products, usually by distillation, and reacted with a further non-alkylated aromatic reagent in the presence of an acid catalyst to form further monoalkylated products by means of the well-known transalkylation reaction.

[0005] The state of the art of the transalkylation reaction is important for polyalkylates derived from alkylation with olefins, but nothing has been found in particular for polyalkylates derived from alkylation with alcohols. The state of the art tends not to distinguish the origin of the polyalkylates.

[0006] Published European Patent Application EP1069100 (in the name of the applicant) describes an alkylation process of benzene with propylene and isopropanol (IPA), where the water content of the liquid-phase reaction mixture must be less than 8000 ppm. In fact, it has been highlighted that at high concentrations of water in the liquid phase exceeding 8000 ppm, the catalyst is rapidly deactivated when using a beta-zeolite catalyst. The aforementioned drawback can be mitigated by increasing the benzene / IPA ratio, or by increasing the olefin / alcohol ratio in the alkylation mixture at the same ratio, thereby reducing the water content in the liquid phase and the ability to reuse the IPA. Finally, by recycling a portion of the reaction effluent benzene, or by operating with a mixed phase of water in the gas phase, at least partially. However, in this case, the operating window is limited.

[0007] US2011 / 218366 (in the name of the present applicant) claims the use of a ZSM-12 zeolite catalyst in a gas-phase alkylation process for the production of cumene, which enables operation even at benzene / IPA ratios of 2 or less without showing signs of catalyst deactivation. On the other hand, a drawback of its reaction in the gas phase is the significant formation of diisopropylbenzene and triisopropylbenzene, which require expensive transalkylation with benzene to recover cumene. In fact, the patent claims a selectivity of 82% for cumene and a selectivity of 98.8% for the recoverable products (cumene, diisopropylbenzene, triisopropylbenzene)

[0081] . This means that 16.8% of the products are sent for transalkylation. In particular, a specific formation of 147 g of diisopropylbenzene per 1 kg of cumene is obtained in the gas phase (190°C, 8 bar, benzene / IPA 3.25 mol / mol).

[0008] U.S. Patent No. 9096488 describes a process for alkylating benzene with IPA under trickle-flow conditions. These conditions ensure that the catalyst (always based on ZSM-12 zeolite) remains active even at a benzene / IPA ratio of 2.4. These conditions also favor a low molar ratio of diisopropylbenzene / cumene in the product exiting the reactor. At 190°C, with 13 bar and a benzene / PAH ratio of 3.25, 92% selectivity for cumene is obtained, yielding 51.7 g of diisopropylbenzene per kg of cumene produced. n-propylbenzene is present at 570 ppm relative to the formed cumene. In any case, it should be noted that trickle-flow conditions are achieved through significant recycling, resulting in higher energy costs compared to the first two options, which emphasize the elimination of the need for recycling.

[0009] As is well known, one advantage of using IPA to produce cumene by substituting all or part of propylene in a benzene alkylation reaction is that acetone produced in the phenol manufacturing process can be reduced to IPA and subsequently recycled for the alkylation reaction, thus allowing for the reuse of acetone. However, despite each of the three alkylation options having several technical advantages, they often come with the typical drawbacks of the approach used, in particular, that all of them produce to some extent polyalkylated aromatic products that make up the transalkylation section required downstream of the alkylation section. This is to recover the maximum possible amount of monoalkyl aromatic compound from the polyalkyl aromatic compound obtained in the alkylation section.

[0010] Transalkylation processes are fundamentally industrially important for optimizing the alkylation processes of aromatic compounds, particularly those aimed at producing monoalkyl aromatics.

[0011] The latest technologies for optimizing transalkylation reactions, particularly the optimization of polyethylbenzene for obtaining ethylbenzene and polyisopropylbenzene for obtaining cumene, are important and essentially cover the optimization of catalysts, operating conditions, and the use of absorbents for purifying the starting materials. The objective is to maximize the performance and stability of the catalytic system.

[0012] While the latest technologies for transalkylation reactions are important for polyalkylates resulting from olefin-based alkylation, there are few, if any, specific examples for polyalkylates resulting from alcohol-based alkylation. The latest technologies, especially recent ones, tend not to distinguish the origin of the polyalkylate and include both olefinic alkylating agents and alcohols.

[0013] The main alkylation and transalkylation processes are described by C. Perego et al., "Combining alkylation and transalkylation for alkylaromatic production," Green Chem., 2004(6), 274-279. Furthermore, it has been pointed out that reducing acetone to isopropanol and then using acetone for the alkylation of benzene constitutes a possible approach for obtaining cumene.

[0014] International Publication No. 2006 / 107452 claims a process for the transalkylation of aromatics, particularly polyisopropylbenzene (PIPB) and polyethylbenzene (PEB), without distinguishing the origin of the polyalkylates, and in fact, it teaches that the alkylating agent may be indistinguishable from olefins, alcohols, aldehydes, and alkylaldehydes. The catalyst is selected from several zeolite families suitable for the purpose. There is no data on the duration of the catalyst, nor on the possibility of its deactivation over time.

[0015] U.S. Patent Application Publication 2011 / 201858 describes a process for producing cumene from acetone and benzene, in which the acetone is pre-reduced by hydrogen in the presence of a reduction catalyst. It reports a selectivity to cumene of less than 71%, but does not describe a transalkylation process, although a much less extensive preliminary transalkylation treatment is reported.

[0016] EP1257517 describes a process for preparing cumene by alkylation of benzene with isopropanol or an isopropanol / propylene mixture. This patent demonstrates that transalkylation, which can be appropriately applied to polyalkylates obtained by alkylation of aromatic compounds with alcohols, is a reaction well known to those skilled in the art.

[0017] International Publication 2017 / 065771 describes an alkylation process useful for the production of alkyl aromatic compounds, particularly ethylbenzene and cumene. In the case of cumene, the alkylating agent includes propylene and / or isopropanol. This patent teaches how transalkylation can be conveniently applied to the polyalkylates obtained by the described alkylation reactions, without mentioning issues related to the transalkylation reaction itself.

[0018] While pretreatment methods for absorbing impurities in feedstocks for catalytic processes are known in the art, the materials used often have limited absorption capacity, and it is crucial to perform multiple regenerations in situ to at least partially restore their absorption capacity before any removal / replacement / disposal of the material itself, which can make the approach unattractive from an economic standpoint.

[0019] International Publication No. 2003 / 074452 describes methods for reducing impurities, particularly nitrogen compounds, in feedstocks of acid zeolite-catalyzed processes, including aromatic alkylation and transalkylation processes. Pretreatment by distillation, extraction, and adsorption is mentioned. However, mixtures of polyalkyl aromatic compounds derived from alkylation processes are not specifically considered.

[0020] International Publication No. 2016 / 099715 describes a material to be used as a guard bed with improved toxic absorption capacity for supplies, such as those used in alkylation and transalkylation processes of aromatic compounds. However, typical problems of guard beds, such as limited absorption capacity and the need for frequent regeneration / replacement of the bed itself, still remain.

[0021] U.S. Patent Publication No. 2007 / 112240 describes a pretreatment of a feed stream consisting of an aromatic mixture from a purification process to reduce oxygen-containing compound impurities to less than 5 ppm. The pretreatment is based on an absorbent material such as alumina or molecular sieves. Alkylation or transalkylation processes are not mentioned.

[0022] Therefore, the drawbacks related to the stability and durability of catalyst systems in the process of transalkylation of polyalkyl aromatic compounds, particularly alkylation reactions with aromatic compounds and alcohols and / or olefins, more specifically with alcohols, such as the alkylation of benzene with an alkylation mixture containing isopropyl alcohol (IPA), do not appear to be clearly identified or adequately resolved.

[0023] The applicant has surprisingly discovered that in the process of transalkylation of aromatic compounds, a simple hydrogenation treatment of the mixture to be transalkylated can significantly improve the catalyst duration, expressed, for example, as TOS (times of operation, i.e., the period during which the catalyst can operate at minimum predetermined performance).

[0024] Its importance is not clearly identified in the literature of that sector. The scientific literature on transalkylation with zeolite catalysts has so far not shown that the pre-hydrogenation treatment of the mixture to be transalkylated can slow down or even inhibit the disintegration of the catalyst.

[0025] Surprisingly, therefore, the reduction treatment of a mixture containing polyalkylated aromatic compounds resulting from the alkylation step of aromatic compounds with an alcohol or an olefin, preferably an alcohol, even more preferably isopropyl alcohol, with hydrogen can significantly improve the stability and duration of the transalkylation catalyst (e.g., from the perspective of productivity and / or operating time, TOS), avoid the management and optimization of the absorption bed, and has been found to overcome the aforementioned problems.

[0026] The productivity herein refers to the monoalkylated product and is expressed in kg of monoalkylated product per kg of catalyst used in the reaction.

[0027] Therefore, a first object of the present invention is a process comprising a reduction step of a polyalkylated product containing at least one polyalkyl aromatic compound, preferably in the presence of a suitable hydrogenation catalyst using hydrogen, wherein the polyalkylated product is obtained in at least one step of an alkylation process of at least one aromatic compound, preferably benzene, with an alkylating agent selected from an alcohol, a primary olefin or a mixture thereof, preferably an alcohol or a mixture of an alcohol and a primary olefin.

[0028] Other aims and objects of the present invention may become apparent in the following description and claims of this description.

[0029] For the purposes of this description and the following claims, the definition of a numerical interval always includes the extreme values unless otherwise specified.

[0030] For the purposes of this description and the following claims, percentages are always in terms of weight unless otherwise specified.

[0031] In describing embodiments of the present invention, the use of the terms “includes” and “includes” indicates that the options described, for example, with respect to steps of a method or process or components of a product or device are not necessarily exhaustive. However, it is important to note that terms such as “consisting of” or “essentially consisting of” as used herein, or their synonyms, are included in the meaning and scope of the terms “contains” and “contains,” even if not explicitly stated.

[0032] For the purposes of this specification and the following claims, with respect to chemical elements and the groups to which they belong, we refer to the periodic table of elements published by IUPAC in 2016, using CAS ("Chemical Abstract" service) numbers. For the purposes of the present invention, references to groups in the periodic table include any element of said group, except for transuranic elements.

[0033] For the purposes of this description and the following claims, the meanings of terms such as at least one, at least a, and at least an also include the meanings of indefinite articles such as one, a, and an.

[0034] In this specification and the following claims, polyalkyl aromatic compounds mean any aromatic compound substituted with at least two alkyl groups on the same ring or more rings condensed together, and optionally substituted with halogen atoms, particularly fluorine. Preferred polyalkyl aromatic compounds have 8 to 20 carbon atoms. Preferably, the aromatic compounds and polyalkyl aromatic compounds according to the present invention do not contain heteroatoms in their aromatic rings. Typical non-limiting examples of polyalkyl aromatic compounds according to the present invention are xylene, 1,3,5-trimethylbenzene, 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, 4-ethyltoluene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, 1,3,5-triisopropylbenzene, 1,4-dimethylnaphthalene, 1,7-dimethylnaphthalene, and mixtures thereof. Preferred polyalkyl aromatic compounds are mixtures of polyethylbenzene and polyisopropylbenzene isomers obtained from alkylation processes of benzene with ethyl alcohol and / or ethylene and isopropyl alcohol and / or propylene, respectively.

[0035] The polyalkylation product to be reduced by the method according to the present invention typically consists of a mixture of compounds. It may consist of one or more polyalkyl aromatic compounds, or, in addition to the at least one polyalkyl aromatic compound, may also include other components, such as a solvent or diluent, a non-alkyl-substituted aromatic compound such as benzene or naphthalene, a monoalkyl-substituted aromatic compound such as toluene, ethylbenzene, isopropylbenzene, or n-propylbenzene, and water, as well as other impurities or by-products resulting from the alkylation process, such as an oxygen-containing organic compound such as an alcohol, acetone, or benzophenone. Preferably, the polyalkylation product supplied to the process contains 1 to 50% by weight, preferably 2 to 25% by weight, more preferably 5 to 25% by weight of the polyalkyl aromatic compound and 2% or less, preferably 0.0010 to 0.50% by weight of the oxygen-containing organic compound.

[0036] In embodiments of the present invention, the polyalkylation product may be further mixed with a solvent, a diluent, a non-alkylated aromatic compound, and any recycled product of the corresponding alkylation process before being subjected to the reduction step with hydrogen.

[0037] Suitable solvents and diluents included in or added to the polyalkylation product according to the present invention are typically liquids that are intrinsically inert to reduction reactions, such as saturated and unsaturated, preferably aromatic hydrocarbons, having 6 to 20 carbon atoms. In a preferred embodiment, the polyalkylation product includes or is added to an aromatic compound, such as benzene, which can have both the function of a solvent and / or diluent, as well as the function of a reactant in the subsequent transalkylation step. In a preferred embodiment, the polyalkylation product to be reduced is obtained by an alkylation process of benzene, preferably using an alcohol or an alcohol / olefin mixture, and the mixture thus obtained is reduced and mixed with benzene to such an extent that it contains 40 to 90% by mass, more preferably 60 to 85% by mass, of the total mass of the mixture.

[0038] The polyalkylation product is a mixture of other compounds (which can be defined as a stream if the process is carried out continuously) obtained as a byproduct of an alkylation process in the presence of an acid catalyst, preferably a zeolite-based acid catalyst, preferably a polyalkyl aromatic compound and an aromatic compound, preferably benzene and at least one alcohol, at least one olefin, or a mixture thereof, preferably an alcohol or a mixture of an alcohol and a primary olefin. As known in the literature of the art and as described above, the alkylation process of aromatic compounds by acid catalysts involves the formation of undesirable polyalkylated aromatic compounds or other types known in the art, which are separated from the desired monoalkylation product and from other reaction byproducts by distillation operations, and therefore usually undergo a transalkylation reaction in the presence of an excess of non-alkylated aromatic compounds to form a polyalkylation product (or stream) that further produces a monoalkylated aromatic product. The polyalkylation product constitutes the polyalkylation product supplied to the process according to the present invention.

[0039] The process according to the present invention is preferably a transalkylation process comprising, in addition to the hydrogen reduction step, a subsequent reaction step of the polyalkylation product to be reduced, wherein at least one polyalkylated aromatic compound, preferably the alkyl group is ethyl or propyl, and preferably at least one dialkylated aromatic compound, is reacted with a different aromatic compound, preferably non-alkylated, preferably benzene, in the presence of an acid catalyst, so that at least a portion of the alkyl substituent of the polyalkylated aromatic compound is transferred to the different aromatic compound, preferably non-alkylated.

[0040] In another embodiment, the present invention relates to an alkylation process for at least one aromatic compound, comprising the steps of alkylating the aromatic compound by reaction with an alkylating agent selected from olefins, alcohols or mixtures thereof, preferably alcohols, in the presence of a suitable acid catalyst, and at least a reduction step of a polyalkylation product obtained, preferably by hydrogen, as at least one by-product of the type specified above, followed by a transalkylation step.

[0041] Alkylation processes for aromatic compounds are known and can be carried out under various conditions using various acid catalysts. These are described, for example, in EP 1069100, U.S. Patent Publication No. 2011 / 0218366, U.S. Patent No. 9096488, U.S. Patent No. 9259722, and U.S. Patent No. 7371910, the contents of which are incorporated herein by reference.

[0042] The alkylation process of aromatic compounds can be carried out industrially in gas, liquid, or mixed phases, in a continuous, semi-continuous, or discontinuous manner, to maintain the temperature within an optimal range and reduce underproduction of polyalkylated aromatic compounds, and the catalyst can be placed in several layers within the reactor. As just one example, rapid quenching (in the most commonly used terminology) can be carried out between one layer and another using an inert solvent and / or a portion of the aromatic compound and / or an alkylating reagent, an alcohol, or a portion of an olefin.

[0043] With proper handling, a high aromatic / alkylating agent ratio can be obtained in a single layer without increasing the overall ratio, which offers clear advantages in subsequent aromatic separation and recycling. Temperature control can be achieved not only by quenching with reagents and / or inert substances, but also by mutual cooling between layers, for example, by interposing a refrigerant. The alkylation reaction can be adequately carried out in two or more reactors in series, intercooled to control the temperature. The supply of olefins, alcohols and / or aromatic compounds can be adequately segmented between different reactors and different reactor layers; i.e., the alkylating agent and / or aromatic compound are added in multiple steps; optionally, the alkylating agent can be diluted with an aromatic compound or inert substance to facilitate temperature control.

[0044] The amount of alkylating agent supplied is such that the overall molar ratio [aromatic] / [alkylating agent] is preferably 1 to 20, more preferably 2 to 8.

[0045] The reaction temperature is 100°C to 300°C, preferably 120°C to 230°C; the pressure is 0.5 to 5 MPa, preferably 1 to 4 MPa; and the space velocity WHSV is 0.1 to 200 h. -1 Preferably 1 to 10 hours -1 That is the case.

[0046] However, it should be noted that the combination of temperature and pressure conditions adopted for effective use must ensure that the alkylation reaction occurs at least partially in the liquid phase, and preferably substantially in the liquid phase.

[0047] Typical acid catalysts for the alkylation of aromatic compounds are heterogeneous zeolite catalysts, which have replaced catalysts such as AlCl3-HCl, hydrofluoric acid, and common homogeneous phase catalysts, especially in newly designed plants. Depending on the type of alkylation, zeolite catalysts with different pore sizes can be used to make the reaction more selective for the desired product. For example, 10MR structures such as ZSM-5(MFI) are patented and used in the gas phase. Liquid-phase processes using 12MR zeolites can significantly extend the catalyst life. Also, Y(FAU) and beta(BEA) zeolites are claimed and / or used industrially. For the production of cumene, a fixed-bed process using mordenite (MOR)-based catalysts has been described and patented. MCM-22(MWW) zeolite has been mentioned as a catalyst that produces low concentrations of dialkylation products. A consistent list of alkylation technologies for aromatic compounds and related catalysts can be found in Catalysis Today 73 (2002) 3-22 (Recent advances in the industrial alkylation of aromatics: new catalyst and new processes), Thomas F. Degnan et al., Applied Catalysis A: General Volume 221, Issue 1-2, 30 November 2001, pp. 283-294 (Alkylation of aromatics with ethylene and propylene: recent developments in commercial processes), and C. Perego et al., Green Chem., 2004, 6, pp. 274-279 (Combining alkylation and transalkylation for alkylaromatic production).

[0048] The alkylation step is preferably carried out using an alcohol or an alcohol / olefin mixture as the alkylating agent. Typically, ethanol and / or ethylene are used to alkylate benzene to ethylbenzene, and isopropanol and / or propylene are used to alkylate benzene to cumene. According to known principles of organic chemistry, appropriate alcohols and / or olefins corresponding to the alkyl residue to be introduced into the aromatic compound are used to prepare other alkylated aromatic compounds.

[0049] Subsequently, the product of the alkylation step is fed to one or more separation steps according to the prior art to recover the desired alkylation product and separate any polyalkylated aromatic compounds that are inevitably produced in small amounts for their subsequent use or for their supply to a transalkylation process.

[0050] For example, by distilling the reaction residue from the alkylation step of benzene with isopropanol, the monoalkylate can be separated, and a main mixture consisting of diisopropylbenzene (e.g., 93.2%) and trace amounts of acetophenone, in addition to some heavy polyalkylates, can be obtained. This cut is mixed with benzene, preferably without H2O (H2O < 100 ppm), in an appropriate weight ratio (e.g., 20-80 by weight), to produce a mixture containing the polyalkylation product, which can be readily hydrogenated, for example, on a chromite copper-based catalyst, before transalkylation. The advantages of the present invention can be highlighted by comparing it with the transalkylation of a similar but unhydrogenated mixture.

[0051] According to the present invention, the polyalkylated product obtained after the separation step of the mixture that has left the alkylation step is preferably subjected to a reduction treatment using hydrogen and a suitable reduction catalyst as described in the claims.

[0052] According to the present invention, the hydrogenation step of the polyalkylation product is preferably carried out at a temperature of 60 to 220°C, preferably 100 to 180°C, and at a hydrogen pressure of 0.1 to 5.0 MPa, preferably 1.0 to 3.0 MPa. The step can be carried out continuously or discontinuously in a reactor equipped with a solid catalyst, either in a suspension state or in a fixed bed or fluidized bed. Preferably, the catalyst is used in a fixed bed for a continuous process and in a suspension state for a discontinuous process. The reduction reaction, preferably a hydrogenation reduction reaction, is preferably carried out under conditions that do not result in hydrogenation of the aromatic rings of compounds present in the mixture. These conditions are known to those skilled in the art and can be easily determined depending on the catalyst used or by simple preliminary testing.

[0053] The reducing agent, preferably hydrogen, is preferably supplied to the reduction step in pure or substantially pure form. However, the present invention does not preclude the hydrogen from also containing a considerable amount of other gases, provided that they are inert to the catalyst and the substrate to be hydrogenated, such as nitrogen, noble gases, or methane. The hydrogen may optionally be preheated to a temperature higher than room temperature. Hydrogen and The polyalkylation product includes RuPo The molar ratio with the dialkyl aromatic compound is preferably 0.01 to 10, more preferably 0.1 to 5.

[0054] In the case where the process of the present invention is preferably carried out continuously, the space velocity (WHSV) calculated based on the total volume of the feed containing any diluent is preferably 0.5 to 10 h. -1 Comfortable for 1-5 hours -1 More preferably 1 to 3 hours -1 That is the case.

[0055] The polyalkylation product is optionally replenished with a suitable solvent, which may coincide with the same aromatic reagent to be alkylated in the subsequent transalkylation step, and reacts with hydrogen under the above conditions in the presence of a suitable catalyst, with substantially no hydrogenation of the aromatic group or ring. Therefore, it is preferable that the process of the present invention be carried out such that the amount of aromatic rings hydrogenated in the hydrogenation reduction step is less than 1%, preferably less than 0.5%, and more preferably 0-0.1%, of the total amount of aromatic rings supplied. The amount of aromatic rings hydrogenated can be determined by an expert using any known technique, such as infrared or gas chromatography.

[0056] According to the present invention, reduction by hydrogen is carried out in the presence of a suitable catalyst. Suitable catalysts are those commonly used in the selective hydrogenation of oxygen-containing organic substrates, such as Ni, Ni Raney, Pd, Pt, Cu, and copper chromite catalysts. In this specification, the term "selective" means that the hydrogenation reaction does not cause significant hydrogenation of any rings of the aromatic compound. Such hydrogenation catalysts are well known in the art and commercially available. See, for example, the following publications: "Handbook of Heterogeneous Catalysis" (2008) (eds G. Ertl, H. Knоzinger, F. Schuth and J. Weitkamp): Blaser H., Schnyder A., ​​et al., "Selective Hydrogenation of Functionalized Hydrocarbons," and; Smith AJ and Wainwright MS "Skeletal Metal Catalysts".

[0057] Preferably, the catalyst usable in the reduction process of the present invention using hydrogen is based on copper chromite. The catalyst is a known catalyst for selective hydrogenation reactions and is commercially available, and is reported, for example, in the publication "PRASAD e SINGH, Bulletin of Chemical Reaction Engineering & Catalysis, pp. 63-113, Nov. 2011," which describes its applications and methods for preparing the copper chromite-based catalyst.

[0058] Other copper-based catalysts, particularly copper chromites, suitable for the hydrogen reduction step of the present invention are reported, for example, in EP563327 and International Publication No. 2017 / 144337.

[0059] The process of the present invention has proven particularly advantageous when at least 15%, preferably at least 40%, more preferably at least 60%, and up to 100% of the polyalkylation product is obtained from an alkylation process of an aromatic compound using an alcohol (with the remainder from an alkylation process using an olefin), the percentages being based on the mass of the polyalkylation product. For example, the process may begin with at least 25%, more preferably 40%, from an alkylation process of benzene using isopropyl alcohol, with the remainder coming from an alkylation process using propylene.

[0060] Preferably, the polyalkylation product is separated from the monoalkylation product and higher boiling point by-products and then supplied to the reduction step with hydrogen without undergoing any other treatment to reduce the impurity content, such as purification in molecular sieves, filtration in a selective membrane, or other reduction treatments, but these are not excluded from the scope of the process of the present invention. In any case, the process according to the present invention is easy to apply, efficient and economically advantageous, and at the same time, with respect to the use of olefins, it contributes to carrying out alkylation processes of aromatic compounds with alcohols or mixtures of alcohols and olefins, making it more effective and competitive.

[0061] The process according to the present invention may include other steps and reactions in addition to the hydrogen reduction step described above. In a preferred embodiment, the process of the present invention includes a step of transalkylation of an aromatic compound contained in the polyalkylation product, following its impurity reduction treatment with hydrogen.

[0062] Accordingly, the process according to the present invention preferably comprises a hydrogen reduction step followed by a transalkylation step of at least one polyalkyl aromatic compound contained in the polyalkylation product, which can be carried out according to one of the various methods known to those skilled in the art, for example, as described in EP847802 (in the name of the present applicant), the contents of which are incorporated herein by reference. A transalkylation catalyst suitable for the present invention may be a material known in the art, for example, an acid or protonate zeolite, used in a form suitable for fixed-bed applications known in the art, for example, extruded, to which a conventional binder such as alumina (Al2O3), silica (SiO2), zirconium oxide, titanium oxide, preferably silica (SiO2) or alumina (Al2O3) or a mixture thereof is added. When alumina is used as a binder, a gamma-alumina phase structure is preferred. Typical examples of binder alumina precursors are commercially available materials based on pseudoboehmite (sometimes called boehmite), such as those sold under the VERSAL brand (e.g., Versal V-250 from UOP). Materials having a gamma-alumina structure are generally known to experts in the art and can be obtained, for example, by calcining pseudoboehmite, as reported in the pamphlet "UOP 5502, April 2012".

[0063] In many industrial applications, such as fixed-bed catalytic reactors, it is necessary to form a catalyst, and often a binder must be added to enable catalyst formation. In applications requiring a formed catalyst, it is important that the catalyst maintains its physical integrity during use; in fact, if it does not have sufficient strength, the catalyst may be damaged or degraded, potentially adversely affecting the reaction and / or the apparatus. Preferably, the catalyst is formed in fixed-bed applications, for example, as spheres or pellets. At the end of the formation, the resulting "pellets" are generally calcined. The solid obtained after bonding and formation may contain 5% to 90% by weight, preferably 10% to 75% by weight, and more preferably 20% to 55% by weight of a binder, relative to the total weight of the zeolite-based catalyst.

[0064] Particularly useful in the transalkylation process are the beta-zeolite-based catalysts described in EP No. 847802, or the Y-zeolite-based catalysts described in U.S. Patent No. 8658553.

[0065] Preferably, the subsequent step for transalkylation of an aromatic compound by reaction with one or more polyalkylated aromatic compounds is catalyzed by a catalyst composition comprising a zeolite (broad-porous zeolite) having a crystalline structure with 12 tetrahedral openings and γ-alumina as an inorganic binder, preferably characterized by a pore volume of 0.7 cc / g or more obtained by adding mesoporous and macroporous fractions present in the catalyst composition itself, wherein at least 30% of the volume consists of pores with a diameter of 100 nanometers or more.

[0066] A catalyst composition containing acidic form Y or beta-zeolite is preferably used. The aromatic hydrocarbon is preferably benzene. The polyalkylated aromatic hydrocarbon is preferably selected from diethylbenzene, and optionally triethylbenzene and diisopropylbenzene, and optionally triisopropylbenzene. It is particularly preferable to obtain cumene by transalkylating benzene with diisopropylbenzene and optionally triisopropylbenzene.

[0067] The transalkylation reaction must be carried out under conditions that occur at least partially in the liquid phase, preferably substantially in the liquid phase. This is preferably at a temperature of 150-300°C, a pressure of 2-5 MPa, and for 0.5-10 hours. -1 The reaction is carried out at a space velocity (WHSV). The molar ratio of the aromatic hydrocarbon to be transalkylated to the total polyalkylated aromatic hydrocarbons in the feed mixture to the transalkylation reaction can vary from 1 to 40, preferably from 3 to 30. The catalyst is usually placed on a fixed bed, and is used in particular in a chamber reactor with one or more fixed catalyst beds.

[0068] Further aspects of the present invention also include, a) Contacting and reacting an aromatic hydrocarbon with at least one alcohol and / or at least one primary olefin, preferably an alcohol or a mixture of an alcohol and a primary olefin, more preferably an alcohol, wherein the alcohol and olefin have 2 to 4, preferably 3, carbon atoms, in the presence of an alkylating acid catalyst; b) Separating the reaction product obtained in step a) into a fraction containing aromatic hydrocarbons that did not react in step a), a fraction containing monoalkylated aromatic hydrocarbons, a fraction containing a polyalkylated product containing at least one polyalkyl aromatic compound, preferably containing at least 60% by weight of dialkylated aromatic hydrocarbons; c) The fraction containing the polyalkylation product obtained in step b) is subjected to a hydrogen reduction step in the presence of a suitable hydrogenation catalyst to obtain a reduced polyalkylation product; d) The reduced polyalkylation product obtained in step c) Reacting with an aromatic hydrocarbon, preferably the same as that reacted in step (a), under transalkylation conditions in the presence of a suitable acid catalyst, preferably selected from beta-zeolite or Y-zeolite. It consists of a process for preparing monoalkylated aromatic hydrocarbons, including [specific compound / component].

[0069] In the alkylation step a), it is preferable to use a solid acid catalyst containing a medium-pore or large-pore zeolite. The zeolites preferred for use in the catalyst composition used in the alkylation step are zeolites having an MWW (MCM-22) structure in a medium-pore structure, and zeolites having a BEA (beta)FAU (Y) zeolite and MTW (ZSM-12) structure in a large-pore structure, as described in, for example, International Publication No. 2015 / 056167 and International Publication No. 2012 / 175614. Beta or ZSM-12 zeolite is preferred, and more preferably ZSM-12 is used, as described in, for example, International Publication No. 2015 / 056167.

[0070] The alcohols preferably used in the alkylation step are selected from ethanol and isopropanol. The aromatic hydrocarbon used in the alkylation step is preferably benzene. In a particularly preferred embodiment, in alkylation step (a), benzene and isopropanol are brought into contact in the presence of beta-zeolite, Y-zeolite, or ZSM-12.

[0071] Step (a) can be carried out substantially in the gas phase, substantially in the liquid phase, or in a mixed phase, preferably in a parallel flow or flow bed, as described above.

[0072] The separation of fractions in step (b) is usually carried out by distillation according to known methods. In particular, for example, when the alkylation product is obtained by alkylation reactions of benzene and ethanol or isopropanol, respectively, or with a mixture of ethanol or isopropanol and the corresponding olefin, in step (b), the first fraction consists of benzene, the second consists of ethylbenzene or cumene, the third is formed mainly of diethylbenzene or diisopropylbenzene, and the last fraction is formed of a mixture of heavy hydrocarbons having a boiling point of 260°C to 300°C or higher.

[0073] In step (c), a third fraction substantially formed from a polyalkylation product comprising at least one polyalkyl aromatic compound (e.g., a mixture mainly formed of dialkylbenzene and less than 10% trialkylbenzene), optionally supplemented with an appropriate volume of the same aromatic hydrocarbon as in step (a), is placed in contact with a selective hydrogenation catalyst, preferably selected from Ni, Ni Raney, Pd, Pt, Cu, and copper chromite catalysts.

[0074] Preferably, the hydrogen reduction step (c) is carried out at a temperature of 60 to 220°C, preferably 100 to 180°C, and a hydrogen pressure of 0.1 to 5.0 MPa, preferably 1.0 to 3.0 MPa.

[0075] The transalkylation step d) is carried out in the presence of an acid catalyst, preferably comprising a beta or Y zeolite, and under the transalkylation conditions described above, preferably at least partially in the liquid phase.

[0076] Preferably, step (c) or (c) and (d) of the aforementioned process corresponds to or is performed concurrently with the process described in claim 1 or claim 8. [Examples]

[0077] To better understand and implement the present invention, some exemplary and non-limiting examples are reported below.

[0078] Reagents and catalysts Hydrogenation catalyst: A commercially available catalyst called BASF 1230, based on copper chromite manufactured by BASF GMbH (composed of 7-10% barium oxide, 15-25% copper oxide, and 25-50% chromium(III) oxide, extruded using a 1 / 16-inch trilobe); Hydrogen: (Sapio Corporation, 99.95% purity); Benzene: Sigma Aldrich, code 319953, purity >99%. Chromatographic analysis: The gas chromatography analyses reported herein were obtained using a Thermo Electron Focus gas chromatograph equipped with a 25m HP1 column. The conditions applicable to chromatographic analysis are as follows: • Carrier gas: Helium • Column: HP1-25m capillary, inner diameter 0.32mm, film thickness 0.52μm Oven temperature: 40°C for 2 minutes and 45 seconds, then increase to 290°C at a rate of 10°C per minute, and finally to 290°C for 5 minutes. • Detector: FID Moisture content measurement: Using Metrohm's KarlFischer 701 instrument.

[0079] Preparation example A An extruded beta-zeolite catalyst suitable for alkylation and transalkylation reactions of aromatic compounds was prepared as described in Example 4 of EP No. 847802, which is incorporated herein by reference.

[0080] In particular, 58.8 g of tetraethylammonium hydroxide and 1.9 g of sodium aluminate (56% Al2O3) in 40% by weight in aqueous solution are added to 58.4 g of demineralized water. The mixture is heated to approximately 80°C and stirred until completely dissolved. The resulting clear solution is added to 37.5 g of colloidal LudoxHS silica with 40% by weight SiO2. A homogeneous suspension at pH 14 is obtained, which is placed in a steel autoclave and crystallized under hydrothermal conditions at 150°C for 10 days under static and self-stimulating conditions. The crystallized product is separated by filtration, redispersed in demineralized water (approximately 150 g), and re-filtered: a wet zeolite panel still containing a considerable amount of the organic template agents tetraethylammonium and sodium is obtained.

[0081] The wet panel is redispersed in an aqueous solution of ammonium acetate (200 g water and 16 g ammonium acetate) for ion exchange. This suspension is heated at 80°C for about 1 hour with stirring. Next, the suspension is filtered, and the resulting solid is washed by redispersing it in desalinated water (150 cc). Then, the suspension is filtered again to obtain a wet beta-zeolite panel in ammonium / alkylammonium form.

[0082] Elemental chemical analysis revealed that the sodium residue in this last sample is actually 112 ppm. The aluminum content is 3.38% [Al] / [Na] = 257.

[0083] The solid obtained in this way (wet beta-zeolite in ammonia form containing an organic template agent) was premixed with a solution of pseudobohemite as a precursor for a gamma-alumina binder and acetic acid as a decoagulant, resulting in a binder content of 50% by weight in the solid after calcination, and then extruded. The solid obtained in this way was calcined in an air atmosphere at 350°C for 2 hours, followed by a further 3 hours at 550°C. After calcination, an extruded catalyst was obtained with a zeolite-alumina (gamma) weight ratio of 50:50. The catalyst obtained in this way had a pore ratio of over 35% with a radius of over 100 Å, and the total volume of the outer pores of the EPV was 0.81 ml / g.

[0084] Example 1 (Pre-hydrogenation) From a benzene alkylation process using isopropyl alcohol (IPA) for the production of cumene, a primer mixture containing a polyalkylated aromatic compound is obtained by distillation, which constitutes the polyalkylation product according to the present invention.

[0085] A liquid mixture (mixture A) obtained by mixing benzene and the polyalkylation product in a weight ratio of approximately 1 / 4 was supplied upflow to a continuous fixed-bed reactor (25 cm long, 1 cm section) containing 22.9 g of hydrogenation catalyst Cu-1230E 1 / 16 (BASF). Mixture A exhibited the composition shown in Table 1 below under gas chromatography.

[0086] [Table 1]

[0087] In Table 1, "high boiling point" refers to all compounds that elute after diisopropylbenzene in gas chromatography analysis until the analysis is complete.

[0088] The reactor was set to T=120℃, P=20 bar, H2, WHSV=2h -1 The reaction was then carried out in an upflow regime to obtain a hydrogenated mixture (mixture B) with the output shown in the third column of Table 1. Note the significant decrease in acetophenone content during the reaction. It should also be noted that under the reaction conditions employed, the aromatic compounds do not undergo substantial hydrogenation of the aromatic ring.

[0089] Example 2 The transalkylation test of diisopropylbenzene was performed continuously in an upflow regime (tube length 5 m, section 2.98 mm) spiral fixed-bed reactor heated by forced air circulation in a thermostat-controlled chamber. A pneumatic valve at the oven outlet regulates the pressure in the system. The reagent is stored in a steel tank (capacity 25 liters). The tank is saturated with nitrogen to avoid the possibility of oxidation of the reagent. Reaction effluent is periodically sampled and analyzed by gas chromatography and by determining the water content according to the method described above.

[0090] The hydrogenation mixture obtained according to the previous Example 1 (Mixture B in Table 1) was subjected to transalkylation in the reactor. The thermostat was set to 220°C, the hydrogen pressure to 2 MPa and the WHSV to 5h -1 The 12.7 g extruded beta-zeolite catalyst described in the previous preparation example A was used.

[0091] The transalkylation reaction was carried out on-stream for over 200 hours, corresponding to the productivity and conversion reported in Table 2. As observed, the catalyst showed no significant signs of deactivation during this period.

[0092] [Table 2]

[0093] The conversion rate of diisopropylbenzene is the molar percentage ratio between converted and supplied diisopropylbenzene. The yield of cumene is the molar percentage ratio between the cumene produced and supplied diisopropylbenzene.

[0094] Example 3 (Comparison) Using the same catalyst system and conditions as in Example 2, and in the same reactor, the unpretreated mixture (Mixture A in Table 1) was used, but the mixture supplied to the reactor to be transalkylated was changed. Table 3 shows the trends in the conversion of diisopropylbenzene and the yield of cumene. These clearly tend to decrease over time.

[0095] [Table 3]

[0096] Therefore, as reported, the reduction pretreatment of the mixture to be transalkylated, preferably alkylation with IPA, surprisingly allows for improved stability of the catalytic transalkylation system by eliminating, or at least reducing the frequency of, the need to apply regeneration processes known to those skilled in the art with respect to the latest technology.

Claims

1. A process comprising a hydrogenation step of a polyalkylation product comprising at least one polyalkyl aromatic compound and 2% by weight or less of an oxygen-containing organic compound, wherein the polyalkylation product is obtained in at least one step of an alkylation process of at least one aromatic compound with an alkylating agent selected from an alcohol, or an alcohol and a primary olefin, The reduction step with hydrogen is carried out under conditions such that the amount of aromatic rings to be hydrogenated is less than 1% by mass of the total amount of aromatic rings supplied, the molar ratio of hydrogen to the polyalkyl aromatic compound contained in the polyalkylation product is 0.01 to 10, the catalyst is selected from Cu-based catalysts, and downstream of the reduction step with hydrogen is a transalkylation step of the aromatic compound contained in the polyalkylation product to be reduced, the transalkylation step is carried out in the presence of a beta-zeolite or Y-zeolite catalyst. In the reduction step, the amount of the oxygen-containing organic substrate decreases, A process wherein, in the reduction step, the polyalkylation product is not subjected to treatment with a molecular sieve.

2. The process according to claim 1, wherein the polyalkylation product comprises at least one polyethylbenzene or at least one polyisopropylbenzene.

3. The process according to claim 1 or 2, wherein the reduction step is carried out at a temperature of 60 to 220°C and a hydrogen pressure of 0.1 to 5.0 MPa.

4. The process according to any one of claims 1 to 3, wherein the polyalkylation product is obtained from an alkylation process of an aromatic compound with an alcohol in an amount of at least 15% by mass and 100% by mass or less.

5. The process according to any one of claims 1 to 4, wherein in the reduction step with hydrogen, the amount of hydrogenated aromatic rings is 0.1% by mass or less relative to the total amount of the supplied aromatic rings.

6. The process according to any one of claims 1 to 5, wherein the polyalkylation product is obtained from a benzene alkylation process and is mixed with benzene before the reduction step with hydrogen, and the mixture thus obtained contains 40 to 90% by mass of benzene based on the mass of the mixture itself.

7. The transalkylation step is performed at a temperature of 150 to 300°C, a pressure of 2 MPa to 5 MPa, and for 0.5 to 10 hours. －１ The process according to claim 1, carried out at the spatial velocity (WHSV).

8. A process for preparing monoalkylated aromatic hydrocarbons, a) Contacting and reacting an aromatic hydrocarbon and at least one alcohol, or at least one alcohol and at least one primary olefin, under alkylation conditions in the presence of an alkylating acid catalyst, wherein the alcohol and olefin have 2 to 4 carbon atoms; b) Separating the reaction product obtained in step (a) into a fraction containing the aromatic hydrocarbon that did not react in step (a), a fraction containing the monoalkylated aromatic hydrocarbon, and a fraction containing a polyalkylated product comprising at least one polyalkyl aromatic compound and 2% by weight or less of an oxygen-containing organic compound; c) The fraction containing the polyalkylation product obtained in step (b) is subjected to a hydrogenation step in the presence of a hydrogenation catalyst for an oxygen-containing organic substrate to obtain a reduced polyalkylation product, wherein in the hydrogenation step, the amount of aromatic rings hydrogenated is less than 1% by mass of the total amount of aromatic rings supplied, the catalyst is selected from Cu-based catalysts, the amount of oxygen-containing organic substrate is reduced, and the polyalkylation product is not subjected to treatment with molecular sieves; d) The reduced polyalkylation product obtained in step (c) is reacted with an aromatic hydrocarbon under transalkylation conditions in the presence of a beta-zeolite or Y-zeolite catalyst. A process for preparing monoalkylated aromatic hydrocarbons, including [specific compound / component].

9. The process according to claim 8, wherein the reduction step c) is carried out at a temperature of 60 to 220°C and a hydrogen pressure of 0.1 to 5.0 MPa.

10. The process according to claim 8 or 9, wherein the alcohol is ethanol or isopropanol, and the aromatic hydrocarbon in step a) is benzene.

11. The process according to any one of claims 8 to 10, wherein the aromatic hydrocarbon in step d) is a non-alkylated aromatic hydrocarbon.

12. The process according to claim 8, wherein in the reduction step of step c), the molar ratio of hydrogen to the polyalkyl aromatic compound contained in the polyalkylation product is 0.01 to 10.

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