TWI450753B - Methods for removing unsaturated aliphatic hydrocarbons from a hydrocarbon stream using clay - Google Patents

Description

Method for removing unsaturated aliphatic hydrocarbons from hydrocarbon streams using clay

This invention relates to a process for the removal of unsaturated aliphatic compounds from a hydrocarbon stream. More particularly, the invention relates to the removal of unsaturated aliphatic compounds from hydrocarbon streams comprising aromatic compounds.

This application claims the priority rights of US Provisional Application Nos. 61/424,813, 61/424,822 and 61/424,831, all of which were filed on December 20, 2010.

The use of molecular sieves as catalysts in aromatic conversion processes is well known in the chemical processing and refining industries. Aromatic conversion reactions of considerable commercial value include the alkylation of aromatic compounds (for example, the production of aromatic mixtures of ethyltoluene, xylene, ethylbenzene, cumene or higher alkyl groups and disproportionation of toluene) Isomerization reaction, isomerization of xylene or transalkylation of polyalkylbenzene to monoalkylbenzene. The feedstock used in this aromatic conversion process will often comprise an aromatic component (i.e., an alkylation base such as benzene) and a C2 to C20 olefin alkylating agent or a polyalkyl aromatic hydrocarbon transalkylating agent. As used herein, terms such as "C4", "C5", "C6" and the like indicate the number of carbon atoms per molecule of hydrocarbon or hydrocarbon material. In the alkylation zone, the aromatic feed stream and the olefin feed stream can be reacted on an alkylation catalyst to produce an alkylated aromatic compound, such as cumene or ethylbenzene. Part or all of the alkylation matrix may be provided by other process units comprising separate sections of the styrene process unit. The polyalkylated benzene is separated from the monoalkylated benzene product and recycled to the transalkylation zone and contacted with benzene over a transalkylation catalyst to produce monoalkylated benzene and benzene.

Catalysts for aromatic conversion processes typically include zeolite molecular sieves. Examples include zeolite beta (US 4,891,458); zeolite Y, zeolite Ω and zeolite beta (US 5,030,786); X, Y, L, B, ZSM-5 and Ω crystal type zeolites (US 4,185,040); X, Y, ultrastable Y , L, Ω, and mordenite zeolite (US 4,774,377); and UZM-8 zeolite (US 6,756,030 and US 7,091,390). It is known in the art that aromatic feed streams for aromatic conversion processes often contain nitrogen compounds (including weakly basic organic nitrogen compounds such as nitriles) which can accumulate downstream aromatic conversions even at ppm and ppb concentrations. Catalysts such as aromatic alkylation catalysts are poisoned and significantly shorten their useful life. Various guard beds with clay, zeolite or resin adsorbents are known in the art to remove one or more types of nitrogen compounds from the aromatic hydrocarbon stream upstream of the aromatic conversion process. Examples include: US 7,205,448, US 7,744,828, US 6,297,417, US 5,220,099, WO 00/35836, WO 01/07383, US 4,846,962, US 6,019,887, and US 6,107,535.

It has recently been discovered that unsaturated aliphatic hydrocarbons such as olefinic compounds and in particular diolefins can shorten the useful life of adsorbents (e.g., nitrogen-adsorbing zeolites or molecular sieves) used in nitrogen-protected beds, such as alkyl-containing beds. Various process streams for the aromatic hydrocarbon feed upstream of the aromatic conversion process. The unsaturated aliphatic (e.g., olefin) compounds are present in an aromatic process stream contaminated with a nitrogen compound, the aromatic process stream comprising a benzene stream formed in a separate section of the styrene process and which is susceptible to nitrogen poisoning The other stream of nitrogen compounds is removed prior to contacting the catalyst or other material. In particular, the presence of highly unsaturated olefinic compounds (e.g., C4-C6 diolefins) in aromatic streams having nitrogen compound contaminants adversely affects the performance of the nitrogen sorbent material. Without wishing to be bound by theory, it is believed that olefinic compounds and/or other unsaturated aliphatic compounds can shorten the life of the nitrogen adsorbent by competing with the nitrogen compound for adsorption sites and/or with, for example, aromatic compounds such as benzene. The reaction is carried out to form a heavy reaction product deposited on a nitrogen guard bed adsorbent.

This invention relates to a process for the removal of unsaturated aliphatic compounds (including olefins and/or dienes) present in an aromatic hydrocarbon stream. In one embodiment, the present invention provides a longer lifetime for the adsorbent in the downstream nitrogen removal zone, which minimizes the need to regenerate or replace the nitrogen adsorbent.

In one embodiment, the invention is a process for treating a hydrocarbon feed stream comprising an aromatic compound, a nitrogen compound, and an unsaturated aliphatic compound. In one form, the method comprises contacting a hydrocarbon feed stream with a sorbent comprising clay under contact conditions to remove unsaturated fatty compounds and to produce a treated hydrocarbon stream, the contacting conditions comprising a temperature of at least 50 ° C and the presence Water in an amount of at least 50 ppm by weight relative to the hydrocarbon feed stream. In another form, the method comprises contacting a hydrocarbon feed stream with an acidic molecular sieve under contact conditions to remove an unsaturated fatty compound and producing a treated hydrocarbon stream, the contacting conditions comprising a temperature of at least 25 ° C and the presence relative to The hydrocarbon feed stream is water in an amount of at least 50 ppm by weight. In yet another form, the method comprises contacting a hydrocarbon feed stream with activated carbon under contact conditions to remove unsaturated fatty compounds and producing a treated hydrocarbon stream, the contacting conditions comprising a temperature of at least 50 ° C and the presence relative to The hydrocarbon feed stream is water in an amount of at least 50 ppm by weight.

In another embodiment, the invention is a process for producing an alkylated benzene compound. The method comprises (i) contacting a hydrocarbon feed stream comprising benzene, an organic nitrogen compound, and a diolefin compound with one of an adsorbent comprising clay, an acidic molecular sieve, and activated carbon to remove the diolefin compound and produce a treated a hydrocarbon stream; (ii) passing at least a portion of the treated hydrocarbon stream through the nitrogen removal zone, which produces an alkylation substrate stream; and (iii) passing at least a portion of the alkylation substrate stream through the alkylation zone, which produces an alkane A benzene compound.

The removal of one or more unsaturated aliphatic compounds from the aromatic stream and the combination of removing nitrogen may extend the life of the catalyst in the alkylation zone and/or the life of the adsorbent in the nitrogen removal zone, which may be Located between the unsaturated aliphatic removal zone and the alkylation zone. Additionally, the removal of reactive unsaturated aliphatic hydrocarbons such as olefins and/or diolefins minimizes the loss of benzene and other desired aromatics to be recycled and reacted. Surprisingly, it has been found that adsorbents comprising clay have a higher selectivity for the removal of diolefins having from 4 to 6 carbon atoms per molecule than for the overall mixture of unsaturated aliphatic hydrocarbons in the hydrocarbon feed stream.

The present invention relates to a process for treating a hydrocarbon feed stream wherein one or more unsaturated aliphatic hydrocarbon compounds are removed from a feed stream by one of a clay-containing adsorbent, an acidic molecular sieve, and activated carbon to produce a treated hydrocarbon stream. . The treated hydrocarbon stream has a lower unsaturated aliphatic hydrocarbon content relative to the hydrocarbon feed stream. The hydrocarbon feed stream of the present invention includes aromatic compounds, nitrogen compounds, and unsaturated aliphatic compounds.

The aromatic hydrocarbon compound may be selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene and substituted derivatives thereof, of which benzene and its derivatives are preferred aromatic compounds. The aromatic compound may have one or more substituents selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, a hydroxyl group and an alkoxy group (the alkyl group also having 1 to at most 20 carbon atoms). In the case of a substituted alkyl or alkoxy group, the phenyl group may also be substituted on the alkyl chain.

Although unsubstituted and monosubstituted benzene, naphthalene, anthracene and phenanthrene are most commonly used in the practice of the invention, polysubstituted aromatics may also be employed. In addition to those given above, examples of suitable alkylatable aromatic compounds also include biphenyl, toluene, xylene, ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, and octylbenzene. Etc.; phenol, cresol, anisole, ethoxybenzene, propoxybenzene, butoxybenzene, pentyloxybenzene, hexyloxybenzene, and the like. Sources of benzene, toluene, xylene, and/or other feed aromatics include a product stream from a naphtha reforming unit, an aromatic extraction unit, a recycle stream from a styrene monomer production unit, and used to generate a pair A petrochemical compound of xylene and other aromatic compounds. The hydrocarbon feed stream can include one or more aromatic hydrocarbon compounds. In one embodiment, the concentration of aromatics in the hydrocarbon feed stream ranges from 5 wt% to 99.9 wt% of the hydrocarbon feed. In another embodiment, the hydrocarbon feed stream comprises between 50 wt% and 99.9 wt% of an aromatic compound and may comprise between 90 wt% and 99.9 wt% of an aromatic compound.

The hydrocarbon feed stream nitrogen compound can include one or more organic nitrogen compounds. The organic nitrogen compound usually contains a relatively large proportion of a basic nitrogen compound such as hydrazine, pyridine, quinoline, diethanolamine (DEA), morpholine containing N-methylmercapto-morpholine (NFM), and N-methyl- Pyrrolidone (NMP). The organic nitrogen compound may also contain weakly basic nitriles such as acetonitrile, propionitrile and acrylonitrile. As discussed below, the present invention does not require, but encompasses the use of an optional nitrogen removal zone that reduces the nitrogen content of the hydrocarbon stream.

In one embodiment, the hydrocarbon feed stream has a nitrogen content ranging from 1 ppm-wt to 10 ppm-wt. In another embodiment, the concentration of the organic nitrogen compound in the hydrocarbon feed is in the range of 30 ppb-wt (billionths by weight) to 1 mol% of the hydrocarbon feed; the concentration of the organic nitrogen compound can be From 100 ppb-wt to 100 ppm-wt (parts per million by weight) of the hydrocarbon feed. In one embodiment, the concentration of the weakly basic organic nitrogen compound, such as a nitrile, in the hydrocarbon feed is in the range of from 30 ppb-wt to 100 ppm-wt of the hydrocarbon feed.

The hydrocarbon feed stream comprises one or more unsaturated aliphatic compounds comprising an unsaturated cyclic hydrocarbon having one or more double bonds and a linear and olefinic hydrocarbon (olefin). Thus, as used herein, the term "olefinic hydrocarbon" encompasses a diolefin compound. In one embodiment, the unsaturated aliphatic compound is an olefin compound, and the unsaturated aliphatic compound may be a diene compound. In one embodiment, the unsaturated aliphatic compound is one or more diolefin compounds having 4, 5 or 6 carbon atoms per molecule, ie, the unsaturated aliphatic compound may be selected from C4 diolefins, C5 diolefins, C6 II. a group of diolefins composed of olefins and mixtures thereof. In another embodiment, the diene compound is selected from the group consisting of butadiene, pentadiene, methyl butadiene, hexadiene, methyl pentadiene, dimethyl butadiene, acetylene, and Its mixture.

In one embodiment, the concentration of the diene compound in the hydrocarbon feed is in the range of from 30 ppb-wt to 3000 ppm-wt of the hydrocarbon feed; and the concentration of the diolefin compound can be between 50 ppb-wt of the hydrocarbon feed. Up to 2000 ppm-wt. The hydrocarbon feed stream can include other olefins, such as monoolefins. Typically, the total concentration of all olefins in the hydrocarbon feed stream is no greater than 1.0 wt-% olefin.

In one embodiment, the aromatic compound includes benzene, the nitrogen compound includes an organic nitrogen compound, and the unsaturated aliphatic compound includes an olefin compound. In another embodiment, the aromatic compound comprises benzene, the nitrogen compound comprises an organic nitrogen compound, and the unsaturated aliphatic compound comprises a diolefin compound, optionally having from 4 to 6 carbon atoms per molecule.

In one mode, the adsorbent used in the present invention comprises clay. Suitable clays include, for example, beidellite, lithium bentonite, laponite, montmorillonite, nontronite, saponite, bentonite, and mixtures thereof. Examples of suitable commercially available clay adsorbents include F-series adsorbents available from BASF and TONSIL adsorbents such as CO 630 G and CO 616 GS available from SudChemie. In one embodiment, the clay adsorbent is acid activated bentonite and/or montmorillonite clay.

In another aspect, the method comprises using activated carbon. Activated carbon is well known in the art and can be derived from various sources including petroleum coke, coal, wood, and shells (e.g., coconut shells) using carbonization and/or activation process steps. Activation can be accomplished, for example, by heat treatment in an atmosphere of CO ₂ , H ₂ O, and mixtures thereof, by chemical processing steps, and combinations thereof. Suitable activated carbons are commercially available and are available, for example, from Calgon.

In yet another aspect, the method comprises using an acidic molecular sieve to adsorb or otherwise remove the unsaturated aliphatic compound from the hydrocarbon feed stream. Suitable acidic molecular sieves include various forms of bismuth aluminum phosphate and aluminum phosphate and zeolite molecular sieves as disclosed in U.S. Patent No. 4,440,871, U.S. Patent No. 4,310,440, and U.S. Patent No. 4,567,. As used herein, the term "molecular sieve" is defined as a type of adsorbent desiccant having a highly crystalline nature and a crystallographically defined microporosity or channel, as opposed to materials such as gamma-alumina. A preferred type of molecular sieve system of such a crystalline adsorbent is commonly referred to as aluminosilicate material of zeolite. The term "zeolite" generally refers to a group of naturally occurring or synthetic hydrated metal aluminosilicates, many of which have a crystalline structure. The zeolite molecular sieve in calcined form can be represented by the following formula:

Me _2/n O: Al ₂ O ₃ : xSiO ₂ : yH ₂ O

Wherein Me is a cation, x has a value from 2 to infinity, n is a cationic valence and y has a value of 2 to 10. Typical well-known zeolites which may be used include the following chabazite (also known as zeolite D), clinoptilolite, erionite, faujasite, zeolite beta (BEA), zeolite Ω, zeolite X, zeolite Y, MFI. Zeolite, zeolite MCM-22 (MWW), ferrierite, mordenite, zeolite A, zeolite P and UZM-8 type zeolite. A detailed description of some of the zeolites identified above can be found in D. W. Breck, ZEOLITE MOLECULAR SIEVES, John Wiley and Sons, New York, 1974.

There are significant differences in chemical composition, crystal structure, and physical properties (such as X-ray powder diffraction patterns) between various synthetic materials and natural materials. The molecular sieve system is present as an accumulation of fine crystals or synthesized as a fine powder, and is preferably tableted or granulated for large-scale adsorption applications. The granulation process is known in the art and is highly satisfactory because the adsorption characteristics of the molecular sieve remain substantially unchanged in terms of both selectivity and capacity. In one embodiment, the adsorbent comprises zeolite Y and/or zeolite X having an alumina or ceria binder and/or beta zeolite having an alumina or ceria binder. In one embodiment, the acidic molecular sieve is zeolite Y.

In one embodiment, the molecular sieve will typically be used in combination with a refractory inorganic oxide binder. The binder may comprise alumina or ceria, with the former being preferred and gamma-alumina, eta-aluminum and mixtures thereof being especially preferred. The molecular sieve may be present in the range of from 5 wt-% to 99 wt-% of the adsorbent and the refractory inorganic oxide may be present in the range of from 1 wt-% to 95 wt-%. In one embodiment, the molecular sieve will be present in an amount of at least 50 wt-% of the adsorbent and more preferably in an amount of at least 70 wt-% of the adsorbent.

The molecular sieve in the adsorbent of the present invention is acidic. Using the ratio of bismuth to aluminum as the specification of acidity, in one embodiment the ratio of bismuth to aluminum should be no greater than 100 and in another embodiment no greater than 25. The cations on the molecular sieve are undesirable. Therefore, pickling may be desirable in the case of zeolite Y and zeolite beta to remove an alkali metal such as sodium to reveal more acid sites, thereby increasing the adsorption capacity. Aluminum should also be prevented from migrating out of the skeleton into the binder, thus reducing acidity. To some extent, the inclusion of cations (such as alkaline earth elements and rare earth elements) in zeolite X or Y will improve the thermal stability and hydrothermal stability of the framework aluminum, and minimize the amount of framework aluminum that migrates out of the skeleton. Sites with different acid strengths are obtained. The amount of cation incorporated should be balanced to improve overall acidity and/or hydrothermal stability without inhibiting adsorption performance, which may occur at higher cation loadings. The molecular sieve adsorbent of the present invention may have the same composition as the alkylation catalyst in a downstream reactor such as an alkylation or transalkylation unit. However, when the alkylation catalyst is more expensive than the molecular sieve adsorbent, the composition of the alkylation catalyst and the molecular sieve is preferably different.

The hydrocarbon feed stream to be treated is contacted with one of a clay adsorbent, an acidic molecular sieve, and activated carbon under contact conditions to remove one or more unsaturated aliphatic compounds and produce a treated hydrocarbon stream. The unsaturated aliphatic compound can be removed from the hydrocarbon stream by various mechanisms, such as adsorption with an adsorbent, reaction with an adsorbent, and reactive adsorption. The unsaturated hydrocarbon content of the treated hydrocarbon stream is reduced relative to the unsaturated fatty acid content of the hydrocarbon feed stream.

Contact conditions include a temperature of at least 50 ° C in the case of using a clay adsorbent or activated carbon, and a temperature of at least 25 ° C in the case of using an acidic molecular sieve, and at least 50 ppm by weight relative to the hydrocarbon feed stream. The amount of water is carried out in the presence of water. Water may be present in an amount equal to or greater than the saturation point of the hydrocarbon feed stream under contact conditions. In one embodiment, the water system is present in an amount of at least 250 ppm by weight relative to the hydrocarbon feed stream. In another embodiment, the water system is present in an amount ranging from 300 ppm to 800 ppm by weight relative to the hydrocarbon feed stream, and the water may be between 450 ppm by weight relative to the hydrocarbon feed stream. The amount in the 700 ppm range exists. The amount of water during the contact can be controlled in any suitable manner. For example, the water content of the hydrocarbon feed can be monitored and controlled by drying the feed stream and/or adding water or a compound that produces water to the feed stream. Water or water-forming compounds can be introduced as an individual stream to the contacting step, and the feed stream can be dried to a consistent water content while water or water-forming compounds are added to achieve the desired level.

In the manner of using a clay adsorbent, the contact temperature is in the range of 50 ° C to 300 ° C and the contact temperature may be in the range of 50 ° C to 125 ° C. In another embodiment, the contact temperature is in the range of from 75 °C to 250 °C; and the contact temperature can be in the range of from 100 °C to 225 °C. In the manner in which activated carbon is used to contact the hydrocarbon stream, the contact temperature is in the range of from 100 °C to 300 °C. In another embodiment, the contact temperature is in the range of from 125 °C to 300 °C; and the contact temperature can be in the range of from 150 °C to 300 °C. In yet another mode in which the hydrocarbon stream is contacted with the acidic molecular sieve, the contact temperature is in the range of from 25 °C to 300 °C and the contact temperature can be in the range of from 45 °C to 115 °C. In another embodiment, the contact temperature is in the range of from 45 °C to 110 °C; and the contact temperature can be in the range of from 50 °C to 110 °C.

In embodiments where a clay adsorbent is used to contact the hydrocarbon stream, the amount of water is at least 50 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 50 ° C Up to 300 ° C; (iii) in the range of 50 ° C to 125 ° C; (iv) in the range of 75 ° C to 250 ° C; or (v) in the range of 100 ° C to 225 ° C. In one embodiment, the amount of water is at least 250 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 50 ° C and 300 ° C; ) ranging from 50 ° C to 125 ° C; (iv) ranging from 75 ° C to 250 ° C; or (v) ranging from 100 ° C to 225 ° C. In another embodiment, the amount of water is equal to or exceeds the saturation point of the hydrocarbon feed stream under contact conditions, and the contact temperature: (i) is at least 50 ° C; (ii) is between 50 ° C and 300 ° C. (iii) in the range of 50 ° C to 125 ° C; (iv) in the range of 75 ° C to 250 ° C; or (v) in the range of 100 ° C to 225 ° C. In another embodiment, the amount of water is in the range of 300 ppm to 800 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 50 ° C and In the range of 300 ° C; (iii) in the range of 50 ° C to 125 ° C; (iv) in the range of 75 ° C to 250 ° C; or (v) in the range of 100 ° C to 225 ° C. In one embodiment, the amount of water is in the range of 450 ppm to 700 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 50 ° C and 300 Within the range of °C; (iii) in the range of 50 °C to 125 °C; (iv) in the range of 75 °C to 250 °C; or (v) in the range of 100 °C to 225 °C. The contact conditions may additionally include a pressure of from 34.5 kPa (g) to 4136.9 kPa (g), as the case may be. In one embodiment, the contacting is carried out using a feed in a liquid phase or a partial liquid phase. Gas phase contact can be used.

In another embodiment in which the activated carbon is used to contact the hydrocarbon stream, the amount of water is at least 50 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 100 ° C Up to 300 ° C; (iii) in the range of 125 ° C to 300 ° C; or (iv) in the range of 150 ° C to 300 ° C. In one embodiment, the amount of water is at least 250 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 100 ° C and 300 ° C; Iii) ranging from 125 ° C to 300 ° C; or (iv) ranging from 150 ° C to 300 ° C. In another embodiment, the amount of water is equal to or exceeds the saturation point of the hydrocarbon feed stream under contact conditions, and the contact temperature: (i) is at least 50 ° C; (ii) is between 100 ° C and 300 ° C. (iii) in the range of 125 ° C to 300 ° C; or (iv) in the range of 150 ° C to 300 ° C. In another embodiment, the amount of water is in the range of 300 ppm to 800 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 100 ° C and In the range of 300 ° C; (iii) in the range of 125 ° C to 300 ° C; or (iv) in the range of 150 ° C to 300 ° C. In one embodiment, the amount of water is in the range of 450 ppm to 700 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 50 ° C; (ii) is between 100 ° C and 300 Within the range of °C; (iii) in the range of 125 ° C to 300 ° C; or (iv) in the range of 150 ° C to 300 ° C. The contact conditions may additionally include a pressure of from 34.5 kPa (g) to 4136.9 kPa (g), as the case may be. In one embodiment, the contacting is carried out using a feed in a liquid phase or a partial liquid phase. Gas phase contact can be used.

In another embodiment in which the acidic molecular sieve is used to contact the hydrocarbon stream, the amount of water is at least 50 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 25 ° C; (ii) is between 25 ° C Up to 300 ° C; (iii) in the range of 45 ° C to 115 ° C; (iv) in the range of 45 ° C to 110 ° C; or (v) in the range of 50 ° C to 110 ° C. In one embodiment, the amount of water is at least 250 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 25 ° C; (ii) is between 25 ° C and 300 ° C; Iii) ranging from 45 °C to 115 °C; (iv) ranging from 45 °C to 110 °C; or (v) ranging from 50 °C to 110 °C. In another embodiment, the amount of water is equal to or exceeds the saturation point of the hydrocarbon feed stream under contact conditions, and the contact temperature: (i) is at least 25 ° C; (ii) is between 25 ° C and 300 ° C. (iii) is in the range of 45 ° C to 115 ° C; (iv) is in the range of 45 ° C to 110 ° C; or (v) is in the range of 50 ° C to 110 ° C. In another embodiment, the amount of water is in the range of 300 ppm to 800 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 25 ° C; (ii) is between 25 ° C and In the range of 300 ° C; (iii) in the range of 45 ° C to 115 ° C; (iv) in the range of 45 ° C to 110 ° C; or (v) in the range of 50 ° C to 110 ° C. In one embodiment, the amount of water is in the range of 450 ppm to 700 ppm by weight relative to the hydrocarbon feed stream, and the contact temperature: (i) is at least 25 ° C; (ii) is between 25 ° C and 300 Within the range of °C; (iii) in the range of 45 °C to 115 °C; (iv) in the range of 45 °C to 110 °C; or (v) in the range of 50 °C to 110 °C. The contact conditions may additionally include a pressure of from 34.5 kPa (g) to 4136.9 kPa (g), as the case may be. In one embodiment, the contacting is carried out using a feed in a liquid phase or a partial liquid phase. Gas phase contact can be used.

The bromine index is typically used to assess the content of unsaturated aliphatic (including olefins and diolefins) of the hydrocarbon mixture. In one embodiment, the present invention removes at least 50% of the unsaturated aliphatic compound from the hydrocarbon feed stream. That is, in this embodiment, the bromine index of the treated hydrocarbon stream is at most 50% of the bromine index of the hydrocarbon feed stream. As used herein, the bromine index of a hydrocarbon stream or mixture is determined using the method UOP304. In embodiments in which a clay adsorbent is used to contact a hydrocarbon stream, the present invention removes at least 70 wt% of the diolefin compound from the hydrocarbon feed stream; and the present invention can remove at least 90 wt% or at least 95 wt% from the hydrocarbon feed stream. % diolefin compound. In another embodiment using activated carbon to contact a hydrocarbon stream, the present invention removes at least 30 wt% of the diolefin compound from the hydrocarbon feed stream; and the present invention can remove at least 50 wt% or at least 80 from the hydrocarbon feed stream. A wt% diolefin compound. In another embodiment in which an acidic molecular sieve is used to contact a hydrocarbon stream, the present invention removes at least 50 wt% of the diolefin compound from the hydrocarbon feed stream; and the present invention can remove at least 70 wt% or at least 85 from the hydrocarbon feed stream. A wt% or at least 90 wt% diolefin compound. Herein, the diene content of the hydrocarbon stream or mixture is determined by the method UOP980. Analytical methods used herein (e.g., UOP 304 and UOP 980) are obtained from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA, USA, unless otherwise indicated.

In another embodiment, the invention additionally includes passing at least a portion of the treated hydrocarbon stream through a nitrogen removal zone that produces an alkylation substrate stream having a lower nitrogen compound concentration relative to the treated hydrocarbon stream. As discussed above, various methods of removing nitrogen compounds from aromatic hydrocarbon streams are well known in the art. See, for example, US 7,205,448, US 7, 744, 828, US 6, 297, 417; each of which is incorporated herein by reference in its entirety. Briefly, the treated hydrocarbon stream is introduced into a nitrogen removal zone comprising at least one adsorbent that effectively removes nitrogen. Suitable adsorbents include clays, resins and zeolites. Typically, clay and zeolite adsorbents are acidic. The nitrogen removal zone can include two adsorbents, such as a clay or resin adsorbent located upstream of the zeolite adsorbent such that the treated hydrocarbon stream first contacts the clay or resin adsorbent to create an intermediate stream which is then contacted with the zeolite adsorbent. Different operating conditions including temperature and amount of water present have been disclosed for different adsorbents and for the use of multiple adsorbents in the nitrogen removal zone.

In one embodiment, the treated hydrocarbon stream is contacted with an adsorbent comprising an acidic molecular sieve under nitrogen removal conditions to produce an alkylated substrate stream having a reduced nitrogen content. In one embodiment, the molecular sieve is a zeolite. Well-known zeolites which may be used include the following chabazite (also known as zeolite D), clinoptilolite, erionite, faujasite, zeolite beta (BEA), zeolite Ω, zeolite X, zeolite Y, MFI zeolite, Zeolite MCM-22 (MWW), ferrierite, mordenite, zeolite A, zeolite P and UZM-8 type zeolite. In one embodiment, the nitrogen removal conditions comprise a temperature in the range of at least 120 ° C to 300 ° C and the presence of water in an amount ranging from 20 ppm to 500 ppm by weight relative to the treated hydrocarbon stream.

In another embodiment, the invention further comprises passing at least a portion of the alkylation substrate stream from the nitrogen removal zone through the alkylation zone, wherein the partially alkylated matrix stream and the alkylating agent are alkylated The catalyst is contacted to produce an alkylated benzene product.

In the selective alkylation of an aromatic alkylation matrix by an acid catalyst-catalyzed olefin alkylating agent, the olefin may contain from 2 to at least 20 carbon atoms and may have a branched or linear olefin, terminal Or internal olefins. Therefore, the specific nature of the olefin is not particularly important. Common to the alkylation reaction is that the reaction is carried out under at least a portion of the liquid phase conditions, a criterion readily achievable by adjusting the reaction pressure for lower carbon number members. Among the lower carbon number olefins, ethylene and propylene are the most important representatives. The olefin feed stream comprising an alkylating agent can comprise ethylene and/or propylene. Typically, the olefin feed stream comprising propylene can be at least 65 wt% pure and the olefin feed stream comprising ethylene can be more than 80 wt% pure. Among the remaining olefins, detergent-range olefins composed of linear olefins having 6 or up to 20 carbon atoms which are internally or terminally unsaturated are of particular interest. Linear olefins having from 8 to 16 carbon atoms and especially from 10 to up to 14 carbon atoms are particularly useful as detergent range olefins. The alkylating agent can also be provided by the alkyl component of the polyalkylbenzene in the transalkylation reaction zone. Diethylbenzene, triethylbenzene and diisopropylbenzene provide outstanding examples of polyalkylbenzenes of such alkylating agents.

A variety of catalysts can be used in the alkylation reaction zone. Suitable catalysts for use in the alkylation zone comprise a catalyst that does not suffer from the deleterious effects of the water present. Preferably, a large amount of water can be tolerated or desired in the presence of an alkylation catalyst. A large amount of water preferably means that the concentration of water in the reactants entering the alkylation zone is at least 50 wppm. The water content of the alkylation reaction zone can be as little as 20 wppm to over 200 wppm and up to 1000 wppm or more. A preferred catalyst-based zeolite catalyst for use in the present invention. The catalyst of the present invention is typically used in combination with a refractory inorganic oxide binder. Preferred binders are alumina or cerium oxide. Suitable zeolites include zeolite beta, ZSM-5, PSH-3, MCM-22, MCM-36, MCM-49, MCM-56, Y-type zeolite and UZM-8 as described in US 5,723,710, which is described in UZM-8 Aluminosilicates and substituted aluminosilicate zeolites in U.S. Patent 6,756,030 and modified UZM-8 zeolites (e.g., UZM-8HS as described in U.S. Patent 7,091,390). Each of US 6,756,030 and US 7,091,390 is incorporated herein by reference in its entirety.

The basic configuration of the catalytic aromatic alkylation zone is known in the art. The feed aromatic alkylation base and feed olefin alkylating agent are preheated and loaded into typically 1 to 4 reactors in series. Suitable cooling means can be provided between the reactors to compensate for the net exotherm of the reaction in each reactor. Suitable mechanisms may be provided upstream of each reactor or provided to each reactor to feed additional aromatics, feed olefins or other streams (eg, reactor effluent or containing one or more polyalkyl groups) The benzene stream) is loaded into any of the alkylation zones. Each alkylation reactor may contain one or more alkylation catalyst beds. The present invention encompasses a two-zone aromatic alkylation process, such as those described in US 7,420,098, which is incorporated herein by reference in its entirety.

The specific conditions for carrying out the alkylation reaction depend on the aromatic compound and the olefin used. A necessary condition is to carry out the reaction under at least partial liquid phase conditions. Thus, the reaction pressure is adjusted to maintain at least partial dissolution of the olefin in the liquid phase. For higher carbon number olefins, the reaction can be carried out under autogenous pressure. The alkylation conditions typically comprise a pressure in the range between 1379 kPa (g) and 6985 kPa (g). In one embodiment, the pressure system is in the range of between 2069 kPa (g) and 4137 kPa (g). Alkylation of the aromatic compound with an olefin in the range of from C2 to C20 can be carried out at a temperature of from 60 ° C to 400 ° C, and preferably from 90 ° C to 250 ° C, for a time sufficient to form the desired product. In a continuous process, this time can vary considerably, but in the case of olefins it is typically from 0.1 hr -1 to 8 hr -1 weight hourly space velocity (WHSV). As used herein, the weight hourly space velocity of a component means the weight flow per hour component divided by the catalyst weight in the same measurement unit. In particular, the alkylation of benzene with ethylene can be carried out at a temperature of from 150 ° C to 250 ° C and the alkylation of benzene with propylene is carried out at a temperature of from 90 ° C to 200 ° C. The ratio of alkylatable aromatic compound to olefin used in the process of the present invention depends on the degree of monoalkylation desired and the relative cost of the aromatic and olefin components of the reaction mixture. For alkylation of benzene by propylene, the molar ratio of benzene to olefin can be as low as 0.1 and as high as 10, with a ratio of 0.5 to 3 being preferred. If benzene is alkylated with ethylene, the ratio of benzene to olefin may be between 0.1 and 10, with a ratio of 0.5 to 4 being preferred. For C6 to C20 detergent range olefins, a ratio of benzene to olefin between 5 and 30 is typically sufficient to achieve the desired monoalkylation yield, with a range between 8 and 20 being even better.

The alkylation reaction zone will often provide a variety of secondary by-products. For example, in the alkylation of benzene with ethylene to produce ethylbenzene, the reaction zone may also produce diethylbenzene and triethylbenzene in addition to other ethylene condensation products. Similarly, in the alkylation of benzene with propylene to produce cumene, dipropylbenzene and triisopropylbenzene can be produced in the reaction zone in addition to more condensation products. As is well known in the art, the polyalkylated aromatic compounds can be contacted with other aromatic matrices in the transalkylation zone to produce other monoalkylated products. See, for example, US 7,622,622 and US 7,268,267. Furthermore, since the transalkylation reaction takes place in the alkylation reaction zone and the alkylation reaction takes place in the transalkylation reaction zone, the two zones may be referred to as alkylation zones. Thus, as used herein, the term "alkylation zone" encompasses a transalkylation zone. In one embodiment, the alkylated benzene product comprises at least one of ethylbenzene and cumene.

In another embodiment, the invention is a process for producing an alkylated benzene compound. The method includes contacting a hydrocarbon feed stream comprising benzene, an organic nitrogen compound, and a diolefin compound with one of an adsorbent comprising clay, an acidic molecular sieve, and activated carbon. The diolefin compound has 4 to 6 carbon atoms per molecule, as the case may be. Contact conditions include a temperature of at least 50 ° C in the case of using a clay adsorbent or activated carbon and a temperature of at least 25 ° C in the case of using an acidic molecular sieve, and an amount of at least 50 ppm by weight relative to the hydrocarbon feed stream. water. The contacting step removes the diolefin compound and produces a concentration of the diolefin compound that is lower than the treated hydrocarbon stream of the hydrocarbon feed stream. At least a portion of the treated hydrocarbon stream is passed through a nitrogen removal zone, which removes the organic nitrogen compound and produces an alkylation substrate stream having a lower concentration of organic nitrogen compounds relative to the treated hydrocarbon stream. At least a portion of the alkylation substrate stream is passed through an alkylation zone wherein the portion of the alkylation substrate stream and the alkylating agent are contacted with an alkylation catalyst to produce an alkylated benzene compound. In one embodiment, the alkylated benzene compound is a monoalkylated benzene compound, which can include at least one of ethylbenzene and cumene.

Example 1

According to one embodiment, the adsorbent used in the present invention is a commercially available acid-treated clay obtained from Sud-Chemie under the product name TONSIL CO 630 G.

Example 2

According to another approach, commercially available activated carbon is available from Calgon.

Example 3

According to another embodiment, the sample of zeolite Y exchanged by mass of ammonium ions slurried steam reforming and the solution temperature was raised to 75 ℃ (167 ℉) to 15 wt% NH ₄ NO ₃ solution. The steam-modified ammonium ion exchange Y zeolite is a stabilized sodium Y zeolite having an overall Si/Al ₂ ratio of 5.2, a unit cell size of 24.53, and a sodium content of 2.7 calculated as Na ₂ O on a dry weight basis. Wt%. The steam reformed ammonium ion exchange Y zeolite system was prepared from sodium Y zeolite having a total Si/Al ₂ ratio of 4.9, a unit cell size of 24.67 and a sodium content calculated as Na ₂ O on a dry weight basis. 9.4 wt%, which is ammonium exchanged to remove 75% of Na and then generally by the following steps (1) and (the procedure set forth in the fourth row, column 47, column 5, column 2 of US 5,324,877; 2) Dealuminization by steam at 600 ° C (1112 ° F). After 1 hour of contact at 75 ° C (167 ° F), the slurry was filtered and the filter cake was washed with excess warm deionized water. The NH ₄ + ion exchange, filtration and water washing steps were repeated two more times, and the overall Si/Al ₂ ratio of the obtained filter cake was 5.2, and the sodium content calculated by Na ₂ O was 0.13 wt% on a dry basis. The unit cell size is 24.572 And the absolute intensity as determined by X-ray diffraction is 96. The obtained filter cake is dried to a suitable moisture content, and mixed with HNO ₃ peptized Pural SB alumina to obtain a mixture of 80 parts by weight of the zeolite and 20 parts by weight of the Al 2 O 3 binder on a dry basis, and then extruded. Into a 1.6 mm diameter cylindrical extrudate. The extrudate was dried and calcined in flowing air at 600 ° C for 1 hour to obtain a comparative zeolite adsorbent having a unit cell size of 24.494. The absolute intensity of XRD was 61.1, and the proportion of aluminum in the modified Y zeolite was 57.2%.

Example 4

A sample of an industrial benzene recycle stream (>99 wt% benzene) containing olefins, diolefins, and nitrogen compounds that was not dried or otherwise treated was used as a hydrocarbon feed to evaluate the adsorbents of Examples 1-3 to remove unsaturated aliphatics. The potency of the compound. The analysis of the feed and the analysis of the effluent or product from each test are reported in Table 1. The unsaturated aliphatic content was determined by the bromine index method UOP304. The diolefin content was determined by UOP 980, which was modified to improve the sensitivity of the process to detect lower levels of diolefins. UOP 980 is followed in addition to sample size changes, and as is known to those skilled in the art, lower concentration standard solutions are used during instrument calibration to improve the detection of lower concentrations of diolefins in the sample. Modification of UOP 980 does not alter the relative measurement between different samples, but it is possible to quantify and/or make it possible to modify the concentration of diolefins having a concentration of less than 500 ppm-wt and especially less than 100 ppm-wt. The industrial benzene recycle stream also contains water near saturation, so the contact conditions comprise water in an amount of from 600 ppm to 800 ppm by weight relative to the hydrocarbon feed stream.

Prior to testing, the adsorbent was pre-dried in flowing nitrogen at 250 °C for 4 hours. The adsorption experiments were carried out in an autoclave which was first purged with nitrogen followed by 0.6 g of adsorbent and 30 g of hydrocarbon feed. The autoclave was then pressurized to 400 psig for each test and ramped to the temperatures listed in Table 1. The autoclave contained a mixer set to 100 rpm. When the specified temperature was reached, the autoclave was kept at the same temperature for 1 hour while mixing. Thereafter, the heating was turned off to cool the autoclave to room temperature and the mixing was stopped. The used adsorbent is separated from the liquid product or effluent, sampled and analyzed.

The data shows that each of the materials in Examples 1-3 is effective for removing unsaturated aliphatic hydrocarbons (as determined by the bromine index) and removing diolefins. The clay adsorbent of Example 1 of the present invention exhibits unexpected selectivity and stability in removing diolefins. At each of the temperatures evaluated, the clay adsorbent exhibited significantly higher diene removal compared to the removal of unsaturated aliphatics, thereby exhibiting removal of the diene relative to the general type of unsaturated aliphatic compound. Higher selectivity. Surprisingly, the amount of diene removed by the clay adsorbent of Example 1 was largely unaffected by the temperature range evaluated. The activated carbon of Example 2 of the present invention exhibits similar selectivity for removal of unsaturated aliphatic hydrocarbons and removal of diolefins, wherein the amount removed at higher contact temperatures is greater. The acidic molecular sieve of Example 3 of the present invention exhibits similar selectivity for removal of unsaturated aliphatic hydrocarbons and removal of diolefins, wherein the amount removed at higher contact temperatures is greater.

Claims (10)

A method for treating a hydrocarbon feed stream comprising an aromatic compound, a nitrogen compound, and an unsaturated aliphatic compound, the method comprising: contacting the hydrocarbon feed stream with an adsorbent comprising clay under contact conditions Contacting one of an acidic molecular sieve and activated carbon to remove the unsaturated aliphatic compound and produce a treated hydrocarbon stream, the contacting conditions comprising a temperature of at least 25 ° C and the presence of a weight relative to the hydrocarbon feed stream At least 50 ppm of water. The method of claim 1 wherein the water system is present in an amount equal to or greater than a saturation point of the hydrocarbon feed stream under the contacting conditions. The method of claim 1 wherein the aqueous system is present in an amount of at least 250 ppm by weight relative to the hydrocarbon feed stream. The method of claim 1 wherein contacting the hydrocarbon feed stream comprises contacting the hydrocarbon feed stream with a clay adsorbent and the temperature is in the range of from 50 °C to 300 °C. The method of claim 1, wherein contacting the hydrocarbon feed stream comprises contacting the hydrocarbon feed stream with an acidic molecular sieve and the temperature is in the range of from 45 °C to 115 °C. The method of claim 1, wherein contacting the hydrocarbon feed stream comprises contacting the hydrocarbon feed stream with activated carbon and the temperature is in the range of from 100 °C to 300 °C. The method of claim 1 wherein the hydrocarbon feed stream has a nitrogen content ranging from 1 ppm to 10 ppm-wt. The method of claim 1, wherein the nitrogen compound is selected from the group consisting of organic nitrogen compounds consisting of basic organic nitrogen compounds, nitriles, and mixtures thereof. The method of claim 1, wherein the unsaturated aliphatic compound is a diolefin compound. The method of claim 9, wherein the diolefin compound is selected from the group consisting of butadiene, pentadiene, methyl butadiene, hexadiene, methyl pentadiene, dimethyl butadiene , acetylene and mixtures thereof.