Process for production of xylenes and olefin cracking feedstocks

Abstract

The invention relates to the technical field of catalytic cracking and alkylation, and discloses a method for producing xylene and an olefin cracking material. The method comprises the following steps: in the presence of a catalyst and hydrogen, carrying out catalytic cracking coupling alkylation reaction on aromatic hydrocarbon and aliphatic hydrocarbon; the catalyst comprises a silicon-modified molecular sieve and carbon loaded on the silicon-modified molecular sieve; on the basis of the total amount of the catalyst, the content of silicon is 0.5-10 wt% and the content of carbon is 0.05-2 wt% on the basis of oxides. According to the method, aliphatic hydrocarbon and aromatic hydrocarbon can be effectively converted into xylene and olefin cracking materials, the problems that in the prior art, the aromatic hydrocarbon production technology is short and the low-carbon light hydrocarbon source is insufficient are effectively solved, and the selectivity of the target product p-xylene and the stability of the catalyst can be effectively improved by selecting the silicon modified and pre-carbon-deposited catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic cracking and alkylation, and in particular to a method for producing xylene and olefin cracking materials. Background Art

[0002] With the rapid growth of my country's economy and the rapid development of the polyester industry, the demand for aromatics is growing. Traditional BTX production is based on catalytic reforming and cracking gasoline as the main raw materials. However, due to the scarcity of petroleum resources and the increasing demand for BTX, the existing aromatics generation technology can no longer meet the market demand, and new process production technologies are urgently needed to increase the production of light aromatics. Among them, xylene is widely used in coatings, resins, dyes, inks and other industries. In particular, p-xylene is the main raw material for the production of p-dibenzoic acid, and then produces polyester resins such as polyethylene terephthalate and butanediol. At present, the production methods of olefins mainly come from three categories: naphtha cracking, methanol to olefins and light hydrocarbon cracking. Among them, naphtha steam cracking has always been the main route for the preparation of olefins, but the shale gas revolution in the United States has driven the rapid expansion of non-oil olefins. Compared with traditional naphtha processing olefins, low-carbon light hydrocarbons to olefins have the advantages of high olefin yield, low energy consumption, short process, low cost, strong economy and pollution. Therefore, the proportion of light hydrocarbon cracking to prepare olefins has been gradually increasing in recent years. Due to the shortage of low-carbon light hydrocarbon resources in my country, it is urgent to expand the sources of low-carbon light hydrocarbons. Ethane cracking to produce ethylene and propane dehydrogenation to produce propylene are both affected by the raw materials ethane and propane.

[0003] C5 and above alkanes are rich in C 1 , C 2 and C 3 Resources. 1 The resource can be effectively connected with benzene or toluene ring to produce xylene, and the C 2 and C 3 As a raw material for olefin cracking, the resource will effectively increase the added value of alkanes with carbon 5 and above. However, the acid catalyst has a high initial activity and is prone to carbon deposition during the cracking reaction, which leads to a decrease in the number of active centers of the catalyst, thereby causing the catalyst to slowly deactivate. It is a common method of industrial production to inhibit the initial activity through effective means. Ammonia injection is a common way to passivate industrial acid catalysts, which increases the energy consumption of industrial production. By passivating the catalyst production process in advance, the production efficiency will be greatly improved. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of shortage of new routes for producing light aromatics, insufficient demand for domestic low-carbon light hydrocarbon sources and easy deactivation of catalysts in the prior art, and to provide a method for producing xylene and olefin cracking materials. The method can effectively convert aliphatic hydrocarbons and aromatics into xylene and olefin cracking materials, effectively solving the problems of shortage of aromatics production technology and insufficient low-carbon light hydrocarbon sources in the prior art, and the selection of silicon-modified and pre-carbonized catalysts can effectively improve the selectivity of the target product to xylene and the stability of the catalyst.

[0005] In order to achieve the above-mentioned object, the present invention provides a method for producing xylene and olefin cracking materials, wherein the method comprises: in the presence of a catalyst and hydrogen, subjecting aromatic hydrocarbons and aliphatic hydrocarbons to a catalytic cracking coupled alkylation reaction; the catalyst comprises a silicon-modified molecular sieve and carbon supported on the silicon-modified molecular sieve; based on the total amount of the catalyst, the content of silicon in terms of oxide is 0.5-10% by weight, and the content of carbon is 0.05-2% by weight.

[0006] The method provided by the present invention can, under preferred circumstances, effectively convert C5 and above alkanes with benzene and / or toluene into xylene and olefin cracking materials by catalytic cracking coupled alkylation reaction, effectively solving the problems of shortage of aromatic production technology and insufficient sources of low-carbon light hydrocarbons in the prior art. In addition, under preferred circumstances, by silicon modification and pre-carbon deposition treatment of the catalyst, silicon oxide and carbonaceous materials are loaded on the molecular sieve body, which can effectively improve the selectivity of p-xylene in the target product and the stability of the catalyst.

[0007] The method provided by the present invention develops an alkane protonation cracking coupled benzene alkylation reaction, couples the endothermic reaction of alkane cracking and the exothermic reaction of benzene alkylation, fully realizes energy complementarity and reduces the defect of needing to supplement heat for the alkane. In addition, the methyl group produced by the alkane cracking is directly connected to the benzene ring, reducing the production of cheap methane. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the system provided by the present invention.

[0009] Description of Reference Numerals

[0010] 1-Aromatic hydrocarbons 2-Aliphatic hydrocarbons 3-Feed buffer tank

[0011] 4-Heat exchanger 5-Heating furnace 6-Fixed bed reactor

[0012] 7-High separation tank 8-Gas phase product 9-Liquid phase product DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] The present invention provides a method for producing xylene and olefin cracking materials, wherein the method comprises: in the presence of a catalyst and hydrogen, subjecting aromatic hydrocarbons and aliphatic hydrocarbons to a catalytic cracking coupled alkylation reaction; the catalyst comprises a silicon-modified molecular sieve and carbon supported on the silicon-modified molecular sieve; based on the total amount of the catalyst, the content of silicon in terms of oxide is 0.5-10% by weight, and the content of carbon is 0.05-2% by weight.

[0015] In the present invention, it should be noted that the silicon content here refers to the silicon loading amount during silicon modification in the catalyst preparation process, which does not include the silicon contained in the molecular sieve itself.

[0016] In the present invention, on the one hand, aromatic hydrocarbons and aliphatic hydrocarbons are selected as reaction raw materials for catalytic cracking coupled alkylation reaction to produce xylene and olefin cracking materials, which can solve the problems of shortage of aromatic hydrocarbon production technology and insufficient source of low-carbon olefins in the prior art; on the other hand, the catalyst composed of silicon-modified molecular sieve and carbonaceous material is selected to reduce the initial activity of the catalyst, and the pre-carbon deposition of the catalyst is achieved with the help of carbon-containing material, thereby avoiding the ammonia injection passivation in the prior art, reducing the production cost and improving the stability of the catalyst, thereby improving the selectivity of xylene in the target product and the stability of the catalyst.

[0017] In the present invention, preferably, the content of silicon in oxide is 0.5-5% by weight, and the content of carbon is 0.05-1% by weight, based on the total amount of the catalyst. The advantages of adopting this preferred embodiment are stable reaction activity and high selectivity for para-xylene. If the silicon content and carbon content are too high, there will be a defect of blocking the molecular sieve pores, resulting in a decrease in the active sites of the catalyst and a decrease in the cracking of alkanes; on the contrary, if the silicon content and carbon content are too low, there will be a high initial reaction activity, many side reactions, rapid carbon deposition, and accelerated catalyst deactivation.

[0018] In the present invention, the content of loaded silicon oxide is obtained by analyzing the chemical composition of the sample before and after silicon modification using the S4 PIONEER X-ray fluorescence spectrometer (XRF) of Bruker, Germany, and then performing difference calculation. The specific test conditions are as follows: the powder sample needs to be at least 3-5g, and the primary X-rays emitted by the X-ray tube of the X-ray fluorescence spectrometer are injected into the sample to excite the characteristic spectral lines of each element in the sample.

[0019] In the present invention, the carbon content is calculated by feeding the material.

[0020] In the present invention, preferably, the specific surface area of ​​the catalyst is 200-400cm 2 / g, more preferably 250-400cm 2 / g, more preferably 300-400cm 2 / g. By loading carbon-containing substances on the silicon-modified molecular sieve, the initial activity of the reaction can be suppressed, the size of the pores on the surface of the molecular sieve can be reduced, and the stability of the catalyst and the selectivity of the target product p-xylene can be improved.

[0021] In the present invention, the specific surface area of ​​the catalyst is measured by using an ASAP2020 HD physical adsorption instrument from Micromeritics, USA. 2 The physical adsorption test was carried out under the following conditions: the sample was vacuum degassed at 350°C for 4 h before the test, and then the test was performed according to the operating program of the ASAP2020 HD physical adsorption instrument. The specific surface area of ​​the molecular sieve was calculated using the Brunauer-Emmett-Teller (BET) method.

[0022] In the present invention, there is no particular limitation on the type of molecular sieve. Preferably, the silicon-modified molecular sieve is at least one of Beta, MWW, MOR and ZSM-5 molecular sieves, and more preferably ZSM-5 molecular sieve. Advantages of this preferred embodiment ZSM-5 molecular sieve has strong acidity and exhibits better effects in alkane cracking and alkylation reactions.

[0023] In the present invention, preferably, the catalyst further includes a binder and / or an active metal. Based on the total amount of the catalyst, the content of the binder on a dry basis is 0-50% by weight, more preferably 10-40% by weight, and the content of the active metal on an oxide basis is 0-5% by weight, more preferably 0.05-1% by weight.

[0024] In the present invention, the contents of the binder and active metal in the catalyst are calculated by the feed amount.

[0025] In the present invention, preferably, the binder is aluminum oxide and / or silicon oxide, more preferably aluminum oxide.

[0026] In the present invention, there is no particular limitation on the type of active metal, and any active metal conventionally defined in the art is applicable to the present invention. Preferably, the active metal is selected from at least one of Mo, Ni, Cu, Ga, Zn, Mg and La, and more preferably at least one of Mo, Zn and Ni. The advantages of this preferred embodiment are used to improve the reaction activity and effectively inhibit hydrogen transfer.

[0027] It should be noted that when the active metal is Mo, the content of the active metal in the catalyst is expressed as molybdenum trioxide (MoO 3 ); When the active metal is Ni, the content of the active metal in the catalyst is measured in nickel oxide (NiO).

[0028] In the present invention, preferably, the method for preparing the catalyst comprises:

[0029] (a) mixing the molecular sieve and optionally a binder to form a body, followed by drying and first calcining;

[0030] (b) immersing the body obtained in step (a) in an organic silicon compound solution to perform silicon modification, and then performing a second calcination to obtain a silicon-modified body;

[0031] (c) impregnating the silicon-modified body obtained in step (b) into an impregnation solution containing a saccharide compound and optionally an active metal precursor, and then performing a third calcination under a protective gas to obtain a catalyst.

[0032] The stability of the catalyst and the selectivity for xylene can be improved by silicon-modifying the molecular sieve and performing a pre-carbon deposition treatment.

[0033] In the present invention, the molecular sieve, the sugar compound, and optionally the binder and the active metal precursor are used in such amounts that, based on the total amount of the catalyst, the silicon content in terms of oxide is 0.5-10% by weight, the carbon content is 0.05-2% by weight, the binder content in terms of dry basis is 0-50% by weight, and the active metal content in terms of oxide is 0-5% by weight.

[0034] In the present invention, there is no particular limitation on the type of molecular sieve, which is the same as the type of molecular sieve in the above content and will not be described in detail here.

[0035] In the present invention, preferably, in step (a), the molar ratio of silicon oxide to aluminum oxide in the molecular sieve is 25-100.

[0036] In the present invention, the molar ratio of silicon oxide to aluminum oxide of the molecular sieve is measured by S4PIONEER X-ray fluorescence spectrometry (XRF) analysis by Bruker Corporation of Germany. The test conditions are as follows: at least 3-5 g of powder sample is required, and primary X-rays emitted by an X-ray tube of the X-ray fluorescence spectrometry are injected into the sample to excite the characteristic spectral lines of each element in the sample.

[0037] In the present invention, preferably, in step (a), the amount of the binder used on a dry basis is 0-50 parts by weight based on 100 parts by weight of the molecular sieve.

[0038] In the present invention, the types of adhesives have been described in the foregoing content and will not be described again here.

[0039] In the present invention, preferably, the method for preparing the catalyst further comprises optionally introducing an extrusion aid and / or a peptizing agent during the molding process of step (a).

[0040] In the present invention, there is no specific limitation on the type and amount of the extrusion aid and the peptizing agent. Those skilled in the art can select the type and amount of the extrusion aid and the peptizing agent within a reasonable range according to the specific conditions of the extrusion molding. Preferably, the extrusion aid is selected from at least one of sesbania powder, dextrin and methylcellulose. Preferably, the peptizing agent is selected from at least one of nitric acid, acetic acid and citric acid.

[0041] In the present invention, preferably, based on 100 parts by weight of the molecular sieve, the amount of the extrusion aid is 0-5 parts by weight, and the amount of the peptizing agent is 0-2 parts by weight.

[0042] In the present invention, there is no specific limitation on the molding method. For example, the existing standard molding method can be used. Specifically, the molecular sieve and the optional binder are mixed, and the materials are added to an extruder equipped with a mold to extrude a strip-shaped extrudate.

[0043] In the present invention, the drying conditions can be selected in a wide range. Preferably, in step (a), the drying conditions include: a temperature of 80-120°C and a time of 12-24 hours.

[0044] In the present invention, preferably, the method for preparing the catalyst further comprises step (a) curing the catalyst before drying. Preferably, the curing time is 10-24 hours.

[0045] In the present invention, the conditions for the first calcination can be selected in a wide range. Preferably, in step (a), the conditions for the first calcination include: a temperature of 500-600°C and a time of 2-12 hours, and more preferably, a temperature of 550-600°C and a time of 3-6 hours.

[0046] In the present invention, there is no particular limitation on the type of the organosilicon compound. Preferably, the organosilicon compound is selected from at least one of silicone oil, silane, siloxane and polysiloxane, and more preferably at least one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methylethoxy silicone oil, polyphenylmethylsiloxane and dimethylsiloxane. The advantages of this preferred embodiment are that silicon dioxide can be effectively deposited on the outer surface of the molecular sieve, reducing the acidity of the outer surface and inhibiting the isomerization of p-xylene to other C 8 Aromatic hydrocarbons.

[0047] In the present invention, preferably, in the silicon modification process of step (b), the organosilicon compound is dissolved in a solvent to form an organosilicon compound solution as an impregnation liquid. The present invention does not particularly limit the type of solvent, for example, it can be n-hexane and / or n-heptane, and the amount of solvent used is such that the concentration of the prepared organosilicon compound solution meets the use requirements. Preferably, in step (b), the concentration of the organosilicon compound solution is 0.5-30% by weight, more preferably 10-30% by weight. The advantages of adopting this preferred embodiment can improve the selectivity of the target product to xylene.

[0048] In the present invention, the range of selection of silicon modification conditions is relatively wide. Preferably, in step (b), the silicon modification conditions include: temperature of 20-25°C, time of 2-6h, and solid-liquid weight ratio of 1:1-10. In the present invention, it should be noted that the liquid content in the solid-liquid weight ratio refers to the content of the organosilicon compound solution.

[0049] In the present invention, the second calcination conditions can be selected in a wide range. Preferably, in step (b), the second calcination conditions include: a temperature of 300-600°C and a time of 2-12 hours, and more preferably, a temperature of 500-550°C and a time of 2-6 hours.

[0050] In the present invention, there is no particular limitation on the atmosphere types of the first calcination and the second calcination. Preferably, the first calcination and the second calcination are each independently performed in an air atmosphere. The advantage of adopting this preferred embodiment is that the catalyst surface can be loaded with silicon material more uniformly.

[0051] In the present invention, there is no particular limitation on the specific method of impregnation of organosilicon modification in the silicon modification process of step (b), and it can be an impregnation method conventionally defined in the art, for example, it can be at least one of equal volume impregnation, co-impregnation and step-by-step impregnation. In a preferred embodiment, the present invention adopts equal volume impregnation for silicon modification. In a more preferred embodiment, the equal volume impregnation method comprises: impregnating the body obtained in step (a) in an equal volume in an organosilicon compound solution, and the impregnation time is 2-6 hours.

[0052] In the present invention, it should be noted that when step (a) does not contain a binder, in step (b), the silicon-modified entity refers to a silicon-modified molecular sieve.

[0053] In the present invention, preferably, in step (c), the sugar compound is selected from at least one of monosaccharides, disaccharides, polysaccharides and complex sugars, more preferably at least one of sucrose, glucose, fructose and sucralose, and even more preferably sucrose and / or sucralose. The advantages of this preferred embodiment are used to improve the catalyst stability and the selectivity of the target product p-xylene.

[0054] In the present invention, preferably, in step (c), based on 100 parts by weight of the molecular sieve, the amount of the carbohydrate compound used is 0.1-8 parts by weight, more preferably 0.1-3.5 parts by weight.

[0055] In the present invention, there is no particular limitation on the type of active metal precursor. Preferably, in step (c), the active metal precursor is selected from soluble compounds of each active metal, and more preferably is at least one of molybdenum nitrate, basic molybdenum carbonate, nickel nitrate, basic nickel carbonate, nickel acetate, copper nitrate, copper chloride, magnesium nitrate, zinc nitrate, gallium nitrate, magnesium chloride and lanthanum nitrate.

[0056] In the present invention, preferably, in step (c), based on 100 parts by weight of the molecular sieve, the amount of the active metal precursor is 1-4 parts by weight, more preferably 1-2 parts by weight.

[0057] In the present invention, there is no particular limitation on the method for introducing the active metal and the saccharide compound in step (c), and it can be an impregnation method conventionally defined in the art, for example, it can be at least one of equal volume impregnation, co-impregnation and step-by-step impregnation. In a preferred embodiment, the equal volume impregnation method is selected in the present invention. In a more preferred embodiment, the equal volume impregnation method comprises: impregnating the silicon-modified body obtained in step (b) in an equal volume in an impregnation solution containing a saccharide compound and optionally an active metal precursor, and the impregnation time is 2-12 hours.

[0058] In the present invention, preferably, in step (c), the conditions for the third calcination include: a temperature of 450-600° C. and a time of 2-12 h, and more preferably, a temperature of 550-600° C. and a time of 2-4 h.

[0059] In the present invention, preferably, in step (c), the protective gas is nitrogen and / or an inert gas. The type of the inert gas is not particularly limited in the present invention, and can be an inert gas conventionally defined in the art, such as helium, neon, argon, etc., which is not specifically limited in the present invention. The advantages of this preferred embodiment are to effectively preload the carbon in the catalyst, thereby improving the stability of the catalyst.

[0060] In the present invention, preferably, the conditions for the catalytic cracking coupled alkylation reaction include: a reaction temperature of 400-600°C, a reaction pressure of 1-6 MPa, and a weight space velocity of 0.5-20 h -1 , the volume ratio of hydrogen to oil is 500-2000:1; further preferably, the conditions of the catalytic cracking coupled alkylation reaction include: reaction temperature of 400-550°C, reaction pressure of 1-5MPa, weight space velocity of 2-10h -1 , the volume ratio of hydrogen to oil is 500-1000:1.

[0061] In the present invention, preferably, in the catalytic cracking coupled alkylation reaction, the mass ratio of the aromatic hydrocarbons to the aliphatic hydrocarbons is 1-9:1, preferably 2-9:1.

[0062] In the present invention, preferably, the aromatic hydrocarbon is benzene and / or toluene, more preferably benzene.

[0063] In the present invention, preferably, the aliphatic hydrocarbon includes C 5 -C 16 At least one of normal alkanes and cycloalkanes, such as normal heptane.

[0064] In the present invention, preferably, the catalytic cracking coupled alkylation reaction is carried out in at least one of a fixed bed reactor, a moving bed and a fluidized bed, preferably in a fixed bed reactor.

[0065] In the present invention, preferably, the method further comprises: performing gas-liquid separation on the product obtained by the catalytic cracking coupled alkylation reaction to obtain a gas phase product containing olefin cracking material and a liquid phase product containing light aromatic hydrocarbons.

[0066] In the present invention, preferably, the olefin cracking material comprises ethane and / or propane.

[0067] In the present invention, preferably, the light aromatic hydrocarbons include xylene and optionally benzene and toluene.

[0068] According to a specific embodiment of the present invention, the above method is as follows Figure 1 In the system shown, the following steps are performed: the reaction raw materials aromatic hydrocarbons 1 and aliphatic hydrocarbons 2 enter the feed buffer tank 3 and are mixed evenly, then are mixed with hydrogen and enter the heat exchanger 4 for heat exchange, then enter the heating furnace 5 to be heated to the reaction temperature and enter the fixed bed reactor 6 for catalytic cracking coupled alkylation reaction. After the reaction is completed, gas-liquid separation is performed in the high separation tank 7 to obtain a gas phase product 8 containing olefin cracking material and a liquid phase product 9 containing light aromatic hydrocarbons. The gas phase product and the liquid phase product enter the chromatographic detector respectively for product analysis.

[0069] The present invention will be described in detail below through examples.

[0070] The gas phase product analysis was performed by Agilent 7890A gas chromatograph with a hydrogen flame ionization detector. The chromatographic column used was an HP-Al / S type 50m*0.53mm*15μm capillary column, and the tail gas composition was quantified by the external standard method.

[0071] The liquid product analysis was measured by Agilent 7890A gas chromatograph. The test conditions were: hydrogen flame ionization detector, chromatographic column using HP-1 type 60m*0.25mm*0.25μm capillary column, detector temperature 250°C, injection port temperature 250°C, and analysis data were quantified using the area normalization method. The liquid product was directly introduced into the chromatograph through a high-pressure liquid injection valve.

[0072] The calculation basis of the main result data involved in the embodiments of the present invention is:

[0073] The single-pass conversion rate of aromatics = (the weight of aromatics entering the reactor - the weight of aromatics leaving the reactor) / the weight of aromatics entering the reactor * 100%.

[0074] Aliphatic hydrocarbon single-pass conversion rate = (weight of aliphatic hydrocarbon entering the reactor - weight of aliphatic hydrocarbon leaving the reactor) / weight of aliphatic hydrocarbon entering the reactor * 100%.

[0075] Xylene yield = weight of xylene in reaction product / total amount of raw materials*100%.

[0076] Para-selectivity of p-xylene = (weight of p-xylene in the reaction product / weight of xylene in the reaction product)*100%.

[0077] Ethane yield = weight of ethane in reaction product / total amount of raw materials*100%.

[0078] Propane yield = propane weight in reaction product / total amount of raw materials*100%.

[0079] Example 1

[0080] 35 g H-ZSM-5 (SiO 2 / Al 2 O 3 Molecular sieve (molar ratio 25, Sinopec Catalyst Company), 15g of pseudo-boehmite and sesbania powder were evenly mixed, nitric acid and water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air for 3h to obtain the catalyst body.

[0081] Take 20g of the catalyst body, add methyl silicone oil modifier (weight concentration 20%, solvent is n-hexane) according to the solid-liquid weight ratio of 1:4, stir at room temperature for 4 hours, filter and dry, and then roast at 600℃ for 3 hours (roast in air) to obtain a silicon-modified body. The silicon-modified body is impregnated, 0.15g of ammonium molybdate tetrahydrate and 0.04g of sucrose are dissolved in 13g of water to obtain an impregnation solution, the impregnation time is 4h, and the catalyst is roasted at 550℃ for 3h in nitrogen to obtain catalyst A-1. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2.

[0082] The reactivity of A-1 was investigated in a fixed bed reaction evaluation device. Figure 1 As shown, the reaction raw materials aromatic hydrocarbon 1 (benzene) and aliphatic hydrocarbon 2 (n-heptane) enter the feed buffer tank 3 and are mixed evenly, then mixed with hydrogen and enter the heat exchanger 4, and then enter the heating furnace 5 to be heated to 500°C before entering the fixed bed reactor 6 for catalytic cracking coupled alkylation reaction. With a mass ratio of benzene to n-heptane of 3:2 and a weight space velocity of 4.0h -1 Under the conditions of reaction temperature of 500°C, reaction pressure of 3.0MPa, and hydrogen-to-oil volume ratio of 500, after 500 hours of stable operation, the benzene conversion rate was 57.93%, the n-heptane conversion rate was 99%, the xylene yield was 8.35%, the ethane yield was 12.30%, the propane yield was 7.98%, and the xylene para-selectivity was 67.51%.

[0083] Example 2

[0084] 35 g H-ZSM-5 (SiO 2 / Al 2 O 3 Molecular sieve (molar ratio 38, Sinopec Catalyst Company), 15g of pseudo-boehmite on a dry basis and sesbania powder were evenly mixed, nitric acid and water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air for 3h to obtain the catalyst body.

[0085] Take 20g of the catalyst body, add polyphenylmethylsiloxane modifier (weight concentration 25%, solvent is n-hexane) according to the solid-liquid weight ratio of 1:4, stir at room temperature for 4 hours, filter and dry, and then roast at 600℃ for 3 hours (roast in air) to obtain a silicon-modified body. The silicon-modified body is impregnated, 0.20g of zinc nitrate hexahydrate and 0.2g of sucrose are dissolved in 13g of water to obtain an impregnation solution, the impregnation time is 4h, and the catalyst is roasted at 550℃ for 3h in nitrogen to obtain catalyst A-2. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2.

[0086] The reactivity of A-2 was investigated in a fixed bed reaction evaluation device. Figure 1 As shown, the reaction raw materials aromatic hydrocarbon 1 (benzene) and aliphatic hydrocarbon 2 (n-heptane) enter the feed buffer tank 3 and are mixed evenly, then mixed with hydrogen and enter the heat exchanger 4, and then enter the heating furnace 5 to be heated to 500°C before entering the fixed bed reactor 6 for catalytic cracking coupled alkylation reaction. With a mass ratio of benzene to n-heptane of 4:1 and a weight space velocity of 4.0h -1Under the conditions of reaction temperature of 500°C, reaction pressure of 3.0MPa, and hydrogen-to-oil volume ratio of 500, after 500 hours of stable operation, the benzene conversion rate was 56.43%, the n-heptane conversion rate was 99%, the xylene yield was 9.21%, the ethane yield was 14.13%, the propane yield was 8.08%, and the xylene para-selectivity was 68.91%.

[0087] Example 3

[0088] 35 g H-ZSM-5 (SiO 2 / Al 2 O 3 Molecular sieve (molar ratio 50, Sinopec Catalyst Company), 15g of pseudo-boehmite on a dry basis and sesbania powder were evenly mixed, nitric acid and water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air atmosphere for 3h to obtain the catalyst body.

[0089] Take 20g of the catalyst body, add dimethylsiloxane modifier (weight concentration 30%, solvent is n-heptane) according to the solid-liquid weight ratio of 1:4, stir at room temperature for 4 hours, filter and dry, and then roast at 600℃ for 3 hours (roast in air) to obtain a silicon-modified body. The silicon-modified body is impregnated, 0.20g of nickel nitrate hexahydrate and 0.44g of sucralose are dissolved in 13g of water to obtain an aqueous solution of an impregnation solution, the impregnation time is 4h, and the catalyst is roasted at 550℃ for 3h in nitrogen to obtain a catalyst A-3. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2.

[0090] The reactivity of A-3 was investigated in a fixed bed reaction evaluation device. Figure 1 As shown, the reaction raw materials aromatic hydrocarbon 1 (benzene) and aliphatic hydrocarbon 2 (n-heptane) enter the feed buffer tank 3 and are mixed evenly, then mixed with hydrogen and enter the heat exchanger 4, and then enter the heating furnace 5 to be heated to 500°C before entering the fixed bed reactor 6 for catalytic cracking coupled alkylation reaction. With a mass ratio of benzene to n-heptane of 3:2 and a weight space velocity of 4.0h -1 Under the conditions of reaction temperature of 500°C, reaction pressure of 3.0MPa, and hydrogen-to-oil volume ratio of 500, after 500 hours of stable operation, the benzene conversion rate was 58.43%, the n-heptane conversion rate was 99%, the xylene yield was 8.76%, the ethane yield was 13.33%, the propane yield was 8.58%, and the xylene para-selectivity was 67.52%.

[0091] Example 4

[0092] The method of Example 3 was followed, except that the silicon-modified body was impregnated, 0.20 g of nickel nitrate hexahydrate and 0.88 g of sucralose were dissolved in 13 g of water to obtain an impregnation solution, the impregnation time was 4 h, and the catalyst A-4 was obtained by calcining at 550°C in nitrogen for 3 h. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2. After 500 h of stable operation, the benzene conversion rate was 58.43%, the n-heptane conversion rate was 99%, the xylene yield was 7.76%, the ethane yield was 10.33%, the propane yield was 6.58%, and the xylene para-selectivity was 62.23%.

[0093] Example 5

[0094] According to the method of Example 1, the difference is that 20g of the catalyst body is taken, and a dimethylsiloxane modifier (weight concentration 30%, solvent is n-heptane) is added and mixed twice according to a solid-liquid weight ratio of 1:4 to obtain catalyst A-5. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2. After 500h of stable operation, the benzene conversion rate is 57.38%, the n-heptane conversion rate is 99%, the xylene yield is 7.65%, the ethane yield is 10.65%, the propane yield is 6.67%, and the xylene para-selectivity is 61.35%.

[0095] Example 6

[0096] The catalyst of Example 1 was selected and the method of Example 1 was followed, except that the mass ratio of benzene to n-heptane was 1:1. The test results were as follows: after 500 h of stable operation, the benzene conversion rate was 45.38%, the n-heptane conversion rate was 98%, the xylene yield was 8.65%, the ethane yield was 10.65%, the propane yield was 9.67%, and the xylene para-selectivity was 65.57%.

[0097] Example 7

[0098] The catalyst of Example 1 was selected and the method of Example 1 was followed, except that the mass ratio of benzene, toluene and n-heptane was 2:1:2. The test results were as follows: after 500 h of stable operation, the benzene conversion rate was 23.38%, the toluene conversion rate was 35.34%, the n-heptane conversion rate was 99%, the xylene yield was 10.65%, the ethane yield was 9.65%, the propane yield was 7.67%, and the xylene para-selectivity was 63.2%.

[0099] Comparative Example 1

[0100] 35 g H-ZSM-5 (SiO 2 / Al 2 O 3Molecular sieve (molar ratio 25, Sinopec Catalyst Company), 15g of pseudo-boehmite and sesbania powder were evenly mixed, nitric acid and water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air for 3h to obtain the catalyst body.

[0101] Take 20g of the catalyst body, dissolve 0.15g of ammonium molybdate tetrahydrate in 13g of water to obtain an impregnation solution, the impregnation time is 4h, and calcine at 550℃ for 3h to obtain catalyst D-1. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2. The reaction activity of D-1 was investigated on a fixed bed reaction evaluation device. Figure 1 As shown, the reaction raw materials aromatic hydrocarbon 1 (benzene) and aliphatic hydrocarbon 2 (n-heptane) enter the feed buffer tank 3 and are mixed evenly, then mixed with hydrogen and enter the heat exchanger 4, and then enter the heating furnace 5 to be heated to 450°C before entering the fixed bed reactor 6 for catalytic cracking coupled alkylation reaction. With a mass ratio of benzene to n-heptane of 3:2 and a weight space velocity of 4.0h -1 Under the conditions of reaction temperature of 450℃, reaction pressure of 3.0MPa and hydrogen-to-oil volume ratio of 500, during the operation of 500h, the catalyst activity showed a downward trend, the benzene conversion rate was 50.37%, the n-heptane conversion rate was 92%, the xylene yield was 3.84%, the ethane yield was 10.16%, the propane yield was 5.52%, and the para-selectivity of para-xylene was 32.19%.

[0102] Comparative Example 2

[0103] The method of Example 1 was followed, except that an equal volume of the silicon-modified molecular sieve body was immersed in the impregnation solution of Comparative Example 1 for 4 hours, and the catalyst D-2 was obtained by calcining at 550° C. in nitrogen for 3 hours. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2.

[0104] According to the evaluation test method of Example 1, the catalyst showed a downward trend in activity, with a benzene conversion rate of 49.37%, an n-heptane conversion rate of 90.5%, a xylene yield of 3.76%, an ethane yield of 10.54%, a propane yield of 4.52%, and a para-selectivity of p-xylene of 55.19%.

[0105] Comparative Example 3

[0106] The method of Example 1 was followed, except that 20 g of the catalyst body was not silicon-modified, and was directly immersed in the impregnation solution of Example 1 in equal volume for 4 h, and calcined at 550° C. for 3 h in nitrogen to obtain catalyst D-3. The catalyst composition is shown in Table 1, and the specific surface area of ​​the catalyst is shown in Table 2.

[0107] According to the evaluation test method of Example 1, after 500 hours of stable operation, the benzene conversion rate was 55.43%, the n-heptane conversion rate was 99%, the xylene yield was 8.76%, the ethane yield was 13.33%, the propane yield was 8.58%, and the xylene para-selectivity was 42.52%.

[0108] Table 1

[0109]

[0110]

[0111] In Table 1, “ / ” means not contained, and the contents are all % by weight.

[0112] Table 2

[0113] <![CDATA[Specific surface area (cm 2 / g)]]> Example 1 313.5 Example 2 303.5 Example 3 310.4 Example 4 290.4 Example 5 316.8 Example 6 320.1 Example 7 312.4 Comparative Example 1 329.5 Comparative Example 2 315.2 Comparative Example 3 325.5

[0114] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for producing xylene and olefin cracking material, characterized in that: The method comprises: in the presence of a catalyst and hydrogen, subjecting aromatic hydrocarbons and aliphatic hydrocarbons to a catalytic cracking coupled alkylation reaction; the catalyst comprises a silicon-modified molecular sieve and carbon loaded on the silicon-modified molecular sieve; based on the total amount of the catalyst, the silicon content in terms of oxide is 0.5-10% by weight, and the carbon content is 0.05-2% by weight.

2. The method according to claim 1, wherein: Based on the total amount of the catalyst, the silicon content calculated as oxide is 0.5-5% by weight, and the carbon content is 0.05-1% by weight; Preferably, the specific surface area of ​​the catalyst is 200-400 cm 2 / g, more preferably 250-400cm 2 / g, more preferably 300-400cm 2 / g.

3. The method according to claim 1 or 2, wherein: The molecular sieve in the silicon-modified molecular sieve is at least one of Beta, MWW, MOR and ZSM-5 molecular sieves, preferably ZSM-5 molecular sieve.

4. The method according to any one of claims 1 to 3, wherein: The catalyst further comprises a binder and / or an active metal, wherein the content of the binder on a dry basis is 0-50% by weight, preferably 10-40% by weight, based on the total amount of the catalyst, and the content of the active metal on an oxide basis is 0-5% by weight, preferably 0.05-1% by weight; Preferably, the binder is aluminum oxide and / or silicon oxide, more preferably aluminum oxide; Preferably, the active metal is selected from at least one of Mo, Ni, Cu, Ga, Zn, Mg and La, and more preferably at least one of Mo, Zn and Ni.

5. The method according to any one of claims 1 to 4, wherein: The preparation method of the catalyst comprises: (a) mixing the molecular sieve and optionally a binder to form a body, followed by drying and first calcining; (b) immersing the body obtained in step (a) in an organic silicon compound solution to perform silicon modification, and then performing a second calcination to obtain a silicon-modified body; (c) impregnating the silicon-modified body obtained in step (b) into an impregnation solution containing a saccharide compound and optionally an active metal precursor, and then performing a third calcination under a protective gas to obtain a catalyst.

6. The method according to claim 5, wherein: In step (a), the amount of the binder used on a dry basis is 0-50 parts by weight based on 100 parts by weight of the molecular sieve; Preferably, in step (a), the conditions for the first calcination include: a temperature of 500-600° C. and a time of 2-12 h, and more preferably, a temperature of 550-600° C. and a time of 3-6 h.

7. The method according to claim 5, wherein: In step (b), the organosilicon compound is selected from at least one of silicone oil, silane, siloxane and polysiloxane, preferably at least one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methylethoxy silicone oil, polyphenylmethylsiloxane and dimethylsiloxane; Preferably, in step (b), the concentration of the organosilicon compound solution is 0.5-30 wt %, more preferably 10-30 wt %; Preferably, in step (b), the conditions for silicon modification include: temperature of 20-25°C, time of 2-6h, and solid-liquid weight ratio of 1:1-10; Preferably, in step (b), the conditions of the second calcination include: a temperature of 300-600°C and a time of 2-12h, and more preferably, a temperature of 500-550°C and a time of 2-6h; Preferably, the first calcination and the second calcination are each independently performed in an air atmosphere.

8. The method according to claim 5, wherein: In step (c), the carbohydrate compound is selected from at least one of monosaccharides, disaccharides, polysaccharides and complex sugars, preferably at least one of sucrose, glucose, fructose and sucralose, and more preferably sucrose and / or sucralose; Preferably, in step (c), based on 100 parts by weight of the molecular sieve, the amount of the carbohydrate compound is 0.1-8 parts by weight, more preferably 0.2-3.5 parts by weight; Preferably, in step (c), the active metal precursor is selected from soluble compounds of various active metals, and more preferably at least one of molybdenum nitrate, basic molybdenum carbonate, nickel nitrate, basic nickel carbonate, nickel acetate, copper nitrate, copper chloride, magnesium nitrate, zinc nitrate, gallium nitrate, magnesium chloride and lanthanum nitrate; Preferably, in step (c), based on 100 parts by weight of the molecular sieve, the amount of the active metal precursor is 1-4 parts by weight, more preferably 1-2 parts by weight; Preferably, in step (c), the conditions of the third calcination include: a temperature of 450-600° C. and a time of 2-12 h, and more preferably, a temperature of 550-600° C. and a time of 2-4 h; Preferably, in step (c), the protective gas is nitrogen and / or an inert gas.

9. The method according to any one of claims 1 to 8, wherein: The conditions of the catalytic cracking coupled alkylation reaction include: reaction temperature of 400-600°C, reaction pressure of 1-6MPa, and weight space velocity of 0.5-20h -1 , the volume ratio of hydrogen to oil is 500-2000:1; Preferably, the conditions for the catalytic cracking coupled alkylation reaction include: a reaction temperature of 400-550°C, a reaction pressure of 1-5 MPa, and a weight space velocity of 2-10 h -1 , the volume ratio of hydrogen to oil is 500-1000:

1.

10. The method according to any one of claims 1 to 9, wherein: In the catalytic cracking coupled alkylation reaction, the mass ratio of the aromatic hydrocarbons to the aliphatic hydrocarbons is 1-9:1, preferably 2-9:1; Preferably, the aromatic hydrocarbon is benzene and / or toluene, more preferably benzene; Preferably, the aliphatic hydrocarbons include C5-C 16 At least one of normal alkanes and cycloalkanes.

11. The method according to any one of claims 1 to 10, wherein: The catalytic cracking coupled alkylation reaction is carried out in at least one of a fixed bed reactor, a moving bed reactor and a fluidized bed reactor, preferably in a fixed bed reactor; Preferably, the method further comprises: performing gas-liquid separation on the product obtained by the catalytic cracking coupled alkylation reaction to obtain a gas phase product containing olefin cracking material and a liquid phase product containing light aromatic hydrocarbons; Preferably, the olefin cracking material comprises ethane and / or propane; Preferably, the light aromatics include xylenes and optionally benzene and toluene.

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