CN112125771B - Method for producing xylene - Google Patents

Method for producing xylene Download PDF

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CN112125771B
CN112125771B CN201910548536.XA CN201910548536A CN112125771B CN 112125771 B CN112125771 B CN 112125771B CN 201910548536 A CN201910548536 A CN 201910548536A CN 112125771 B CN112125771 B CN 112125771B
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methylation
molecular sieve
catalyst
aromatic hydrocarbon
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CN112125771A (en
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吴历斌
周亚新
孔德金
李为
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/86Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
    • C07C2/862Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
    • C07C2/864Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an alcohol
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2529/00Catalysts comprising molecular sieves
    • C07C2529/04Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
    • C07C2529/06Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • C07C2529/80Mixtures of different zeolites
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/50Improvements relating to the production of bulk chemicals
    • Y02P20/52Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention relates to a production method of dimethylbenzene, which mainly solves the problems of low toluene conversion rate, low para-selectivity and low methyl utilization rate in the prior art. The invention adopts a production method of dimethylbenzene, which comprises the steps of carrying out gas-phase reaction on reaction raw materials in the presence of a catalyst to generate dimethylbenzene, wherein the reaction raw materials comprise aromatic hydrocarbon and a methylation reagent; wherein the aromatic hydrocarbon is taken from benzene and/or toluene, and the catalyst contains ZSM-22/ZSM-23 intergrowth molecular sieve and/or ZSM-22/ZSM-5 intergrowth molecular sieve, so that the technical scheme well solves the problem, and can be used in the industrial production of dimethylbenzene.

Description

Method for producing xylene
Technical Field
The invention relates to a method for producing dimethylbenzene, in particular to a fluidized bed method for producing paradimethylbenzene by aromatic hydrocarbon methylation.
Background
In 2015, global PX production continues to increase due to new plant offerings in china and india. By 2015, the effective capacity of PX in the world reaches 4697 ten thousand tons/year, which is 163 ten thousand tons/year higher than 2014; the PX 3696 ten thousand tons are produced in the whole year, and the PX is increased by 191 ten thousand tons in the last year, and the PX is increased by 5.5 percent in the same proportion; the operating rate of the device is increased to 79%, and the operating rate is increased by about 2% compared with the last year. The global PX consumption of 3688 ten thousand tons in the current year is increased by 179 ten thousand tons in the last year and is increased by 5 percent by pulling the newly built PTA device in Asia. In 2015, global PX supply was mainly concentrated in northeast asia, southeast asia, north america and the middle east, and PX supply capacity in these four areas reached 3995 ten thousand tons/year, accounting for 85.1% of the world total; the yield reaches 31 to 94 ten thousand tons and accounts for 86.4 percent of the total world; the consumption amount reaches 3212 ten thousand tons and accounts for 87.1 percent of the total world.
By the end of 2015, the PX production capacity of China reaches 1379 ten thousand tons/year, the newly increased capacity is 171 ten thousand tons/year, and the capacity is increased by 14.1% compared with the last year. The PX output 929 ten thousand tons in 2015 is increased by 3.3% in the same ratio, and the downstream demand is kept to be increased rapidly, so that the imported PX output in 2015 is increased rapidly to 1165 ten thousand tons, and the national PX output is increased by 16.8% in the same ratio. It is estimated that in 2015-2020, the new 1200 ten thousand tons/year of PTA capacity is increased in China, and the new device has the 'advantage of late generation', large scale and high load, such as 200 ten thousand tons/year of PTA project trial production of Jiaxing petrochemical in 2017, and further drives the continuous increase of the demand quantity for PX. In 2020, the PX demand would be 2710 ten thousand tons
Aromatic alkylation is a catalytic reaction of an aromatic compound with an alkylating agent to produce para-xylene. The most studied toluene methylation and benzyl methylation reactions are currently performed by using benzene and/or toluene and methanol as reaction raw materials.
U.S. patent 6504072 discloses a process for the preparation of para-xylene comprising reacting toluene with methanol in an alkylation reactor in the presence of a catalyst comprising a porous crystalline material, which reaction may be carried out in a fixed, moving or fluidized reactor. U.S. patent 6642426 discloses a reaction scheme of an alkylation reactant comprising aromatic hydrocarbon and methanol in a fluidized bed reactor, which requires an operating temperature of 500 to 700 ℃ and a density of 300 to 600Kg/m 3.
Many side reactions of aromatic hydrocarbons may also occur during alkylation. Methanol can polymerize with itself to form olefins, and aromatics can also be over-alkylated to form heavy aromatics. Over time, the acid sites on the catalyst surface are covered by these olefins and heavy aromatics and deactivate, and the main cause of catalyst coking is high temperature. U.S. patent 4761513 discloses a multistage process for aromatic alkylation wherein the temperature in the reactors is controlled by the proportional addition of vapor and liquid phase alkylating agents to each reactor to provide cooling. The addition of recycle hydrogen/nitrogen to the reaction system is also effective in reducing coking. U.S. patent 4337718 discloses a multistage process for producing para-xylene in a plurality of separate, series-connected fixed catalyst layers. Wherein toluene is fed into the first stage along with hydrogen and sequentially through each subsequent fixed catalyst layer, the methylating agent is fed into each fixed catalyst layer.
In addition to any co-feed gas, water convertible to vapor form may be introduced into the reactor as co-feed with the alkylation feed. The water and steam used for the methylation reaction may be introduced into the reactor as co-feeds with the alkylation feed, with or without hydrogen or nitrogen, at the beginning of the alkylation reaction, or it may be introduced after the beginning. In any case liquid water may be added and vaporized before it is mixed with the co-feed gas and the alkylation feed. U.S. patent 7321072 discloses a process for the selective methylation of toluene to para-xylene in a flow reactor wherein the reactants are a mixture of toluene, methanol and water, the reactor may be in the form of a single or multiple reactors in series. Other U.S. patent 7060864 and 7186872 also disclose the use of water co-feeds.
From the above overview, in recent years, the technology of aromatic hydrocarbon alkylation has been advanced to some extent, but in the reaction system, circulating hydrogen and other inert gases are added to slow down catalyst coking, prolong the service life of the catalyst, and if the service life of the catalyst is shorter, frequent replacement of the catalyst is required, resulting in lower production efficiency and higher product cost.
Because of a plurality of defects of the fixed bed process, the fluidized bed technology gradually becomes a development hot spot, but alkylation catalysts (including shape-selective methylation catalysts) are all required to be modified, and generally, molecular sieves are subjected to various modifications and then spray forming, so that the preparation process is long, the steps are more, and the material loss is large. Liu Zhongmin modifying zeolite molecular sieve with alkaline earth metal, non-metal or/and rare earth metal, mixing with amorphous binder containing aluminum or silicon, spray drying, and modifying with siloxane compound to obtain fluidized bed catalyst [ CN101417236B ] for preparing p-xylene and low-carbon olefin by alkylation of toluene and methanol. The results show that the selectivity of paraxylene in the product is more than 99%, and the selectivity of ethylene and propylene in the C1-C5 components is more than 90%. The method takes ZSM-5 molecular sieve and matrix material binder as raw materials to prepare high-activity aromatic alkylation fluidized bed catalyst, the benzene conversion rate is 65-72%, the toluene conversion rate is 45-53%, and the alkylating agent utilization rate is 60-95% [ CN 105457670A ]. Economic analysis of the process suggests that the PX yield is doubled over toluene shape selective disproportionation, the toluene consumption per ton of PX product can also be reduced by 64%, and benzene production is negligible [ petrochemical technology and economy, 26 (1): 8-10]. CN 103804112 discloses a high selectivity toluene-methanol fluid bed catalyst, which is obtained by spray-forming molecular sieve, binder, etc., then sequentially dipping and modifying with different modifiers, drying and roasting. Specifically, ZSM-5 molecular sieve, matrix material and binder are mixed and molded to prepare fluidized bed catalyst raw powder, then phosphorus-containing compound aqueous solution or/and rare earth metal aqueous solution or/and alkaline earth metal aqueous solution is adopted for impregnation and drying, and then silica kang-based compound ethanol solution is adopted for impregnation and drying to obtain the catalyst. The binder and the matrix material are directly added into the crystallized slurry of the SAPO molecular sieve, and then the crystallized slurry is subjected to spray forming [ CN 101121148], but the content of the organic template agent in the crystallized slurry is high, the types are various, and the physical and catalytic performances of the catalyst prepared by the method are to be evaluated.
In addition to single molecular sieves, there are numerous synthetic reports on composite and/or intergrowth molecular sieves, including various mesoporous molecular sieves and microporous molecular sieves, with research on microporous intergrowth molecular sieves being relatively extensive. Such as ZSM-5/beta, Y/ZSM-5, MCM-22/ZSM-5, ZSM-5/ZSM-11[ chemical reaction engineering and process, 32 (5): 400-407] and ZSM-5/mercerization [ silicate journal, 37 (11): 1847-1853], etc. CN104624226 uses synthesized ZSM-5/ZSM-11 intergrowth molecular sieve in reaction for preparing propylene (MTP) from methanol; CN1048655C uses hydrogen-type ZSM-5/ZSM-11 catalyst containing rare earth for benzene-ethylene alkylation reaction; CN106466625 takes ZSM-5/ZSM-11 molecular sieve as raw material to prepare binder-free phosphorus rare earth-ZSM 5/ZSM11 molecular sieve catalyst and apply the catalyst to butane conversion reaction; CN 105294374 is used for preparing the reaction of paraxylene and propylene from methanol after preparing a catalyst by using ZSM-5 or ZSM-11 or a mixture thereof. CN107376991 discloses a catalyst for preparing methyl ethyl benzene from toluene ethylene, and adopts a two-step method to implement acidity regulation on ZSM-5/ZSM-11 intergrowth molecular sieve. Dealuminating the symbiotic molecular sieve by dilute acid, molding and roasting, and then respectively soaking and roasting by using compounds containing alkali metal, alkaline earth metal and P, si.
CN106807442 discloses a high-efficiency toluene-methanol shape-selective methylation catalyst, which is prepared by mixing and forming and drying a symbiotic molecular sieve raw powder, an aluminum compound, silicon oxide, an alkaline substance and a binder, performing secondary crystallization and roasting treatment to obtain a binder-free symbiotic molecular sieve, and then dipping the modifier, and sequentially drying and roasting. The binderless ZSM-5/ZSM-11 obtained by secondary crystallization has the advantages of increased active sites and common pore channels, has higher p-toluene conversion rate and can improve toluene methylation efficiency to a certain extent, but the fixed bed catalysis and the moving bed have higher requirements on the stability of the catalyst, and the secondary crystallization has the risks of uncontrollable phase change process, impurity crystal introduction and collapse of the catalyst structure due to stress. Meanwhile, the invention aims to increase the acidic active site, but the aim is more easily achieved by adjusting the silicon-aluminum ratio of the molecular sieve, and complex processes such as adhesive crystal transformation and the like are not needed; in addition, to control aromatic selectivity, the added active sites also need to be modified, and the modification difficulty is increased. In a word, the CN106807442A catalyst is aimed at a fixed bed reactor and a moving bed reactor, and the catalyst is prepared by mixing, forming, drying, crystal transformation and roasting, and then is subjected to impregnation modification and re-roasting, so that the catalyst has the advantages of multiple production steps, complex process and long preparation flow. The steps are numerous and the process is complex, so that the production cost of the catalyst is increased, the competitive advantage of the catalyst is reduced, the difficulty of controllable and repeated preparation is increased, the discreteness and fluctuation amplitude between the same batch and different batches in the preparation of the catalyst are increased, the compression of the operation elastic space is narrowed, and the subsequent use difficulty is increased.
CN106466625 is used in preparing non-adhesive RE-ZSM-5/ZSM-11 molecular sieve catalyst and butane converting reaction. CN102039173 is used for preparing the ZSM-5/MCM-22 catalyst without the binder after secondary crystallization of the ZSM-5/MCM-22 catalyst; CN 104549467 is used for secondarily crystallizing a binder, kaolin and the like in the ZSM-5 catalyst into a ZSM-5/Y molecular sieve catalyst and is applied to preparing ethylene and propylene by naphtha pyrolysis; CN 104117387 applies ZSM-22/ZSM-5 to increase gasoline octane number; CN 100494060C uses synthesized ZSM-22/ZSM-23 molecular sieve in isodewaxing process of lubricating oil.
But the toluene conversion rate, para-selectivity and methyl utilization rate of para-xylene produced by aromatic hydrocarbon methylation in the prior art are low.
Disclosure of Invention
The invention aims to solve the technical problems of low methyl utilization rate, low toluene conversion rate and low para-selectivity in the existing method for producing paraxylene by aromatic hydrocarbon methylation, and provides a novel method for producing the paraxylene. The method has the characteristics of high methyl utilization rate, high toluene conversion rate and high para-position selectivity.
In order to solve the technical problems, the technical scheme of the invention is as follows:
The production method of the dimethylbenzene comprises the steps of carrying out gas-phase reaction on reaction raw materials in the presence of a catalyst to generate the dimethylbenzene, wherein the reaction raw materials comprise aromatic hydrocarbon and a methylation reagent; wherein the aromatic hydrocarbon is taken from benzene and/or toluene, and the catalyst comprises ZSM-22/ZSM-23 intergrowth molecular sieve and/or ZSM-22/ZSM-5 intergrowth molecular sieve.
The ZSM-22 molecular sieve and the ZSM-23 molecular sieve in the ZSM-22/ZSM-23 intergrowth molecular sieve have interaction promotion effect in the aspects of improving toluene conversion rate, para-position selectivity and methyl utilization rate. At this time, the specific ratio of ZSM-22 molecular sieve to ZSM-23 molecular sieve in the ZSM-22/ZSM-23 intergrowth molecular sieve is not particularly limited, as long as the ZSM-22 molecular sieve and the ZSM-23 molecular sieve exist in an intergrowth form to achieve comparable interaction. For example, but not limited to, a ratio of ZSM-22 molecular sieve to ZSM-23 molecular sieve of from 1 to 10, further non-limiting values within this ratio range may be, for example, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, etc. For ease of comparison, the ZSM-22 molecular sieve to ZSM-23 molecular sieve ratio in the intergrowth molecular sieve of the embodiments of the invention is 3.
ZSM-22/ZSM-23 intergrowth molecular sieve is different from core-shell type molecular sieve.
The ZSM-22/ZSM-23 intergrowth molecular sieve may be obtained commercially or may be synthesized by methods known in the art, such as, but not limited to, ZSM-22/ZSM-23 intergrowth molecular sieve may be synthesized by: a reaction mixture of a silica alumina colloid expressed as :SiO2/Al2O3=25~1500、M/SiO2=0.05~3、OH-/SiO2=0.05~0.5、H2O/SiO2= 10~65 and a ZSM-23 molecular sieve according to the mol ratio of oxides, wherein the ZSM-23 molecular sieve is 0.01 to 0.6 of the weight of silicon dioxide, and M is a template agent; the method comprises the following steps: a) Mixing a silicon source, an aluminum source, inorganic alkali, water and a template agent to obtain a silicon-aluminum colloid; b) Adding a ZSM-23 molecular sieve into the silicon-aluminum colloid in the step a, and crystallizing under a hydrothermal condition to obtain the ZSM-22/ZSM-23 composite molecular sieve, wherein the crystallization temperature is 100-220 ℃ and the crystallization time is 8-120 hours; c) And b, after crystallization in the step b is finished, cooling the reaction mixture to room temperature, and filtering to obtain a powdery product.
The ZSM-22 molecular sieve and the ZSM-5 molecular sieve in the ZSM-22/ZSM-5 intergrowth molecular sieve have interaction promotion effect in the aspects of improving toluene conversion rate, para-position selectivity and methyl utilization rate. At this time, there is no particular limitation on the specific ratio of ZSM-22 to ZSM-5 in the ZSM-22/ZSM-5 intergrowth molecular sieve, as long as ZSM-22 and ZSM-5 exist in intergrowth form to achieve comparable interaction. For example, but not limited to, a ZSM-22 to ZSM-5 ratio of 0.1 to 0.8, further non-limiting values within this ratio range may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, etc. To facilitate this same ratio, the ZSM-22/ZSM-5 intergrowth molecular sieve of embodiments of the invention has a ZSM-22 to ZSM-5 ratio of 0.4.
ZSM-22/ZSM-5 intergrowth molecular sieve is different from core-shell type molecular sieve.
The ZSM-22/ZSM-5 intergrowth molecular sieve may be obtained commercially or may be synthesized using prior art methods such as, but not limited to, ZSM-22/ZSM-5 intergrowth molecular sieve may be synthesized using the following methods: (1) Mixing an aluminum source, a silicon source, a template agent, a ZSM-22 molecular sieve, water and an optional pH regulator to form raw material slurry, wherein SiO 2/Al2O3=10~220, Na2O/SiO2 =0.1-0.5, and the template agent/SiO 2=0.05~0.5,H2O/SiO2=5~50,ZSM-22/SiO2 =0.01-0.8, wherein the pH of the raw material slurry is 11-13; (2) aging; (3) Crystallizing the aged raw material slurry for 1-96 hours under the hydrothermal condition of 160-180 ℃, filtering, washing and drying to obtain the ZSM-22/ZSM-5 intergrowth molecular sieve.
In the above embodiment, the methylating agent is preferably at least one selected from the group consisting of C 1~C3 alkanes, C 1~C3 alcohols and C 2~C6 ethers.
In the above technical scheme, the method for producing xylene by aromatic hydrocarbon methylation is preferably a fluidized bed method or a fixed bed method.
In the above technical scheme, the reaction temperature is preferably 300-600 ℃. More preferably in the range of 350 to 550 ℃.
In the above technical scheme, the reaction pressure is preferably 0.05-1 MPa. But more preferably 0.05 to 0.1MPa.
In the technical scheme, the weight space velocity of the aromatic hydrocarbon is preferably 1-10 h -1. More preferably in the range of 2.5 to 4.5h -1.
In the above embodiments, the molar ratio of the aromatic hydrocarbon to the methylating agent is preferably 0.5 to 10, such as, but not limited to, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, etc., more preferably 1 to 4.
In the above technical solution, the catalyst includes a binder. Preferably, the binder is selected from at least one of the group consisting of alumina, titania, zirconia, and silica. Preferably, the binder in the catalyst is 20 to 900 parts by weight based on 100 parts by weight of the molecular sieve. Such as, but not limited to, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 100 parts, 150 parts, 200 parts, 250 parts, 300 parts, 350 parts, 400 parts, 450 parts, 500 parts, 550 parts, 600 parts, 650 parts, 700 parts, 750 parts, 800 parts, 850 parts, and the like.
Those skilled in the art will appreciate that the catalyst may optionally include a matrix material that is added to improve the attrition resistance of the catalyst and to adjust the total level of molecular sieve and modifier in the catalyst. The matrix material may be selected from at least one selected from the group consisting of clay, bentonite diatomaceous earth, and kaolin. More preferably, the amount of the matrix material in the catalyst is greater than 0 and 500 parts by weight or less, such as, but not limited to, 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 100 parts, 150 parts, 200 parts, 250 parts, 300 parts, 350 parts, 400 parts, 450 parts, etc., based on 100 parts by weight of the molecular sieve.
In the above technical solution, the catalyst preferably includes a molecular sieve modifier, and the modifier includes at least one selected from the group consisting of B, P, la, mg and Ti.
In the above technical scheme, the catalyst is preferably obtained by a catalyst preparation method comprising the following steps, or the method for producing the xylene by aromatic hydrocarbon methylation preferably comprises the following catalyst preparation method steps:
(1) Obtaining a slurry comprising the corresponding substances of the desired components;
(2) Spray forming;
(3) And (5) roasting.
In the above technical scheme, the temperature of the step (3) is preferably 350-700 ℃, such as, but not limited to, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, and the like.
In the above technical scheme, the roasting atmosphere in the step (3) is independently preferably an oxidizing atmosphere, and air is preferred from the economical point of view.
In the above technical scheme, the roasting mode in the step (3) is independently preferably a mesh belt tunnel kiln, a box kiln/furnace with interval overturning, or a continuous rotary/rotary furnace, and the continuous rotary/rotary furnace is preferred from the aspects of operation convenience and technical economy.
In the above embodiment, the baking time in the step (3) is independently preferably more than 1 hour, but in view of energy consumption, the baking time is not too long, for example, but not limited to, 2 to 10 hours, and in this time range, non-limiting point values may be, for example, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 3.0 hours, 3.5 hours, 4.0 hours, 4.5 hours, 6.0 hours, 6.5 hours, 7.0 hours, 7.5 hours, 8.0 hours, 8.5 hours, 9.0 hours, 9.5 hours, and the like.
It will be readily understood by those skilled in the art that in step (1), the substance corresponding to the molecular sieve may be the molecular sieve itself, the substance corresponding to the binder may be the binder itself or a sol of the binder, the substance corresponding to the matrix material may be the matrix material, and the substance corresponding to the modifier may be a precursor of the modifier.
The precursors of the modifier are not particularly limited, such as those which can be converted to the oxide form of the modifier under calcination conditions, and those commonly used in the art can be employed by those skilled in the art without the need for inventive labor. Such as, but not limited to:
The B precursor is a substance which can be converted into B 2O3 when being roasted, and the B precursor can be H 3BO3、HBO2、H2B4O7, ammonium tetraborate, ammonium pentaborate and the like.
The P precursor is a substance which can be converted into P 2O5 when being baked, and the P precursor can be H 3PO4、NH4H2PO4、 (NH4)2HPO4 and the like.
The La precursor is a substance that can be converted into La 2O3 upon baking, and the La precursor may be La (NO 3)3、La(NO3)3.6H2 O or the like.
The Mg precursor is a substance that can be converted into MgO upon firing, and the Mg precursor may be Mg (NO 3)2、MgAc2 or the like.
The Ti precursor is a substance that can be converted to TiO 2 upon firing, and the Ti precursor may be Ti (SO 4)2, titanate, or the like.
When the method for producing xylene by aromatic hydrocarbon methylation adopts a fluidized bed method, the reactor may adopt a one-stage fluidized bed reactor or a multi-stage fluidized bed reactor.
The evaluation method of the catalyst comprises the following steps:
In a fluidized bed reactor (dense phase section phi 30 mm. Times.300 mm, dilute phase section phi 68 mm. Times.160 mm), 80g of the above catalyst was packed, and the raw materials consisted of toluene and methanol, toluene: methanol=2: 1-1:4 (molar ratio), wherein the weight space velocity of the raw materials is 2.5-4.5 hours -1 based on toluene, the reaction temperature is 350-550 ℃, and the reaction pressure is 0.05-0.1 MPa. Sampling is started after 10 minutes of reaction, the sampling time is 2 minutes, sampling is continuously performed for 3 times, and the toluene conversion, the initial selectivity of paraxylene and the methyl utilization are calculated according to the average value of 3 times of sampling. The specific calculation formula is as follows:
the catalyst obtained by the method has toluene conversion rate of more than 45 percent, para-position selectivity of 98 percent and methyl utilization rate of more than 91 percent, and achieves better technical effect.
The invention is further illustrated by the following examples.
Detailed Description
[ Example 1]
1. Catalyst preparation
500 Parts by weight of deionized water is taken, 400 parts by weight of hydrogen ZSM-22 (SiO 2/Al2O3 mol ratio 60), 400 parts by weight of alumina sol (Al 2O3 content 30wt% in the alumina sol) and 100 parts by weight of kaolin are added, and the mixture is mixed and stirred for 1 hour, pulped, colloid-milled, debubbled, spray-dried and molded, and the mixture is roasted in an air atmosphere at 550 ℃ for 3 hours to obtain a fluidized bed catalyst with the particle size of 40-120 mu m and the wear index of 1.1.
2. Catalyst evaluation
The fluidized bed reactor (dense phase section. Phi. 30 mm. Times.300 mm, dilute phase section. Phi. 68 mm. Times.160 mm) was charged with 80g of the above catalyst, and the toluene/methanol mixture was introduced into the reactor after mixing. The pressure at the top of the reactor is 0.05MPa, the reaction temperature is 500 ℃, the space velocity of toluene is 4.0h -1, the total molar ratio of toluene to methanol is 2.0, the toluene conversion rate is 24%, the para-selectivity is 24%, and the methyl utilization rate is 62%.
The composition of the catalyst and the evaluation results are shown in Table 1 for comparison.
[ Example 2]
The procedure of example 1 was followed except that ZSM-5 molecular sieve having a SiO 2/Al2O3 molar ratio of 60 was used instead of ZSM-22, and the catalyst had a particle size of 40 to 120. Mu.m, and a attrition index of 1.2. The catalyst evaluation conditions were the same as in example 1, and the evaluation results are shown in Table 1.
[ Example 3]
The procedure of example 1 was followed except that ZSM-23 molecular sieve having a SiO 2/Al2O3 molar ratio of 60 was used instead of ZSM-22, and the catalyst had a particle size of 40 to 120. Mu.m, and a attrition index of 1.5. The catalyst evaluation conditions were the same as in example 1, and the evaluation results are shown in Table 1.
[ Example 4]
1. Molecular sieve synthesis
In the synthesis of the molecular sieve, 34 parts by weight of aluminum isopropoxide, 200 parts by weight of sodium hydroxide, 1464 parts by weight of tetrapropylammonium hydroxide (M) and 4000 parts by weight of deionized water are uniformly stirred to form a solution A, 3000 parts by weight of deionized water and 2083 parts by weight of TEOS are mixed and stirred overnight to form a solution B, the solution B is slowly added into the solution A and is simultaneously stirred strongly, after finishing aging and stirring for 2 hours, 138 parts by weight of ZSM-22 seed crystals are added and stirring is continued for 1 hour, the mixture is placed into a crystallization kettle to crystallize for 30 hours at 180 ℃, and the mixture is filtered, washed, dried and baked at 550 ℃ to obtain the Na-ZSM-22/ZSM-5 intergrowth molecular sieve, wherein SiO 2/Al2O3 is 60, ZSM-22: ZSM-5=30: 70 is subjected to citric acid and ammonium nitrate exchange and roasting to prepare the H-ZSM-22/ZSM-5 intergrowth molecular sieve.
2. Catalyst preparation
The catalyst preparation process is the same as in example 1, only the hydrogen ZSM-22 in example 1 is replaced by the hydrogen ZSM-22/ZSM-5 intergrowth molecular sieve, the catalyst particle size is 40-120 mu m, and the attrition index is 1.0.
3. Catalyst evaluation
The above catalyst was subjected to performance test under the process conditions of example 1, and the evaluation results are shown in table 1.
[ Example 5]
1. Catalyst preparation
Taking 500 parts by weight of deionized water, adding 120 parts by weight of commercial hydrogen ZSM-22 (SiO 2/Al2O3 mol ratio 60), 280 parts by weight of commercial hydrogen ZSM-5 (SiO 2/Al2O3 mol ratio 60), 400 parts by weight of aluminum sol (Al 2O3 content 30wt% in the aluminum sol) and 100 parts by weight of kaolin, mixing and stirring for 1 hour, pulping, colloid milling, defoaming, spray drying and forming, and roasting in an air atmosphere at 550 ℃ for 3 hours to obtain the fluidized bed catalyst, wherein the particle size of the catalyst is 40-120 mu m, and the wear index is 1.2.
2. Catalyst evaluation
The above catalyst was subjected to performance test under the process conditions of example 1, and the evaluation results are shown in table 1.
[ Example 6]
1. Molecular sieve synthesis
In the synthesis of the molecular sieve, 548 parts by weight of deionized water are stirred and dissolved to 5 parts by weight of sodium chlorate (the weight content of alumina is 41%) and 4.9 parts by weight of sodium hydroxide, halved for 4 hours, 17 parts by weight of Na-ZSM-23 molecular sieve is added, stirring is carried out for 3 hours, 106 parts by weight of diethyl triamine is added, finally 270 parts by weight of silica sol (the weight content of silica is 30%) is added, stirring is carried out uniformly, then room temperature aging is carried out for 12 hours, crystallization is carried out at 170 ℃ for 72 hours, filtering, washing, drying and roasting are carried out at 550 ℃ to obtain the Na-ZSM-22/ZSM-23 intergrowth molecular sieve, siO 2/Al2O3 is 60, ZSM-22: ZSM-23=75:25: and (3) exchanging citric acid and ammonium nitrate, and roasting to obtain the H-ZSM-22/ZSM-23 intergrowth molecular sieve.
2. Catalyst preparation
The catalyst preparation process is the same as in example 1, only the hydrogen ZSM-22 in example 1 is replaced by the H-ZSM-22/ZSM-23 intergrowth molecular sieve prepared in the above way, and the rest processes are the same as in example 1, wherein the catalyst particle size is 40-120 mu m, and the attrition index is 0.9.
3. Catalyst evaluation
The above catalyst was subjected to performance test under the process conditions of example 1, and the evaluation results are shown in table 1.
[ Example 7]
1. Catalyst preparation
500 Parts by weight of deionized water is taken, 300 parts by weight of commercial hydrogen ZSM-22 (SiO 2/Al2O3 mol ratio 60), 100 parts by weight of commercial hydrogen ZSM-5 (SiO 2/Al2O3 mol ratio 60), 400 parts by weight of aluminum sol (Al 2O3 content 30wt% in the aluminum sol) and 100 parts by weight of kaolin are added, and after mixing and stirring for 1 hour, pulping, colloid milling, defoaming, spray drying and forming are carried out, and the fluidized bed catalyst is obtained after roasting for 3 hours in an air atmosphere at 550 ℃, wherein the catalyst particle size is 40-120 mu m, and the wear index is 1.3.
2. Catalyst evaluation
The above catalyst was subjected to performance test under the process conditions of example 1, and the evaluation results are shown in table 1.
Comparison by the above examples reveals that:
1) Compared with the performance of a catalyst prepared by a single molecular sieve (such as ZSM-22, ZSM-5 and ZSM-23), the catalyst has the advantages that the H-ZSM-22/ZSM-5 or H-ZSM-22/ZSM-23 intergrowth molecular sieve is used for substitution, and under the same condition, the toluene conversion rate, para-selectivity and methyl utilization rate of the obtained catalyst are obviously improved, and excellent interaction is shown;
2) Simple mixing with single molecular sieve (such as mechanically mixing ZSM-22 and ZSM-5 molecular sieve or simply mixing ZSM-22 and ZSM-23 molecular sieve), replacing with H-ZSM-22/ZSM-5 or H-ZSM-22/ZSM-23 intergrowth molecular sieve, and under the same condition, the toluene conversion rate, para-selectivity and methyl utilization rate of the obtained catalyst are all obviously improved, and excellent molecular level interaction is shown.
TABLE 1

Claims (18)

1. A method for producing dimethylbenzene comprises the steps of carrying out gas-phase reaction on reaction raw materials in the presence of a catalyst to produce dimethylbenzene, wherein the reaction raw materials comprise aromatic hydrocarbon and a methylation reagent; wherein the aromatic hydrocarbon is taken from benzene and/or toluene, and the catalyst contains ZSM-22/ZSM-23 intergrowth molecular sieve, and the ratio of the ZSM-22 molecular sieve to the ZSM-23 molecular sieve is 2.5-3.5;
The ZSM-22/ZSM-23 intergrowth molecular sieve is prepared by adopting the following method:
a) Mixing a silicon source, an aluminum source, inorganic alkali, water and a template agent to obtain a silicon-aluminum colloid;
b) And c, adding a ZSM-23 molecular sieve into the silicon-aluminum colloid in the step a, and crystallizing under a hydrothermal condition to obtain the ZSM-22/ZSM-23 intergrowth molecular sieve, wherein the crystallization temperature is 100-220 ℃ and the crystallization time is 8-120 hours.
2. The method for producing xylene by methylation of aromatic hydrocarbons according to claim 1, wherein the methylating agent is at least one selected from the group consisting of C 1~C3 alcohols and C 2~C6 ethers.
3. The method for producing dimethylbenzene by aromatic hydrocarbon methylation according to claim 1, wherein the method for producing dimethylbenzene by aromatic hydrocarbon methylation is a fluidized bed method or a fixed bed method.
4. The process for producing xylene by methylation of aromatic hydrocarbon according to claim 1, characterized in that the reaction temperature is 300 to 600 ℃.
5. The process for producing xylene by methylation of aromatic hydrocarbon according to claim 4, wherein the reaction temperature is 350 to 550 ℃.
6. The process for producing xylene by methylation of aromatic hydrocarbon according to claim 1, characterized in that the reaction pressure is 0.05 to 1MPa.
7. The process for producing xylene by methylation of aromatic hydrocarbon according to claim 6, wherein the reaction pressure is 0.05 to 0.1MPa.
8. The method for producing dimethylbenzene by methylation of aromatic hydrocarbon according to claim 1, wherein the weight space velocity of the aromatic hydrocarbon is 1-10 h -1.
9. The method for producing xylene by methylation of aromatic hydrocarbon according to claim 8, wherein the weight space velocity of aromatic hydrocarbon is 2.5-4.5 h -1.
10. The process for producing xylene by methylation of aromatic hydrocarbons according to claim 1, characterized in that the molar ratio of said aromatic hydrocarbons to said methylating agent is comprised between 0.5 and 10.
11. The process for producing xylene by methylation of aromatic hydrocarbons according to claim 10, characterized in that the molar ratio of said aromatic hydrocarbons to said methylating agent is comprised between 1 and 4.
12. The process for producing xylenes by the methylation of aromatic hydrocarbons according to claim 1, wherein said catalyst comprises a binder.
13. The method for producing xylene by methylation of aromatic hydrocarbons according to claim 12, wherein the binder is selected from at least one of the group consisting of alumina, titania, zirconia and silica.
14. The method for producing xylene by methylation of aromatic hydrocarbon according to claim 13, wherein the binder in the catalyst is 30 to 900 parts by weight based on 100 parts by weight of the molecular sieve.
15. The process for producing xylenes by the methylation of aromatic hydrocarbons according to claim 1, wherein the catalyst comprises a matrix material.
16. The method for producing xylene by methylation of aromatic hydrocarbons according to claim 15, characterized in that the matrix material comprises at least one selected from the group consisting of bentonite, diatomaceous earth and kaolin.
17. The method for producing xylene by methylation of aromatic hydrocarbon according to claim 16, wherein the amount of the matrix material used in the catalyst is more than 0 and 500 parts by weight or less based on 100 parts by weight of the molecular sieve.
18. The process for producing xylenes by the methylation of aromatic hydrocarbons according to any one of claims 1 to 17, characterized in that the catalyst is obtained by a preparation process comprising the steps of:
(1) Obtaining a slurry comprising the corresponding substances of the desired components;
(2) Spray forming;
(3) Roasting;
the slurry of the corresponding substances of the components required in the step (1) comprises molecular sieves, binders and matrix materials.
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CN101722035A (en) * 2008-10-28 2010-06-09 中国石油化工股份有限公司 Catalyst with shape selecting function
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CN101722035A (en) * 2008-10-28 2010-06-09 中国石油化工股份有限公司 Catalyst with shape selecting function
CN105457670A (en) * 2015-12-28 2016-04-06 陕西煤化工技术工程中心有限公司 High-activity aromatic hydrocarbon alkylation fluidized bed catalyst and preparation method thereof

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