CN107445788B

CN107445788B - Method for liquid-phase transalkylation of polyethylbenzene and benzene

Info

Publication number: CN107445788B
Application number: CN201610367900.9A
Authority: CN
Inventors: 宦明耀; 杨为民; 孙洪敏; 张斌; 沈震浩; 薛明伟
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2016-05-30
Filing date: 2016-05-30
Publication date: 2021-03-30
Anticipated expiration: 2036-05-30
Also published as: CN107445788A

Abstract

The invention relates to a liquid-phase transalkylation method of polyethylbenzene and benzene, which mainly solves the problems of poor water resistance, poor stability and low triethylbenzene conversion rate of a catalyst in the prior art. The invention adopts a method comprising the steps of contacting polyethylbenzene and benzene with a catalyst under liquid phase transalkylation conditions to generate ethylbenzene; the catalyst comprises the following components in parts by weight: a) 30-90 parts of a Y-type molecular sieve raw powder dry base; b) 10-70 parts of a binder; the technical scheme that the Si/Al molar ratio of the Y-type molecular sieve is between 20 and 60 but does not include 20 solves the problem well, and can be used in industrial production of ethylbenzene by liquid-phase transalkylation of polyethylbenzene and benzene.

Description

Method for liquid-phase transalkylation of polyethylbenzene and benzene

Technical Field

The invention relates to a liquid-phase transalkylation method of polyethylbenzene and benzene.

Background

Ethylbenzene is an important organic chemical raw material and is mainly used as a raw material for producing styrene in industry. Ethylbenzene is mainly prepared from benzene and ethylene through alkylation reaction, and the alkylation process is generally divided into a gas-phase molecular sieve method and a liquid-phase molecular sieve method. In the alkylation process of the gas phase molecular sieve method or the liquid phase molecular sieve method, as the reaction product ethylbenzene can be continuously alkylated with ethylene like the raw material benzene to generate polyethylbenzene components such as diethylbenzene, triethylbenzene, tetra-ethylbenzene and the like, an independent transalkylation reactor is established in the modern ethylbenzene industrial production, and the polyethylbenzene material separated from the alkylation reaction product is mixed with benzene and then reacts with the benzene through a transalkylation catalyst to generate ethylbenzene. By doing so, not only can the occurrence of side reactions in the alkylation reaction be reduced, the life of the alkylation catalyst be increased, but also the yield of ethylbenzene can be increased.

Earlier patents US3751504, US4016218, US3962364 and CN1310051 used gas phase transalkylation processes using ZSM-5 molecular sieve as the active component of the catalyst, unmodified HZSM-5, steam treated HZSM-5 molecular sieve, elemental phosphorus modification treatment and steam treatment with the addition of organic acid to the modified HZSM-5 molecular sieve. This results in a substantial improvement in the performance of the vapor phase alkyl catalyst. However, transalkylation reactions require higher acid strength than alkylation reactions, and vapor phase transalkylation reactions require very high reaction temperatures, typically greater than 400 ℃, to maintain the reaction mass in the vapor phase. This results in a relatively high number of side reactions, high xylene and impurity levels, and a relatively short catalyst life for vapor phase transalkylation reactions. Meanwhile, in order to maintain high selectivity, the conversion rate of gas phase transalkylation is low and is maintained at 60% at the maximum.

As the advantages of low temperature reactions in liquid phase processes have become increasingly recognized by researchers, molecular sieve liquid phase transalkylation processes have been developed in succession. US4774377 discloses a liquid phase transalkylation process using top-in-bottom-out, bottom-in-top-out or horizontally placed reactors with catalysts of X, Y type, L type, USY, omega zeolite and mordenite, with mordenite being recommended. The patent US3551510 discloses a process for obtaining ethylbenzene by separating the product of a gas phase alkylation process, while reacting the separated polyethylbenzene and benzene separately in a top-down transalkylation reactor at a liquid space velocity of 1.0 hour^-1Under the conditions of 250 ℃ and 3.4MPa, mordenite is adopted as a transalkylation catalyst. The use of mordenite in these patents results in higher reaction temperatures and lower space velocities for the feed.

CA2022982 describes a specific liquid phase transalkylation process using zeolite Y as the transalkylation catalyst. US4169111 describes in detail the use of a separate bottom-up transalkylation process, preferably with Na₂The O content is 0.2%, and the Y molecular sieve treated by steam hyperstabilization is used as a transalkylation catalyst. The recommended temperature is 232-343 ℃, the pressure is 2.8-6.9 MPa, and the total material mass airspeed is 2-10 hours^-1Benzene and diethylbenzene in molesThe reaction is carried out under the condition of 2-5. It can be seen that the Y molecular sieve treated by steam hyperstabilization is used as the transalkylation catalyst in the patent, the material space velocity is improved, but the reaction temperature is still higher. Japanese patent JP1135728 discloses a process for preparing diethylbenzene and benzene transalkylation catalysts under liquid phase conditions using iron modified Y zeolite but using H-containing catalyst prior to reaction₂And H₂The pretreatment process of the S gas is relatively complex before the catalyst is used. CN1323739A describes a Y-type molecular sieve used in the liquid phase transalkylation process of polyethylbenzene and benzene, and the prepared molecular sieve is obtained by at least one step of treatment for 0.5-4 hours, preferably for 1-3 hours at 150-600 ℃ under the atmosphere of ammonia gas at room temperature-650 ℃. CN1359752A describes a catalyst for the production of monoalkylbenzene from polyalkylbenzene and benzene, from SiO₂/Al₂O₃The molecular weight ratio of the HY zeolite to the inert components is 8-20, wherein the weight range of the Y zeolite is 40-90%, the balance of the Y zeolite is the inert components, and 0.01-5% (by weight) of one or more auxiliary elements selected from P, alkali metal and alkaline earth metal elements. The catalyst is used for producing ethylbenzene by the liquid phase transalkylation process of polyethylbenzene and benzene, the conversion rate of polyethylbenzene is more than 60%, the selectivity of ethylbenzene production is more than 99%, and the content of dimethylbenzene in ethylbenzene is less than 120 ppm. CN1373006A describes a catalyst for the production of ethylbenzene from polyethylbenzene and benzene, from SiO₂/Al₂O₃The zeolite Y comprises Y zeolite and an inert component, wherein the molar ratio of the Y zeolite to the inert component is 8-20, the weight range of the Y zeolite is 40-90%, and the balance is the inert component. The catalyst has the acid characteristic that the ratio of a medium-strong acid center (330-600 ℃ ammonia desorption corresponds to an acid center) to a weak acid center (150-330 ℃ ammonia desorption corresponds to an acid center) is 65: 35-35: 65. The catalyst is used for producing ethylbenzene in the liquid phase transalkylation process of polyethylbenzene and benzene, the conversion rate of the polyethylbenzene is more than 70 percent, and the selectivity of the ethylbenzene production is more than or equal to 98 percent. The above patents all have in common that the silica alumina ratio of the Y-type molecular sieve is in the range of 5 to 20 in the low silica alumina ratio region, and that the activity of p-diethylbenzene is better, but the activity of triethylbenzene is not mentioned.

Disclosure of Invention

The invention aims to solve the technical problems of poor water resistance, poor stability and low triethyl benzene conversion rate of a catalyst in the prior art, and provides a novel liquid-phase transalkylation method for polyethyl benzene and benzene. The method has the characteristics of good water resistance of the catalyst, good stability and higher conversion rate of the triethyl benzene than that of the diethyl benzene.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a process for the liquid phase transalkylation of polyethylbenzene with benzene comprising the step of contacting polyethylbenzene and benzene with a catalyst under liquid phase transalkylation conditions to produce ethylbenzene; the catalyst comprises the following components in parts by weight: a) 30-90 parts of a Y-type molecular sieve raw powder dry base; b) 10-70 parts of a binder; wherein, the Si/Al molar ratio of the Y-type molecular sieve is between 20 and 60, but not including 20.

In the technical scheme, the silica-alumina molar ratio of the Y-type molecular sieve is 25-50; preferably between 30 and 40.

In the above technical solution, the liquid phase transalkylation conditions include: the reaction temperature is 170-260 ℃, the reaction pressure is 2.0-4.5 MPa, and the weight space velocity of the liquid phase is 1-10 hours^-1The weight ratio of benzene to polyethylbenzene is 1-10.

In the above technical scheme, the polyethylbenzene comprises diethylbenzene and triethylbenzene.

In the technical scheme, the conversion rate of the triethylbenzene is greater than that of the diethylbenzene.

In the above technical solution, the binder is at least one selected from alumina, silica, clay or diatomaceous earth.

In the technical scheme, the polyethylbenzene is polyethylbenzene generated in the preparation of ethylbenzene by a pure ethylene method, a dilute ethylene method or an alcohol method.

The silicon-aluminum ratio of the catalyst in the method is in the range of 20-60, but does not include 20; preferably between 30 and 40. Methods for obtaining such a high silica-alumina ratio include silicon tetrachloride methods, hydrothermal treatment and acid washing treatment well known in the art, and dealumination methods such as ammonium fluorosilicate methods, ethylenediaminetetraacetic acid (EDTA) complexing agents, and the like. Generally, the hydrothermal treatment conditions include: the temperature is 400-900 ℃, the time is 1-8 hours, and the liquid-solid ratio is 0.1-10. The pickling treatment conditions comprise: the temperature is 0-120 ℃, the time is 1-8 hours, the liquid-solid ratio is 0.5-100, the concentration of the acid solution is 0.1-5%, and the acid is selected from organic acids such as oxalic acid, citric acid, acetic acid, tartaric acid and the like. The dealuminization treatment conditions of the ammonium fluosilicate method comprise the following steps: the temperature is 0-100 ℃, the time is 1-8 hours, and the liquid-solid ratio is 0.1-10. The dealuminizing treatment condition of the EDTA complexing agent comprises the following steps: the temperature is 0-100 ℃, the time is 0.1-8 hours, the liquid-solid ratio is 0.05-100, and the concentration of the acid solution is 0.01-5%. The dealuminization treatment conditions of the silicon tetrachloride method comprise the following steps: the temperature is 150-600 ℃, the time is 1-8 hours, and the weight ratio of the silicon tetrachloride to the molecular sieve is 0.01-20. Among them, a preferred method is a method of treating silicon tetrachloride.

In the liquid phase transalkylation of polyethylbenzene and benzene, small amounts of water are carried by the reaction feed benzene and polyethylbenzene, and very small amounts of water cause deactivation of the transalkylation catalyst, which is reversible, but the activity of the catalyst is greatly affected. The water resistance of the catalyst is reflected by the micro-water resistance of the catalyst with different physicochemical properties. The invention adopts the catalyst containing the Y-type molecular sieve with high silica-alumina ratio, and the surface and the orifice of the catalyst have silicon-rich surfaces, so the catalyst has better water resistance than the catalyst with low silica-alumina ratio.

Meanwhile, the Y-type molecular sieve with high silica-alumina ratio adopted by the method has a developed communicating structure in a micropore pore channel system and has more developed secondary pores. These secondary pore structures enhance the mass transfer capability of the material, allowing reactants and products to easily enter and exit the pore channels. The pore opening on the crystal surface is enlarged through dealuminization modification, and some sodium ions are easy to exchange, so that the method is easy for industrial operation.

By adopting the method, the catalyst has better stability, the regeneration period reaches more than 3 years, and better technical effect is achieved.

The present invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

Using a NaY type molecular sieve with a silicon-aluminum ratio of 5.5 as initial treatment raw powder, treating for 0.5 hour under the condition of a treatment temperature of 350 ℃ under silicon tetrachloride vapor, wherein the mass ratio of the silicon tetrachloride vapor to the molecular sieve is 0.05, performing ion exchange by using ammonium nitrate after air replacement, then filtering, washing, drying at 110 ℃, roasting, performing ammonium ion exchange, filtering, drying, roasting by using water vapor, performing ammonium ion exchange, drying and roasting to obtain the Y type molecular sieve with the sodium content of less than 0.01 percent and the silicon-aluminum ratio of 30. Extruding and forming according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished product of the catalyst A.

[ COMPARATIVE EXAMPLE 1 ]

A Y-type molecular sieve with the Si/Al ratio of 14 and the Na content less than 0.01% is adopted. Extruding into strips and forming according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished product of the catalyst B.

[ COMPARATIVE EXAMPLE 2 ]

A Y-type molecular sieve with the Si/Al ratio of 7.5 and the Na content less than 0.01% is adopted. Extruding into strips and forming according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished product of the catalyst C.

[ COMPARATIVE EXAMPLE 3 ]

A Y-type molecular sieve with 5.7 of silicon-aluminum ratio and 0.04 percent of sodium content is adopted. Extruding into strips and forming according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished product of the catalyst D.

[ example 2 ]

A Y-type molecular sieve with the Si/Al ratio of 30 and the Na content less than 0.01% is adopted. Extruding into strips and forming according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished product of the catalyst E.

[ example 3 ]

A Y-type molecular sieve with Si/Al ratio of 40 and Na content less than 0.01% is used. Extruding and molding according to the molecular sieve/alumina (dry basis ratio) of 70/30, drying at 110 ℃, and roasting at 550 ℃ for 3 hours to obtain the finished catalyst F.

[ example 4 ]

The initial activity of the catalyst is observed by using a fixed bed reactor from bottom to top, the reactor is a stainless steel tube with the inner diameter of 28 mm and the length of 800 mm, the loading amount of the catalyst is 3 g, and the upper part and the lower part of the catalyst are fixed by using glass beads to ensure that the catalyst is in a constant temperature section of the reactor.

Before the catalyst is used, the catalyst is stirred for 1 hour at 90 ℃ by using 10% ammonium nitrate aqueous solution, and is washed for 2 times by deionized water. The above ammonium ion exchange process was repeated 2 times. Drying at 110 deg.C, and calcining at 550 deg.C for 3 hr.

Dehydration treatment of reaction raw materials: the mass ratio of the prepared benzene to the polyethylbenzene is 2:1, having a water content of less than 10ppm, as feed 1; the raw material 2 is benzene and polyethylbenzene with saturated water adsorption mass ratio of 2:1, having a water content of 450 ppm. Mixing raw materials 1 and 2 in different proportions to prepare reaction raw materials with different water contents, and sealing the reaction raw materials with nitrogen for later use.

After the catalysts A to F are filled into a reactor, the catalysts are activated under the protection of nitrogen and activated for 1 hour at 400 ℃. Then cooling to below 40 ℃, stopping nitrogen purging, starting to feed the transalkylation material, starting to heat to the reaction temperature after the pressure reaches the set value, and starting to time by taking the temperature of the catalyst bed layer reaching the set temperature as the reaction 0 hour.

The reaction conditions are as follows: the temperature is 210 ℃, the pressure is 3.0MPa, and the total liquid phase space velocity is 2 hours^-1The weight ratio of benzene to diethylbenzene is 2: 1. And after the system is stable, taking a liquid product at regular time for chromatographic analysis. The following data are the stability data for 10 hours of feed, and are shown in table 1.

TABLE 1

Catalyst and process for preparing same	Silicon to aluminum ratio	Water content, ppm	Diethylbenzene conversion%	Triethyl benzene conversion%
					A	35	150	68.53	71.11
B	14	150	66.58	61.63
					C	7.5	50	64.24	54.80
D	5.7	60	67.91	49.76
					E	30	125	69.57	72.54
F	40	120	68.43	71.63
					E	30	250	65.43	68.27

As can be seen from Table 1, the catalyst with high Si/Al ratio not only has strong water resistance, but also has a higher triethylbenzene conversion rate than diethylbenzene conversion rate. The molecular size of the triethylbenzene is larger than that of diethylbenzene, the requirement on the diffusion performance of a molecular sieve pore channel is higher, the conversion rate of the triethylbenzene is high, the development of mesopores of the catalyst can be represented, and the mass transfer effect is good.

[ example 5 ]

The same as in example 4, except that the reaction temperature was 240 ℃ and the space velocity was 10 hours^-1The reaction raw material is added with 3.5 percent of a mixture of diphenylmethane and diphenylethane heavy components, the mass ratio of benzene to diethylbenzene is 0.5, and the stability of the catalyst is inspected. The results are shown in Table 2, and it can be seen that the catalyst with high silica to alumina ratio has better stability.

TABLE 2

Catalyst and process for preparing same	Silicon to aluminum ratio	Diethylbenzene conversion%	Ethyl benzene selectivity,%	Deactivation rate,%/h
					A	30	40.23	99.35	0.078
B	14	38.17	98.33	0.176
					C	7.5	39.42	98.25	0.286
D	5.7	41.75	98.76	0.279
					E	30	41.38	99.17	0.065
F	40	39.17	99.03	0.073

Claims

1. A process for the liquid phase transalkylation of polyethylbenzene with benzene comprising the step of contacting polyethylbenzene and benzene with a catalyst under liquid phase transalkylation conditions to produce ethylbenzene; the catalyst comprises the following components in parts by weight: a) 30-90 parts of a Y-type molecular sieve raw powder dry base; b) 10-70 parts of a binder; wherein the silica-alumina molar ratio of the Y-type molecular sieve is between 30 and 40.

2. The process of liquid phase transalkylation of polyethylbenzenes with benzene as recited in claim 1, wherein the liquid phase transalkylation conditions comprise: the reaction temperature is 170-260 ℃, the reaction pressure is 2.0-4.5 MPa, and the weight space velocity of the liquid phase is 1-10 hours^-1The weight ratio of benzene to polyethylbenzene is 1-10.

3. The process for the liquid phase transalkylation of polyethylbenzenes with benzene as recited in claim 1, wherein polyethylbenzenes comprise diethylbenzene and triethylbenzene.

4. The process for the liquid phase transalkylation of polyethylbenzenes with benzene as recited in claim 1, wherein the triethylbenzene conversion is greater than the diethylbenzene conversion.

5. The method of liquid phase transalkylation of polyethylbenzenes with benzene as recited in claim 1, wherein the binder is selected from at least one of alumina, silica, clay, or diatomaceous earth.

6. The process of claim 1, wherein the polyethylbenzene is polyethylbenzene produced in the production of ethylbenzene by the pure ethylene process, dilute ethylene process or the alcohol process.