WO2022016500A1

WO2022016500A1 - Method for efficiently preparing styrene by means of side chain alkylation of toluene and methanol

Info

Publication number: WO2022016500A1
Application number: PCT/CN2020/104085
Authority: WO
Inventors: 朱志荣; 赵国庆; 洪哲
Original assignee: 浙江环化科技有限公司
Priority date: 2020-07-24
Filing date: 2020-07-24
Publication date: 2022-01-27

Abstract

The present invention relates to a method for preparing styrene by means of the side chain alkylation of toluene and methanol. The method mainly solves the problems that in existing side chain alkylation technology of toluene and methanol, the selectivity of the styrene target product is low, the conversion rate of toluene is low, and the overall catalytic effect of the catalyst is poor, such that the technology of preparing styrene by means of the side chain alkylation of toluene and methanol cannot enter industrial application for a long time. In the present invention, toluene and methanol in a certain molar ratio are used as raw materials; by adding a certain amount of an alkaline reaction auxiliary agent before or during the reaction, under a certain reaction temperature and pressure, the raw materials and a catalyst are brought into continuous contact to perform reaction and conversion; and the styrene product is obtained at a high selectivity under the auxiliary action of the alkaline reaction auxiliary agent. By creating a new efficient reaction process, the method of the present invention efficiently solves the problem, in a breakthrough way, that in the process for preparing styrene by means of the side chain alkylation of toluene and methanol, the selectivity of the styrene product is low and improvement is difficult to achieve for a long time. In particular, the highest selectivity of styrene can reach 100%, so that the technical economy of the preparation of styrene by means of side chain alkylation technology of toluene and methanol meets industrial production application requirements.

Description

A kind of high-efficiency method of toluene and methanol side chain alkylation to prepare styrene

technical field

The invention relates to a method for preparing styrene by high-efficiency toluene and methanol side chain alkylation.

Background technique

As a very important chemical raw material, styrene is widely used in polystyrene, expanded styrene, styrene-butadiene, unsaturated resin, styrene-butadiene rubber, ion exchange resin and other fields. It has a very prominent position in the chemical industry. Existing production methods of styrene mainly include ethylbenzene dehydrogenation method, styrene propylene oxide co-production method, butadiene synthesis method, acetophenone method and the like. Most of the existing methods have disadvantages such as complicated process flow, high reaction energy consumption, many side reactions, and difficulty in product separation and purification. It has attracted much attention at home and abroad due to its many advantages in terms of reaction conditions, reaction energy consumption and market economy. Especially in the context of serious overcapacity of toluene, the breakthrough and development of new processes and new technologies are of greater significance. However, after more than 40 years of development, there are still many bottlenecks in the production of styrene by the side chain alkylation of toluene with methanol. The current research mainly focuses on the modification of molecular sieve catalysts and new process methods. Patents CN106278799A, CN109675610A, etc. improve the performance of catalysts in the catalytic reaction process by preparing nano-X molecular sieve catalysts and composite catalysts, etc. Patents CN109851469A, CN106278778A, etc New attempts have been made in the reaction process. In the existing method and catalyst system, the conversion rate of toluene in the reaction raw materials is not high, methanol is easily decomposed and cannot be fully utilized, and the reaction product styrene is easily generated by hydrogenation or transfer hydrogenation in the reaction process. As a result, the selectivity of styrene is low, the catalyst activity is low and the stability is poor in the reaction process, so that the technology of styrene production by side chain alkylation of toluene and methanol cannot be used in industrial applications for a long time. Therefore, how to solve the insufficiency of catalyst and process in the alkylation reaction of toluene methanol side chain is the top priority of breaking new technology.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is the problems of low toluene conversion rate, low methanol utilization rate and poor styrene selectivity in the prior art, and provides a method for producing styrene by alkylation of side chains of toluene and methanol with high efficiency . The advantages of this method are that there are fewer by-transformations of methanol in the reaction process, the reaction utilization rate is high, the conversion rate of toluene is high, and the selectivity of the target product styrene is particularly high.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows:

A method for producing styrene by high-efficiency toluene and methanol side chain alkylation, at least comprising: after completely mixing reaction raw material toluene and methanol according to a predetermined molar ratio, under a predetermined reaction temperature and pressure, at a predetermined mass space velocity It is continuously fed into the reactor, and a predetermined amount of basic reaction assistant is fed into the reactor before or in the reactor, and after undergoing the process of diffusion, adsorption, reaction and desorption on the porous catalyst, it can react with high selectivity to obtain benzene. vinyl.

As a further preferred technical solution of the present invention, the feeding mode of the alkaline reaction assistant is at least one of continuous feeding, pulse feeding, and wave feeding.

As a further preferred technical solution of the present invention, the addition amount of the basic reaction assistant is 0.1% to 10% of the molar amount of toluene in the reaction raw materials.

As a further preferred technical solution of the present invention, the alkaline reaction assistant is preferably one selected from pyridine, 2-methylpyridine, 4-methylpyridine and 2-aminopyridine.

As a further preferred technical solution of the present invention, the molar ratio of toluene and methanol in the reaction raw materials is 0.1-10; the reaction temperature is 250-500°C; the reaction pressure is 0.1-10MPa; The mass air velocity is 0.1～10h ^-1 .

As a further preferred technical solution of the present invention, the porous catalyst is a modified molecular sieve catalyst, and the molecular sieve catalyst types are X-type molecular sieve, Y-type molecular sieve, ZSM-5 type molecular sieve, SSZ-26 type molecular sieve, SSZ-13 type molecular sieve Type molecular sieve, MCM-22 molecular sieve, MCM-41 molecular sieve.

As a further preferred technical solution of the present invention, the modification method of the molecular sieve catalyst is alkaline earth metal oxide loading, amphoteric oxide loading, alkali metal oxide loading, transition metal loading, alkali metal oxide/basic molecular sieve composite, One of the alkali metal ion exchange.

As a further preferred technical solution of the present invention, the alkaline earth metal is at least one of magnesium, calcium, strontium and barium; the amphoteric oxide is zinc oxide, chromium oxide, aluminum oxide, beryllium oxide, vanadium oxide, at least one of iron oxide, cobalt oxide, germanium oxide, zirconium oxide, silver oxide, manganese oxide, tin oxide, and vanadium oxide; the alkali metal is at least one of sodium, potassium, rubidium, and cesium; the The transition metal is at least one of molybdenum, tungsten, ruthenium, palladium, platinum, rhenium and nickel.

As a further preferred technical solution of the present invention, the reaction process can be carried out in a certain atmosphere, and the atmosphere is at least one _{of CO 2} , N ₂ , Ar, He, NH ₃ , and H _{2 .} The molar ratio of gas consumption to toluene is 0.1-5.

The method described in the present invention is carried out in a self-made fixed-bed continuous flow reactor, and the process is briefly described as follows: take a predetermined amount of porous catalyst and put it into the constant temperature zone of the reactor, the lower part of the porous catalyst is filled with glass beads or quartz sand, and the upper part is filled with glass beads or quartz sand. Put an appropriate amount of glass beads or quartz sand. Before the reaction starts, the porous catalyst is activated at a temperature of 400 to 600 ° C for 1 to 5 hours, and then at the set temperature and pressure, the reaction raw materials are mixed, and the micro-pump is sent to the preheater and mixed with the carrier gas before entering. At the upper end of the reactor, the catalytic reaction is carried out through the catalyst bed, and the reaction product is analyzed by gas chromatography.

The activity and selectivity of the porous catalyst were calculated according to the following equations:

Beneficial effects of the present invention:

The method for preparing styrene by alkylation of toluene and methanol side chain provided by the invention has the characteristics of high toluene conversion rate and high methanol utilization rate, and can effectively suppress the side reaction conversion of benzene ring alkylation and styrene in the reaction process , thereby reducing the generation of the by-product ethylbenzene and greatly improving the selectivity of the target product styrene; it can effectively inhibit the decomposition of methanol and the by-transformation process of non-reactive active sites; the reaction process is simple and the product is easy to separate, which can meet the needs of industrial The requirements of the application are convenient for large-scale industrial production.

detailed description

The present invention will be further described below in conjunction with specific embodiments.

Example 1:

Take 10 g of the original NaX molecular sieve powder, use 0.5 mol/L cesium hydroxide as the precursor solution to carry out ion exchange modification according to the liquid-solid ratio of 5, and exchange at 90 °C for 3 times, each exchange time is 4 hours. After the exchange liquid is filtered, washed, dried, calcined, etc., the modified molecular sieve powder is obtained. The calcined molecular sieve powder, silica sol, and succulent powder are kneaded in a ratio of 80:20:5, extruded into strips, and broken into catalyst particles with a length of 2-4 mm. Then put it in a muffle furnace, calcinate at 520°C for 2 hours, and obtain the catalyst required for the reaction after screening.

5.0g of the above-mentioned catalyst finished product is put into the reactor, the mol ratio of toluene and methanol is 4:1, the mol ratio of 2-picoline and toluene is 2:100, the reaction temperature is 420° C., and the reaction pressure is normal pressure. N ₂ atmosphere, feed WHSV activity was evaluated under the conditions of 1.0h ^-1, the test results are shown in table 1.

Example 2:

Take 10 g of the original powder of NaLSX molecular sieve, and exchange the molecular sieve with 0.7mol/L cesium nitrate as the exchange liquid. At 95 °C, the solid-liquid ratio is 4 for 4 times, and each exchange time is 4 hours. After each exchange, the exchanged liquid is filtered, washed, dried, calcined and other steps to obtain modified molecular sieve powder. The calcined molecular sieve powder, silica sol, and succulent powder are kneaded in a ratio of 80:20:5, extruded into strips, and broken into catalyst particles with a length of 2-4 mm. Then put it in a muffle furnace, calcinate at 520°C for 2 hours, and obtain the catalyst required for the reaction after screening.

Put 5.0g of the above-mentioned catalyst finished product into the reactor, the mol ratio of toluene and methanol is 3:1, the mol ratio of 4-picoline and toluene is 0.5:100, the reaction temperature is 450 ° C, and the reaction pressure is normal pressure , in the He atmosphere, the activity evaluation was carried out under the condition that the mass space velocity of the raw material was 1.0h ^-1 , and the test results are listed in Table 1.

Example 3:

Take 10g of the original powder of hydrogen-type MCM-22 molecular sieve, and exchange the molecular sieve with 0.75mol/L cesium hydroxide as the exchange liquid. At 90 °C, the solid-liquid ratio is 6 for 4 times, and each exchange time is 4 hours. The ion-exchanged precursor solution was then replaced with deionized water under the same conditions, and the solution was rapidly stirred at high temperature for 4 times for 2 hours each time. After each exchange, the exchange liquid was filtered, washed and dried, and the obtained molecular sieve was calcined in a muffle furnace at 520° C. for 4 hours. The obtained molecular sieve is then subjected to the next exchange process under the same conditions. Finally, the calcined molecular sieve powder, silica sol, activated alumina, and succulent powder were mixed uniformly in a high-speed pulverizer according to the ratio of 70:15:15:5, and then a certain amount of 3% dilute nitric acid aqueous solution was added to the solid powder. , kneading, extruding and crushing catalyst particles with a length of 2 to 4 mm. Then put it in a muffle furnace, calcinate at 520°C for 2 hours, and obtain a bonded catalyst after screening.

Put 5.0g of the above-mentioned catalyst finished product into the reactor, and the toluene and methanol molar ratio is 6:1. Before the reaction, pyridine is introduced into a sinusoidal curve, and the cumulative amount of pyridine introduced is 0.3% of the toluene molar amount. The reaction temperature of 450 ℃, a reaction pressure of atmospheric pressure, the NH ₃ gas atmosphere, a space velocity of the raw material mass activity was evaluated under the conditions of 1.0h ^-1, the test results are shown in table 1.

Comparative Example 1:

Take 10 g of the original powder of NaX molecular sieve, use 1.0 mol/L potassium hydroxide as the exchange liquid to exchange the molecular sieve, and exchange it three times at 80 ° C according to the solid-liquid ratio of 5, and each exchange time is 2 hours. After passing the exchange liquid through the steps of filtration, washing and drying, the obtained molecular sieve was calcined in a muffle furnace at 520° C. for 4 hours. The calcined molecular sieve powder, silica sol, and succulent powder are kneaded in a ratio of 80:20:5, extruded into strips, and broken into catalyst particles with a length of 2-4 mm. Then put it in a muffle furnace, calcinate at 520°C for 2 hours, and obtain a bonded catalyst after screening.

5.0g of the above catalyst product was put into the reactor, and the activity evaluation was carried out under the conditions that the molar ratio of toluene and methanol was 4:1, the reaction temperature was 420°C, the reaction pressure was normal pressure, and the mass space velocity of the raw material was 1.0h ^-1. , the test results are listed in Table 1.

Comparative Example 2:

Take 10 g of the original powder of NaLSX molecular sieve, and exchange the molecular sieve with 0.7 mol/L cesium nitrate as the exchange liquid. At 95 °C, the solid-liquid ratio is 8 for 3 times, and each exchange time is 2 hours. After each exchange, the exchange liquid was filtered, washed and dried, and the obtained molecular sieve was calcined in a muffle furnace at 520° C. for 4 hours. The obtained molecular sieve is then subjected to the next exchange process under the same conditions. Finally, the calcined molecular sieve powder, silica sol, and succulent powder are kneaded in a ratio of 80:20:5, extruded into strips, and broken into catalyst particles with a length of 2-4 mm. Then put it in a muffle furnace, calcinate at 520°C for 2 hours, and obtain a bonded catalyst after screening.

5.0g of the above catalyst product was put into the reactor, and the activity evaluation was carried out under the conditions that the molar ratio of toluene and methanol was 6:1, the reaction temperature was 450°C, the reaction pressure was normal pressure, and the mass space velocity of the raw material was 1.0h ^-1. , the test results are listed in Table 1.

Table 1:

编号Numbering	甲苯转化率Toluene conversion	甲醇转化率methanol conversion	苯乙烯选择性Styrene selectivity	乙苯选择性ethylbenzene selectivity
实施例1Example 1	21.8％21.8%	68.5％68.5%	100％100%	0％0%
实施例2Example 2	30.1％30.1%	72.3％72.3%	97.5％97.5%	2.5％2.5%
实施例3Example 3	15.9％15.9%	83.2％83.2%	99.4％99.4%	0.6％0.6%
对比例1Comparative Example 1	6.5％6.5%	93.4％93.4%	30.5％30.5%	69.5％69.5%
对比例2Comparative Example 2	4.7％4.7%	98.6％98.6%	21.2％21.2%	78.8％78.8%

Claims

A method for producing styrene by high-efficiency toluene and methanol side chain alkylation is characterized in that, at least comprising: after the reaction raw material toluene and methanol are completely mixed according to a predetermined molar ratio, at a predetermined reaction temperature and pressure, at a predetermined reaction temperature and pressure. The mass space velocity is continuously fed into the reactor, and a predetermined amount of basic reaction assistant is fed into the reactor before or in the reactor. After the porous catalyst undergoes the processes of diffusion, adsorption, reaction, and desorption, the reaction to obtain styrene.
The method for producing styrene by alkylation of a high-efficiency toluene and methanol side chain according to claim 1, it is characterized in that, the feeding mode of basic reaction assistant is continuous feeding, pulse feeding, wave feeding at least one of them.
A kind of high-efficiency toluene and methanol side chain alkylation method for preparing styrene according to claim 2, it is characterized in that, the addition amount of described basic reaction assistant is 0.1% of toluene molar amount in reaction raw material ~10%.
The method for producing styrene by alkylation of a kind of high-efficiency toluene and methanol side chain according to claim 2, it is characterized in that, described basic reaction assistant is preferably selected from pyridine, 2-methylpyridine, 4-methylpyridine One of pyridine and 2-aminopyridine.
A kind of high-efficiency method for preparing styrene by alkylation of toluene and methanol side chain according to claim 1, is characterized in that, in described reaction raw material, the molar ratio of toluene and methanol is 0.1～10; The temperature is 250-500°C; the reaction pressure is 0.1-10MPa; the mass space velocity is 0.1-10h -1 .
The method for producing styrene by alkylation of a high-efficiency toluene and methanol side chains according to claim 1, wherein the porous catalyst is a modified molecular sieve catalyst, and the molecular sieve catalyst is an X-type molecular sieve. , Y molecular sieve, ZSM-5 molecular sieve, SSZ-26 molecular sieve, SSZ-13 molecular sieve, MCM-22 molecular sieve, MCM-41 molecular sieve.
A kind of high-efficiency method for preparing styrene by alkylation of toluene and methanol side chain according to claim 5, it is characterized in that, the modification method of described molecular sieve catalyst is alkaline earth metal oxide loading, amphoteric oxide loading, One or more of alkali metal oxide loading, transition metal loading, alkali metal oxide/basic molecular sieve composite, and alkali metal ion exchange.
The method for producing styrene by alkylation of a high-efficiency toluene and methanol side chains according to claim 5, wherein the alkaline earth metal is at least one of magnesium, calcium, strontium, and barium; The amphoteric oxide is at least one of zinc oxide, chromium oxide, aluminum oxide, beryllium oxide, vanadium oxide, iron oxide, cobalt oxide, germanium oxide, zirconium oxide, silver oxide, manganese oxide, tin oxide, and vanadium oxide; The alkali metal is at least one of sodium, potassium, rubidium, and cesium; the transition metal is at least one of molybdenum, tungsten, ruthenium, palladium, platinum, rhenium, and nickel.
The method for producing styrene by alkylation of a high-efficiency toluene and methanol side chains according to claim 1, wherein the reaction process can be selected to be carried out in a certain atmosphere, and the atmosphere is CO 2 , at least one of N 2 , Ar, He, NH 3 , and H 2 , and the molar ratio of its gas consumption to toluene is 0.1-5.