Methylphenol compound isomerization method

Abstract

The invention belongs to the technical field of synthesis of chemical products, and discloses a methyl phenol compound isomerization method, which comprises the following steps: at a certain reaction temperature and pressure, mixing a gasified methyl phenol compound with carrier gas, and carrying out isomerization reaction when passing through a fixed bed reactor filled with a double-layer combined modified ZSM-5 catalyst at a certain air speed, the ZSM-5 catalyst contains elements of Si, Al, Fe and Ge. A metal heteroatom component is introduced into a ZSM-5 molecular sieve framework, so that the pore structure and active sites of the molecular sieve can be effectively improved, the carbon deposition resistance of the catalyst is improved, the activity and stability of the catalyst are enhanced, and the service life of the catalyst is greatly prolonged; and meanwhile, the catalyst has a very good catalytic effect on isomerization of various methylphenol compounds.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis of chemical products, and in particular relates to a method for isomerizing methyl phenol compounds. Background Art

[0002] Methylphenol compounds are important chemical raw materials, including o-cresol, p-cresol, m-cresol and various xylenols, which are widely used in medicine, pesticides, dyes, spices, coatings, rubber and plastics. In addition, cresols can also be used as solvents, preservatives and disinfectants. In addition to their wide range of uses, these compounds also have high added value.

[0003] At present, the main way to obtain methylphenol compounds is natural separation, that is, separation from coal tar, but due to limited resources, complex processes, and low product quality, natural separation equipment is being eliminated. Chemical synthesis has begun to emerge in recent years, and the main methods include phenol or cresol alkylation, chlorotoluene hydrolysis, and cresol isomerization.

[0004] However, the catalysts used in the prior art for isomerization of methylphenol compounds generally have low activity, poor selectivity, and are easily deactivated when catalyzing the isomerization reaction. If it is to be applied to a fixed bed device, a catalyst with better activity and stability needs to be found. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a method for isomerization of methyl phenol compounds, and the technical scheme is as follows: A method for isomerizing methylphenol compounds. Under certain reaction temperature and pressure conditions, the methylphenol compounds are gasified and mixed with a carrier gas, and an isomerization reaction occurs when the methylphenol compounds pass through a fixed bed reactor equipped with a double-layer combined modified ZSM-5 catalyst at a certain space velocity to generate isomer products. The ZSM-5 catalyst contains Si, Al, Fe, and Ge elements.

[0006] The methylphenol compound includes one or more of o-cresol, p-cresol, m-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol and 3,5-xylenol.

[0007] The reaction temperature is 270°C to 400°C.

[0008] The reaction pressure is 0.1-2 MPa.

[0009] The space velocity is the feed space velocity of the methylphenol compound, and its range is 0.5~3h -1 .

[0010] The carrier gas is nitrogen or hydrogen, and the molar ratio of the carrier gas to the methylphenol compound is 0.5-5.

[0011] The double-layer combined modified ZSM-5 catalyst is a molded iron-germanium bimetallic modified ZSM-5 molecular sieve catalyst, wherein the element molar ratio of the catalyst loaded in the upper layer of the reactor is Si:Al:Fe:Ge=50-100:1:0.5:0.5, and the element molar ratio of the catalyst loaded in the lower layer of the reactor is Si:Al:Fe:Ge=20-50:1:0.5:0.5, and the mass ratio of the loading amounts of the two catalysts is 2:1-1:2.

[0012] The molding method comprises: mixing modified ZSM-5 molecular sieve raw powder and a binder in proportion, extruding or tabletting, and drying and calcining to obtain a molded catalyst.

[0013] The binder is silica sol or pseudo-boehmite, and the mass ratio of the binder to the molecular sieve raw powder is 5-30:100.

[0014] The drying temperature is 100-200° C., the drying time is 8-24 hours, the roasting temperature is 400-600° C., and the roasting time is 4-24 hours.

[0015] The beneficial effects of the present invention compared with the prior art are: The present invention can effectively improve the pore structure and active sites of molecular sieve by introducing metal heteroatom components in the ZSM-5 molecular sieve framework, improve the anti-carbon deposition ability of catalyst, enhance the activity and stability of catalyst, and greatly prolong the life of catalyst. In addition, because the metal atom introduced by molecular sieve has appropriate hydrogenation performance, therefore, when carrying out cresol hydroisomerization, phenols excessive hydrogenation will not be caused, but the carbon deposition of catalyst can be further suppressed, thereby further prolonging the life of catalyst. When carrying out catalytic isomerization reaction, because the catalyst activity of different silicon-aluminum ratios has certain differences, the catalyst of different silicon-aluminum ratios is used in the reactor for combined loading, so that the reaction distribution can be made more uniform, which is conducive to the raising of reaction selectivity. Simultaneously, the isomerization of various methylphenol compounds is all provided with good catalytic effect. DETAILED DESCRIPTION

[0016] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0017] Example 1

[0018] The preparation method of iron-germanium modified ZSM-5 molecular sieve raw powder is as follows: (1) Weigh 100 g of silica sol (SiO2 ≥ 30 wt%) and mix well with 100 g of deionized water, then add 203 g of 25% tetrapropylammonium hydroxide (TPAOH) solution under stirring, and continue stirring until the solution becomes clear to obtain solution A; (2) Dissolve 5.7 g of aluminum sulfate in 100 g of deionized water and stir evenly to obtain solution B; (3) Slowly drip solution B into solution A while stirring to obtain initial gel C; (4) Weigh 1.4 g of Na2GeO3 and dissolve it in 20 g of deionized water. Stir evenly to obtain solution D. Then slowly drop solution D into the initial gel C while stirring to obtain gel E. (5) Weigh 3.4 g of Fe(NO3)3·9H2O and dissolve it in 5 g of deionized water. Stir evenly to obtain solution F. Then slowly drip solution F into gel E under stirring to obtain a mixed gel. Then adjust the pH of the gel solution to 10 with 1 mol / L sodium hydroxide and age it at 30°C for 24 h. The molar ratio of Si:Al:Fe:Ge:template in the obtained gel is 30:1:0.5:0.5:15. (6) placing the mixed gel in a crystallization kettle and performing hydrothermal crystallization at 180° C. under autogenous pressure for 24 h to obtain a Fe / Ge isomorphously substituted ZSM-5 molecular sieve; (7) The obtained molecular sieve was filtered, washed, dried at 120°C for 24 h and calcined at 550°C for 12 h to remove the template, thereby obtaining the molecular sieve raw powder; (8) The molecular sieve raw powder was ion exchanged three times with 1 mol / L NH4NO3 solution at 70°C, and then filtered, washed, dried at 120°C for 24 h and calcined at 550°C for 8 h to obtain hydrogen-type Fe-Ge-ZSM-5 molecular sieve raw powder, which was recorded as CAT-30.

[0019] The same method was used, except that the Si:Al ratio was changed to 60:1. The resulting catalyst was named CAT-60.

[0020] Example 2

[0021] Take 20g of CAT-30 and 12g of 30% silica sol respectively, mix them evenly, squeeze them into strips and dry them naturally, dry them at 120℃ for 12h, and then calcine them at 550℃ for 6h to obtain catalysts named CAT-30-1 and CAT-60-1.

[0022] Example 3

[0023] Take 20g of CAT-30 and CAT-60 molecular sieve raw powder and 5g of pseudo-boehmite, mix them evenly, press them into tablets, dry them at 120℃ for 12h, and then calcine them at 500℃ for 12h to obtain catalysts named CAT-30-2 and CAT60-2.

[0024] Example 4

[0025] The catalytic performance of the catalyst in the isomerization reaction of o-cresol was evaluated. 3g of catalyst CAT-30-1 was loaded into the lower layer of the fixed bed reactor, and 2g of catalyst CAT-60-1 was loaded into the upper layer of the fixed bed reactor. Under the condition of nitrogen as carrier gas, the temperature was raised to 280°C, and the o-cresol feed rate was 5g / h (space velocity 1h -1 ), nitrogen flow rate of 30mL / min, reaction pressure of 0.2MPa, continuous reaction at 280-380℃ for 2000h, the products were analyzed by gas chromatography, the results showed that the average conversion rate of o-cresol was 47.1%, the average yield of m-cresol was 35.1%, the average yield of p-cresol was 11.4%, and the total selectivity of m-p-cresol was 98.7%.

[0026] Comparative Example 1 The catalytic performance of the catalyst in the isomerization reaction of o-cresol was evaluated. 5 g of catalyst CAT-60-1 was loaded into a fixed bed reactor, and the temperature was raised to 280 ° C under the condition of nitrogen as carrier gas. The o-cresol feed rate was 5 g / h (space velocity 1h -1 ), nitrogen flow rate 30mL / min, reaction pressure 0.2MPa, continuous reaction at 280-380℃ for 2000h, product analysis by gas chromatography, the results show that the average conversion rate of o-cresol is 35.9%, the average yield of m-cresol is 26.8%, the average yield of p-cresol is 8.4%, and the total selectivity of p-cresol is 98.1%. Using CAT-60-1 alone as catalyst, the conversion rate is relatively low.

[0027] Comparative Example 2 The catalytic performance of the catalyst in the isomerization reaction of o-cresol was evaluated. 5 g of catalyst CAT-30-1 was loaded into a fixed bed reactor, and the temperature was raised to 280 ° C under the condition of nitrogen as carrier gas. The o-cresol feed rate was 5 g / h (space velocity 1h -1 ), nitrogen flow rate 30mL / min, reaction pressure 0.2MPa, continuous reaction at 280-380℃ for 2000h, product analysis by gas chromatography, the results show that the average conversion rate of o-cresol is 45.3%, the average yield of m-cresol is 33.3%, the average yield of p-cresol is 10.4%, and the total selectivity of p-cresol is 96.4%. When CAT-30-1 is used alone as catalyst, the selectivity is relatively low.

[0028] Example 5

[0029] The catalytic performance in the isomerization reaction of 2,6-dimethylphenol was evaluated. 2.5 g of catalyst CAT-30-2 was loaded into the lower layer of the fixed bed reactor, and 2.5 g of catalyst CAT-60-2 was loaded into the upper layer of the fixed bed reactor. Under the condition of hydrogen as carrier gas, the temperature was raised to 280°C, and the feed rate of 2,6-dimethylphenol was 8 g / h (space velocity 1.6 h -1 ), hydrogen flow rate of 50mL / min, reaction pressure of 0.4MPa, continuous reaction at 280-360℃ for 2000h, product analysis by gas chromatography, the results showed that the average conversion rate of 2,6-dimethylphenol was 56.2%, the average yield of 2,4-dimethylphenol was 12.9%, the average yield of 2,5-dimethylphenol was 23.7%, the average yield of 2,3-dimethylphenol was 2.8%, the average yield of 3,4-dimethylphenol was 7.5%, the average yield of 3,5-dimethylphenol was 5.4%, and the total selectivity of dimethylphenol was 92.9%.

[0030] Example 6

[0031] The catalytic performance of the catalyst in the isomerization reaction of p-cresol was evaluated. 2g of catalyst CAT-30-2 was loaded into the lower layer of the fixed bed reactor, and 3g of catalyst CAT-60-2 was loaded into the upper layer of the fixed bed reactor. Under the condition of hydrogen as carrier gas, the temperature was raised to 280°C, and the p-cresol feed rate was 5g / h (space velocity 1h -1 ), hydrogen flow rate of 30mL / min, reaction pressure of 0.6MPa, continuous reaction at 280-340℃ for 2000h, the products were analyzed by gas chromatography, the results showed that the average conversion rate of p-cresol was 53.3%, the average yield of o-cresol was 5.7%, the average yield of m-cresol was 46.5%, and the total selectivity of o-m-cresol was 97.9%.

[0032] Example 7

[0033] The catalytic performance of the catalyst in the isomerization reaction of 2,4-dimethylphenol was evaluated. 1.7g of catalyst CAT-30-1 was loaded into the lower layer of the fixed bed reactor, and 3.3g of catalyst CAT-60-2 was loaded into the upper layer of the fixed bed reactor. Under the condition of nitrogen as carrier gas, the temperature was raised to 280°C, and the feed rate of 2,4-dimethylphenol was 5g / h (space velocity 1h -1 ), nitrogen flow rate of 20mL / min, reaction pressure of 0.4MPa, continuous reaction at 280-380℃ for 2000h, product analysis by gas chromatography, the results showed that the average conversion rate of 2,4-dimethylphenol was 59.1%, the average yield of 2,6-dimethylphenol was 3.0%, the average yield of 2,5-dimethylphenol was 38.2%, the average yield of 2,3-dimethylphenol was 2.1%, the average yield of 3,4-dimethylphenol was 8.0%, the average yield of 3,5-dimethylphenol was 5.3%, and the total selectivity of dimethylphenol was 95.8%.

[0034] Example 8

[0035] The catalytic performance of the catalyst in the isomerization reaction of 2,3-dimethylphenol was evaluated. 3g of catalyst CAT-30-2 was loaded into the lower layer of the fixed bed reactor, and 2g of catalyst CAT-60-1 was loaded into the upper layer of the fixed bed reactor. Under the condition of hydrogen as carrier gas, the temperature was raised to 280°C, and the feed rate of 2,3-dimethylphenol was 15g / h (space velocity 3h -1 ), hydrogen flow rate of 50mL / min, reaction pressure of 0.5MPa, continuous reaction at 280-340℃ for 2000h, product analysis by gas chromatography, the results showed that the average conversion rate of 2,4-dimethylphenol was 67.2%, the average yield of 2,6-dimethylphenol was 3.3%, the average yield of 2,5-dimethylphenol was 30.3%, the average yield of 2,4-dimethylphenol was 15.7%, the average yield of 3,4-dimethylphenol was 8.9%, the average yield of 3,5-dimethylphenol was 6.1%, and the total selectivity of dimethylphenol was 95.7%.

[0036] In summary, by using the isomerization method of methyl phenol compounds of the present invention, the product yield can reach more than 95%, while the method of the prior art is generally about 90%.

[0037] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A method for isomerizing methylphenol compounds, characterized in that: Under certain reaction temperature and pressure conditions, methylphenol compounds are gasified and mixed with carrier gas, and undergo isomerization reaction at a certain space velocity through a fixed bed reactor equipped with a double-layer combined modified ZSM-5 catalyst to generate its isomer products. The double-layer combined modified ZSM-5 catalyst is a molded iron-germanium bimetallic modified ZSM-5 molecular sieve catalyst, wherein the element molar ratio of the catalyst loaded in the upper layer of the reactor is Si:Al:Fe:Ge=50-100:1:0.5:0.5, and the element molar ratio of the catalyst loaded in the lower layer of the reactor is Si:Al:Fe:Ge=20-50:1:0.5:0.5; the mass ratio of the loading amounts of the two catalysts is 2:1-1:

2.

2. The method for isomerization of methylphenol compounds according to claim 1, characterized in that: The methylphenol compound includes one or more of o-cresol, p-cresol, m-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol and 3,5-xylenol.

3. The method for isomerization of methyl phenolic compounds according to claim 1, characterized in that: The reaction temperature is 270°C to 400°C.

4. The method for isomerization of methylphenol compounds according to claim 1, characterized in that the reaction pressure is 0.1-2 MPa.

5. The method for isomerization of methyl phenolic compounds according to claim 1, characterized in that: The space velocity is the feed space velocity of the methylphenol compound, and its range is 0.5~3h -1 .

6. The method for isomerization of methylphenol compounds according to claim 1, characterized in that: The carrier gas is nitrogen or hydrogen, and the molar ratio of the carrier gas to the methylphenol compound is 0.5-5.

7. The method for isomerization of methylphenol compounds according to claim 1, characterized in that: The ZSM-5 catalyst is a formed catalyst, and the forming method includes: mixing the modified ZSM-5 molecular sieve raw powder and the binder in proportion, extruding or pressing into sheets, and then drying and roasting.

8. The method for isomerization of methyl phenolic compounds according to claim 7, characterized in that: The binder is silica sol or pseudo-boehmite, and the mass ratio of the binder to the molecular sieve raw powder is 5-30:

100.

9. The method for isomerization of methylphenol compounds according to claim 7, characterized in that: The drying temperature is 100-200° C., the drying time is 8-24 hours, the roasting temperature is 400-600° C., and the roasting time is 4-24 hours.