Method for rich production of methylphenol through transalkylation

Abstract

The invention discloses a method for producing methylphenol through transalkylation, which comprises the following steps: enabling a raw material to pass through a reactor bed filled with a transalkylation catalyst, and reacting at 300-480 DEG C to obtain the methylphenol, the raw material being a mixture of phenol and C8 + heavy alkylphenol. Or a mixture of phenol and C8 + heavy alkylphenol is used as a raw material, and a phenol / C8 + heavy phenol transalkylation reaction is carried out in the presence of a transalkylation catalyst in the presence of hydrogen to obtain the methylphenol. According to the method, phenol is used as a methyl acceptor, a product generated through transalkylation reaction is mainly methyl phenol with o-cresol as a main component, the added value of the product is increased, and the integrating degree with the crude phenol refining industry is higher. The mass ratio of phenol to C8 + heavy phenol in the feed can reach 50: 50, and the heavy phenol treatment capacity, the conversion rate and the total selectivity of methylphenol are high.

Description

Technical Field

[0001] The invention relates to the fields of fine chemicals and coal tar processing, in particular to a method for refining crude phenol and producing and processing alkylphenols, and specifically to a method for enriching methylphenols through alkylation. Background Art

[0002] Medium and low temperature coal tar and coal direct liquefaction oil contain 15~30wt% and 10~20% phenolic compounds respectively. The production of refined phenol by extracting phenol from coal tar not only has a cost advantage that is difficult to match with the petroleum route, but also can reduce my country's dependence on foreign oil and ensure energy security. Due to the relatively low pyrolysis temperature, medium and low temperature coal tar and coal direct liquefaction oil contain a large number of uncracked side chain groups, and their phenolic compounds are mostly C8+ heavy alkylphenols such as xylenol, trimethylol, ethylphenol, and methylethylphenol. The crude phenol obtained by extracting phenol from medium and low temperature coal tar contains about 40wt%~60wt% C8+ heavy alkylphenols. These high-grade alkylphenols have complex compositions and many isomers, making them difficult to separate and utilize. At present, due to the lack of effective utilization methods for C8+ heavy alkylphenols, industry usually only distills and cuts part of the xylenols in C8+ alkylphenols, and most of the rest are used as coal tar hydrogenation raw materials or boiler fuels.

[0003] There are relatively few studies on the conversion and utilization of C8+ heavy alkylphenols at home and abroad. Some researchers have proposed a technical route to achieve dealkylation and increase the production of phenol pairs through cracking reactions, but the dealkylation reaction can only achieve the cracking of propyl and ethyl groups at present. There is no effective solution to the large amount of xylenol, trimethylol and tetramethylol in C8+ heavy alkylphenols. A patent proposes a technical route for using toluene to transfer alkylphenols, which can achieve the conversion of 2,6-xylenol or 4-ethylphenol to phenol, but its xylenol conversion rate and selectivity for the target product phenol are poor (both less than 50%), and a large amount of toluene is required as an alkyl transfer agent (toluene to phenol molar ratio 10:1), which is difficult to achieve industrial application. Summary of the invention

[0004] In order to solve the problems that the crude phenol currently produced by extracting phenol from coal tar has low value and a large amount of C8+ heavy alkylphenol contained therein is difficult to efficiently utilize, the purpose of the present invention is to propose a method for enriching methylphenol by alkyl transfer. The method realizes methyl migration between phenol and C8+ heavy phenol by utilizing phenol in crude phenol and C8+ heavy phenol through isomerization reaction, thereby realizing high-value conversion of crude phenol into methylphenol.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for producing methylphenol by transalkylation comprises the following steps: The raw material is passed through a reactor bed filled with a catalyst and reacted at 300-480° C. to obtain methylphenol, wherein the raw material is a mixture containing phenol and C8+ heavy alkylphenol.

[0006] Furthermore, the mass ratio of the catalyst to the raw material is 5:1-1:10.

[0007] Furthermore, the catalyst is a combination of zeolite and a carrier aid or zeolite.

[0008] Furthermore, the zeolite is a combination of one or more zeolites selected from the group consisting of hydrogen or ammonium MOR, Y, Beta, ZSM-5, and MCM-41 zeolites, and the carrier additive is a combination of one or more metal oxides selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, cerium oxide, lanthanum oxide, and silicon oxide.

[0009] Furthermore, the mass ratio of zeolite to carrier additive is 1:9-9:1.

[0010] A method for producing methylphenol by transalkylation comprises the following steps: A mixture of phenol and C8+ heavy alkylphenol is used as raw materials, and a phenol / C8+ heavy phenol alkyl transalkylation reaction is carried out in the presence of an alkyl transalkylation catalyst and under hydrogenation conditions to obtain methylphenol.

[0011] Furthermore, the reaction pressure is 1-5 MPa.

[0012] Furthermore, the mass space velocity of the raw material is 1-15h -1 .

[0013] Furthermore, the alkyl transfer catalyst is prepared by the following process: uniformly mixing one or more of hydrogen or ammonium type MOR, Y, Beta, ZSM-5, MCM-41 zeolites, one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, cerium oxide, lanthanum oxide and silicon oxide with extrusion type auxiliary agent powder, extruding and molding, drying and then calcining to obtain the alkyl transfer catalyst.

[0014] Further, hydrogen-type Y zeolite is prepared by the following process: reacting USY zeolite with nitric acid, or reacting USY zeolite with a mixed solution of citric acid and nitric acid, or reacting USY zeolite with a mixed solution of oxalic acid and nitric acid at a solid-liquid ratio of 1:10-30 at 60-100°C for 2-10h, filtering, and drying; Preparation of hydrogen-type Beta zeolite: react Hβ zeolite with a mixed solution of citric acid and nitric acid at a solid-liquid ratio of 1:10-30 at 60-100°C for 2-10h, filter and dry.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention realizes the high-value conversion of crude phenol to methylphenol by utilizing the phenol and C8+ heavy phenol in crude phenol to undergo an isomerization reaction, thereby achieving methyl migration between phenol and C8+ heavy phenol. Specifically, using phenol as a methyl acceptor, the product generated by the transalkylation reaction is mainly methylphenol mainly composed of o-cresol, the added value of the product is improved, and the product is more compatible with the crude phenol refining industry. The mass ratio of phenol to C8+ heavy phenol in the feed of the present invention can reach 50:50, and the heavy phenol processing capacity, conversion rate and total selectivity of methylphenol are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a simplified flow chart of the application of C8+ heavy phenol.

[0017] Figure 2 This is the application process flow chart of C8+ heavy phenol. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0019] See also Figure 1 The crude phenol feed obtained by extracting phenol from coal tar and the methylphenol-rich mixed phenol produced by the alkyl transfer unit are cut into fractions in the crude phenol refining unit to obtain the main product methylphenol fraction, and the remaining light component phenol fraction and heavy component C8+ heavy phenol fraction (xylenol and phenol residue fraction) are sent to the alkyl transfer unit for further conversion. In the alkyl transfer unit, phenol and C8+ heavy phenol are converted into methylphenol-rich mixed phenol mainly composed of o-cresol through methyl migration reaction, and the product (methylphenol-rich mixed phenol mainly composed of o-cresol) is sent to the crude phenol refining unit for separation to obtain methylphenol product.

[0020] The crude phenol refining unit is a distillation separation unit, which can be composed of one distillation tower or multiple distillation towers.

[0021] The transalkylation unit is a transalkylation reaction unit. Phenol and C8+ heavy phenol undergo methyl migration reaction under hydrogen conditions in a reactor equipped with a catalyst to obtain a mixed phenol product rich in o-cresol. The dehydrogenated o-cresol-rich mixed phenol is sent to a crude phenol refining distillation tower to be distilled and separated together with the crude phenol feed, and methylphenol is extracted as a product. The remaining phenol and C8+ heavy phenol components are sent to the transalkylation unit for continued reaction and recycling.

[0022] See also Figure 2, the crude phenol feed and the circulating methylphenol-rich mixed phenol are separated into methylphenol products and phenol and C8+ heavy phenol fractions through the distillation tower of crude phenol refining. The supplementary phenol feed, the phenol fraction taken from the crude phenol refining, and the C8+ heavy phenol fraction are preheated with circulating hydrogen in the heating furnace through the mixed phenol buffer tank, and then subjected to transalkylation reaction in the isomerization reactor to be converted into methylphenol. The reaction product is separated by the light removal flash tower and divided into two paths. One path is the light removal non-condensable gas, which is pressurized and used as circulating hydrogen and carrier gas to preheat with the materials and return to the isomerization reactor. The other path is the methylphenol-rich mixed phenol, which is sent to the crude phenol refining tower to separate the methylphenol product.

[0023] A method for producing methylphenol by transalkylation of the present invention comprises the following steps: Phenol is used as a raw material. Under the conditions of transalkylation reaction, it passes through a reactor bed filled with a catalyst, the mass ratio of the catalyst to the raw material is 5:1-1:10, and reacts at 300-480°C to obtain a mixed phenol product rich in methylphenol.

[0024] The catalyst is a composition of zeolite and a carrier additive in a mass ratio of 70:30. The zeolite is a composition of one or more zeolites selected from hydrogen or ammonium types of MOR, Y, Beta, ZSM-5 and MCM-41. Preferably, the zeolite is HZSM-5, and the carrier additive is a composition of one or more metal oxides such as aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, cerium oxide and lanthanum oxide. The mass ratio of zeolite to carrier additive is 1:9-9:1.

[0025] Preferably, the mass ratio of zeolite to carrier additive is 3:1.

[0026] In the present invention, crude phenol containing phenol and C8+ heavy alkylphenol can be used as raw material, and a phenol / C8+ heavy phenol alkyl transalkylation reaction can be carried out in the presence of an alkyl transalkylation catalyst and under hydrogenation conditions to obtain methylphenol.

[0027] Preferably, the raw materials are reacted under hydrogen conditions, the reaction temperature is 300-480°C, the reaction pressure is 1-5 MPa, and the mass space velocity is 1-15h -1 .

[0028] Preparation of transalkylation catalyst: In parts by weight, the transalkylation catalyst is prepared by mixing 75 parts by weight of hydrogen-type Beta zeolite, i.e., Hbeta zeolite (or hydrogen-type Y zeolite, i.e., HY zeolite), 25 parts by weight of HZSM-5 zeolite (SiO2 / Al2O3 molar ratio 24, Nankai Catalyst Factory), 30 parts by weight of pseudo-boehmite and 5 parts by weight of extrusion-type auxiliary agent sesbania powder, kneading them uniformly, extruding them into shapes, drying them at 120°C for 6 hours, and calcining them at 550°C in air for 4 hours to obtain the transalkylation catalyst.

[0029] Preparation of HY zeolite: USY zeolite (SiO2 / Al2O3 molar ratio 2.5, Nankai Catalyst Factory) and a mixed solution of citric acid and nitric acid (citric acid 0.1 mol / L, nitric acid pH 1, mass ratio 3:1) were reacted at 60~100℃ for 2~8h at a solid-liquid ratio of 1:10~30, filtered and washed to neutrality, and dried at 120℃ for 24h.

[0030] Preparation of Hbeta zeolite: The same as the preparation of HY zeolite, except that USY zeolite was replaced by Hβ zeolite (SiO2 / Al2O3 molar ratio 25, Nankai Catalyst Plant).

[0031] Furthermore, the transalkylation catalyst may also include an extrusion-type auxiliary agent.

[0032] The 12-membered ring zeolite with medium and large pore structures is the most ideal catalyst for transalkylation reaction. By optimizing the acidity and pore structure of the zeolite catalyst, the catalytic performance of the transalkylation reaction can be significantly improved, the yield of methylphenol can be increased, and the formation of carbon deposits can be alleviated.

[0033] Conversion rate of transalkylation reaction :

[0034] Where i is 2,4-dimethylphenol, 3,5-dimethylphenol or C8+ heavy phenol, F represents the feed, P represents the reaction product, m is the mass of the mixed phenol feed, m liquid is the liquid yield after the reaction, is the mass fraction of component i in the feed, is the mass fraction of component i in the reaction product.

[0035] Total selectivity of methylphenol :

[0036] Wherein, cresol is methylphenol, phenol is phenol, DMP is dimethylphenol or C8+ heavy phenol (mixed phenol raw material); i and is the mass fraction of methylphenol, is the mass fraction of methylphenol in the initial raw material, is the mixed phenol feed mass, is the molar mass of methylphenol, is the mass fraction of phenol in the raw material, is the mass fraction of phenol in the product, is the molar mass of phenol, is the mass fraction of xylenol or C8+ heavy phenol in the raw material, is the mass fraction of xylenol or C8+ heavy phenol in the product, is the molar mass of xylenol or C8+ heavy phenol.

[0037] The following are specific embodiments.

[0038] Example 1 Preparation of HY zeolite: USY zeolite (SiO2 / Al2O3 molar ratio 2.5, Nankai Catalyst Factory) was reacted with a mixed solution of citric acid and nitric acid (citric acid concentration 0.1 mol / L, nitric acid pH 1, mass ratio of citric acid to nitric acid 3:1) at a solid-liquid ratio of 1:10 at 60 °C for 10 h, filtered and washed to neutrality, and dried at 120 °C for 24 h.

[0039] With phenol and 2,4-dimethylphenol as raw materials, phenol / C8+ heavy phenol transalkylation reaction was carried out to enrich methylphenol.

[0040] The mass ratio of phenol to 2,4-dimethylphenol in the feed is about 70:30, and the reaction temperature is 350°C. The alkyl transfer catalyst is a combination of zeolite and a carrier auxiliary agent, wherein the mass percentage of zeolite is 90wt%, and the zeolite is a combination of HY zeolite and HZSM-5 (SiO2 / Al2O3 molar ratio 24, Nankai Catalyst Factory) with a mass ratio of 3:1, wherein the mass percentage of the carrier auxiliary agent is 10wt%, and the carrier auxiliary agent is a combination of zirconium oxide and aluminum oxide with a mass ratio of 2:1. The loading amount of the alkyl transfer catalyst is 2g, and the feed rate is 0.5ml / min (mass space velocity 15h -1 ) The mixed phenol raw material was fed into a fixed bed reactor, and after feeding 10 g of the raw material, nitrogen was used to purge and collect the reaction product.

[0041] Analysis of the reaction products showed that the conversion rate of C8+ heavy phenol was 63.91%, the total selectivity of o-cresol was 49.49%, and the total selectivity of methylphenol was 84.42%.

[0042] Example 2 The same as Example 1, except that the solid-liquid ratio in the catalyst preparation is increased to 1:30, the reaction temperature is increased to 100°C, the reaction time is shortened to 2h, and the mass ratio of phenol to 2,4-dimethylphenol in the feed of Example 1 is increased to 50:50, and the reaction temperature is 350°C.

[0043] Analysis of the reaction products showed that the conversion rate of C8+ heavy phenol was 55.75%, the total selectivity of o-cresol was 48.97%, and the total selectivity of methylphenol was 85.79%.

[0044] Example 3 The same as Example 2, except that the citric acid in the catalyst preparation is changed to oxalic acid, the nitric acid concentration is increased to 0.1 mol / L, and the feed in Example 2 is changed to be calculated by mass percentage, including 47.58wt% of phenol, 26.31wt% of 2,4-dimethylphenol, 25.82wt% of 3,5-dimethylphenol, and other phenols.

[0045] Analysis of the reaction products showed that the conversion rate of 2,4-dimethylphenol was 72.23%, the conversion rate of 3,5-dimethylphenol was 54.21%, the total conversion rate of C8+ heavy phenol was 54.18%, the total selectivity of o-cresol was 33.84%, and the total selectivity of methylphenol was 65.65%.

[0046] Example 4 The same as Example 2, except that the mixed solution of citric acid and nitric acid in the catalyst preparation is changed to single nitric acid, the nitric acid concentration is changed to 0.1 ml / L, and the feed in Example 2 is changed to 48.17 wt% of phenol, 15.47 wt% of 2,6-dimethylphenol, 3.76 wt% of 2-ethylphenol, 15.12 wt% of 2,4-dimethylphenol, 14.70 wt% of 3,5-dimethylphenol, 2.66 wt% of trimethylol, and other phenols are also included.

[0047] Analysis of the reaction products showed that the conversion rate of 2,4-dimethylphenol was 53.42%, the conversion rate of 3,5-dimethylphenol was 49.75%, the conversion rate of 2-ethylphenol was 72.85%, the total conversion rate of C8+ heavy phenol was 53.93%, the total selectivity of o-cresol was 38.78%, and the total selectivity of methylphenol was 70.64%.

[0048] Example 5 The same as Example 1, except that the mass ratio of citric acid to nitric acid in the catalyst preparation is changed to 1:3, and the crude phenol refined phenol residue (Shenmu Tianyuan phenol residue) is used as the raw material, and the phenol / C8+ heavy phenol alkylation reaction is carried out to enrich the methylphenol. The feed contains 52.13wt% phenol, 19.60wt% 2,4-dimethylphenol, 5.39wt% 3,5-dimethylphenol, 11.98wt% m-cresol, and other alkylphenol compounds.

[0049] Analysis of the reaction products showed that the conversion rate of C8+ heavy phenol was 48.00 wt%, the total selectivity of o-cresol was 34.25 wt%, and the total selectivity of methylphenol was 56.73 wt%.

[0050] Example 6 The same as Example 5, except that the catalyst is changed to a composition of zeolite and a carrier auxiliary agent. The mass percentage of zeolite is 75wt%, and the zeolite is a composition of HY zeolite and HZSM-5 in a mass ratio of 3:1. The mass percentage of the carrier auxiliary agent is 25wt%, and the carrier auxiliary agent is a composition of zirconium oxide and aluminum oxide in a mass ratio of 2:1.

[0051] Analysis of the reaction products showed that the conversion rate of C8+ heavy phenol was 45.25wt%, the total selectivity of o-cresol was 40.07wt%, and the total selectivity of methylphenol was 60.81wt%.

[0052] Example 7 Same as Example 6, except that the mass ratio of zeolite to carrier additive is 1:9.

[0053] Analysis of the reaction products showed that the conversion rate of C8+ heavy phenol was 35.25wt%, the total selectivity of o-cresol was 32.10wt%, and the total selectivity of methylphenol was 53.49wt%.

[0054] Example 8 Using 2,4-dimethylphenol as raw material, phenol / C8+ heavy phenol transalkylation reaction was carried out under hydrogenation conditions. The feed contained 66.52wt% phenol, 33.45wt% 2,4-dimethylphenol, and other phenols. The hydrogenation conditions were reaction temperature of 350℃, reaction pressure of 1MPa, hydrogen-phenol molar ratio of 3:1, alkylation catalyst loading of 2g, and mass space velocity of 4h -1 .

[0055] By weight, 75 parts by weight of HY zeolite, 25 parts by weight of HZSM-5 zeolite (SiO2 / Al2O3 molar ratio 24, Nankai Catalyst Factory), 30 parts by weight of pseudo-boehmite and 5 parts by weight of extrusion-type auxiliary agent sesbania powder were mixed, fully kneaded and uniformly mixed, extruded, dried at 120°C for 6 hours, and calcined at 550°C in air for 4 hours to obtain a transalkylation catalyst. The HY zeolite was prepared by the following process: USY zeolite (SiO2 / Al2O3 molar ratio 2.5, Nankai Catalyst Factory) and a mixed solution of citric acid and nitric acid (citric acid concentration of 0.1 mol / L, nitric acid pH of 1, mass ratio of citric acid to nitric acid of 3:1) were reacted at 80°C for 4 hours at a solid-liquid ratio of 1:10, filtered and washed to neutrality, and dried at 120°C for 24 hours.

[0056] The initial conversion rate of 2,4-dimethylphenol was 77.31%. After 92 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 49.13% and 81.91%, respectively.

[0057] Example 9 The same as Example 8, except that the HY zeolite in the transalkylation catalyst in Example 7 is replaced by HBeta zeolite.

[0058] The initial conversion rate of 2,4-dimethylphenol was 74.79%. After 104 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 28.08% and 62.46%, respectively.

[0059] Example 10 Mixed xylenols are used as raw materials. Phenol / C8+ heavy phenol transalkylation reaction is carried out under hydrogenation conditions. The feed contains 49.06wt% phenol, 22.70wt% 2,4-xylenol, 21.11wt% 3,5-xylenol, 2.76wt% m-p-cresol, 2.26wt% 3,4-xylenol, 1.73wt% 2,3-xylenol, and other alkylphenols. The hydrogenation conditions are reaction temperature of 350℃, reaction pressure of 2.7MPa, hydrogen-phenol molar ratio of 4:1, alkylation catalyst loading of 2g, and mass space velocity of 4h -1 .

[0060] The alkyl transfer catalyst is prepared by mixing 80 parts by weight of HY zeolite, 20 parts by weight of HZSM-5 zeolite (SiO2 / Al2O3 molar ratio 24, Nankai Catalyst Factory), 30 parts by weight of zirconium dioxide and 5 parts by weight of extrusion-type auxiliary agent sesbania powder, kneading them evenly, extruding them, drying them at 120°C for 6 hours, and calcining them at 550°C in air for 4 hours to obtain the alkyl transfer catalyst. The HY zeolite is prepared by the following process: reacting USY zeolite (SiO2 / Al2O3 molar ratio 2.5, Nankai Catalyst Factory) with a mixed solution of citric acid and nitric acid (citric acid concentration of 0.1 mol / L, nitric acid pH of 1, and mass ratio of citric acid to nitric acid of 3:1) at a solid-liquid ratio of 1:20 at 60°C for 8 hours, filtering and washing until neutral, and drying them at 120°C for 24 hours.

[0061] The initial conversion rate of C8+ heavy phenol was 66.92%. After 97 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 35.97% and 73.08%, respectively.

[0062] Embodiment 11 The same as Example 10, except that the HY zeolite in the transalkylation catalyst in Example 9 is replaced by a composition of Hbeta zeolite and HMOR (SiO2 / Al2O3 molar ratio 25, Nankai Catalyst Factory), wherein the mass ratio of Hbeta zeolite to HMOR is 1:1.

[0063] The initial conversion rate of C8+ heavy phenol was 63.45%. After 113 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 24.78% and 58.35%, respectively.

[0064] Example 12 The same as Example 10, except that the zirconium dioxide in the alkyl transfer catalyst in Example 9 is replaced by a combination of silicon dioxide and ceria, wherein the mass ratio of silicon dioxide to ceria is 4:1.

[0065] The initial conversion rate of C8+ heavy phenol was 70.33%. After 106 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 33.71% and 67.16%, respectively.

[0066] Example 13 Same as Example 12, except that the reaction temperature was lowered to 300°C, the hydrogen-phenol ratio was increased to 10:1, the hydrogenation pressure was increased to 5 MPa, and the reaction space velocity was reduced to 1 h -1 .

[0067] The initial conversion rate of C8+ heavy phenol was 67.14%. After 121 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 31.23% and 62.77%, respectively.

[0068] Embodiment 14 The same as Example 12, except that the mixed xylenol in Example 12 was replaced with crude phenol refined phenol residue (Shenmu Tianyuan phenol residue), and the phenol / C8+ heavy phenol transalkylation reaction was carried out under hydrogen conditions. The feed contained 52.77wt% phenol, 19.62wt% 2,4-xylenol, 8.16wt% 3,5-xylenol, 12.04wt% m-cresol, 0.52wt% 3,4-xylenol, 1.61wt% 2,3-xylenol, and other alkylphenols.

[0069] The initial conversion rate of C8+ heavy phenol was 62.76%. After 89 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 43.72% and 70.56%, respectively.

[0070] Embodiment 15 Same as Example 14, except that the reaction temperature was increased to 480°C, the hydrogen-phenol ratio was reduced to 2:1, and the feed space velocity was increased to 10 h -1 The silica and cerium dioxide composition in the transalkylation catalyst is changed to a titanium dioxide, niobium oxide, cerium oxide and lanthanum oxide composition in a mass ratio of 3:1:0.5:0.5.

[0071] The initial conversion rate of C8+ heavy phenol was 66.09%. After 94 hours of reaction, the catalyst conversion rate dropped to 30% of the initial conversion rate of the fresh catalyst. The selectivities of o-cresol and methylphenol in the product were 44.62% and 77.03%, respectively.

[0072] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0073] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for producing methylphenol by transalkylation, characterized in that: The following steps are involved: The raw material is passed through a reactor bed filled with a catalyst and reacted at 300-480° C. to obtain methylphenol, wherein the raw material is a mixture containing phenol and C8+ heavy alkylphenol.

2. The method for producing methylphenol by transalkylation according to claim 1, characterized in that: The mass ratio of catalyst to raw material is 5:1-1:

10.

3. The method for producing methylphenol by transalkylation according to claim 1, characterized in that: The catalyst is a combination of zeolite and a carrier aid or zeolite.

4. The method for producing methylphenol by transalkylation according to claim 2, characterized in that: The zeolite is a combination of one or more zeolites selected from hydrogen or ammonium MOR, Y, Beta, ZSM-5, and MCM-41 zeolites, and the carrier additive is a combination of one or more metal oxides selected from aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, cerium oxide, lanthanum oxide, and silicon oxide.

5. The method for producing methylphenol by transalkylation according to claim 3, characterized in that: The mass ratio of zeolite to carrier additive is 1:9-9:

1.

6. A method for producing methylphenol by transalkylation, characterized in that: The following steps are involved: A mixture of phenol and C8+ heavy alkylphenol is used as raw materials, and a phenol / C8+ heavy phenol alkyl transalkylation reaction is carried out in the presence of an alkyl transalkylation catalyst and under hydrogenation conditions to obtain methylphenol.

7. The method for producing methylphenol by transalkylation according to claim 6, characterized in that: The reaction pressure is 1-5MPa.

8. The method for producing methylphenol by transalkylation according to claim 6, characterized in that: The mass space velocity of the raw material is 1-15h -1 .

9. The method for producing methylphenol by transalkylation according to claim 6, characterized in that: The alkyl transfer catalyst is prepared by the following process: uniformly mixing one or more of hydrogen or ammonium type MOR, Y, Beta, ZSM-5, MCM-41 zeolites, one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, cerium oxide, lanthanum oxide and silicon oxide with extrusion type auxiliary agent powder, extruding and molding, drying and then calcining to obtain the alkyl transfer catalyst.

10. The method for producing methylphenol by transalkylation according to claim 9, characterized in that: The hydrogen-type Y zeolite is prepared by the following process: reacting USY zeolite with nitric acid, or with a mixed solution of citric acid and nitric acid, or with a mixed solution of oxalic acid and nitric acid at a solid-liquid ratio of 1:10-30 at 60-100°C for 2-10h, filtering, and drying; Preparation of hydrogen-type Beta zeolite: react Hβ zeolite with a mixed solution of citric acid and nitric acid at a solid-liquid ratio of 1:10-30 at 60-100°C for 2-10h, filter and dry.

Images