Catalyst for preparing cyclohexylbenzene through biphenyl hydrogenation as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing cyclohexylbenzene through biphenyl hydrogenation as well as a preparation method and application of the catalyst. The catalyst comprises a carrier and active components loaded on the carrier in an eggshell form, the active components comprise Ni, Zn and Cu, and based on the mass of the catalyst, the content of Ni is 2wt%-8wt%, the content of Zn is 0.5 wt%-4wt%, and the content of Cu is 0.5 wt%-4wt%. The catalyst provided by the invention is low in active component loading capacity, is used for preparing cyclohexylbenzene through biphenyl hydrogenation, and is good in activity, high in selectivity and good in stability.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and specifically relates to a catalyst for preparing cyclohexylbenzene by hydrogenating biphenyl and a preparation method thereof, as well as application of the catalyst in preparing high-purity cyclohexylbenzene by hydrogenating biphenyl. Background Art

[0002] Cyclohexylbenzene is an important chemical intermediate and a high-boiling point solvent for the preparation of coatings, plastics and adhesives, etc. It has special physical and chemical properties. Cyclohexylbenzene can be used to prepare phenol and cyclohexanone through oxidation reaction. Phenol is an important chemical raw material, and cyclohexanone is an intermediate for the production of caprolactam and nylon. Cyclohexylbenzene can also be used as a raw material for synthesizing TFT liquid crystal materials and as an additive for lithium-ion secondary battery electrolytes, with anti-overcharge performance. As a raw material for electrolytes, cyclohexylbenzene has high requirements for purity, usually above 99.5%.

[0003] At present, cyclohexylbenzene is mostly prepared by benzene hydrogenation alkylation, and some are prepared by benzene and styrene alkylation. In addition to cyclohexylbenzene, the products prepared by these methods also include polyalkylbenzenes and methylcyclopentylbenzene. Among them, methylcyclopentylbenzene has more isomers, and its boiling point is very close to that of cyclohexylbenzene (2 to 8 ° C difference under normal pressure). Therefore, the product needs to undergo multi-stage complex separation and distillation to obtain high-purity cyclohexylbenzene.

[0004] Cyclohexylbenzene can also be prepared by selective hydrogenation of biphenyl. CN107185548B discloses a catalyst and method for preparing cyclohexylbenzene by selective hydrogenation of biphenyl. The preparation process of the catalyst is as follows: first, a molybdenum-containing compound, a nickel-containing compound, a copper-containing compound, deionized water, ammonia water and an auxiliary agent are prepared into a mixed solution, reacted in an autoclave, formed, dried and calcined to obtain a Ni-Mo-Cu oxidation state catalyst. The oxidation state catalyst is partially pre-reduced to a reduced state catalyst, and a fixed bed reactor is used for the reaction of selective hydrogenation of biphenyl to generate cyclohexylbenzene. The catalyst has a large amount of active metal used, high cost, and is easily deactivated and has poor stability.

[0005] In the process of selective hydrogenation of biphenyl to prepare cyclohexylbenzene, the raw materials and products are similar to liquid wax, and the reaction is exothermic, which leads to poor mass transfer and heat transfer. It is difficult for existing catalysts to take into account both catalyst activity and stability. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a catalyst for preparing cyclohexylbenzene by hydrogenating biphenyl, and a preparation method and application thereof. The catalyst of the present invention has a low loading amount of active components and is used in preparing cyclohexylbenzene by hydrogenating biphenyl. The catalyst has good activity, high selectivity and good stability.

[0007] The first aspect of the present invention provides a catalyst for preparing cyclohexylbenzene by hydrogenating biphenyl, comprising a carrier and an active component loaded on the carrier in the form of eggshells, wherein the active component comprises Ni, Zn and Cu, and based on the mass of the catalyst, the content of Ni is 2wt% to 8wt%, the content of Zn is 0.5wt% to 4wt%, and the content of Cu is 0.5wt% to 4wt%.

[0008] Furthermore, in the catalyst of the present invention, based on the mass of the catalyst, the Ni content is 2wt% to 8wt%, for example, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, 8%, etc., and any value in the range formed by any two of these values.

[0009] Furthermore, in the catalyst of the present invention, the Zn content is 0.5wt% to 4wt%, based on the mass of the catalyst, for example, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, etc., and any value in the range formed by any two of these values.

[0010] Furthermore, in the catalyst of the present invention, the Cu content is 0.5wt% to 4wt%, based on the mass of the catalyst, for example, 0.5%, 1.0%, 1.5%, 1.7%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, etc., and any value in the range formed by any two of these values.

[0011] Furthermore, the catalyst of the present invention also includes an auxiliary agent, which is selected from one or more of Co, Fe and Mo, preferably Mo. Based on the mass of the catalyst, the content of the auxiliary agent is 0-2wt%, preferably 0.2wt%-2wt%, for example 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.5%, 1.8%, 2.0%, etc., and any value in the range formed by any two of these values. Wherein, the auxiliary agent and the active component are loaded on the carrier in an eggshell manner.

[0012] Furthermore, in the catalyst of the present invention, the carrier is an alumina carrier. The carrier may be spherical or bar-shaped. The diameter of the sphere is preferably 2 to 10 mm, more preferably 3 to 5 mm. The diameter of the bar is preferably 0.5 to 3.0 mm, and the length is preferably 3 to 8 mm. Preferably, the specific surface area of ​​the alumina carrier is 150 m 2 / g or more, preferably 200 to 350 m 2 / g, pore volume is 0.5-1.0ml / g, preferably 0.65-1.0ml / g, bulk density is not more than 0.6kg / m 3 , preferably not more than 0.5kg / m 3, more preferably 0.3 to 0.5 kg / m 3 .

[0013] Furthermore, in the catalyst of the present invention, the shell thickness accounts for less than 10% of the catalyst radius, preferably less than 7%, and more preferably 1% to 7%.

[0014] The second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising: a step of loading the active component on a carrier in the form of eggshells; preferably, the carrier is first treated with an alkaline solution, and then the active component is loaded on the carrier in the form of eggshells.

[0015] Furthermore, the active component is loaded on the carrier in the form of eggshells by an impregnation method, that is, the carrier is impregnated with a solution containing the active component precursor, and the catalyst is obtained after drying and calcination.

[0016] Furthermore, preferably, the support is first treated with an alkaline solution, and then impregnated with a solution containing an active component precursor, and then dried and calcined to obtain the catalyst.

[0017] Furthermore, the carrier in the present invention is an alumina carrier, and the carrier is a shaped carrier, and its shape can be a conventional shape, including but not limited to a sphere or a bar. The carrier can be spherical or bar-shaped. The diameter of the sphere is preferably 2 to 10 mm, and more preferably 3 to 5 mm. The diameter of the bar is preferably 0.5 to 3.0 mm, and the length is 3 to 8 mm. Preferably, the specific surface area of ​​the alumina carrier is 150 m 2 / g or more, preferably 200 to 350 m 2 / g, pore volume is 0.5-1.0ml / g, preferably 0.65-1.0ml / g, bulk density is not more than 0.6kg / m 3 , preferably not more than 0.5kg / m 3 , more preferably 0.3 to 0.5 kg / m 3 .

[0018] Furthermore, the alkaline solution is an alkaline earth metal solution, preferably a soluble alkaline earth metal salt (such as nitrate, etc.) dissolved in water, and the alkaline earth metal is preferably magnesium and / or calcium. The process of treating the carrier with the alkaline solution is as follows: the carrier is impregnated with the alkaline solution (preferably equal volume impregnation), and then washed, dried and roasted. The loading amount of the alkaline earth metal in terms of oxide accounts for 5% to 15% of the carrier mass. Among them, impregnation, washing, drying and roasting can be carried out by conventional methods. Generally, the drying conditions are as follows: drying at 50 to 150°C for 2 to 24 hours, and the roasting conditions are as follows: roasting at 500 to 600°C for 2 to 10 hours.

[0019] Furthermore, the impregnation of the support with the solution containing the active component precursor is preferably carried out by an equal volume impregnation method.

[0020] Furthermore, the solution containing the active component precursor also contains an auxiliary agent precursor. The auxiliary agent is selected from one or more of Co, Fe and Mo. Based on the mass of the catalyst, the content of the auxiliary agent is 0-2wt%, preferably 0.2wt%-2wt%.

[0021] Furthermore, the active component precursor and the auxiliary agent precursor may be soluble salts, such as at least one of nitrates, sulfates, and chlorides, preferably chlorides.

[0022] Furthermore, after the support is impregnated with a solution containing an active component precursor, the drying conditions are as follows: drying at 50-160°C for 1-24 hours, and the calcination is preferably as follows: calcining at 250-350°C for 1-8 hours, and calcining at 400-600°C for 2-10 hours.

[0023] Furthermore, after the support is impregnated with the solution containing the active component precursor, it is preferably left to dry before drying, that is, to dry the surface.

[0024] The third aspect of the present invention provides the use of the above catalyst in the preparation of cyclohexylbenzene by hydrogenation of biphenyl.

[0025] Furthermore, the catalyst needs to be reduced and activated before use. The reducing gas can be hydrogen. The reducing conditions are as follows: the temperature is 150-350°C, the hydrogen space velocity is 200-2000h -1 , activation time is 0.5~5h.

[0026] Furthermore, the application includes: in the presence of hydrogen, biphenyl is contacted with the catalyst to react to obtain cyclohexylbenzene.

[0027] Furthermore, the reaction is to feed biphenyl and a solvent after mixing, preferably, the solvent is cyclohexane. In the mixture of biphenyl and the solvent, the mass concentration of biphenyl is 5% to 50%, preferably 15% to 35%.

[0028] Furthermore, the reaction adopts a fixed bed reactor.

[0029] Furthermore, the reaction conditions are as follows: reaction temperature is 90-120°C, hydrogen oil (biphenyl) volume ratio is 0.2-2.0, liquid volume space velocity is 0.5-10h -1 , the pressure is 0.6~2.0MPa.

[0030] Furthermore, the mass purity of the biphenyl is above 99.5%.

[0031] Furthermore, the reaction product is separated (preferably by using two towers for separation, the first tower recovers the solvent cyclohexane, the second tower discharges the dicyclohexane from the top, the cyclohexylbenzene from the side line, and the biphenyl from the bottom of the tower is recycled) to obtain the solvent, cyclohexylbenzene and dicyclohexane. The separated solvent can be recycled. The mass purity of the obtained cyclohexylbenzene reaches more than 99.5%.

[0032] Furthermore, the conversion rate of biphenyl reaches more than 95%, and the selectivity of cyclohexylbenzene reaches more than 95%.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. The existing biphenyl hydrogenation catalyst for preparing cyclohexylbenzene is a high-content active metal catalyst, which has a high initial activity but is easily deactivated and has poor stability. The inventors have found through extensive research that the active components Ni, Zn and Cu are loaded on the carrier in the form of eggshells, which not only has a low active component loading, but also can effectively solve the problem of poor catalyst stability, while also ensuring good activity and selectivity.

[0035] 2. In the preparation method of the catalyst of the present invention, it is preferred to first treat the carrier with an alkaline solution and then impregnate the loaded active components, so that the active components can form a more uniform eggshell on the surface of the carrier, so that the prepared catalyst can be used in the process of hydrogenating biphenyl to prepare cyclohexylbenzene, and has better activity, selectivity and stability.

[0036] 3. The catalyst of the present invention is used in the hydrogenation of biphenyl to prepare cyclohexylbenzene, which not only has good activity and cyclohexylbenzene selectivity, but also has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a photograph of a portion of the catalyst obtained in Example 1 that was cut open. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical solution, purpose and beneficial effects of the present invention, the present invention is described in detail below in conjunction with specific implementation methods, but it should be understood that the protection scope of the present invention is not limited by the specific implementation methods.

[0039] In the present invention, the specific surface area and pore volume are measured by using an American ASAP2600 surface analyzer. The sample is vacuum degassed at 400°C for 2 hours, and then adsorbed and desorbed under liquid nitrogen. The specific surface is calculated by the BET method.

[0040] In the present invention, the bulk density is tested using an American Quantachrome bulk density tester.

[0041] [Example 1]

[0042] Alumina was used as the carrier (radius 1 mm, length 3 mm strip, specific surface area 300 m 2 / g, pore volume is 0.70ml / g, bulk density is 0.42kg / m 3 ), impregnated with an equal volume of calcium nitrate solution, dried at 90°C for 3h, and air-roasted at 550°C for 3h, with the loading amount accounting for 10.5wt% of the mass of the alumina carrier in terms of calcium oxide. A mixed precursor solution was prepared using nickel nitrate, zinc sulfate and copper sulfate, and the active components Ni, Zn and Cu were loaded by an equal volume impregnation method. The Ni loading amount was 4.8wt%, and the Zn and Cu loading amounts were 1.0wt% and 1.7wt%, respectively, based on the mass of the catalyst. After standing and drying, the temperature was raised from 20°C to 150°C per minute for 2h, and then raised to 300°C per minute for 2h, and then raised to 400°C per minute for 6h to obtain catalyst A1.

[0043] The photo of catalyst A1 after cutting is shown in Figure 1 ,Depend on Figure 1 It can be seen that the outer surface of the carrier is an eggshell-shaped active component.

[0044] In catalyst A1, the shell thickness is about 0.07 mm.

[0045] Before use, activate with hydrogen at 250°C and a hydrogen space velocity of 300h. -1 , activation time is 1h. After activation, it can be used.

[0046] A fixed bed reactor was used to dissolve biphenyl in cyclohexane as feed, wherein the mass concentration of biphenyl was 18%. The reaction conditions were as follows: reaction temperature was 95°C, hydrogen to oil volume ratio was 1.0, and liquid volume space velocity was 3h -1 , the pressure is 1MPa. The reaction results are as follows: the initial biphenyl conversion rate is 97.4%, and the cyclohexylbenzene selectivity is greater than 99.3%. After 100h of reaction, the biphenyl conversion rate is 97.1%, and the cyclohexylbenzene selectivity is 98.8%.

[0047] [Example 2]

[0048] Alumina balls were used as carrier (radius 3 mm, specific surface area 310 m 2 / g, pore volume is 0.68ml / g, bulk density is 0.40kg / m 3), an equal volume of magnesium nitrate solution was used for impregnation, dried at 90°C for 3h, and then air-roasted at 550°C for 4h, with the loading amount accounting for 15.5wt% of the mass of the alumina carrier in terms of magnesium oxide. Nickel nitrate, zinc sulfate and copper sulfate were used to prepare a mixed precursor solution, and the active components Ni, Zn and Cu were loaded by an equal volume impregnation method. The Ni loading amount was 6.2wt%, and the Zn and Cu loading amounts were 0.6wt% and 0.6wt%, respectively, based on the mass of the catalyst. After standing and drying, the temperature was increased to 150°C per minute at 10°C per minute and dried for 2h, then increased to 300°C per minute at 10°C per minute and roasted for 2h, and then increased to 450°C per minute at 8°C per minute and roasted for 3h to obtain catalyst A2.

[0049] After cutting open catalyst A2, it can be seen that the outer surface of the carrier is an eggshell-shaped active component.

[0050] In catalyst A2, the shell thickness is about 0.10 mm. Before use, it is activated with hydrogen at 250°C and a hydrogen space velocity of 300 h. -1 , activation time is 1h. After activation, it can be used.

[0051] A fixed bed reactor was used to dissolve biphenyl in cyclohexane as feed, wherein the mass concentration of biphenyl was 18%. The reaction conditions were as follows: reaction temperature was 95°C, hydrogen to oil volume ratio was 1.0, and liquid volume space velocity was 3h -1 , the pressure was 2MPa. The reaction results were as follows: the initial biphenyl conversion rate was 97.6%, and the cyclohexylbenzene selectivity was greater than 99.1%. After 100h of reaction, the biphenyl conversion rate was 97.5%, and the cyclohexylbenzene selectivity was 98.4%.

[0052] [Example 3]

[0053] Alumina balls were used as carriers (radius 5 mm, specific surface area 350 m 2 / g, pore volume is 0.65ml / g, bulk density is 0.38kg / m 3 ), impregnated with an equal volume of calcium nitrate solution, dried at 90°C for 3h, and air-roasted at 550°C for 4h, with the loading amount accounting for 13.6wt% of the mass of the alumina carrier in terms of calcium oxide. A mixed precursor solution was prepared using nickel nitrate, zinc sulfate, molybdenum nitrate and copper sulfate, and the active components Ni, Zn, Mo and Cu were loaded by an equal volume impregnation method. The Ni loading amount was 3.0wt%, and the Zn, Mo and Cu loading amounts were 0.5wt%, 0.4wt% and 0.9wt%, respectively, based on the mass of the catalyst. After standing and drying, the temperature was raised to 150°C per minute at 10°C for 2h, then raised to 300°C for 10°C per minute for 2h, and then raised to 450°C for 8°C per minute for 3h to obtain catalyst A3.

[0054] After cutting open catalyst A3, it can be seen that the outer surface of the carrier is an eggshell-shaped active component.

[0055] In catalyst A3, the shell thickness is about 0.11 mm.

[0056] Before use, activate with hydrogen at 280°C and a hydrogen space velocity of 100h. -1 , the activation time is 3h. After activation, it can be used.

[0057] A fixed bed reactor was used to dissolve biphenyl in cyclohexane as feed, wherein the mass concentration of biphenyl was 18%. The reaction conditions were as follows: reaction temperature was 95°C, hydrogen to oil volume ratio was 0.6, liquid volume space velocity was 2h -1 , the pressure is 2MPa. The reaction results are as follows: the initial biphenyl conversion rate is 97.1%, and the cyclohexylbenzene selectivity is greater than 99.3%. After 100h of reaction, the biphenyl conversion rate is 96.6%, and the cyclohexylbenzene selectivity is 98.9%.

[0058] [Comparative Example 1]

[0059] First, nickel nitrate, zinc sulfate, copper sulfate, deionized water, etc. are prepared into a mixed solution, reacted in an autoclave, dried and calcined to obtain a Ni-Zn-Cu oxidation state catalyst solid solution (the mass ratio of Ni, Zn and Cu is the same as that in Example 1). The solid solution is ground, crushed, and mixed into a paste, kneaded, extruded, dried, and calcined at 450°C for 3 hours to obtain a catalyst. The specific surface area is tested to be 85m 2 / g.

[0060] The oxidized catalyst was reduced to a reduced catalyst and activated with hydrogen at 250°C and a hydrogen space velocity of 300 h. -1 , activation time is 1h. After activation, it can be used.

[0061] In a fixed bed reactor, at 95°C, 1 MPa, a hydrogen-to-oil volume ratio of 1.0, and a liquid hourly space velocity of 3 h -1 Under the conditions, biphenyl was selectively hydrogenated to cyclohexylbenzene, with an initial biphenyl conversion of 97.8% and a cyclohexylbenzene selectivity of 97.2%. After 100 hours of reaction, the biphenyl conversion was 85.1% and the cyclohexylbenzene selectivity was 94.8%.

[0062] The embodiments of the present invention are only detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention can be implemented without relying on the steps described in the above embodiments. In summary, any improvements made by those skilled in the art to the present invention, including replacement of the raw materials and additives described in the present invention, selection of specific implementation methods, etc., all belong to the protection scope and disclosure scope of the present invention.

Claims

1. A catalyst for preparing cyclohexylbenzene by hydrogenating biphenyl, comprising a carrier and an active component loaded on the carrier in the form of eggshells, wherein the active component comprises Ni, Zn and Cu, and based on the mass of the catalyst, the content of Ni is 2wt% to 8wt%, the content of Zn is 0.5wt% to 4wt%, and the content of Cu is 0.5wt% to 4wt%.

2. The catalyst according to claim 1, characterized in that The carrier is an alumina carrier; preferably, the specific surface area of ​​the alumina carrier is 150 m 2 / g or more, preferably 200 to 350 m 2 / g, pore volume is 0.5-1.0ml / g, preferably 0.65-1.0ml / g, bulk density is not more than 0.6kg / m 3 , preferably not more than 0.5kg / m 3 , more preferably 0.3 to 0.5 kg / m 3 .

3. The catalyst according to claim 2, characterized in that The carrier is spherical or strip-shaped; the diameter of the sphere is preferably 2-10 mm, more preferably 3-5 mm; the diameter of the strip is preferably 0.5-3.0 mm, and the length is preferably 3-8 mm.

4. The catalyst according to claim 1 or 3, characterized in that In the catalyst, the shell thickness accounts for less than 10% of the catalyst radius, preferably less than 7%, and more preferably 1% to 7%.

5. The catalyst according to claim 1, characterized in that The catalyst also includes an auxiliary agent, which is selected from one or more of Co, Fe and Mo; based on the mass of the catalyst, the content of the auxiliary agent is 0-2wt%, preferably 0.2wt%-2wt%; wherein the auxiliary agent and the active component are loaded on the carrier in the form of eggshell.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising the step of loading the active component on a carrier in the form of eggshells.

7. The preparation method according to claim 6, characterized in that: The preparation method comprises the steps of first treating the carrier with an alkaline solution and then loading the active component on the carrier in the form of eggshell.

8. The preparation method according to claim 7, characterized in that: The alkaline solution is an alkaline earth metal solution, and the alkaline earth metal is preferably magnesium and / or calcium.

9. The preparation method according to claim 7 or 8, characterized in that: The process of treating the carrier with an alkaline solution is as follows: the carrier is impregnated with the alkaline solution (preferably equal volume impregnation), then washed, dried and calcined; the loading amount of the alkaline earth metal in terms of oxide accounts for 5% to 15% of the carrier mass.

10. The preparation method according to claim 6 or 7, characterized in that: The carrier is impregnated with a solution containing an active component precursor by an equal volume impregnation method; preferably, the solution containing the active component precursor also contains an auxiliary agent precursor, and the auxiliary agent is selected from one or more of Co, Fe and Mo; based on the mass of the catalyst, the content of the auxiliary agent is 0 to 2wt%, preferably 0.2wt% to 2wt%.

11. The preparation method according to claim 6 or 7, characterized in that: After the support is impregnated with a solution containing an active component precursor, the catalyst is obtained by drying and calcining; the drying conditions are as follows: drying at 50-160°C for 1-24 hours, and the calcination is preferably as follows: calcining at 250-350°C for 1-8 hours, and calcining at 400-600°C for 2-10 hours.

12. Use of the catalyst according to any one of claims 1 to 5 or the catalyst prepared by the method according to any one of claims 6 to 11 in the preparation of cyclohexylbenzene by hydrogenation of biphenyl.

13. The use according to claim 12, characterized in that: The application comprises: in the presence of hydrogen, biphenyl is contacted with the catalyst to react to obtain cyclohexylbenzene; the reaction is to mix biphenyl with a solvent and then feed the mixture, and the solvent is preferably cyclohexane; preferably, in the mixture of biphenyl and solvent, the mass concentration of biphenyl is 5% to 50%, preferably 15% to 35%.

14. The use according to claim 12, characterized in that: The reaction adopts a fixed bed reactor; preferably, the reaction conditions are as follows: the reaction temperature is 90-120°C, the volume ratio of hydrogen to biphenyl is 0.2-2.0, and the liquid volume space velocity is 0.5-10h -1 , the pressure is 0.6~2.0MPa.

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