CN110961100B

CN110961100B - Catalyst for preparing cyclohexene by cyclohexane dehydrogenation and preparation method thereof

Info

Publication number: CN110961100B
Application number: CN201811157913.9A
Authority: CN
Inventors: 张觅; 殷玉圣; 袁浩然; 于杨
Original assignee: China Petroleum and Chemical Corp; Research Institute of Sinopec Nanjing Chemical Industry Co Ltd
Current assignee: China Petroleum and Chemical Corp; Research Institute of Sinopec Nanjing Chemical Industry Co Ltd
Priority date: 2018-09-30
Filing date: 2018-09-30
Publication date: 2022-12-20
Anticipated expiration: 2038-09-30
Also published as: CN110961100A

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a catalyst for preparing cyclohexene through cyclohexane dehydrogenation and a preparation method thereof. The method is characterized by comprising two key steps of preparing a composite carrier, impregnating an active component and a passivating agent to obtain the dehydrogenation catalyst for preparing cyclohexene by partial dehydrogenation of cyclohexane. The catalyst can be used in a process for preparing cyclohexene by partial hydrogenation of benzene, so that the cyclohexane by-product in the process is dehydrogenated to be changed into cyclohexene, and the economic value of the by-product cyclohexane is improved.

Description

Catalyst for preparing cyclohexene by cyclohexane dehydrogenation and preparation method thereof

Technical Field

The invention belongs to the technical field of catalysts, and particularly relates to a catalyst for preparing cyclohexene through cyclohexane dehydrogenation, and a preparation method and application thereof

Background

There are two routes for producing cyclohexanone from benzene: 1. preparing cyclohexane by benzene hydrogenation, preparing mixed K oil of cyclohexanone and cyclohexanol by cyclohexane oxidation, and preparing the cyclohexanone by dehydrogenating the residual cyclohexanol after separating the cyclohexanone from the K oil; 2. partial hydrogenation of benzene is carried out to prepare a mixture of cyclohexene and cyclohexane, cyclohexane is separated out, the rest cyclohexene is hydrated to prepare cyclohexanol, and the cyclohexanol is dehydrogenated to prepare cyclohexanone. At present, due to various factors such as energy source, environmental protection and capacity, the production scale of the route 2 is gradually enlarged, and the byproduct cyclohexane obtained by partially hydrogenating the benzene in the route 2 is generally directly sold due to the limitation of yield and plant equipment. If the cyclohexane is dehydrogenated to produce benzene, the equipment investment and the energy consumption are huge. Therefore, the direct preparation of cyclohexene by partial dehydrogenation of the cyclohexane by-product in the route 2 has important practical significance and economic significance.

CN 103214336A discloses a method for preparing cyclohexene by oxidative dehydrogenation of cyclohexane, which takes K, mg and Mo as active components, V as an auxiliary agent, a carrier is alumina or titanium oxide, the reaction temperature is 400-600 ℃ and air is 0.05-1 s under 0-5 KPa, the reaction time is 0.05-1 s, the cyclohexane conversion rate is close to 20%, and the cyclohexene selectivity can reach 46.98% at most. The method has high temperature, short reaction time and difficult control.

Disclosure of Invention

The invention aims to solve the defects in the prior art, and provides a catalyst for preparing cyclohexene from cyclohexane under mild reaction conditions, so that a byproduct cyclohexane in a benzene partial hydrogenation line is effectively utilized.

The purpose of the invention is realized by the following technical scheme: the catalyst for preparing cyclohexene by cyclohexane dehydrogenation comprises the following components in percentage by mass: 1 to 2 percent of ruthenium, 0.1 to 1 percent of passivating agent and the balance of composite carrier.

Typically, the composite support consists of ZrO ₂ -ZnO composition of ZrO in a support ₂ The mass content is 80-95%, and the mass content of ZnO is 5-20%.

The passivating agent is MgO, caO, snO, znO or ZrO ₂ One kind of (1).

The preparation method of the cyclohexene catalyst by cyclohexane dehydrogenation comprises the steps of preparing a composite carrier, and dipping an active component and a passivating agent into the composite carrier step by step to obtain a finished product catalyst.

The preparation method of the composite carrier adopts a coprecipitation method, the Zr-Zn precursor salt solution and a precipitator are precipitated under the stirring condition until the pH value is 9.5-10, the aging is carried out for 1h under the same condition, the filtering, the drying, the crushing, the forming and the roasting are carried out after the temperature programming is increased to 950 ℃, and the composite carrier is prepared.

The molding mode adopts a mechanical mode, so that the composite carrier has a thickness of 70m ² /g-160m ² The specific surface area per gram and the strength are more than 100N/cm, and pore-forming agent is added for pore-forming and molding.

The molding mode adopts a mechanical mode to ensure that the composite carrier has a length of 90m ² /g-140m ² Specific surface area per gram.

The pore-forming agent is at least one of inorganic acid, organic acid, sesbania powder, cellulose substances and stearate.

The impregnation method comprises the steps of impregnating a ruthenium precursor and a competitive adsorbent on a carrier in equal volume at 60 ℃, drying, reducing by a reduction solution, drying, impregnating a passivant precursor in equal volume at 50-60 ℃, drying, and reducing by hydrogen to obtain the catalyst.

The competitive adsorbent is one of volatile inorganic acid or organic acid.

The catalyst provided by the invention can inhibit the hydrogenation activity of ruthenium, improve the selectivity of cyclohexene, and reduce the reaction activation energy, so that the reaction can be carried out at 250-350 ℃. The traditional kettle type reaction is separated, and the catalyst can continuously react in a fixed bed reactor. The reaction time is easy to control, and the stability of the product quality is ensured.

Detailed Description

The present invention will be described in detail with reference to examples.

The preparation method of the cyclohexene catalyst by cyclohexane dehydrogenation comprises the following steps of preparing a composite carrier, and impregnating an active component and a passivating agent by the composite carrier step by step to obtain a finished product catalyst.

Example 1

Preparing a composite carrier: taking [ Zr ] ⁴⁺ ]1L of zirconium nitrate solution of =91g/L, and [ Zn ] is taken ²⁺ ]0.174L of zinc nitrate solution (65 g/L) was mixed to prepare an acid solution. Taking 1mol/L of Na ₂ CO ₃ Taking 1.5L of deionized water as a base solution, heating the base solution to 80 ℃, carrying out parallel flow precipitation at a stirring speed of 300rpm, and controlling the pH value to be 9.5-10 after 40 minutes of precipitation. Aging at 80 deg.C for 1 hr, filtering, washing, drying, crushing, grinding, granulating, oven drying, and tabletting. And (3) programming the temperature to 950 ℃, and roasting the tablets for 3 hours to obtain the carrier 1.

Example 2

Preparing a composite carrier: the amount of the zinc nitrate solution used in example 1 was changed to 0.247L, and the remainder was unchanged, to obtain carrier 2.

Example 3

Preparing a composite carrier: the amount of the zinc nitrate solution used in example 1 was changed to 0.052L, and the remainder was unchanged to obtain carrier 3.

Example 4

Preparing a catalyst: taking 15ml of ruthenium solution in which [ Ru ³⁺ ]=33.3g/L and acetic acid =0.5ml, and the mixture was heated to 60 ℃, uniformly impregnated on 50g of the support 1, and dried. After drying, the mixture is added with NaBH in an excess of 0.2mol/L ₄ The solution is reduced, washed, dried and then impregnated with [ Zn ] ²⁺ ]15ml of the solution (33.3 g/L), dried, and reduced at 400 ℃ under a hydrogen atmosphere by programming for 3 hours to obtain catalyst 1.

Example 5

Preparing a catalyst: catalyst 2 was prepared by changing the carrier 1 from example 4 to carrier 2.

Example 6

Preparing a catalyst: catalyst 3 was prepared by changing the carrier 1 to carrier 3 in example 4.

Example 7

Preparing a catalyst: in example 4 [ Zn ] ²⁺ ]15ml of the solution was changed to [ Zn ] =33.3g/L ²⁺ ]Catalyst 4 was prepared in 15ml of 3.33g/L solution.

Example 8

Preparing a catalyst: in example 5 [ Zn ] ²⁺ ]15ml of the solution was changed to [ Zn ] =33.3g/L ²⁺ ]=16.6g/L catalyst 5 was prepared from 15ml of solution.

TABLE 1 evaluation results of Activity of catalysts 1 to 5

Catalyst and process for producing the same	Cyclohexane conversion rate%	Cyclohexene selectivity. Is based on
			1	19.4	81.8
2	19.6	80.9
			3	20.2	81.8
4	25.5	65.0
			5	22.3	71.7

The reaction conditions are as follows: the diameter of the reactor is 1.8cm, the reaction pressure is 0.2MPa, the temperature is 310 ℃, and the nitrogen flow is 20ml/min.

TABLE 2 evaluation results of catalyst 1 Activity under different reaction conditions

Reaction conditions are as follows: the reactor diameter was 1.8cm and the nitrogen flow was 20ml/min.

Claims

1. The application of the catalyst in preparing cyclohexene by cyclohexane dehydrogenation is characterized in that the catalyst comprises the following components in mass percent: 1-2% of ruthenium, 0.1-1% of passivating agent and the balance of composite carrier; the composite carrier is made of ZrO ₂ -ZnO composition, zrO in a support ₂ The mass content is 80-95%, and the mass content of ZnO is 5-20%; the passivating agent is ZnO.

2. Use of a catalyst according to claim 1 in the dehydrogenation of cyclohexane to cyclohexene, wherein the catalyst is prepared by a process comprising: preparing a composite carrier, impregnating the active component, and impregnating the active component and the passivating agent step by step to obtain the finished catalyst.

3. The use of the catalyst according to claim 2 in the preparation of cyclohexene from cyclohexane dehydrogenation, wherein the preparation of the composite carrier is carried out by coprecipitation, wherein a Zr-Zn precursor salt solution and a precipitant are precipitated under stirring to a pH value of 9.5-10, aging is carried out for 1h under the same conditions, and the composite carrier is prepared by filtering, drying, crushing, molding, programming to a temperature of 950 ℃ and roasting.

4. Use of a catalyst according to claim 3 in the dehydrogenation of cyclohexane to cyclohexene, wherein the shaping is performed mechanically, such that the composite support has a thickness of 70m ² /g-160m ² The specific surface area per gram and the strength are more than 100N/cm, and pore-forming agent is added for pore-forming and molding.

5. The use of a catalyst according to claim 4 in the dehydrogenation of cyclohexane to cyclohexene, wherein the shaping is by mechanical means such that the composite support has a size of 90m ² /g -140 m ² Specific surface area in g.

6. The use of the catalyst of claim 4 for the dehydrogenation of cyclohexane to cyclohexene wherein the pore former is at least one of an inorganic acid, an organic acid, sesbania powder, a cellulosic material, and a stearate.

7. The application of the catalyst in the preparation of cyclohexene through cyclohexane dehydrogenation according to claim 2, wherein the impregnation method comprises the steps of impregnating a ruthenium precursor and a competitive adsorbent on a carrier at 60 ℃ in equal volume, drying, reducing with a reducing solution, drying, impregnating a passivating agent precursor at 50-60 ℃ in equal volume, drying, and reducing with hydrogen to obtain the catalyst.

8. Use of a catalyst according to claim 7 in the dehydrogenation of cyclohexane to cyclohexene wherein the competing adsorbent is one of a volatile inorganic or organic acid.