CN113058585B

CN113058585B - Alpha, alpha-dimethyl benzyl alcohol hydrogenolysis catalyst and preparation method thereof

Info

Publication number: CN113058585B
Application number: CN202010002430.2A
Authority: CN
Inventors: 詹吉山; 沙宇; 李作金; 燕宸; 于海波; 孙康; 初乃波; 黎源; 张昊
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2020-01-02
Filing date: 2020-01-02
Publication date: 2022-07-12
Anticipated expiration: 2040-01-02
Also published as: CN113058585A

Abstract

The invention relates to a preparation method of a catalyst for preparing cumene through hydrogenolysis of alpha, alpha-dimethyl benzyl alcohol. Method for preparing Nb-Al compound by double hydrolysis to generate AlNbO₄The structure is that the plasma generator promotes isopropanol to dehydrate and slowly releases water, and the hydrolysis rate can be controlled. The Cu-based catalyst of the present invention comprises: 30-60% of CuO, 2-10% of MnOx, 1-10% of alkali metal compound assistant, 5-20% of NbOx, and Al₂O₃The content is 30-60%. The catalyst prepared by the method can solve the problem of serious pollution of the existing Cu-Cr catalyst, and can further improve the hydrogenolysis activity of the catalyst.

Description

Alpha, alpha-dimethyl benzyl alcohol hydrogenolysis catalyst and preparation method thereof

Technical Field

The invention belongs to the field of catalysis, and particularly relates to an alpha, alpha-dimethylbenzyl alcohol hydrogenolysis catalyst and a preparation method thereof.

Background

Propylene Oxide (PO) is an important organic chemical raw material, and its yield is second only to polypropylene in propylene derivatives. The propylene oxide is mainly used for producing polyether polyol, propylene glycol, various nonionic surfactants and the like, wherein the polyether polyol is an important raw material for producing polyurethane foam, heat insulation materials, elastomers, adhesives, coatings and the like, and the various nonionic surfactants are widely applied to industries such as petroleum, chemical engineering, pesticides, textile, daily chemicals and the like. Meanwhile, propylene oxide is also an important basic chemical raw material.

Alpha, alpha-dimethyl benzyl Alcohol (alpha-Cumyl Alcohol, CA) is a white prismatic crystal, has rose fragrance, is insoluble in water, is soluble in ethanol, diethyl ether, benzene and ethyl acetate, can be used as a perfume to prepare floral essences such as rose, lily of the valley, clove and the like, is used for cosmetics, is also used as a raw material of other perfumes, and is also an important intermediate for production.

The Cumene Hydroperoxide (CHP) process is a new process for the preparation of PO, developed by the sumitomo chemical company of japan in the beginning of this century, and is industrialized in the case of japanese thousand leaves. The prior Sumitomo CHP process mainly comprises 3 working procedures of preparing CHP by oxidizing cumene, preparing PO by epoxidizing propylene and CHP and preparing isopropylbenzene by hydrogenolyzing alpha, alpha-dimethyl benzyl alcohol (DMBA), wherein the hydrogenolyzing process of the DMBA is mainly used for realizing the recycling of the cumene.

The catalyst used for the hydrogenolysis reaction is usually a Cu-based catalyst or a Pd-based catalyst. U.S. Pat. No. 4, 6646139, 2 describes a process for preparing cumene by hydrogenolysis of an alpha, alpha dimethyl benzyl alcohol catalyst, which uses a Cu-Cr system catalyst, the conversion rate reaches 100%, and the selectivity is more than 97.5%. Although the catalyst has better activity, the Cr component contained in the catalyst can cause environmental pollution in the preparation, use and recovery of the catalyst.

CN 102464567A adopts a Cu-Zn-Mn-Ca/Al system catalyst to prepare the isopropyl benzene by the hydrogenolysis of dimethyl benzyl alcohol. The molar ratio of hydrogen to benzyl alcohol is 1 (0.1-1), the reaction temperature is 160-250 ℃, the reaction pressure is 0.2-5Mpa, and the liquid volume space velocity is 1.0-10h^-1The conversion was 100% and the selectivity was 99%. Although the Cu-Zn system has better hydrogenation activity, the roasting temperature is 350 DEG CThe activity of the provided Cu-Zn solid solution is gradually transformed along with the increase of the reaction temperature, so that the stability is insufficient.

Disclosure of Invention

The invention aims to provide a preparation method of an alpha, alpha-dimethylbenzyl alcohol hydrogenolysis catalyst. The catalyst prepared by the method can adjust Al acidity through Nb-Al compounds generated by double hydrolysis, maintains higher dehydration activity, reduces the generation of heavy component diisopropylbenzene, and obviously improves the activity of Cu catalysts and the high-temperature stability of the catalyst through Li and Mn auxiliaries.

In order to achieve the above purpose and achieve the above technical effects, the present invention adopts the following technical scheme:

a method for preparing a catalyst for preparing cumene by hydrogenolysis of alpha, alpha-dimethylbenzyl alcohol, the method comprising the steps of:

1) dissolving niobium pentachloride in an isopropanol system, adding the isopropanol system into aluminum isopropoxide, dehydrating the isopropanol to generate water and propylene, and carrying out double hydrolysis on the niobium pentachloride and the aluminum isopropoxide by the water to obtain an Nb-Al compound;

2) decomposing the isopropanol in the reaction system and after hydrolysis, removing the propylene generated in the reaction system, treating the water phase, and roasting to generate AlNbO₄Obtaining a carrier a;

3) adding copper salt, manganese salt and a precipitator into a reactor, and precipitating and aging to obtain a precursor b;

4) adding the carrier a into the precursor b to obtain a precursor c;

5) adding an auxiliary agent and a binder into the precursor c, processing, molding, drying and roasting to obtain a target catalyst;

preferably, step 1) dehydrates isopropanol by using a plasma generator;

preferably, the isopropanol is decomposed in step 2) by using a plasma generator.

The preparation method of the catalyst adopts a non-Cr system catalyst, thereby avoiding environmental pollution. On the other hand, the Cu-Mn-Li-Nb/Al system catalyst provided by the invention is used for preparing Nb-Al compound by utilizing double hydrolysis reactions of niobium chloride and aluminum isopropoxideTreating double hydrolysis process with plasma generator to dehydrate isopropanol as hydrolysis source, reacting at two-phase interface of propylene, water, etc. to obtain highly dispersed Nb-Al compound, and high-temperature roasting to prepare AlNbO₄The structure can effectively adjust the acidity and alkalinity of the catalyst, reduce the generation of heavy component diisopropylbenzene, and in addition, the plasma generator is adopted to completely decompose isopropanol after the hydrolysis is finished, thereby reducing the COD content in the wastewater. On the other hand, the addition of the alkaline auxiliary agent Li can further improve the performance of the catalyst, and the addition of the alkaline auxiliary agent Li in the form of lithium silicate can obviously improve the service strength and water resistance of the catalyst. The catalyst provided by the invention is adopted in a dimethyl benzyl alcohol system, so that the problems that the activity of the existing catalyst is low and the yield of the product is influenced by the generated diisopropylbenzene can be effectively solved, and the catalytic performance and the stability are further improved.

In the invention, the niobium pentachloride and the isopropanol in the step 1) are subjected to double hydrolysis at the phase interface of the propylene phase and the water phase.

In the invention, the temperature of the double hydrolysis process in the step 1) is 20-60 ℃, and the hydrolysis time is 0.5-2 h.

In the invention, the plasma generator in the step 1) is a high-frequency plasma generator.

In some embodiments, the plasma generator of step 1) has a RF control of 12-15MHz, discharge parameters of 100V, 100 + -10 mA of solar current, 50 + -10 mA of grid current, and a vacuum degree of 2-200 Pa.

In the present invention, the decomposition of isopropyl alcohol in step 2) is started after the completion of the precipitation.

In some embodiments, step 2) removes propylene produced in the reaction system by a flash unit.

In the present invention, the step 2) of treating the aqueous phase comprises filtration and drying.

In the invention, the roasting temperature in the step 2) is 800-.

In the invention, step 2) and the plasma generator are synchronized to step 1).

In the invention, the process control conditions of the plasma generator in the step 2) are the same as those in the step 1).

In the invention, the copper salt in the step 3) is selected from one or more of copper nitrate, copper acetate, copper sulfate and copper chloride.

In the invention, the manganese salt in the step 3) is selected from one or more of manganese nitrate, manganese acetate, manganese sulfate and manganese chloride.

In the invention, the precipitant in step 3) is an alkaline precipitant, preferably one or more of sodium carbonate, sodium bicarbonate, ammonium bicarbonate and ammonia water.

In the invention, water is added into the reactor before the raw materials are added in the step 3).

In the invention, the temperature of the precipitation process in the step 3) is controlled to be 55-75 ℃, the time is controlled to be 1-3h, and the pH value is controlled to be 6.5-8.0.

In the invention, the temperature of the aging process in the step 3) is controlled to be 60-80 ℃, and the aging time is 1-3 h.

In the invention, in the step 4), the carrier a is firstly added into water and uniformly mixed, and the pre-carrier a is added into the precursor b before the precursor b is precipitated and aged.

In the invention, the slurry obtained by mixing the carrier a and the precursor b in the step 4) is washed, dried and roasted to obtain the precursor c.

In the invention, the drying temperature in the step 4) is 80-120 ℃, and the drying time is 1-6 h.

In the invention, the roasting temperature in the step 4) is 350-550 ℃, and the roasting time is 2-6 h.

In the invention, in the step 5), the precursor c is screened and then the auxiliary agent and the binder are added.

In some embodiments, the binder may be selected from natural clays, alumina sol, portland cement, titanium sol, and the like.

In the invention, the catalyst is obtained by extruding, forming, drying and roasting in the step 5).

In the invention, the drying temperature in the step 5) is 80-120 ℃, and the drying time is 1-6 h.

In the invention, the roasting temperature in the step 5) is 550-850 ℃, and the roasting time is 2-6 h.

Another object of the present invention is to provide a catalyst prepared by the catalyst preparation method.

A catalyst prepared by the catalyst preparation method.

In the invention, based on the total weight of the catalyst, the chemical composition of the catalyst is as follows:

a) the content of CuO is 30-60%,

b) 2 to 10 percent of MnOx,

c) the content of the auxiliary agent is 1 to 10 percent,

d) the content of NbOx is 5-20%,

e)Al₂O₃the content of the active ingredients is 30 to 60 percent,

preferably, the catalyst has a chemical composition of:

a) the content of CuO is 35-50%,

b) the content of MnOx is 2-5%,

c) the content of the auxiliary agent is 2-5%,

d) the content of NbOx is 5-15%,

e)Al₂O₃the content is 35-50%.

In the invention, the auxiliary agent in the catalyst is an alkali metal compound auxiliary agent, and preferably, the auxiliary agent is Li₂SiO₃、Li₃PO₄And Na₂Ti₃O₇More preferably Li₂SiO₃。

It is a further object of the present invention to provide a use of said catalyst.

The application of the catalyst is to catalyze the reaction of preparing the isopropylbenzene by hydrogenolysis of the alpha, alpha-dimethyl benzyl alcohol.

In some embodiments, the following hydrogenolysis reaction process may be employed: the catalyst was introduced with 5% H by volume before use₂-95％N₂The mixed gas is reduced for 16h at the temperature of 220 ℃ by temperature programming, and then the catalyst is soaked by cumene for standby. The loading of the catalyst is 100ml, the reaction temperature is 200 ℃, the reaction pressure is 2Mpa, and the liquid hourly space velocity is 3h^-1The molar ratio of hydrogen to benzyl alcohol is 8:1, and the reaction is carried out for 100 h.

The pressures stated in the present invention are absolute pressures.

The invention has the beneficial effects that:

(1) Nb-Al compound with strong interaction can be obtained by hydrolyzing niobium pentachloride and aluminum isopropoxide, a plasma generator is adopted for treatment in the hydrolysis process, isopropanol is promoted to decompose and slowly release water to control the hydrolysis rate, the prepared Nb-Al carrier has strong interaction, the growth of Nb-Al compound crystal grains is inhibited, and the smaller carrier particles are beneficial to improving the dispersion degree of Cu-Mn active components in the subsequent precipitation process and enhancing the activity of the catalyst.

(2) The AlNbO can be formed by introducing niobium oxide into alumina carrier₄The structure can adjust the acidity and alkalinity of the catalyst, and can inhibit the generation of a main byproduct, namely diisopropylbenzene in the catalyst. Can improve the yield of the isopropyl benzene, the stability of the catalyst and the service life.

(3) The addition of Li auxiliary agent can further improve the hydrogenation activity of the catalyst, and Li is used₂SiO₃Using Li as an auxiliary₂SiO₃The caking property of the catalyst can obviously improve the strength of the catalyst, improve the liquid resistance of the catalyst and avoid the loss of the auxiliary agent Li in a high-water-content system.

(4) The plasma is adopted to promote the isopropanol to be decomposed into water and propylene, and the propylene is separated, so that COD (chemical oxygen demand) in the wastewater can be reduced, and the wastewater treatment difficulty is reduced.

Drawings

FIG. 1 is long-term stability operating data for the long-term stability experiment of example 1.

Detailed Description

The method according to the invention will be further illustrated by the following examples, but the invention is not limited to the examples listed, but also encompasses any other known modification within the scope of the claims.

The specifications of the main raw materials are as follows:

isopropyl benzene: analyzer pure, Aladdin reagent;

the hydrogenolysis raw material is self-made;

niobium pentachloride: an alatin reagent, analytically pure;

isopropyl alcohol: an alatin reagent, analytically pure;

aluminum nitrate: kemi Euro reagent, analytically pure;

copper nitrate: kemi Euro reagent, analytically pure;

50% manganese nitrate solution: the reagent for west longu is analytically pure;

alumina sol binder, julonga reagent, industrial grade.

Equipment and characterization instrument:

the plasma generator is provided by Shenzhen Yoeplulley plasma technology Limited; the evaluation equipment is provided for automatic control of the moxa; the forming equipment is a double-screw extruder of south China university of science and technology.

The element test equipment is AXIOS Max Petroleum; chromatographic analysis conditions: the analysis was carried out using a DB-5MS (30 m.times.0.25 mm.times.0.25 μm) column, under the following operating conditions: keeping the temperature at 50 ℃ for 2 minutes, heating to 80 ℃ at 5 ℃/min, keeping the temperature for 0min, heating to 240 ℃ at 15 ℃/min, and keeping the temperature for 5 min. The injector temperature was 260 ℃ and the detector temperature was 260 ℃.

Example 1

10.15g of niobium pentachloride is dissolved in 11.3g of isopropanol, and after the niobium pentachloride is completely dissolved, the niobium pentachloride is added into 120g of aluminum isopropoxide, and the mixture is processed by a high-frequency plasma generator at room temperature and the radio frequency is 15 MHz. The discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 2 Pa. The hydrolysis time was 2 h.

And (3) continuously adopting the plasma reactor to treat the reaction system, completely decomposing the isopropanol, wherein the COD in the wastewater is less than 50 ppm. The carrier a is obtained by filtering, drying and roasting for 6 hours at 800 ℃.

And adding 0.68L of water into the precipitation kettle, uniformly mixing 151g of copper nitrate and 20.59g of 50% manganese nitrate aqueous solution, and adding the mixture and 15 wt% of sodium carbonate solution into the reactor in a concurrent flow manner to obtain a precursor b. The temperature in the precipitation process is controlled at 75 ℃, the precipitation time is 1h, the precipitation pH is 8.0, the addition amount of sodium carbonate is controlled until the precipitation end point pH, the temperature in the aging process is controlled at 80 ℃, and the aging time is 1 h. And preparing a precursor b.

40g of carrier a was dissolved in 0.1L of water and added to precursor b before precipitation of precursor b and aging. The precursor was dried at 120 ℃ for 1 h. The roasting temperature is 550 ℃, and the roasting time is 2 hours. Obtaining a precursor c.

And screening the precursor c, adding 5g of lithium silicate and a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 120 ℃, and the drying time is 1 h. The roasting temperature is 850 ℃ and the roasting time is 2 h. Catalyst composition 50% CuO + 5% MnO_x+5％Li₂SiO₃+5％Nb₂O₅+35％Al₂O₃。

Evaluation of hydrogenolysis reaction: the catalyst was introduced with 5% H by volume before use₂-95％N₂The mixed gas is heated and reduced for 16h at 220 ℃, and then the catalyst is soaked by the isopropyl benzene for standby. The loading of the catalyst is 100ml, the reaction temperature is 200 ℃, the reaction pressure is 2Mpa, and the liquid hourly space velocity is 3h^-1The molar ratio of hydrogen to benzyl alcohol was 8: 1. After the reaction is carried out for 100 hours, the conversion rate of the benzyl alcohol is 99 percent, and the selectivity of the isopropyl benzene is 99.2 percent. FIG. 1 shows the results of the long-term stability experiment of the catalyst.

Example 2

16.24g of niobium pentachloride is dissolved in 18.0g of isopropanol, added to 160g of aluminum isopropoxide after complete dissolution, heated to 40 ℃, and subjected to radio frequency of 14MHz by a high-frequency plasma generator. The discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 50 Pa. The hydrolysis time was 1.5 h.

And (3) continuously adopting the plasma reactor to treat the reaction system, completely decomposing the isopropanol, wherein the COD in the wastewater is less than 50 ppm. The carrier a is obtained by filtering, drying and roasting for 6 hours at 900 ℃.

And adding 0.62L of water into the precipitation kettle, uniformly mixing 136g of copper nitrate and 20.59g of 50% manganese nitrate aqueous solution, and adding the mixture and 15 wt% of sodium carbonate solution into the reactor in a concurrent flow manner to obtain a precursor b. The temperature in the precipitation process is controlled at 65 ℃, the precipitation time is 1.5h, the precipitation pH is 7.5, the addition amount of sodium carbonate is up to the precipitation end point pH, the temperature in the aging process is controlled at 70 ℃, and the aging time is 1.5 h. And preparing a precursor b.

48g of carrier a was dissolved in 0.1L of water and added to precursor b before precipitation of precursor b and aging. The precursor was dried at 100 ℃ for 4 h. The roasting temperature is 500 ℃, and the roasting time is 3 h. Obtaining a precursor c.

And screening the precursor c, adding 2g of lithium silicate and a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 100 ℃, and the drying time is 4 h. The roasting temperature is 750 ℃, and the roasting time is 3 h. Catalyst composition 45% CuO + 5% MnO_x+2％Li₂SiO₃+8％Nb₂O₅+40％Al₂O₃。

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 99.5% and the selectivity to cumene was 99.5%.

Example 3

And adding 0.58L of water into the precipitation kettle, uniformly mixing 136g of copper nitrate and 8.23g of 50% manganese nitrate aqueous solution, and adding the mixture and 15 wt% of sodium carbonate solution into the reactor in a concurrent flow manner to obtain a precursor b. The temperature in the precipitation process is controlled at 65 ℃, the precipitation time is 1.5h, the precipitation pH is 7.5, the addition amount of sodium carbonate is up to the precipitation end point pH, the temperature in the aging process is controlled at 70 ℃, and the aging time is 1.5 h. And preparing a precursor b.

48g of carrier a was dissolved in 0.1L of water, and carrier a was added to precursor b before precipitation of precursor b and aging. The precursor was dried at 100 ℃ for 4 h. The roasting temperature is 500 ℃, and the roasting time is 3 h. Obtaining a precursor c.

And screening the precursor c, adding 2g of lithium silicate and a binder, extruding into strips, drying and roasting to obtain the catalyst. The drying temperature is 100 ℃, and the drying time is 4h. The roasting temperature is 750 ℃, and the roasting time is 3 h. Catalyst composition 45% CuO + 2% MnO_x+5％Li₂SiO₃+8％Nb₂O₅+40％Al₂O₃。

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 99.4% and the selectivity to cumene was 99.4%.

Example 4

20.30g of niobium pentachloride is dissolved in 22.6g of isopropanol, added to 160g of aluminum isopropoxide after complete dissolution, heated to 50 ℃, and subjected to radio frequency of 13MHz by a high-frequency plasma generator. The discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 150 Pa. The hydrolysis time was 1.0 h.

And (3) continuously adopting the plasma reactor to treat the reaction system, completely decomposing the isopropanol, wherein the COD in the wastewater is less than 50 ppm. The carrier a is obtained by filtering, drying and roasting for 6 hours at 1000 ℃.

And adding 0.56L of water into the precipitation kettle, uniformly mixing 121g of copper nitrate and 20.59g of 50% manganese nitrate aqueous solution, and adding the mixture and 15 wt% of sodium carbonate solution into the reactor in a concurrent flow manner to obtain a precursor b. The temperature in the precipitation process is controlled at 60 ℃, the precipitation time is 2 hours, the precipitation pH is 7.0, the addition amount of sodium carbonate is up to the precipitation end point pH, the temperature in the aging process is controlled at 65 ℃, and the aging time is 2 hours. And preparing a precursor b.

50g of the carrier a was dissolved in 0.1L of water, and the carrier a was added to the precursor b before the precipitation of the precursor b was completed and the aging was carried out. The precursor was dried at 100 ℃ for 4 h. The roasting temperature is 450 ℃, and the roasting time is 4 h. Obtaining a precursor c.

And screening the precursor c, adding 5g of lithium silicate and a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 100 ℃, and the drying time is 4 h. The roasting temperature is 650 ℃, and the roasting time is 4 h. Catalyst composition 40% CuO + 5% MnO_x+5％Li₂SiO₃+10％Nb₂O₅+40％Al₂O₃。

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 99.2% and the selectivity to cumene was 99.6%.

Example 5

30.45g of niobium pentachloride is dissolved in 33.8g of isopropanol, added into 180g of aluminum isopropoxide after being completely dissolved, heated to 60 ℃, and subjected to radio frequency of 12MHz by a high-frequency plasma generator. The discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 200 Pa. The hydrolysis time was 0.5 h.

And (3) continuously adopting the plasma reactor to treat the reaction system, completely decomposing the isopropanol, wherein the COD in the wastewater is less than 50 ppm. The carrier a is obtained by filtering, drying and roasting at 1100 ℃ for 6 h.

And adding 0.46L of water into the precipitation kettle, uniformly mixing 106g of copper nitrate and 8.23g of 50% manganese nitrate aqueous solution, and adding the mixture and 15 wt% of sodium carbonate solution into the reactor in a concurrent flow manner to obtain a precursor b. The temperature in the precipitation process is controlled at 55 ℃, the precipitation time is 3 hours, the precipitation pH is 6.5, the addition amount of sodium carbonate is controlled until the precipitation end point pH, the temperature in the aging process is controlled at 60 ℃, and the aging time is 3 hours. And preparing a precursor b.

60g of the carrier a was dissolved in 0.1L of water, and the carrier a was added to the precursor b before the precipitation of the precursor b was completed and the aging was carried out. The precursor was dried at 80 ℃ for 6 h. The roasting temperature is 350 ℃, and the roasting time is 6 hours. Obtaining a precursor c.

And (3) screening the precursor c, adding 3g of lithium silicate and a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 80 ℃ and the drying time is 6 h. The roasting temperature is 550 ℃ and the roasting time is 6 hours. Catalyst composition 35% CuO + 2% MnO_x+3％Li₂SiO₃+15％Nb₂O₅+45％Al₂O₃。

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 99.0% and the selectivity to cumene was 99.7%.

Example 6

20.30g of niobium pentachloride is dissolved in 22.6g of isopropanol, added to 200g of aluminum isopropoxide after complete dissolution, heated to 50 ℃, and subjected to radio frequency of 13MHz by a high-frequency plasma generator. The discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 150 Pa. The hydrolysis time was 1.0 h.

And (3) continuously adopting the plasma reactor to treat the reaction system, completely decomposing the isopropanol, and enabling COD (chemical oxygen demand) in the wastewater to be less than 50 ppm. The carrier a is obtained by filtering, drying and roasting for 6 hours at 1000 ℃.

And (3) screening the precursor c, adding 3g of lithium silicate and a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 80 ℃ and the drying time is 6 h. The roasting temperature is 550 ℃, and the roasting time is 6 h. Catalyst composition 35% CuO + 2% MnO_x+3％Li₂SiO₃+10％Nb₂O₅+50％Al₂O₃。

Comparative example 1

40g of Al₂O₃And 10g of Nb₂O₅Uniformly mixing, and roasting at 1000 ℃ for 6h to obtain the carrier a.

0.62L of water was added to the precipitation kettle, and 151g of copper nitrate and 15 wt% of sodium carbonate solution were co-currently added to the reactor to obtain precursor b. The temperature in the precipitation process is controlled at 75 ℃, the precipitation time is 1h, the precipitation pH is 8.0, the addition amount of sodium carbonate is controlled until the precipitation end point pH, the temperature in the aging process is controlled at 80 ℃, and the aging time is 1 h. And preparing a precursor b.

50g of the carrier a was dissolved in 0.1L of water, and the carrier a was added to the precursor b before the precipitation of the precursor b was completed and the aging was carried out. The precursor was dried at 120 ℃ for 1 h. The roasting temperature is 550 ℃, and the roasting time is 2 hours. Obtaining a precursor c.

And (4) screening the precursor c to a certain particle size, adding a binder, extruding into strips, forming, drying and roasting to obtain the catalyst. The drying temperature is 120 ℃, and the drying time is 1 h. The roasting temperature is 550 ℃ and the roasting time is 4 hours. Catalyst composition 50% CuO + 10% Nb₂O₅+40％Al₂O₃。

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 98.0% and the selectivity to cumene was 97.5%.

Comparative example 2

0.56L of water was added to the precipitation kettle, and 136g of copper nitrate and 20.59g of a 50% aqueous solution of manganese nitrate were mixed uniformly and added to the reactor in parallel with a 15 wt% sodium carbonate solution. The temperature in the precipitation process is controlled at 60 ℃, the precipitation time is 2 hours, the precipitation pH is 7.0, the temperature in the aging process is controlled at 65 ℃, and the aging time is 2 hours. 50g of Al is added before the precipitation of the precursor is finished and the precursor is aged₂O₃Added to carrier b. The precursor was dried at 100 ℃ for 4 h. The roasting temperature is 450 ℃, and the roasting time is 4 h. To prepare a precursor b.

And (4) screening the precursor c to a certain particle size, adding a binder, extruding, forming, drying and roasting to obtain the catalyst. The drying temperature is 120 ℃, and the drying time is 1 h. The roasting temperature is 550 ℃ and the roasting time is 4 hours.

Evaluation of hydrogenolysis reaction: the evaluation conditions were the same as in example 1. The conversion of benzyl alcohol was 99.0% and the selectivity to cumene was 94.5%.

Comparative example 3(comparison with example 1)

A commercially available Cu-Cr catalyst was used.

The evaluation conditions for the evaluation of the hydrogenolysis reaction were the same as in example 1. The conversion of benzyl alcohol obtained was 91.8% and the selectivity to cumene was 98.5%.

As can be seen from the comparison between the above examples and comparative examples, the catalyst prepared by the preparation method of the present invention has stable structure, high catalyst activity and good long-term stability.

It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims

1. A method for preparing a catalyst for preparing cumene through hydrogenolysis of alpha, alpha-dimethyl benzyl alcohol, which is characterized by comprising the following steps:

2) decomposing isopropanol in the reaction system and after hydrolysis, removing propylene generated in the reaction system, treating water phase, and roasting to generate AlNbO₄Obtaining a carrier a;

4) adding the carrier a into the precursor b to obtain a precursor c;

wherein, in the step 1), isopropanol is dehydrated by adopting a plasma generator;

wherein, in the step 2), the isopropanol is decomposed by adopting a plasma generator.

2. The method for preparing the catalyst of claim 1, wherein the double hydrolysis of niobium pentachloride and isopropanol in step 1) occurs at the phase interface of two phases of propylene and water;

and/or the temperature of the double hydrolysis process is 20-60 ℃, and the hydrolysis time is 0.5-2 h;

and/or the plasma generator is a high-frequency plasma generator;

and/or the radio frequency of the plasma generator is controlled at 12-15MHz, the discharge parameters are voltage 100V, positive current (100 +/-10) mA, grid current (50 +/-10) mA and treatment vacuum degree 2-200 Pa.

3. The catalyst preparation method according to claim 1, wherein the decomposition of isopropanol in step 2) is started after the completion of precipitation;

and/or, step 2) removing propylene generated in the reaction system through a flash evaporation device;

and/or, the roasting temperature in the step 2) is 800-1100 ℃;

and/or, step 2) the plasma generator is synchronized to step 1);

and/or, step 2) the plasma generator process control conditions are the same as step 1).

4. The method for preparing a catalyst according to claim 1, wherein the copper salt in step 3) is selected from one or more of copper nitrate, copper acetate, copper sulfate and copper chloride;

and/or, the manganese salt in the step 3) is selected from one or more of manganese nitrate, manganese acetate, manganese sulfate and manganese chloride;

and/or, the precipitant in the step 3) is alkaline precipitant;

and/or, adding water into the reactor before adding the raw materials in the step 3);

and/or, the temperature in the precipitation process in the step 3) is controlled to be 55-75 ℃, the time is controlled to be 1-3h, and the pH is controlled to be 6.5-8.0;

and/or, the temperature in the aging process in the step 3) is controlled to be 60-80 ℃, and the aging time is 1-3 h.

5. The method of preparing a catalyst according to claim 1, wherein the precipitant in step 3) is one or more of sodium carbonate, sodium bicarbonate, ammonium bicarbonate and ammonia water.

6. The preparation method of the catalyst according to claim 1, wherein the carrier a is added into water in the step 4) and uniformly mixed, and the carrier a is added into the precursor b before the precursor b is precipitated and aged;

and/or, washing, drying and roasting the slurry obtained by mixing the carrier a and the precursor b in the step 4) to obtain a precursor c;

and/or, the drying temperature in the step 4) is 80-120 ℃, and the drying time is 1-6 h;

and/or, the roasting temperature in the step 4) is 350-550 ℃, and the roasting time is 2-6 h.

7. The method for preparing the catalyst according to claim 1, wherein in the step 5), the precursor c is screened and then added with the auxiliary agent and the binder;

and/or, in the step 5), obtaining the catalyst after extrusion molding, drying and roasting;

and/or, in the step 5), the drying temperature is 80-120 ℃, and the drying time is 1-6 h;

and/or, in the step 5), the roasting temperature is 550-850 ℃, and the roasting time is 2-6 h.

8. A catalyst prepared by the method of preparing a catalyst of any one of claims 1-7.

9. The catalyst of claim 8, wherein the catalyst has a chemical composition, based on the total weight of the catalyst, of:

a) the content of CuO is 30-60%,

b) 2 to 10 percent of MnOx,

c) 1 to 10 percent of auxiliary agent,

d) the content of NbOx is 5-20%,

e)Al₂O₃the content is 30-60%.

10. The catalyst of claim 8, wherein the catalyst has a chemical composition, based on the total weight of the catalyst, of:

a) the content of CuO is 35-50%,

b) the content of MnOx is 2-5%,

c) the content of the auxiliary agent is 2-5%,

d) the content of NbOx is 5-15%,

e)Al₂O₃the content is 35-50%.

11. The catalyst according to claim 8 or 9, wherein the promoter in the catalyst is an alkali metal compound promoter.

12. The catalyst according to claim 8 or 9, wherein the promoter in the catalyst is Li₂SiO₃、Li₃PO₄And Na₂Ti₃O₇One or more of (a).

13. The catalyst according to claim 8 or 9, wherein the promoter in the catalyst is Li₂SiO₃。

14. Use of a catalyst prepared by the method of preparing a catalyst according to any one of claims 1 to 7 or a catalyst according to any one of claims 8 to 13 for catalysing the hydrogenolysis of α, α -dimethylbenzyl alcohol to cumene.