阅读说明：本技术 一种雷尼催化剂及其制备方法，一种α,γ-二烯酮制备γ-烯酮的方法 (Raney catalyst and preparation method thereof, and method for preparing gamma-ketene from alpha, gamma-dienone ) 是由 沈稳 黄文学 谢硕 张永振 黎源 于 2020-08-28 设计创作，主要内容包括：本发明提供一种雷尼催化剂及其制备方法,一种α,γ-二烯酮制备γ-烯酮的方法。所述催化剂为锌盐修饰的Ni-Al-Cd雷尼催化剂,所述锌盐选自氯化锌、硫酸锌、硝酸锌和醋酸锌中的一种或多种,优选醋酸锌。用于选择性的氢化α,γ-二烯酮制备γ-烯酮,该催化剂具有催化活性高、选择性高、强度高和制备简单等优点。本发明还提供一种α,γ-二烯酮制备γ-烯酮的方法。连续流动固定床反应工艺进行催化加氢还原α,γ-二烯酮制备的方法γ-烯酮。解决了现有的间歇工艺存在的催化剂成本高昂、催化剂重复使用困难或效果差、操作工艺复杂等缺点,能够以成本低廉的催化剂实现连续加氢还原α,γ-二烯酮制备γ-烯酮,并且反应操作简单、目标产物的选择性和收率高,易于工业化生产。(The invention provides a Raney catalyst and a preparation method thereof, and relates to a method for preparing gamma-ketene from alpha, gamma-dienone. The catalyst is a Ni-Al-Cd Raney catalyst modified by zinc salt, the zinc salt is selected from one or more of zinc chloride, zinc sulfate, zinc nitrate and zinc acetate, and the zinc acetate is preferred. The catalyst is used for selectively hydrogenating alpha, gamma-dienone to prepare gamma-ketene, and has the advantages of high catalytic activity, high selectivity, high strength, simple preparation and the like. The invention also provides a method for preparing gamma-ketene from alpha, gamma-dienone. The gamma-ketene is prepared by catalytic hydrogenation reduction of alpha, gamma-dienone by a continuous flow fixed bed reaction process. The method overcomes the defects of high catalyst cost, difficult catalyst reuse or poor effect, complex operation process and the like of the existing batch process, can realize the continuous hydrogenation reduction of the alpha, gamma-dienone to prepare the gamma-ketene by using the catalyst with low cost, has simple reaction operation, high selectivity and yield of the target product, and is easy for industrial production.)

1. A zinc salt modified Ni-Al-Cd Raney catalyst comprises the following components: based on the weight of the catalyst,

the weight percentage of the nickel is 90.0-95.0%, preferably 92.5-93.5%;

the weight percentage of the aluminum is 3.5-9.5%, preferably 5.5-6.5%;

the weight percentage content of the cadmium is 0.3-1.0%, preferably 0.5-0.75%;

the weight percentage of the zinc salt is 0.1-0.5%, preferably 0.3-0.4%.

2. Catalyst according to claim 1, characterized in that the zinc salt is selected from one or more of zinc chloride, zinc sulphate, zinc nitrate and zinc acetate, preferably zinc acetate.

3. The catalyst according to claim 1 or 2, wherein the mass ratio of cadmium to zinc salt in the catalyst is 0.6-3: 1, preferably 1.25-2.5: 1.

4. a process for preparing a catalyst as claimed in any of claims 1 to 3, comprising the steps of,

(1) heating and melting metal nickel and metal aluminum to obtain an alloy, preparing an alloy strip from the molten alloy through a water-cooling copper roller rotating at a high speed, and grinding and screening the alloy strip to obtain Ni-Al alloy powder with the average particle size of 10-50 mu m;

(2) mixing Ni-Al alloy powder and metal cadmium powder, adding a wetting agent and a forming agent, homogenizing and forming to obtain a Ni-Al-Cd mixture, drying and roasting to obtain a Ni-Al-Cd forming product;

(3) treating the Ni-Al-Cd forming product by using NaOH aqueous solution, and then washing with water;

(4) and (3) dipping the product obtained in the step (3) by using an ethanol solution of zinc salt, and then washing the product by using ethanol to obtain the Ni-Al-Cd Raney's Ni-Al-Cd catalyst modified by the zinc salt.

5. The method according to claim 4, wherein in the step (1), the mass ratio of the metal nickel to the metal aluminum is 1-1.5: 1, and/or,

in the step (1), the melting temperature is 1600-1700K.

6. The method according to claim 4 or 5, wherein in the step (2), the mass ratio of the metal cadmium powder to the Ni-Al alloy powder is 0.1-0.5: 100, preferably 0.25-0.35: 100.

7. The method according to any one of claims 4 to 6, wherein the concentration of the ethanol solution of the zinc salt in the step (4) is 0.05 to 0.1 wt%, and/or the temperature of the dipping treatment in the step (4) is 60 to 80 ℃ and the time of the dipping treatment is 3 to 6 hours.

8. A method for preparing gamma-ketene from alpha, gamma-dienone, which is characterized in that the alpha, gamma-dienone is hydrogenated and reduced into the gamma-ketene under the action of the catalyst of any one of claims 1 to 3 or the catalyst prepared by the method of any one of claims 4 to 7 and a hydrogen atmosphere.

9. The method of claim 8, wherein the α, γ -dienone has the structure of formula I, and the γ -enone has the structure of formula II:

wherein R is₁、R₂、R₃、R₄、R₅、R₆Independently of one another, represents H, a substituted or unsubstituted, saturated or unsaturated alkyl radical having from C1 to C10 (e.g. methyl, chloromethyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-octyl), a C6 to C12 aryl radical (e.g. phenyl, substituted phenyl); and R₂And R₃Between or R₄And R₅Form a saturated or unsaturated ring therebetween; preferably, the alpha, gamma-dienone is 6-methyl-3, 5-heptadien-2-one, beta-ionone or pseudoionone.

10. The method according to claim 9 or 10, characterized in that the temperature of the hydrogenation reduction is 30 to 80 ℃, preferably 40 to 60 ℃; and/or the pressure of hydrogenation reduction is 0.5-3.0 MPaG, preferably 1.0-2.0 MPaG.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a Raney catalyst and a method for preparing gamma-ketene by using the catalyst to continuously hydrogenate and reduce alpha, gamma-dienone.

Background

The selective reduction of the alpha, beta-carbon double bond of the conjugated alpha, gamma-dienone is an important reaction, and a series of fine chemical products with high added values can be obtained, such as the selective reduction of the alpha, beta-carbon double bond of 6-methyl-3, 5-heptadien-2-one, and the obtaining of 6-methyl-5-hepten-2-one, which is an important synthetic intermediate of the spices such as linalool, citral, citronellal, ionone and the like; while the beta-ionone selectively reduces alpha, beta-carbon double bonds to obtain dihydro beta-ionone, which is a key intermediate for synthesizing ambergris.

The α, γ -dienone contains two C ═ C double bonds and one C ═ O double bond, and from a thermodynamic perspective, the bond energy of the C ═ C double bond is 615KJ/mol, and the bond energy of the C ═ O double bond is 715KJ/mol, so that the C ═ C double bond is easier to reduce than the C ═ O double bond, but three double bonds of α, γ -dienone form a conjugated system, there are theoretically many different reduction products, the selectivity of the reaction is controlled, and the hydrogenation of the α, β -carbon double bond is a very challenging target, and there are few patents and literature reports in this field at present.

The selective reduction reaction of alpha, gamma-dienone reported in the known literature or patent basically adopts a homogeneous noble metal catalytic system. For example, Ojima et al reported rhodium catalyzed selective reduction of α, γ -unsaturated dienones with a substrate of β -ionone and a reducing agent of hydrosilane to selectively reduce the α, β -carbon double bond or carbonyl group of β -ionone in an alkaline, alcohol solution (Organomet,1982,1390). Ojima et al, however, use expensive rhodium complexes as catalysts and use relatively high amounts of catalyst (substrate to catalyst molar ratio of only 1000/1), resulting in very costly processes. In addition, the hydrosilylation reaction reported by Ojima is carried out by two steps of hydrosilylation and desilication, the operation steps are complex, the product separation and purification are complicated, and the adoption of alkaline alcohol solution to remove silane can cause the product gamma-ketene to generate side reaction, so that the actual separation yield (88%) is far lower than the yield (96%) detected by an instrument.

Patent CN103384657A reports a homogeneous rhodium and diphosphine catalytic system, which realizes the selective hydrogenation of α, γ -unsaturated dienal to obtain corresponding unconjugated-enal, and the catalytic system has high reaction activity and good chemical selectivity, but the rhodium complex has high cost and harsh reaction conditions, and is difficult to be applied to industrial production.

Patent CN105218339A reports a homogeneous Rh/Pd and bisphosphine ligand catalytic system, which selectively hydrogenates 6-methyl-3, 5-heptadien-2-one to obtain 6-methyl-5-hepten-2-one, wherein the reaction selectivity is between 90% and 94%, but the initial catalyst usage is large (the molar ratio of the substrate to the noble metal catalyst is only 1000/1 at the highest), although the distillation heavy component containing the noble metal catalyst is recycled for 12 times, which reduces the cost to a certain extent, the operation is complex, and the reaction selectivity decreases with the increase of the recycling times, and the reaction selectivity after recycling for 12 times is already lower than 90%.

Patent CN110922321A reports a method for preparing γ -ketene from α, γ -unsaturated dienone, which uses monohydrogen silane as a silicon hydrogen reducing agent, palladium complex as a catalyst, and lewis acid as an auxiliary agent, and performs a silicon hydrogen reduction reaction on α, γ -unsaturated dienone by a one-step method to obtain γ -ketene. The process has mild reaction conditions, simple operation and high selectivity and yield of target products; the catalyst has high activity, less dosage and low cost, but the dosage of the hydrosilation reagent is larger, and more three wastes are generated.

Heterogeneous catalyst systems such as raney nickel, palladium carbon and the like are widely applied to hydrogenation reactions, and are also reported in the field of some alpha, beta-unsaturated ketene, for example, patent CN110479297A reports that a multi-metal supported nickel catalyst system is used for preparing 4, 4-dimethyl-1- (4-chlorophenyl) -3-pentanone by hydrogenation of alpha, beta-ketene. However, the heterogeneous catalyst systems such as raney nickel, palladium carbon and the like have no patent or literature report in the field of alpha, gamma-dienone hydrogenation, because the catalysts cannot realize the selective hydrogenation reduction of alpha, beta-carbon double bonds of alpha, gamma-dienone. Laboratory research results show that the hydrogenation reaction of 6-methyl-3, 5-heptadiene-2-ketone adopts palladium carbon or Raney nickel as a catalyst to obtain a mixture of a plurality of reduction products, and the selectivity of the target product methyl heptenone is not more than 50%.

In summary, the selective reduction of α, β -carbon double bonds reported in the literature at present adopts a batch reduction process using homogeneous precious metals rhodium, ruthenium or palladium, etc. as catalysts, and has the disadvantages of high catalyst cost, difficult catalyst reuse or poor effect, complex operation process, etc. The selective reduction of alpha, gamma-dienone lacks a general, feasible and low-cost technology, so that the development of a novel method for reducing the alpha, beta-carbon double bond of the conjugated alpha, gamma-dienone has very important significance.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a zinc salt modified Ni-Al-Cd Raney catalyst and a preparation method thereof, which are used for selectively hydrogenating alpha, gamma-dienone to prepare gamma-ketene. The invention also provides a method for preparing gamma-ketene from alpha, gamma-dienone. The gamma-ketene is prepared by catalytic hydrogenation reduction of alpha, gamma-dienone by a continuous flow fixed bed reaction process. The method overcomes the defects of high catalyst cost, difficult catalyst reuse or poor effect, complex operation process and the like of the existing batch process, can realize the continuous hydrogenation reduction of the alpha, gamma-dienone to prepare the gamma-ketene by using the catalyst with low cost, has simple reaction operation, high selectivity and yield of the target product, and is easy for industrial production.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing gamma-ketene from alpha, gamma-dienone is characterized by hydrogenating and reducing the alpha, gamma-dienone into gamma-ketene under the action of a zinc salt modified Ni-Al-Cd Raney catalyst and in a hydrogen atmosphere.

Preferably, the method of the present invention is to dissolve α, γ -dienone in N-methylpyrrolidone, and provide the solution, wherein the mass concentration of the α, γ -dienone solution is 10 to 40%, preferably 15 to 25%.

In the method, the temperature of hydrogenation reduction is 30-80 ℃, and preferably 40-60 ℃.

In the method, the pressure of hydrogenation reduction is 0.5-3.0 MPaG, and preferably 1.0-2.0 MpaG.

In the process of the present invention, the continuous hydrogenation reduction can be achieved by using processes known in the art, including but not limited to batch or continuous tank, fixed bed processes, preferably fixed bed processes. When a fixed bed process is adopted, the liquid hourly space velocity of the alpha, gamma-dienone solution is 1.0-8.0 h^-1Preferably 2 to 4 hours^-1Can prevent the excessive hydrogenation of gamma-ketene caused by too long retention time.

In the method, the structure of alpha, gamma-dienone is shown as a formula I, and the structure of gamma-ketene is shown as a formula II:

wherein R is₁、R₂、R₃、R₄、R₅、R₆Independently of one another, represents H, a substituted or unsubstituted, saturated or unsaturated alkyl group having from C1 to C10 (e.g., methyl, chloromethyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-octyl), a C6 to C12 aryl group (e.g., phenyl, substituted phenyl, etc.); and R₂And R₃Between or R₄And R₅Form a saturated or unsaturated ring therebetween. Examples of suitable α, γ -dienones include, but are not limited to, 6-methyl-3, 5-heptadien-2-one, β -ionone, pseudoionone, and the like.

The zinc salt modified Ni-Al-Cd Raney catalyst comprises the following components: based on the weight of the catalyst,

the weight percentage of the nickel is 90.0-95.0%, preferably 92.5-93.5%;

the weight percentage of the aluminum is 3.5-9.5%, preferably 5.5-6.5%;

the weight percentage content of the cadmium is 0.3-1.0%, preferably 0.5-0.75%;

the weight percentage of the zinc salt is 0.1-0.5%, preferably 0.3-0.4%.

The catalyst has the particle size of 3-5 mm and the specific surface area of 50-150 m²/g。

Preferably, in the catalyst, the mass ratio of cadmium to zinc salt is 0.6-3: 1, preferably 1.25-2.5: 1.

a method of preparing the catalyst of the present invention, comprising the steps of: firstly, preparing Ni-Al alloy powder by a quenching method; then mixing and molding Ni-Al alloy powder and metal cadmium powder to obtain a Ni-Al-Cd molding product; extracting the Ni-Al-Cd forming product with NaOH aqueous solution to obtain a skeleton catalyst, and then soaking and modifying with zinc salt ethanol solution to obtain the zinc salt modified Ni-Al-Cd Raney catalyst.

The zinc salt is selected from one or more of zinc chloride, zinc sulfate, zinc nitrate and zinc acetate, and preferably zinc acetate.

As a preferable scheme, the preparation method of the catalyst comprises the following steps:

(1) heating and melting metal nickel and metal aluminum to obtain an alloy, preparing an alloy strip from the molten alloy through a water-cooling copper roller rotating at a high speed, and grinding and screening the alloy strip to obtain Ni-Al alloy powder with the average particle size of 10-50 mu m;

(2) mixing Ni-Al alloy powder and metal cadmium powder, adding a wetting agent and a forming agent, homogenizing and forming to obtain a Ni-Al-Cd mixture, drying and roasting to obtain a Ni-Al-Cd forming product;

(3) treating the Ni-Al-Cd forming product by using NaOH aqueous solution, and then washing with water;

(4) and (3) dipping the product obtained in the step (3) by using an ethanol solution of zinc salt, and then washing the product by using ethanol to obtain the Ni-Al-Cd Raney's Ni-Al-Cd catalyst modified by the zinc salt.

In the step (1), the mass ratio of the metal nickel to the metal aluminum is 1-1.5: 1.

in the step (1), the melting temperature is 1600-1700K, the atmosphere is inert gas, and argon is preferably used.

As a preferred scheme, the step (1) of the invention comprises the following steps: adding metal nickel and metal aluminum into a quartz tube according to the mass ratio of 1.0-1.5: 1, heating the quartz tube in an argon atmosphere in a high-frequency furnace to 1600-1700K for melting, alloying the alloy, then throwing the molten alloy from the quartz tube to a water-cooled copper roller rotating at a high speed by using argon to obtain an alloy strip, grinding the alloy strip in an agate pot, and then screening to obtain Ni-Al alloy powder with the average particle size of 10-50 mu m.

In the step (2), the drying temperature is 80-130 ℃, the atmosphere is inert gas, and argon is preferred.

In the step (2), the roasting temperature is 500-700 ℃, the roasting time is 4-6 hours, and the atmosphere is inert gas, preferably argon.

In the step (2), the mass ratio of the metal cadmium powder to the Ni-Al alloy powder is 0.1-0.5: 100, preferably 0.25-0.35: 100.

The Ni-Al-Cd forming matter in the step (2) can be any shape matter commonly used in the field of catalysts, can be one or more of spherical, cylindrical, disc-shaped, clover-shaped and annular, and is preferably spherical (with better strength and wear resistance), the particle size range of the spherical forming matter is 3-5 mm, and the BET specific surface area range of the spherical forming matter is 50-80 m²/g。

The wetting agent in step (2) of the present invention is selected from one or more of water, ethanol and dihydric alcohol.

The forming agent in the step (2) of the invention is polyvinyl alcohol and methyl cellulose. The mass ratio of the polyvinyl alcohol to the methyl cellulose is (1-5): 1, preferably 1-2: 1.

in the step (3), the concentration of the NaOH aqueous solution is 10-20 wt%.

In the step (3), the treatment temperature is 80-100 ℃.

In the step (3), the treatment time is 6-8 h.

In the step (3), the solution is washed by water until the pH value of the washed solution is 7-8.

As a preferable scheme, the step (3) of the present invention comprises the following steps: putting the Ni-Al-Cd formed product into a quartz glass tube, enabling a NaOH aqueous solution with the concentration of 10-20 wt% to flow into a bed layer of the Ni-Al-Cd formed product from the bottom of the quartz glass tube at the speed of 2.5-3.0L/h, enabling the NaOH aqueous solution to flow out of the top of the bed layer, enabling the temperature of the bed layer to be 80-100 ℃, carrying out alkali extraction for 6-8 h, and then washing with deionized water at the temperature of 60-80 ℃ until the pH value of the washed solution is 7-8.

In the step (4), the concentration of the zinc salt ethanol solution is 0.05-0.1 wt%.

In the step (4), the temperature of the dipping treatment is 60-80 ℃, and the time of the dipping treatment is 3-6 h.

As a preferable scheme, the step (4) of the present invention comprises the following steps: dipping the mixture by using 0.05 to 0.1 weight percent of zinc salt ethanol solution, wherein the weight space velocity of the zinc salt ethanol solution is 1 to 2 hours^-1The temperature of a bed layer is 60-80 ℃, and the dipping treatment time is 3-6 h; and then washing the catalyst with ethanol at the temperature of 60-80 ℃ for 1-2 h to prepare the zinc salt modified Ni-Al-Cd Raney catalyst.

The possible catalytic mechanism of the Ni-Al-Cd Raney catalyst modified by zinc salt provided by the invention for selectively hydrogenating alpha, gamma-dienone is as follows: ni is an active component of the whole catalytic system; al provides a framework structure for the whole catalytic system; cd is introduced to modify the framework Ni, so that the ketocarbonyl of a substrate molecule (alpha, gamma-dienone) can be promoted to be preferentially hydrogenated to obtain an enol intermediate, and the enol intermediate is isomerized to obtain a target product gamma-ketene; the zinc salt is impregnated on the skeleton nickel in a molecular form and competes with an active center on the surface of the Ni to adsorb substrate molecules (alpha, gamma-dienone), so that the hydrogenation activity of the catalyst is reduced, and the hydrogenation of the alpha, gamma-dienone into other byproducts is inhibited.

By adopting the technical scheme, the invention has the following positive effects:

(1) the method for preparing the gamma-ketene by catalytic hydrogenation reduction of the alpha, gamma-dienone by adopting a continuous flow fixed bed reaction process has the advantages of mild reaction conditions, simple operation, high selectivity and yield of a target product, byproduct inhibition, obvious cost advantage and potential for industrial amplification;

(2) the self-made zinc salt modified Raney catalyst has the advantages of low cost, simple preparation, high hydrogenation activity and high selectivity of target products.

Detailed description of the invention

The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

The main raw material information is as follows:

beta-ionone and pseudoionone are purchased from carbofuran technologies and have the purity of 98 percent;

6-methyl-3, 5-heptadiene-2-ketone (abbreviated as methyl heptadiene ketone) is purchased from Annaiji reagent, and the purity is 98%;

ethanol and N-methylpyrrolidone were purchased from julonga chemical, AR;

zinc acetate and metal cadmium powder were purchased from the alatin reagent with a purity of 99.98%;

the nickel powder and the aluminum sheet are purchased from an Aladdin reagent, and the purity is 99.5 percent;

polyvinyl alcohol is purchased from an alatin reagent, the alcoholysis degree is 98-99 mol%, and the viscosity is 20-30 mPa.s;

methylcellulose is available from alatin reagent at a viscosity of 400 mpa.s;

lanthanum triflate required for comparative example 3 was purchased from the avastin reagent with a purity > 98%;

the 5% Pd/C catalyst required for comparative example 15 was obtained from Xinnauoke;

the Raney6800 catalyst required for comparative example 16 was purchased from GRACE.

The gas chromatography test conditions of the present invention are as follows:

the instrument model is as follows: agilent GC; a chromatographic column: agilent DB-5(30 m.times.0.25 mm.times.0.25 μm); column temperature: the initial temperature is 40 ℃, the temperature is raised to 70 ℃ at the speed of 3 ℃/min, then the temperature is raised to 100 ℃ at the speed of 10 ℃/min, finally the temperature is raised to 280 ℃ at the speed of 12 ℃/min, and the temperature is kept for 6 min; sample inlet temperature: 280 ℃; FID detector temperature: 300 ℃; split-flow sample injection with a split-flow ratio of 30: 1; sample introduction amount: 2.0 mu L; h₂Flow rate: 40 mL/min; air flow rate: 400 mL/min.