In the prior art, citral is mostly used as a raw material for preparing citronellal or citronellol by hydrogenation, and two different production processes are derived because two different hydrogenation reactions are involved in the preparation process. One-step method, namely, one-step preparation of citronellal or citronellol by hydrogenation, has the defect that only a single product can be produced, and the product can be switched only by switching catalysts, so that the market flexibility and variability requirements cannot be met.

The other is a two-step method, namely, the citronellal is firstly hydrogenated to produce the citronellal, and then the citronellal is hydrogenated to produce the citronellol through one-step hydrogenation reaction.

In summary, the existing hydrogenation synthesis methods, such as the citral hydrogenation method, can only prepare single citronellal or citronellol, and cannot modulate and switch hydrogenation products, so that flexible market demands cannot be met. In view of the foregoing, there is a need to develop a process that allows flexible modulation of the hydrogenated synthesis product.

Disclosure of Invention

The invention aims to provide a catalyst which can solve the defects of the prior art, flexibly modulate hydrogenation synthesized products and directly obtain different target products or target products with different composition ratios, thereby meeting the production requirements and the market requirements.

In experimental studies of hydrogenation catalysts, the inventors have surprisingly found a catalyst having piezoresistive properties, which can respond to pressure changes of a hydrogenation reaction system, thereby achieving the purpose of selectively switching hydrogenation products by changing the pressure.

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

a selective hydrogenation catalyst comprising a catalytically active metal component and a support having piezoresistive properties; wherein the metal active component is VIII metal element, and the carrier is inorganic piezoresistive material.

The catalyst can achieve the purpose of switching hydrogenation products by changing the system pressure. The essence of the product switching is that the activity of the catalyst is changed, when the pressure of a system is increased, the resistivity of a carrier with piezoresistive property is increased, the mobility of electrons on the surface of the carrier is weakened, and the electronic action between a metal active center and a reaction substrate is weakened, so that the activity of the catalyst is reduced, and the catalyst can only catalyze the hydrogenation of a C=C bond and can not catalyze the hydrogenation of a C=O bond, thereby achieving the purpose of switching hydrogenation products.

In the invention, the metal active component is preferably one or more of metal Ru, rh and Ir; preferably, the metals Ru, rh, ir are derived from soluble metal compounds; of these, ru is preferably one or more from ruthenium trichloride, tris (triphenylphosphine) ruthenium dichloride and ruthenium acetylacetonate, more preferably ruthenium trichloride; rh is preferably one or more from rhodium chloride, rhodium iodide, triphenylphosphine rhodium chloride, rhodium dicarbonyl acetylacetonate and rhodium triacetylacetonate, more preferably rhodium chloride; ir is preferably one or more selected from iridium chloride, iridium acetate, iridium dicarbonyl acetylacetonate, ammonium chloride and iridium acetylacetonate, and more preferably iridium chloride.

In the invention, the loading amount of the metal active component is 5-20wt%, preferably 8-15wt%, calculated by taking the carrier as 100%; preferably, when the metal active center is two or more, each metal element is supported in an amount of not less than 10wt% based on the total metal load.

In the invention, the carrier is one or more of monocrystalline silicon, polycrystalline silicon, silicon carbide, zinc oxide, quartz, barium titanate and lead zirconate titanate, preferably zinc oxide.

It is another object of the present invention to provide a method for preparing the catalyst.

A method of preparing the catalyst, the method of preparing the catalyst comprising the steps of:

s1: dissolving a metal compound containing a metal active center to prepare a solution;

s2: and adding the carrier into the solution for soaking, drying and roasting to obtain the target catalyst.

In the present invention, the S1 solvent is selected from one or more of small molecule alcohols, halogenated hydrocarbons, ethers and esters, preferably one or more of ethanol, ethyl acetate and methyl tert-butyl ether, more preferably ethanol.

In the present invention, the metal-containing compound in the solution is 10 to 40wt%, preferably 15 to 30wt%, based on the mass of the solvent.

In the invention, the S2 is immersed for 10 to 20 hours at the temperature of 10 to 40 ℃, dried for 3 to 5 hours at the temperature of 80 to 120 ℃ and baked for 3 to 5 hours at the temperature of 300 to 500 ℃.

It is a further object of the present invention to provide a process for selective hydrogenation synthesis.

A selective hydrogenation synthesis method adopts the catalyst or the catalyst prepared by the method, wherein the synthesis method is a high-pressure reaction, and the pressure of a reaction system is preferably changed by introducing hydrogen into the reaction system.

In the invention, the method obtains different hydrogenation products by adjusting the pressure of a reaction system. Preferably, when the target product of citral hydrogenation synthesis is citronellal, the system pressure is set to be 4-5 MPa (G), and when the target product of citral hydrogenation synthesis is citronellol, the system pressure is set to be 1-2 MPa (G). It will be appreciated by those skilled in the art that the different hydrogenation products may also be hydrogenation products of different composition ratios, which may also be obtained by adjusting the respective pressures.

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

The use of a catalyst, which is the aforementioned catalyst, or a catalyst prepared by the method, or a catalyst used in the hydro-synthesis method, for the selective hydrogenation of alpha, beta-unsaturated carbonyl compounds; preferably, the catalyst is used for catalyzing the hydrogenation of citral to citronellal and/or citronellol.

Compared with the prior art, the dot product effect of the invention is as follows:

(1) The carrier of the catalyst increases the specific surface area of the catalyst, improves the reaction activity, and more importantly, plays a role in modulating the catalyst activity along with the change of external pressure conditions, thereby influencing the selectivity of the catalyst and playing a role in switching target products.

(2) The production device has the capability of producing two products or products with different proportions, different products can be obtained very conveniently according to the production conditions of the market demand regulating device, and the device has strong market flexibility.

Detailed Description

The following examples will further illustrate the process provided by the present invention, but the invention is not limited to the examples listed and should include any other known modifications within the scope of the invention.

Analytical instrument and method:

gas chromatograph: agilent 7890, column DB-5, sample inlet temperature: 300 ℃; the split ratio is 50:1; carrier gas flow rate: 50ml/min; heating program: maintaining at 120deg.C for 15min, increasing to 250deg.C at 10deg.C/min, maintaining for 10min, and detecting temperature: 280 ℃.

Main raw materials and reagent sources:

anhydrous ruthenium trichloride, 99wt%, alas Ding Shiji limited;

rhodium chloride, 98wt%, company, ala Ding Shiji limited;

iridium chloride, 99.99wt%, available from ala Ding Shiji limited;

ZnO,99wt%, alaa Ding Shiji limited;

barium titanate, 99wt%, a company of alaa Ding Shiji;

ethanol, 99wt%, national pharmaceutical group chemical company, inc;

Pd/C catalyst, ara Ding Shiji Co., ltd;

Ru/C catalyst, ala Ding Shiji Co.

The main equipment comprises:

the hydrogenation device is a 500ml batch kettle type reaction kettle, the material is 316L, the blade is a self-priming blade, the heating power is 1100W, and the rotating speed is 0-1000 rpm.

Example 1(preparation of piezoresistive catalyst)

0.82g of ruthenium trichloride is dissolved in 5.47g of ethanol to prepare a solution, 5.0g of carrier ZnO is added into the solution, the solution is immersed for 20 hours at 10 ℃, then dried for 3 hours at 80 ℃, and then baked for 3 hours in a muffle furnace at 300 ℃ to obtain the 1# load type piezoresistive catalyst.

Example 2(preparation of piezoresistive catalyst)

1.92g of rhodium chloride is dissolved in 7.68g of ethanol to prepare a solution, 5.0g of carrier ZnO is put into the solution, immersed for 15 hours at 25 ℃, then dried for 4 hours at 120 ℃, and then baked for 5 hours in a muffle furnace at 500 ℃ to obtain the 2# load type piezoresistive catalyst.

Example 3(preparation of piezoresistive catalyst)

0.78g of iridium chloride is dissolved in 2.59g of ethanol to prepare a solution, 5.0g of carrier ZnO is put into the solution, immersed for 10 hours at 40 ℃, then dried for 5 hours in a vacuum oven at 100 ℃, and then baked for 4 hours in a muffle furnace at 400 ℃ to obtain the 3# load type piezoresistive catalyst.

Example 4(preparation of piezoresistive catalyst)

0.51g of ruthenium trichloride and 0.64g of rhodium chloride are dissolved in 3.84g of ethanol to prepare a solution, 5.0g of carrier ZnO is put into the solution, immersed for 20 hours at 10 ℃, then dried for 3 hours at 80 ℃, and then baked for 3 hours in a muffle furnace at 400 ℃ to obtain the 4# supported piezoresistive catalyst.

Example 5(preparation of piezoresistive catalyst)

0.82g of ruthenium chloride is dissolved in 5.47g of ethanol to prepare a solution, 5.0g of carrier barium titanate is put into the solution, immersed for 20 hours at 10 ℃, then dried for 5 hours at 80 ℃, and then baked for 3 hours in a muffle furnace at 400 ℃ to obtain the 5# load type piezoresistive catalyst.

Example 6(Synthesis of hydrogenation product)

A batch kettle reactor is adopted, 0.1G of 1# catalyst and 100G of substrate citral are filled, the catalyst dosage is 0.1wt% of the substrate, hydrogen is introduced to 1MPa (G), the temperature is set to 40 ℃, after 5 hours of reaction, the substrate conversion rate is detected to be 99.2%, the citronellal selectivity is 0.6%, and the citronellol selectivity is 99.1%.

Example 7(Synthesis of hydrogenation product)

A batch reactor was used, and 0.5G of 2# catalyst and 100G of the substrate citral were charged, the catalyst amount was 0.5wt% of the substrate, hydrogen was introduced to 2MPa (G), the temperature was set at 90℃and after 5 hours of reaction, the substrate conversion was 99.6%, the citronellal selectivity was 0.9% and the citronellol selectivity was 98.8%.

Example 8(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G of 3# catalyst and 100G of the substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 5MPa (G), the temperature was set at 70℃and after 5 hours of reaction, the substrate conversion was 99.1%, the citronellal selectivity was 99.3% and the citronellol selectivity was 0.3%.

Example 9(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G of 3# catalyst and 100G of the substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 1MPa (G), the temperature was set at 70℃and after 5 hours of reaction, the substrate conversion was 99.0%, the citronellal selectivity was 0.5% and the citronellol selectivity was 99.3%.

Example 10(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G of 4# catalyst and 100G of the substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 5MPa (G), the temperature was set at 40℃and after 5 hours of reaction, the substrate conversion was 99.2%, the citronellal selectivity was 99.2% and the citronellol selectivity was 0.5%.

Example 11(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G of catalyst No. 5 and 100G of substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 2MPa (G), the temperature was set at 40℃and after 5 hours of reaction, the substrate conversion was 99.1%, the citronellal selectivity was 0.8% and the citronellol selectivity was 99.0%.

Example 12(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G of catalyst No. 5 and 100G of substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 5MPa (G), the temperature was set at 40℃and after 5 hours of reaction, the substrate conversion was 98.9%, the citronellal selectivity was 99.1% and the citronellol selectivity was 0.7%.

Comparative example 1(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G Pd/C catalyst and 100G substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 5MPa (G), the temperature was set at 40℃and after 5 hours of reaction, the substrate conversion was 98.7%, the citronellal selectivity was 98.8% and the citronellol selectivity was 1.0%.

Comparative example 2(Synthesis of hydrogenation product)

A batch reactor was used, and 1.0G Pd/C catalyst and 100G substrate citral were charged, the catalyst amount was 1.0wt% of the substrate, hydrogen was introduced to 2MPa (G), the temperature was set at 40℃and after 5 hours of reaction, the substrate conversion was 97.1%, the citronellal selectivity was 97.8% and the citronellol selectivity was 1.1%.

As can be seen from a comparison of examples 8 and 9, in particular with the 3# catalyst, both examples have high conversion, while citronellal and citronellol products (differing in composition ratio) are obtained under different pressure conditions, respectively, and similar results are obtained from examples 11 and 12 with the 5# catalyst. In comparative examples 1 and 2 using the Pd/C catalyst used in the prior art, the composition ratio of citronellal and citronellol in the product was not significantly changed under the condition of significant pressure change. The method of the invention not only can improve the reactivity of the catalyst, but also can achieve the purpose of switching hydrogenation products through the modulation of the system pressure, and has extremely strong flexibility for adapting to the market.

Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.

Claims

1. A method for synthesizing by selective hydrogenation, which is characterized in that a catalyst is adopted, and the method is a high-pressure reaction;

the catalyst comprises a metal active component with catalysis and a carrier with piezoresistive property;

when the target product of the catalytic citral hydrogenation synthesis is citronellal, the system pressure is set to be 4-5 MPaG, and when the target product of the catalytic citral hydrogenation synthesis is citronellol, the system pressure is set to be 1-2 MpaG;

wherein the metal active component is VIII metal element, and the carrier with piezoresistive property is inorganic piezoresistive material;

wherein the inorganic piezoresistive material is one or more of monocrystalline silicon, polycrystalline silicon, zinc oxide, silicon carbide, quartz, barium titanate and lead zirconate titanate.

2. The method of claim 1, wherein the metal active component is one or more of the metals Ru, rh, ir.

3. The method according to claim 2, characterized in that the metals Ru, rh, ir originate from soluble metal compounds.

4. The method of claim 3, wherein the Ru is one or more from the group consisting of ruthenium trichloride, ruthenium tris (triphenylphosphine) dichloride, and ruthenium acetylacetonate; rh is one or more of rhodium chloride, rhodium iodide, triphenylphosphine rhodium chloride, rhodium dicarbonyl acetylacetonate and rhodium triacetylacetonate; ir is one or more of iridium chloride, iridium acetate, iridium dicarbonyl acetylacetonate, ammonium chloride iridium and iridium acetylacetonate.

5. The method of claim 4, wherein the Ru is ruthenium trichloride; rh is rhodium chloride; ir is iridium chloride.

6. The method of claim 1, wherein the loading of the metal active component is 5wt% to 20wt%, based on 100% of the support.

7. The method of claim 6, wherein the loading of the metal active component is 8wt% to 15wt%, based on 100% of the support.

8. The method according to claim 6, wherein when the metal active center is two or more, each metal element is supported in an amount of not less than 10wt% based on the total metal load.

9. The method according to claim 1, wherein the pressure of the reaction system is changed by introducing hydrogen gas into the reaction system.

10. The process according to claim 1, wherein the process obtains different hydrogenation products by adjusting the pressure of the reaction system.

11. A process for preparing a catalyst for use in the process of any one of claims 1 to 10, comprising the steps of:

12. The method for preparing a catalyst according to claim 11, wherein the solvent in S1 is selected from one or more of small molecule alcohols, halogenated hydrocarbons, ethers and esters;

and/or 10wt% to 40wt% of the metal-containing compound in the solution, based on the mass of the solvent.

13. The method for preparing a catalyst according to claim 12, wherein the solvent in S1 is selected from one or more of ethanol, ethyl acetate and methyl t-butyl ether;

and/or 15 to 30wt% of metal-containing compound in the solution, based on the mass of the solvent.

14. The method for preparing a catalyst according to claim 13, wherein the solvent in S1 is ethanol.

15. The method for preparing a catalyst according to claim 11, wherein the S2 is impregnated at 10 to 40 ℃ for 10 to 20 hours, dried at 80 to 120 ℃ for 3 to 5 hours, and calcined at 300 to 500 ℃ for 3 to 5 hours.