CN110975867A

CN110975867A - Pd-ZnO/Al2O3Catalyst, preparation method and application thereof

Info

Publication number: CN110975867A
Application number: CN201911271473.4A
Authority: CN
Inventors: 王永钊; 田雨润; 武瑞芳; 幸忠; 王晶晶; 王淑娟
Original assignee: Shanxi University
Current assignee: Shanxi University
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2020-04-10

Abstract

本发明公开了一种Pd‑ZnO/Al₂O₃催化剂及其制备方法和应用，所述催化剂以Pd为活性组分，ZnO为助催化剂，Al₂O₃为载体，各组分的质量百分比：Pd为0.1%~0.25%，ZnO为0.5%~2.0%，Al₂O₃为97.75%~99.4%。制备方法为：将Pd源、Zn源、Al源和双氰胺混合均匀并充分研磨，然后放入管式炉中，通入H₂/N₂混合气升温处理，处理结束后在N₂或惰性气氛下冷却至室温制得催化剂。所制备的催化剂用于聚二乙烯基乙炔加氢反应，在相对温和的反应条件下，聚二乙烯基乙炔加氢度可达25.8%。The invention discloses a Pd-ZnO/Al ₂ O ₃ catalyst and a preparation method and application thereof. The catalyst uses Pd as an active component, ZnO as a co-catalyst, and Al ₂ O ₃ as a carrier. : Pd is 0.1%~0.25%, ZnO is 0.5%~2.0%, Al ₂ O ₃ is 97.75%~99.4%. The preparation method is as follows: the Pd source, the Zn source, the Al source and the dicyandiamide are mixed uniformly and fully ground, then put into a tube furnace, and the H ₂ /N ₂ mixed gas is introduced for heating treatment, and after the treatment is completed, the N ₂ or The catalyst was prepared by cooling to room temperature under an inert atmosphere. The prepared catalyst is used for the hydrogenation reaction of polyvinylacetylene, and under relatively mild reaction conditions, the hydrogenation degree of polyvinylacetylene can reach 25.8%.

Description

Pd-ZnO/Al2O3Catalyst, preparation method and application thereof

Technical Field

The invention relates to Pd-ZnO/Al₂O₃A catalyst, a preparation method and application thereof, belonging to the technical field of catalyst preparation.

Background

Synthetic rubbers are generally classified into general synthetic rubbers and semi-general synthetic rubbers, with chloroprene rubbers being of the semi-general type. Chloroprene rubber has the general properties of most general synthetic rubbers and outstanding properties such as solvent resistance, chemical stability, heat resistance, aging resistance, air tightness and the like, so that the application field is very wide. There are two main processes for producing chloroprene rubber, the acetylene process and the butadiene process. China mainly adopts an acetylene method to produce chloroprene rubber. However, in the production of chloroprene rubber by the acetylene process, Divinylacetylene (DVA) is produced as a by-product.

Formula of acetylene method for producing chloroprene rubber:

equation for the production of divinylacetylene as a by-product:

DVA contains double and triple bonds and is very reactive and therefore very susceptible to polymerization to form polydivinyl acetylene (PDVA). At present, most PDVA concentrated solution is subjected to incineration treatment, only a small part of PDVA concentrated solution is used for waterproof coating and coastal wooden ship anticorrosive paint, but the problems of poor adhesion and easy falling exist, and the application of PDVA concentrated solution is limited. Catalytic hydrogenation of unsaturated polymers is a process for preparing new materials by converting unsaturated polymers into saturated or semi-saturated polymers, thereby changing the properties of the polymers.

The catalyst for catalytic hydrogenation can be divided into two types, namely heterogeneous hydrogenation catalyst and homogeneous hydrogenation catalyst. Wherein the heterogeneous catalyst mainly comprises noble metals such as Pt, Pd, Rh and the like and transition metal elements such as Fe, Co, Ni and the like which are loaded on carriers such as kieselguhr, active carbon, aluminum oxide, calcium carbonate, silicon dioxide and the like. Chemical modification and corrosion resistance research of polydivinyl acetylene in cheschreza [ cheschreza ] university of Chongqing, 2011 ] uses raney nickel and Pd/C catalyst, and researches the reaction conditions with the best hydrogenation effect of PDVA from the aspects of catalyst dosage, polymer concentration, reaction temperature, reaction time, additives and the like. Experiments show that both Raney nickel and Pd/C catalysts can partially hydrogenate polymers, the better conditions of the hydrogenation reaction of the Raney nickel catalyst are that the reaction time is 200-300 min, the reaction temperature is 110 ℃, the reaction pressure is 2 MPa, the catalyst dosage is 8% of the polymer, the polymer concentration is 10-15%, and the polymer hydrogenation degree can reach 10% under the conditions; the preferable conditions of the Pd/C catalyst hydrogenation reaction are that the reaction time is 200-300 min, the reaction temperature is 110 ℃, the reaction pressure is 1.4 MPa, the catalyst dosage is 4% of the polymer, the polymer concentration is 10-15%, and the additive is 5%, and the hydrogenation degree can reach 17% under the conditions.

It is well known that modification by catalytic hydrogenation of polydivinyl acetylene to reduce its unsaturation is an important means to improve its application properties. However, from few literature reports at present, the polydivinyl acetylene hydrogenation modified catalyst still has the defects of harsh reaction conditions, low hydrogenation degree, high noble metal loading in the catalyst and the like. Therefore, it is of great practical significance to design and prepare catalysts with low Pd loading and good catalytic activity.

Disclosure of Invention

The invention aims to provide Pd-ZnO/Al₂O₃The invention also provides a Pd-ZnO/Al catalyst and a preparation method thereof₂O₃The application of the catalyst in polydivinyl acetylene hydrogenation.

The invention provides Pd-ZnO/Al₂O₃The catalyst takes Pd as an active component, ZnO as a cocatalyst and Al₂O₃Is used as a carrier, and comprises the following components in percentage by mass:

the mass percent of the active component Pd is 0.1-0.25%, the mass percent of ZnO is 0.5-2.0%, and the carrier Al is₂O₃The mass percentage of the component (A) is 97.75% -99.4%.

Preferably, in the catalyst, the mass percentages of the components are as follows:

an active component Pd: 0.15 to 0.2 percent

And (3) a cocatalyst ZnO: 1.0% -2.0%

Carrier Al₂O₃：97.8%~98.85%。

The invention provides the Pd-ZnO/Al₂O₃The preparation method of the catalyst comprises the following steps:

(1) weighing a Pd source, a Zn source, an Al source and dicyandiamide, uniformly mixing and fully grinding, wherein the mass ratio of the Pd salt to the Zn salt to the Al salt to the dicyandiamide is 1: 1.1-43.9: 276.2-4388.6: 100-500;

(2) placing the ground mixed sample in a tube furnace, and introducing H₂/N₂Slowly heating the mixed gas to 80-90 ℃ for treatment for 3-10 h, and then quickly heating to 300-600 ℃ for treatment for 3-10 h;

(3) after the treatment is finished, H₂/N₂Switching the mixed gas to N₂Or inert gas, and naturally cooling to room temperature to obtain the catalyst.

In the preparation method, the Pd source in the step (1) is one or more of palladium nitrate, palladium chloride and palladium acetate; the Zn source is one or more of zinc nitrate, zinc hydroxide, zinc chloride and zinc acetate; the Al source is one or more of aluminum nitrate, aluminum chloride and aluminum acetate.

The above production process, step (2) said H₂/N₂The volume ratio of the mixed gas is 1: 1-10, and the flow rate of the mixed gas is 20-100 mL/min; the slow heating rate is 1-3 ℃/min, and the fast heating rate is 5-10 ℃/min.

Further, said H in step (2)₂/N₂The ratio of the mixed gas is 1: 1-5, and the flow rate is 40-60 mL/min; the slow heating rate is 1-2 ℃/min, the treatment is carried out for 5-8 h at 80-85 ℃, the fast heating rate is 5-8 ℃/min, and the treatment is carried out for 4-6 h at 350-500 ℃.

In the preparation method, the inert gas in the step (3) is one or two of Ar and He, and the flow rate of the inert gas is 20-100 mL/min.

Further, the flow rate of the inert gas is 40-60 mL/min.

The invention also provides the Pd-ZnO/Al₂O₃The application of the catalyst in polydivinyl acetylene hydrogenation specifically comprises the following steps: PDVA toluene solution and Pd-ZnO/Al₂O₃Adding catalyst into high-pressure reactor, Pd-ZnO/Al₂O₃The mass ratio of the catalyst to the PDVA is 1: 30-60, nitrogen is firstly introduced for replacement for three times, then hydrogen is introduced, the reaction pressure is controlled to be 0.1-1.0 MPa, heating and stirring are started, the heating rate is 2-5 ℃/min, the stirring speed is 100-300 rpm, and the temperature is increased to 90-105 ℃ for reaction for 1-3 hours.

Pd-ZnO/Al₂O₃The catalyst is used in the reaction of catalytic hydrogenation of polydivinyl acetylene, and the hydrogenation degree of the polydivinyl acetylene can reach 25.8%.

The invention has the beneficial effects that:

(1) after the catalyst prepared by the invention is used for the catalytic hydrogenation reaction of polydivinyl acetylene, the unsaturation degree of the polymer can be effectively reduced;

(2) the catalyst has the advantages of mild use condition, high catalytic activity, reusability, low content of noble metal Pd and low cost;

(3) the catalyst has the advantages of simple preparation process, wide raw material source, no harm to human bodies and environment, easy realization of industrial production and good application prospect.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following examples.

Example 1:

0.1 g of PdCl is weighed out₂，1.76 g Zn(NO₃)₂·6H₂O，35.88 g Al(OH)₃And 10 g of dicyandiamide were mixed together and sufficiently ground, and the ground mixed sample was placed in a tube furnace and H was introduced at a flow rate of 50 mL/min₂/N₂Mixed gas (H)₂/N₂The volume ratio is 1: 5), the temperature is increased to 80 ℃ at the speed of 1 ℃/min for processing for 8H, then the temperature is increased to 400 ℃ at the speed of 8 ℃/min for processing for 4H, the heating is stopped after the processing is finished, and H is added₂/N₂The mixed gas is switched to helium with the flow rate of 50 mL/min, and the mixed gas is naturally cooled to the room temperature to obtain the Pd-ZnO/Al₂O₃CatalysisAnd (3) preparing. Wherein the mass percent of Pd is 0.25wt%, the mass percent of ZnO is 2.0wt%, Al₂O₃Is 97.75 wt%.

30g of a toluene solution of PDVA (PDVA concentration 20%) and 0.2 g of Pd-ZnO/Al₂O₃Adding the catalyst into a high-pressure reaction kettle, introducing nitrogen for three times, then introducing hydrogen, controlling the reaction pressure at 1.0 MPa, starting heating and stirring, wherein the heating rate is 2 ℃/min, the stirring speed is 300 rpm, and heating to 105 ℃ for reaction for 3 hours. The unsaturation degree of the PDVA toluene solution and the reacted solution is measured by a bromine number method, so that the hydrogenation degree of the polydivinyl acetylene is calculated to be 25.8%.

Example 2

0.15 g Pd (NO) is weighed₃)₂·2H₂O，1.76 g Zn(NO₃)₂·6H₂O，35.88 g Al(OH)₃And 10 g of dicyandiamide by the preparation method of example 1 to obtain Pd-ZnO/Al₂O₃A catalyst. Wherein the mass percent of Pd is 0.25wt%, the mass percent of ZnO is 2.0wt%, Al₂O₃Is 97.75 wt%.

Using the reaction conditions and measurement method of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 25.4%.

Example 3

0.05 g of PdCl are weighed out₂，0.88 g Zn(NO₃)₂·6H₂O，35.88 g Al(OH)₃And 10 g of dicyandiamide by the preparation method of example 1 to obtain Pd-ZnO/Al₂O₃A catalyst. Wherein the mass percent of Pd is 0.13 wt%, the mass percent of ZnO is 1.02 wt%, Al₂O₃The mass percentage of (B) is 98.85 wt%.

Using the reaction conditions and measurement method of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 18.7%.

Example 4

0.1 g of PdCl is weighed out₂，0.59g Zn(OH)₂，35.88 g Al(OH)₃And 10 g of dicyandiamide by the preparation method of example 1 to obtain Pd-ZnO/Al₂O₃A catalyst. Wherein P isd is 0.25wt%, ZnO is 2.0wt%, Al₂O₃Is 97.75 wt%.

Example 5

35.88g of Al (OH) in example 1₃Changed to 61.38g AlCl₃The Pd-ZnO/Al is prepared by the same method under the same other conditions₂O₃A catalyst. Wherein the mass percent of Pd is 0.25wt%, the mass percent of ZnO is 2.0wt%, Al₂O₃Is 97.75 wt%.

Using the reaction conditions and measurement method of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 24.9%.

Example 6

The same method is adopted to prepare Pd-ZnO/Al by changing the using amount of dicyandiamide in the example 1 to 30g and keeping other conditions unchanged₂O₃A catalyst. Wherein the mass percent of Pd is 0.25wt%, the mass percent of ZnO is 2.0wt%, Al₂O₃Is 97.75 wt%.

Using the reaction conditions and measurement method of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 25.0%.

Example 7

The Pd-ZnO/Al is prepared by the same method by changing the temperature-raising treatment process in the preparation condition of the catalyst in the embodiment 1 into the temperature-raising treatment process of 2 ℃/min to 90 ℃ for 8h, then raising the temperature of 5 ℃/min to 400 ℃ for 4 h, and keeping the other conditions unchanged₂O₃A catalyst. Wherein the mass percent of Pd is 0.25wt%, the mass percent of ZnO is 2 wt%, and Al₂O₃Is 97.75 wt%.

Using the reaction conditions and measurement method of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 23.1%.

Example 8

The amount of the PDVA toluene solution used in the reaction conditions of example 1 was changed to 60 g, and the degree of hydrogenation of polydivinyl acetylene was calculated to be 21.6% under the same other conditions.

Example 9

The degree of hydrogenation of polydivinyl acetylene was calculated to be 21.2% by controlling the reaction pressure under the reaction conditions of example 1 to 0.5 MPa and keeping the other conditions unchanged.

Example 10

The stirring speed was changed to 150 rpm under the reaction conditions of example 1, and the degree of hydrogenation of polydivinyl acetylene was calculated to be 24.1% under the other conditions.

Example 11

The reaction temperature in the reaction conditions of example 1 was changed to 95 ℃ and the degree of hydrogenation of polydivinyl acetylene was calculated to be 22.3% under the same conditions.

Example 12

The reaction time in the reaction condition of example 1 was changed to 2 hours, and the degree of hydrogenation of polydivinyl acetylene was calculated to be 24.6% without changing other conditions.

Cycle performance testing of the catalyst:

example 13

The catalyst of example 1 was recovered and labeled as Pd-ZnO/Al₂O₃-1. Using the evaluation conditions of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 25.2% under the evaluation conditions.

Example 14

The catalyst from example 13 was recovered, labelled Pd-ZnO/Al₂O₃-2. Using the evaluation conditions of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 24.5% under the evaluation conditions.

Example 15

The catalyst from example 14 was recovered and labeled as Pd-ZnO/Al₂O₃-3. Using the evaluation conditions of example 1, the degree of hydrogenation of polydivinyl acetylene was calculated to be 24.7% under the evaluation conditions.

Examples 13 to 15 show that the catalyst has good cycle performance and can be reused.

Claims

1. a Pd _- ZnO/Al ₂ O catalyst, characterized in that: the catalyst takes Pd as an active component, ZnO as a promoter, and Al ₂ O as a carrier, and the mass percent _of each component is:

Active component Pd: 0.1%~0.25%

Co-catalyst ZnO: 0.5%~2.0%

Carrier Al ₂ O ₃ : 97.75%~99.4%.

2. The Pd-ZnO/Al ₂ O ₃ catalyst according to claim 1, wherein: in the catalyst, the mass percentage of each component is:

Active component Pd: 0.15%~0.2%

Co-catalyst ZnO: 1.0%~2.0%

Carrier Al ₂ O ₃ : 97.8%~98.85%.

3. the preparation method of the described Pd-ZnO/Al ₂ O ₃ catalyst of claim 1 or 2, is characterized in that: comprises the following steps:

(1) Weigh the Pd source, Zn source, Al source and dicyandiamide and mix them evenly and fully grind them. The mass ratio of the Pd salt, Zn salt, Al salt and dicyandiamide is 1:1.1~43.9:276.2~ 4388.6:100~500;

(2) Place the ground mixed sample in a tube furnace, pass in H ₂ /N ₂ mixed gas, slowly heat up to 80~90 °C for 3~10 h, and then rapidly heat up to 300~600 °C for 3~10 h. 10 hours;

(3) After the treatment, the H ₂ /N ₂ mixture is switched to N ₂ or an inert gas, and the catalyst is naturally cooled to room temperature.

4. The preparation method of the Pd-ZnO/Al ₂ O ₃ catalyst according to claim 3, wherein the Pd source described in the step (1) is one of palladium nitrate, palladium chloride and palladium acetate or multiple; the Zn source is one or more of zinc nitrate, zinc hydroxide, zinc chloride, and zinc acetate; the Al source is one or more of aluminum nitrate, aluminum hydroxide, aluminum chloride, and aluminum acetate one or more.

5. The preparation method of the Pd-ZnO/Al ₂ O ₃ catalyst according to claim 3, characterized in that: the volume ratio of the H ₂ /N ₂ mixed gas described in the step (2) is 1:1～10, The mixed gas flow rate is 20~100 mL/min;

The slow heating rate is 1-3 °C/min, and the rapid heating rate is 5-10 °C/min.

6. The preparation method of Pd-ZnO/Al ₂ O ₃ catalyst according to claim 5, characterized in that: the ratio of the H ₂ /N ₂ mixed gas described in the step (2) is 1:1～5, and the flow rate 40-60 mL/min; the slow heating rate is 1-2 ℃/min, the temperature is 80-85 ℃ for 5-8 h, the rapid heating rate is 5-8 ℃/min, and the temperature is 350-500 ℃ 4 to 6 hours.

7. The preparation method of the Pd-ZnO/Al ₂ O ₃ catalyst according to claim 3, wherein the inert gas in step (3) is one or both of Ar and He, N ₂ or The flow rate of the inert gas is 20~100 mL/min.

8. The preparation method of the Pd-ZnO/Al ₂ O ₃ catalyst according to claim 7, wherein the flow rate of the inert gas is 40-60 mL/min.

9. the application of the described Pd-ZnO/Al ₂ O ₃ catalyst of claim 1 or 2, it is characterized in that: PDVA toluene solution and Pd-ZnO/Al ₂ O ₃ catalyzer are added in the autoclave, Pd - The mass ratio of ZnO/Al ₂ O ₃ catalyst and PDVA is 1:30~60. First, nitrogen is introduced for three times, and then hydrogen is introduced. The reaction pressure is controlled at 0.1 to 1.0 MPa. ~5 ℃/min, the stirring speed is 100~300 rpm, and the temperature is raised to 90~105 ℃ for 1~3 h.

10 . The application according to claim 9 , wherein the Pd-ZnO/Al ₂ O ₃ is used for the catalytic hydrogenation reaction of polydiethylene acetylene, and the hydrogenation degree of polydivinyl acetylene can reach 25.8%. 11 .