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Preparation method of palladium-lead bimetallic catalyst with eggshell structure

A bimetallic catalyst, catalyst technology, applied in catalyst activation/preparation, preparation of organic compounds, metal/metal oxide/metal hydroxide catalysts, etc., can solve the problem of low catalytic efficiency, high noble metal loading, and cumbersome preparation process And other issues

Active Publication Date: 2013-12-18
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The purpose of the present invention is to overcome the shortcomings of existing Pd-Pb bimetallic catalysts such as low catalytic efficiency, high noble metal loading, and tedious preparation process, and provide a method for preparing Pd-Pb bimetallic catalysts with "eggshell" structure

Method used

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  • Preparation method of palladium-lead bimetallic catalyst with eggshell structure
  • Preparation method of palladium-lead bimetallic catalyst with eggshell structure
  • Preparation method of palladium-lead bimetallic catalyst with eggshell structure

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Embodiment 1

[0021] Put 5g of spherical alumina carrier into a 500mL beaker, add deionized water, put it in a water bath, add 4.0mL of H 2 PdCl 4 The solution was heated to 60°C. 20 mL of n-butanol was added dropwise, and the reaction was stopped after 0.5 h. Cool to room temperature, filter with suction, wash with plenty of water, and dry in a vacuum oven at 40°C for 12 hours. Gained catalyst is counted as: Pd 2 / Al 2 o 3 . The contents of Pd and Pb in the catalyst were measured by ICP-AES, see Table 1. Example 2

Embodiment 2

[0022] 0.16g of lead acetylacetonate was dissolved in deionized water, added to the alumina carrier, allowed to stand, and then put into a vacuum drying oven to dry for 12 hours. Calcined at 300°C for 0.5h in air atmosphere. Put the impregnated-roasted lead-containing alumina carrier into a 500mL beaker, add deionized water, put it in a water bath, add 4.6mL of palladium acetate solution under mechanical stirring, and raise the temperature to 60°C. 25mL of 37wt% formaldehyde solution was added dropwise, and the reaction was stopped after 6h. Cool to room temperature, filter with suction, wash with plenty of water, and dry in a vacuum oven at 80°C for 12 hours. Gained catalyst is counted as: Pd 1 Pb 1 / Al 2 o 3 . The contents of Pd and Pb in the catalyst were measured by ICP-AES, see Table 1.

Embodiment 3

[0024] 2.56g PbCl 2 After dissolving with deionized water, add it to the alumina carrier, let it stand still, and then put it into a vacuum drying oven to dry for 12 hours. Calcined at 500°C for 3h in air atmosphere. Put the impregnated-calcined lead-containing alumina carrier into a 500mL beaker, add deionized water, and add 9.0mL H 2 PdCl 4 solution. At 25°C, add 30mL NaBH dropwise 4 solution, the reaction stopped after 10 h. Filter with suction, wash with plenty of water, and dry in a vacuum oven at 80°C for 12 hours. Gained catalyst is counted as: Pd 2 Pb 8 / Al 2 o 3 . The distribution of Pd on the alumina support is shown in figure 1 , it can be seen that Pd in ​​the catalyst prepared by the new method is enriched in the "eggshell" region 20 μm below the outer surface of the alumina microspheres. The contents of Pd and Pb in the catalyst were measured by ICP-AES, see Table 1.

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Abstract

The invention relates to a preparation method of a palladium-lead bimetallic catalyst with an eggshell structure. The method comprises the following steps: introducing a Pb species into an aluminum oxide carrier by adopting a method of firstly loading a Pb precursor and improving the loading amount of Pb, and then performing liquid phase reduction to prepare the Pd-Pb bimetallic catalyst, wherein Pd-Pb bimetallic nanoparticles in the obtained catalyst are distributed in an eggshell region at 20 mu m below the outer surface of the aluminum oxide carrier. The catalyst has high catalytic activity, product selectivity and stability in reaction for preparing methyl methacrylate (MMA) by alcohol aldehyde one-step oxidative esterification. Compared with the traditional Pd-Pb bimetallic catalyst, the novel Pd-Pb bimetallic catalyst with the eggshell structure has the advantages of simple preparation method, high Pd dispersion degree, easiness in control of composition of the catalyst and the like, so that the loading amount of the precious metal Pd can be reduced by about 150%, and the investment cost of the catalyst is significantly reduced.

Description

technical field [0001] The invention relates to a preparation method of an "eggshell" structure bimetallic catalyst, in particular to a preparation method of a high-efficiency, low-loaded palladium-lead bimetallic catalyst. The oxidative esterification reaction has high catalytic activity, product selectivity and stability, and belongs to the field of catalyst preparation. Background technique [0002] Carboxylate is an important class of compounds, widely used in medicine, pesticides, spices, additives and other fields. Correspondingly, the research on the synthesis method of esters has a history of more than one hundred years. So far, chemists have established a variety of methods for the efficient synthesis of esters. For example: the esterification reaction of carboxylic acid or carboxylic acid derivatives with alcohol is the earliest and most effective method for the synthesis of ester compounds; the synthesis of ester compounds by one-step hydroesterification reactio...

Claims

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Application Information

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IPC IPC(8): B01J23/62B01J35/02B01J37/02
CPCC07C67/39C07C69/54
Inventor 韩军兴闫瑞一刁琰琰王蕾公茂明张锁江
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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