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Spherical catalyst with Pd wrapped by cerium dioxide and preparation method thereof

A technology of ceria and catalyst, which is applied in the field of ceria-wrapped Pd spherical catalyst and its preparation, can solve the problems of limited scale industrial application, high Pd content, complex control conditions, etc., and achieve excellent activity and stability, The effect of increasing dispersion

Active Publication Date: 2018-08-31
FUZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

M. Cargnello et al disclosed a Pd@CeO in the literature [Science, 2012, 43(47): 713-717] 2 Loaded on Al 2 o 3 The synthesis method of the catalyst above, the catalyst shows good activity in the catalytic combustion of methane, but the organic solvent is used more in the synthesis steps, and the key steps must be carried out under the atmosphere of complete isolation of oxygen, the synthesis method is costly , difficult to reproduce
Xiao Wang et al disclosed Pd@CeO in literature [Angew.Chem. 2016, 128, 4618-4622] 2 Loaded on Al 2 o 3 A catalyst with a stable structure can be obtained above, but it needs complex treatment of Pd during the synthesis process, and the Pd content in the catalyst is high (4.5-50 wt%), and the yield is low
All in all, currently these wrapped Pd-CeO 2 The main disadvantages of catalyst synthesis methods are many synthesis steps, complex control conditions, low yield, and the use of a large amount of raw materials that are harmful to the environment and human health, which limits the large-scale industrial application of these methods

Method used

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  • Spherical catalyst with Pd wrapped by cerium dioxide and preparation method thereof
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  • Spherical catalyst with Pd wrapped by cerium dioxide and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] At room temperature, dissolve 0.56 g PVP and 1.74 g citric acid in a mixture of water: absolute ethanol = 2:1, then add 17.1 mg palladium nitrate solution containing Pd, stir for 10 min, add 4.2 g nitric acid After adding cerium, 0.6 g urea, and adding 6 mL hydrogen peroxide, stirring for another 20 min, put the resulting solution in a polytetrafluoroethylene bottle, and place it in an oven at a temperature of 2 ℃ / min to 120 ℃ for 12 h. The resulting product is used Wash with deionized water and absolute ethanol, centrifuge, and dry at 60 ℃ for 7 hours; the resulting product is placed in a muffle furnace and raised to 400 ℃ at a rate of 0.5 ℃ / min. After 4 hours of heat preservation, the product is heated at 0.5 ℃ / min Continue to heat up to 600 ℃, calcinate for 2 h, and cool down naturally to obtain the desired catalyst.

Embodiment 2

[0032] At room temperature, dissolve 0.42 g PVP and 1.74 g citric acid in a mixed solution of water: anhydrous ethanol=3:1, then add a palladium nitrate solution containing 4.3 mg of Pd, stir for 10 min, add 3.2 g nitric acid Cerium, 0.6 g urea, stir for another 20 minutes, put the resulting solution in a polytetrafluoroethylene bottle, place it in an oven at 2 ℃ / min to 80 ℃ for 1 h, then program to 120 ℃ for 24 h, The resultant product was washed with deionized water and absolute ethanol, centrifuged, and dried at 60 ℃ for 7 h; the resultant product was placed in a muffle furnace and raised to 400 ℃ at a rate of 1 ℃ / min. After 4 hours of heat preservation, Continue to heat up to 600 ℃ at a rate of 1 ℃ / min, calcinate for 2 h, and cool down naturally to obtain the desired catalyst.

Embodiment 3

[0034] At room temperature, dissolve 0.42 g PVP and 1.23 g citric acid in a mixed solution of water: absolute ethanol = 4:1, then add a palladium nitrate solution containing 8.8 mg of Pd, stir for 10 min, add 2.1 g nitric acid Cerium, 0.3 g of urea, and 3 mL of hydrogen peroxide were added, and then stirred for another 20 minutes. The resulting solution was placed in a polytetrafluoroethylene bottle and placed in an oven at a rate of 2 ℃ / min to 80 ℃. After reaction for 2 h, the program The temperature was raised to 120 ℃ and reacted for 24 hours. The product was washed with deionized water and absolute ethanol, centrifuged, and dried at 60 ℃ for 7 h; the product was placed in a muffle furnace and heated to 400 ℃ at a rate of 1 ℃ / min After the heat preservation treatment for 4 h, continue to heat up to 600 ℃ at a rate of 1 ℃ / min, calcinate for 2 h, and naturally lower the temperature to obtain the desired catalyst.

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Abstract

The invention discloses a spherical catalyst with Pd wrapped by cerium dioxide and a preparation method thereof. The preparation method comprises the steps: firstly, preparing a precursor solution A of cerium salt and palladium salt, and then carrying out a reaction of the precursor solution A in a hydrothermal reaction kettle to produce a product B; and carrying out centrifugal washing, drying and calcination of the product B, to obtain the spherical catalyst with Pd wrapped by cerium dioxide. The synthesis method is simple, and the obtained catalyst has high Pd metal dispersion degree and catalytic oxidation performance. Under the conditions of the gas composition of 2% of CH4, 4% of O2 and 20% of CO2, N2 balance and the space velocity of 100000 mL*g<-1>*h<-1> and at the reaction temperature of 470 DEG C, the methane conversion rate of the catalyst can reach 90%, and the structure of the catalyst has no obvious change after thermal aging for 2 h at the temperature of 1000 DEG C, theactivity of the catalyst is kept 99% or more in a 50 h stability test carried out at the temperature of 500 DEG C in the same atmosphere, and the catalyst has excellent methane combustion catalytic activity and stability.

Description

Technical field [0001] The invention belongs to the field of material preparation and application, and specifically relates to a spherical catalyst coated with cerium oxide and Pd and a preparation method thereof. Background technique [0002] In the process of oil and coal mining, there will be a large number of oilfield associated gas and coalbed methane. Due to the constraints of technical means, and the associated gas is relatively difficult to control in the process of oilfield and coal mining, a large part of the oilfields containing low concentrations of methane ( (Or coalbed methane) associated gas is emptied. In addition, the coal chemical process also emits a large amount of low-concentration methane purge gas. Because methane-containing gas such as oilfield associated gas or industrial purge gas has a low methane concentration, conventional combustion cannot be achieved; on the other hand, the conventional combustion temperature of methane is as high as 1600 ℃, and th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/63B01J35/08F23G7/07
CPCF23G7/07B01J23/63F23G2209/14B01J35/394B01J35/51
Inventor 詹瑛瑛罗薇肖益鸿蔡国辉郑勇钟富兰
Owner FUZHOU UNIV
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