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

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...

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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

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