Modification of Pd/CeO2 catalyst by Atomic Layer Deposition of ZrO2

•Pd/CeO2 catalysts were modified with Atomic Layer Deposition of ZrO2.•ALD of ZrO2 preserved surface area and crystallite size of catalysts upon heating to 1073 K.•CH4 oxidation activity of the catalysts did not decrease with increasing calcination temperature.•ALD ZrO2-modified catalysts exhibit excellent water–gas-shift activity.•ZrO2 film improved sulfur tolerance by preventing cerium sulfate formation.

Modification of a 1 wt% Pd/CeO2 catalyst by Atomic Layer Deposition of thin ZrO2 films was studied. Calcination of the unmodified Pd/CeO2, prepared by precipitation of aqueous Ce(NO3)3 solutions, with Pd added by impregnation, caused a large decrease in surface area and an increase in crystallite size between 673 K and 1073 K; however, catalysts modified by 0.4 nm ZrO2 films showed no change in either surface area or CeO2 crystallite size upon calcination to 1073 K. Methane-oxidation rates in 0.5% CH4 and 5% O2 were slightly lower on the ZrO2-covered catalyst when both materials were calcined at 673 K but the activity of the ZrO2-modified catalyst did not decrease with catalyst calcination temperature. Both catalysts showed good activity for the water–gas-shift reaction but the ZrO2 film improved sulfur tolerance by preventing formation of cerium sulfates.

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