Nanostructured NiO for Catalytic Oxidation of CO: Microstructural and Anionic Effects of the Precursors

Abstract

Transition metal oxides are suitable catalysts, capable of converting toxic carbon monoxide to carbon dioxide. Morphological and textural behaviors of the catalyst influence the catalytic conversion efficiencies. The present work highlights the role of anions of the nickel‐based precursor salts in hydrothermally synthesized (180 °C/24 h) nickel oxide catalysts toward CO conversion concerning their surface area, pore dimensions, and microstructural characteristics. Precursors having different anions used in NiO synthesis have distinct effects in shaping the physicochemical features of the synthesized catalysts governing the catalytic conversion process which were investigated in this study. The nitrate and acetate‐based NiO with flower‐like morphology exhibit a comparatively low surface area (BET) and larger pore volume and diameter than the sulfate‐based precursor. Catalytic CO oxidation study reveals that T100 i.e., the temperature to reach 100 % volume conversion of CO to CO2 was 249, 209, and 274 °C for nitrate, acetate, and sulfate‐based precursors, respectively. It was evident that the higher pore volume is a critical parameter that facilitates and governs efficient catalytic CO oxidation at comparatively low temperatures. The evolution of the pore properties and their reciprocity with the catalytic activity has been expounded in this study.