Insights into the influence of Pd loading on CeO2 catalysts for CO2 hydrogenation to methanol

Abstract

One of the most significant industrial processes is the catalytic methanol synthesis from carbon dioxide because methanol is a future energy carrier for producing fuels and high-value-added commodities, the so-called “methanol economy” is carbon neutral. As a solution to climate change, the widespread belief that carbon dioxide can be recycled by hydrogenation into methanol has motivated the development of more efficient and selective catalysts. Efficient 2 wt% Pd/CeO₂ catalysts for thermochemical CO₂ hydrogenation have recently been investigated. However, the rationale behind the low Pd loading (2 wt%) in CeO₂ needs to be clarified, and comprehensive research into Pd tuning is lacking. In this article, we describe the synthesis ofvarious palladium contents (0.5, 1, 2, 4, and 6 wt%) supported on ceria nanorods (Pd/CeO₂) for selective hydrogenation of CO₂ to methanol under vapor-phase. The impact of Pd on the physicochemical properties of CeO₂ was examined using various characterization techniques. The enhanced catalytic activity was caused by the 2 wt% Pd/CeO₂ catalyst's most significant level of metallic Pd species, strong interactions between Pd and CeO₂, uniform Pd dispersion on CeO₂, increased reducibility, oxygen mobility, and weak basic sites. This study reveals that changing the percentage of metal in the catalyst supports a valuable technique for designing efficient oxides-supported metal-based catalysts for CO₂ conversions.