Dry reforming of methane (DRM) has been used to convert the two most hazardous greenhouse gases, carbon dioxide and methane, to desirable fuels (i.e., syngas). However, this process requires significant heat input traditionally provided from a furnace, leading to reemission of greenhouse gases. Photothermochemical dry reforming of methane (PTC-DRM) is a newly explored approach, utilizing renewable solar energy to drive the energy demanding endothermic reaction. Catalysts designed using scarce and high-cost noble metals show excellent catalytic activity and stability under PTC-DRM conditions, although their widespread use is unrealistic. Cerium oxide (CeO2) is an earth abundant semiconductor with enhanced redox properties under light irradiation, yet its large bandgap and small surface area limit its photocatalytic activity. Ni has been shown to narrow the bandgap of CeO2 and has promising catalytic activity by being an active site for methane and possessing localized surface plasmon resonance (LSPR). However, nickel catalysts are susceptible to nanoparticle aggregation and coke formation, deactivating the catalyst and compromising its stability. In this investigation, catalyst surface area and nanoparticle aggregation were addressed by exploring a metal organic framework (MOF) derived approach to synthesize CeO2. XRD analysis confirmed highly crystalline CeO2, while SEM images showed hollow, rod-like morphology of CeO2. Ni nanoparticles were prepared on CeO2 via wet impregnation followed by reduction under H2/Ar flow, resulting in metallic nickel confirmed by XRD. Diffuse Reflectance UV-Vis spectroscopy suggested visible light absorption features and a red shift in the bandgap energy with respect to bare CeO2. This was attributed to the incorporation of metallic Ni. To resist deactivation due to coking, amphoteric Ga2O3 nanoparticles were incorporated on Ni/CeO2 using the same wet impregnation method followed by calcination under an inert environment. XPS confirmed the presence of metallic nickel and gallium oxide. Preliminary photothermochemical conversions of CO2 and CH4 will be presented.

Synthesis of a MOF-derived catalyst with highly dispersed nanoparticles for photothermochemical dry reforming of methane

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