Synthesis of tungsten carbide nanoparticles in biochar matrix as a catalyst for dry reforming of methane to syngas

Abstract

Tungsten carbide (WC) nanoparticles were synthesized by carbothermal reduction (CR) of tungsten-promoted biochar. The tungsten carbide nanoparticles were characterized for physicochemical properties by multiple morphological and structural methods (e.g. SEM, TEM, and XRD). Characterization results revealed that the transformation of tungsten oxide (WO₃) to tungsten carbide nanoparticles involved the following sequence steps: WO₃ → WO₂ → W → W₂C → WC. The lower the reaction temperature, the lower the CH₄ and CO₂ conversions, as well as the lower CO yield, since dry reforming is an endothermic reaction. CH₄ conversion was observed to decrease with an increase in CH₄/CO₂ ratio, whereas CO₂ conversion increased with an increase in CH₄/CO₂ ratio. The higher the GHSV, the lower the CH₄ and CO₂ conversions as well as the lower the CO yield. Stability testing of the tungsten carbide nanoparticles in the biochar matrix showed no catalyst deactivation during the 500 hours test duration.