Recent advances in hydrogen production through catalytic steam reforming of ethanol: Advances in catalytic design

Catalytic reforming is a promising technology for producing renewable fuels; however, developing highly stable, efficient, green, and economical metallic catalysts that reduce metal sintering and carbon formation while improving catalyst activity, selectivity, and stability remains a major issue. In this regard, numerous studies have been documented in the past couple of decades evaluating the effects of various supports and promoters using ethanol as a co-reactant in the catalytic steam reforming to produce energy-efficient gaseous fuel, that is, hydrogen. This review article compiles research work focused on the catalytic reforming of ethanol reported in the last decade. Also, the outcomes of experimental studies have been presented and discussed for parametric analysis as case studies. The review shows that ethanol conversion, hydrogen selectivity, and catalyst stability are strongly influenced by the physicochemical properties of the catalyst, synthesis method, support choice, promoters, temperature, pressure, steam-to-ethanol ratio, and hourly space velocity. Noble metals (e.g., Pt, Rh, Ru, Pd, and Au), transition metals (e.g., Ni, Co, and Cu), and bimetallic composites were the most used catalysts in ethanol-steam reforming reactions. Also, proper selection of support and promoter plays a significant role in modifying catalyst morphology, surface area, and particle size, enhancing selectivity, and reducing catalyst carbon deposition.