Development and Test Performance of Heterogeneous Catalysts on Steam Reforming of Bioethanol for Renewable Hydrogen Synthesis: A Review

Abstract

The demand for sustainable energy supply due to the significant population growth has led to the search for more energy generation sources to assist the depleting fossil fuel energy. This clean energy source will help in eliminating the environmental challenges posed by conventional fossil fuel. However, this research focuses on high efficient energy resources area to obtain sufficient energy from the hydrogen fuel cell. The hydrogen fuel cell is considered as an option because it releases water as a by-product during combustion and possesses high energy density per mass of 120.7kJ/kg compared to other fuels, with three times more energy content than gasoline. However, hydrogen production is predominantly from fossil-based feedstock via steam reforming over nickel-based catalysts. Because of the carbon footprint and fossil resource depletion, attention is being shifted to non-fossil based feedstock to reduce greenhouse gas emission and enhance energy efficiency. During steam reforming of hydrocarbon, catalysts help to activate and rupture the C-C and C-H bonds. This paper discusses the recent development of solid catalysts, the preparation method, catalytic activity, selectivity and reusability, level of conversion of the reactants, yield, and purity of hydrogen. The structural modifications of the catalysts are also discussed based on actual metal particle size, the oxidation state of the based metal, spatial distribution of the metal on the reducible oxide support, and microstructure of the catalyst. This study concluded that a better catalyst system would improve the efficiency of hydrogen yield due to the displacement of the thermodynamic equilibrium of the product.