Applications of calcium oxide–based catalysts in biomass pyrolysis/gasification – A review

Catalytic pyrolysis/gasification (CPG) is demonstrated to be a promising technology to convert biomass into valuable biofuels, in which catalyst plays a critical role. As a non–toxic and low–cost material, calcium oxide (CaO) has been widely used as a catalyst in biomass CPG. To understand the function of various CaO catalyst, the present review gives an overview of the application of CaO–based catalyst in biomass CPG. The necessity of biomass CPG catalyzed by CaO–based catalyst was firstly described in introduction, followed by comparison of CaO with other catalysts. By reviewing recent studies, CaO–based catalysts were classified into three types: pure CaO, modified CaO (doped CaO and loaded CaO), and waste CaO. An emphasis was focused on catalytic activity of various CaO–based catalysts, kinetic study and influence of operating conditions. The research gap and future perspectives were also proposed. Results indicated that the catalytic activity and stability of pure CaO was restricted, it should be further modified for different target biofuels. Calcium wastes have great potential to be used as CaO–based catalyst, in which the effect of impurities are supposed to be elucidated in advance.