Intrinsic promotion mechanism of calcium oxide on ketone production during catalytic fast pyrolysis of biomass via experiment and density functional theory simulation.

CaO modified with acetic acid solution or sodium hydroxide (H-CaO/OH-CaO) was used to explore the relationship between the physical and chemical properties of CaO and the components of bio-oil during the pyrolysis of rice straw (RS) and model compounds via experiment and density functional theory(DFT) simulation. The results showed that the modification changed the properties of CaO, and thus the catalytic performance on production of bio-oil components. H-CaO with the larger number of strong basic sites (1.10 ∼ 2 times than commercial CaO) and the longer Ca-O bond length showed the better selectivity and performance on formation of ketones (the maximum relative content in bio-oil reached 43 %). The conversion pathway of cellulose/hemicellulose was changed by H-CaO, which promoted the formation of ketones. The easier combining of H-CaO with the pyrolysis primary products due to the longer Ca-O bond was the key to its better performance.