Comparison between in-situ and ex-situ catalytic pyrolysis of sawdust for gas production

In this work, in-situ and ex-situ catalytic pyrolysis (CP) of sawdust by Ni-based and Cu-based catalysts are compared in a two-stage fixed bed reactor. Alkali metal K and alkaline earth metal Mg are used to modify the catalysts for comparison. The ex-situ configuration plays a more dominant role in reducing tar while increasing gas production for all catalysts. Reduced Ni shows the best catalytic activity for hydrogen production, obtaining 36.4 vol.% of hydrogen with a yield of 13.6 mmol/g-bio in ex-situ CP. With the increase of temperature, ex-situ CP has a more significant effect on improving gas product and reducing liquid product than in-situ CP. K presents better modification effect than Mg, resulting in a higher yield of gaseous products. Also, TG and Raman analysis indicate that K can decrease the amount of coke deposition on catalysts and make the coke easier to be removed.