Catalytic effects of Na2CO3 additive on coal pyrolysis and gasification

Abstract

Catalytic pyrolysis and gasification characteristics of coal using Na2CO3 as a catalyst were studied in a high-frequency furnace and thermogravimetric analyzers (TGA), respectively. Interactions of Na2CO3 with carbon at both pyrolysis and gasification phases were observed by in-situ heating stage microscope. The effects of pyrolysis temperature (650–800°C) and catalyst loading amount (0–15wt.%) on the associated pyrolysis and gasification processes were investigated. The results show that, H2 and CO are the main pyrolysis gas products and the yields of these two gas increase with the increasing of Na2CO3 in the range of 0–15wt.%. The in-situ heating stage experiments indicated that one main gasification reaction form was observed for Shenfu char samples. Most of SF char particles reacted with CO2 in the form of shrinking core mode without cracking, and certain particles presented fragmentation phenomenon in the reaction process. There is an optimal loading amount of Na2CO3 for the best catalytic gasification effect of Shenfu bituminous char, while Na2CO3 does not reach the saturation amount for the catalytic gasification of Zunyi anthracite coal. The activation energy of catalytic Shenfu coal gasification with 10wt.% Na2CO3 is 31.5kJmol−1 less than that of non-catalytic coal gasification, which indicates that Na2CO3 can improve the kinetics of coal gasification with CO2.