Steam Gasification of Low Rank Coal with A Nanoscale Ca/Na Composite Catalyst Prepared by the Ion Exchange Method

Abstract

Catalytic gasification of an Indonesian low rank coal has been studied with a fixed bed quartz reactor. Ca^<2+> and Na^+ cations are separately and consecutively ion-exchanged with the coal using aqueous solutions of Ca(OH)_2 and natural soda ash to produce a 3.8% Ca/1.0% Na catalyst. The XRD measurement after pyrolysis at 700℃ reveals the absence of any Ca and Na species, suggesting the formation of nanoscale particles. The Ca/Na shows the larger effect on the steam gasification than a single 3.5% Ca or 1.6% Na catalyst prepared by the same method, and char conversion with the Ca/Na reaches almost 100% after 1h at 700℃. The use of the binary catalyst can lower reaction temperature by >100℃, compared with the un-catalyzed gasification.