Direct production of high hydrogen syngas by steam gasification of Shengli lignite/chars: Remarkable promotion effect of inherent minerals and pyrolysis temperature

Abstract

The steam gasification of Shengli (SL) lignite and the demineralized lignite/chars were tested on a laboratory fixed-bed micro reactor system. The evolution rates of syngas, carbon conversions to gas, yields of gaseous products, and H2/CO molar ratios of SL lignite/chars were systematically investigated. Meanwhile, the gasification performance of SL lignite/chars was compared with the corresponding demineralized samples. The results showed that the inherent minerals in SL lignite/chars not only effectively promoted the steam gasification reaction but also considerably improved the gasification selectivity towards the production of H2 and CO2. Further characterizations by the scanning electron microscope (SEM-EDS) and X-ray fluorescence (XRF) demonstrated that it became more difficult for the minerals in SL lignite being eluted by hydrochloric acid solution with the temperature increasing of pyrolysis process. The results confirmed that the inherent minerals and lignite formed metals-lignite intermediate complex during pyrolysis process. The formed metals-lignite intermediate complex works as the active sites which effectively promote the steam gasification performance of SL lignite/chars, especially in favor of the direct generation of high hydrogen syngas.