Production of High H2/CO Syngas by Steam Gasification of Shengli Lignite: Catalytic Effect of Inherent Minerals
2015
The steam gasification of Shengli lignite (SL-raw) and demineralized samples (SL-HCl and SL-HF) obtained by sequential leaching with hydrochloric acid and hydrofluoric acid aqueous solutions was conducted using fixed-bed microreactor equipment. The high steam gasification rate of Shengli lignite was achieved at a lower temperature range of 616–750 °C compared to the demineralized lignite SL-HCl and SL-HF, indicating that the inherent minerals within Shengli lignite had a distinguished catalytic effect on the steam gasification. The initiating temperature for the steam gasification of SL-raw was 616 °C, which was about 140 °C lower compared to the initiating temperature of demineralized lignite samples SL-HCl and SL-HF at 756 °C. On the basis of the very similar characteristics of steam gasification of SL-HCl and SL-HF, it was indeed confirmed that the principal component of inherent minerals that played a catalytic effect on the steam gasification reaction was calcium ion, which can be readily eluted by hydrochloric acid aqueous solution. The natural minerals within SL-raw not only effectively accelerated the reactivity of steam gasification but also significantly enhanced the H₂ production and substantially reduced the formation of CO, especially in the low-temperature range from 616 to 750 °C. The optimal performances of steam gasification of Shengli lignite at lower temperatures were majorly attributed to the significant improvement of the water-gas shift (WGS) reaction by the inherent minerals. This study demonstrated that Shengli lignite could be a potential feedstock for the production of H₂-rich synthesis gas by the steam gasification at the temperatures below 750 °C.
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