Influence of calcium oxide on Shengli lignite char microstructure and steam gasification performance

The Influence of calcium oxide on Shengli lignite char microstructure and steam gasification performance was studied. Demineralized coal samples were loaded with different content of calcium oxide and then pyrolyzed at 1 100 ℃. The char is gasified with steam in a micro fixed-bed reactor. The X-ray diffraction apparatus and Raman spectra apparatus were used to characterize the structure of coal char. The results show that the char with 5% calcium exhibits the highest gasification reactivity, while the catalysis for the steam gasification of char with 2% calcium is almost negligible. The results of XRD suggest that calcium can effectively hinder the carbon graphitization in the process of pyrolysis. The intensity of (002) and (100) peaks of char decreases with the rise of calcium loading. With the increase of calcium loading, the aromaticity f_a is reduced from 66.8% to 39.9%. Raman spectra results show that I_D/I_G increases from 1.363 to 1.541 and I_G/I_all reduces from 0.423 to 0.394 with the increase of calcium loading, respectively. It means that the decomposition of large polyaromatic ring structure in coal is greatly enhanced by the catalytic action of calcium, and the disordering degree and the structural defects of char increase with the increase of calcium loading.