Analysis of active microstructure during steam gasification of Shengli char catalyzed by calcium component

The catalytic effect of calcium component on steam gasification of Shengli lignite char was studied. Demineralized coal samples were loaded with calcium oxide and pyrolyzed at 1 100℃ (Ca-J). Ca-J⁺ was prepared from Ca-J treated by hydrochloric acid. The char samples were characterized by BET, SEM-EDS, XRD, FT-IR and XPS. The steam gasification of the char samples was performed in a micro fixed bed reactor. The possible catalytic active micro structure was discussed and proposed. The results show that carbon conversion and reactivity index of Ca-J and Ca-J⁺ samples during steam gasification were substantially similar, but much higher than those of demineralized char samples (SL⁺-J). Ca (CH₃COO)₂ and Ca-OOR, two calcium species are present in Ca-J⁺ sample determined by XPS. Chemical analysis and SEM-EDS prove that calcium content of Ca-J⁺ decreases by more than 97% than that of Ca-J sample. XRD analysis indicates free inorganic mineral (CaS, CaO) is removed by hydrochloric acid. FT-IR spectra show C=O, C-O peaks present in Ca-J and Ca-J⁺ samples. So it is postulated that "R-O-Ca-O-R'" (R and R' are aliphatic and aromatic structures, respectively) is the catalyst active microstructure during char steam gasification.