The Effects of sodium and alkalinity on the microcrystalline structure and the steam gasification performance of Shengli lignite

Abstract The pyrolysis of Shengli lignite (SL-Raw) and sodium-based anion doped into coal samples (SL-NaOH, SL-Na 2 CO 3 and SL-NaNO 3 ) was analyzed by investigating the effects of sodium and alkalinity on the differences in crystallite structure of chars by XRD, Raman, XPS and FT-IR. The steam gasification of chars was performed in a fixed-bed reactor. The char gasification results showed that sodium and alkalinity have a catalytic effect on the char reactivity, and the chars have better activity when the sodium compounds are more alkaline. The XRD and Raman results showed that NaNO 3 , Na 2 CO 3 and NaOH inhibited the growth of the aromatic ring structure, and the carbon microcrystalline structure of the chars was destroyed due to sodium atoms during pyrolysis. The XPS and FT-IR results indicated that the phenolic hydroxyl (C OH) was converted into sodium phenolate (C O Na), and the reactivity of chars was better.