Effect Of Acid-washing On Wulagai Lignite Pyrolysis And Distribution Of Phenols

The paper has given the qualitative and quantitative analysis of oxygen groups of Huolinhe lignite, Wulagai lignite, Xiaolongtan lignite and Dongfeng lignite by three methods, and systematically studied the yield of Wulagai lignite and the acid-washed lignite pyrolysis production in a fixed bed reactor, yield of phenols and distribution of phenols from the pyrolysis of them.There was a big difference on the analysis of carboxyl and phenolic hydroxyl of the same lignite by the methods of exchange titration, new schafer and13C NMR. There was a positive correlation between the content of phenolic hydroxyl in lignite and the yield of phenols from lignite low temperature pyrolysis.The experiments were carried out at atmospheric pressure in a fixed bed reactor. As carrier gas the flow speed of nitrogen was0.2SLM. The pyrolysis temperature ranged from460℃to560℃. At500℃, the tar yield of Wulagai lignite pyrolysis reached the maximum7.29%(wt, daf), and that of the acid-washed lignite was7.67%(wt, daf), the char yield of Wulagai lignite pyrolysis was higher than that of the acid-washed lignite, the gas yield and component content of Wulagai lignite pyrolysis were well than that of the acid-washed lignite. At500℃, the phenols yield of Wulagai lignite pyrolysis reached the maximum3.24%(wt, daf), and the content of phenols in tar was44.44%(wt), the phenols yield of the acid-washed lignite pyrolysis was higher than that of Wulagai lignite pyrolysis and the content of phenols in tar reached the maximum71%(wt) at560℃.At the pyrolysis temperature range of500℃to560℃, there was difference in the low boiling-point phenols yield, the content of low boiling-point phenols in tar from Wulagai lignite pyrolysis reached the maximum of9.1%(wt) and that from the acid-washed lignite pyrolysis was11.56%(wt) at560℃. The high boiling-point phenols yield of Wulagai lignite pyrolysis was higher than that of the acid-washed lignite pyrolysis, at500℃the high boiling-point phenols yield of Wulagai lignite pyrolysis reached the maximum2.88%(wt, daf), and that of the acid-washed lignite pyrolysis was4.63%(wt, daf), the content of high boiling-point phenols in tar from Wulagai lignite pyrolysis reached the maximum of39.51%(wt) at500℃, the content of high boiling-point phenols in tar from the acid-washed lignite pyrolysis was about60%(wt). The phenol yield of acid-washed coal pyrolysis was higher than that of Wulagai lignite pyrolysis when the temperature was higher than480℃, the cresol yield of the acid-washed lignite pyrolysis was significantly higher than that of Wulagai lignite pyrolysis range from520℃to540℃as well as xylenol yield. Eleven kinds of phenols were detected in Wulagai lignite pyrolysis tar by GC, it was ten in the acid-washed lignite pyrolysis tar. Thirty kinds of phenols were detected in Wulagai lignite pyrolysis tar at500℃by GC/MS, it was seven in the acid-washed lignite pyrolysis tar.The minerals in Wulagai lignite have a significant impact on the yield of char and tar, the composition and yield of gas, composition and distribution of phenols by the fixed-bed pyrolysis.