Abstract:
Coal pyrolysis integrated with dry reforming of low-carbon alkane (CP-DRA) is an effective way to improve tar yield. Ni/La
2O
3-ZrO
2 with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition and obtain high tar yield in CP-DRA. In this study, the fraction distribution and component of tars from CP-DRA and coal pyrolysis in N
2 atmosphere (CP-N
2) were characterized by using several methods to understand the effect of DRA on coal pyrolysis. The isotope trace method was also used to discuss the role of low-carbon alkane in CP-DRA. The results showed that the tar from CP-N
2 is mainly composed of aliphatic compounds with more C
al, H
al, and CH+CH
2, and the tar from CP-DRA contains more C
ar, H
ar, and CH
3, and has lower weight-average molecular weight and more light tar content than CP-N
2. A small amount of C
2H
6 addition in CP-DRA will raise the ratio of H
β and CH+CH
2. Electron paramagnetic resonance (EPR) analysis shows that the tar from CP-DRA has a higher radical concentration while the corresponding char has a lower radical concentration. The isotope trace experiment showed that alkanes provide ·H, ·CH
3, etc. to stabilize the radicals from coal pyrolysis and result in more alkyl aromatic compounds during CP-DRA.