Pyrolysis behavior of Daliuta coal and its macerals under different atmospheres

The integrated process of coal pyrolysis with CO2 reforming of methane (CP-CRM) is one of the most im- portant routes to improve tar yield. The composition of coal macerals is one of the factors affecting the pyrolysis reaction process. However,there is a lack of research on the pyrolysis behavior of macerals in the CP-CRM process. This work studied the differences of pyrolysis characteristics of Daliuta raw coal and its macerals under N2 and CRM atmosphere. The effects of different reaction temperatures and atmospheres on the distribution of pyrolysis products of macerals were investigated on a fixed bed pyrolysis apparatus. The obtained pyrolysis tar was analyzed by simulated distillation,NMR and GC-MS to understand the effect of the structure of macerals on the composition of tar. The results show that the vitrinite and inertinite exhibit different reaction characteristics under N2 atmosphere. The tar yield of vitrinite is signifi- cantly higher than that of inertinite,which is mainly attributed to the difference in the reactivity caused by the differ- ence in the structure of macerals. The CRM atmosphere could obviously increase tar yield. In comparison,the enhancement effect is more pronounced when the inertinite is used,and the tar yield of inertinite is increased by 16% com- pared with that under N2 atmosphere,which is mainly ascribed to the participation of free radicals from CRM. The a- nalysis of tar composition shows that the vitrinite pyrolysis tar contains higher aliphatics,while inertinite pyrolysis tar includes more aromatics under N2 atmosphere. Under the CRM atmosphere,the content of light aromatic hydrocarbons is greatly increased,especially,the content of anthracene oil is most remarkably enhanced,and the content of tricyclic and tetracyclic aromatic hydrocarbons in the inertinite pyrolysis tar is obviously decreased.