The structural and pyrolysis characteristics of vitrinite and inertinite from Shendong coal and the gasification performance of chars

Abstract

Different coal macerals have different pyrolysis characteristics. The in-depth study of their pyrolysis characteristics is helpful to realize coal graded utilization. The objective of this paper is to get more information on structural and pyrolysis characteristics of vitrinite (SD-VC) and inertinite (SD-IC) from Shendong coal (SD-R). SD-VC and SD-IC were separated from SD-R by the float and sink method, and their structure and morphology were characterized by POM, XRD, FTIR, and 13C-CP/MAS NMR. The pyrolysis characteristics of the coal sample and its separated macerals were investigated by TG-FTIR and FBR, and the structural feature and gasification performance of pyrolysis chars were analyzed using FTIR, XRD, and TG. The results show that SD-VC has been enriched from 61.80 vol% to 91.49 vol%, and SD-IC has been enriched from 37.12 vol% to 83.66 vol%. The order of weight loss of coal samples is SD-VC > SD-R > SD-IC, and the maximum weight loss rate of SD-VC is − 5.36 wt%/°C at the final pyrolysis temperature of 800 °C and heating rate and 10 °C/min. The maximum peak temperature of aromatic hydrocarbons from SD-VC pyrolysis moves to the lower temperature region compared with SD-IC. In addition, more coal tar and less char have been generated from SD-VC pyrolysis, 11.02 wt% and 66.36 wt%, respectively. SD-VC pyrolysis tar contains more straight chain aliphatic hydrocarbons such as C21 alkanes and alkyl side chains. The values of d002, Lc and Nave of SD-VC char are smaller than those of SD-IC char, indicating that the graphitization degree of SD-VC char is lower than that of SD-IC char. The gasification time of SD-VC char is shortened by 2.77 min than that of SD-IC char, and its gasification maximum weight loss rate is − 7.03 wt%/°C at 1200 °C and 10 °C/min.