C1∼C2 hydrocarbons generation and mutual conversion behavior in coal pyrolysis process

Abstract

Different hydrocarbon species in coal pyrolysis gases have the NOx reduction potential. To investigate hydrocarbons CxHy mutual conversion in the coal pyrolysis gases, four typical coals were pyrolyzed under slow and fast heating rate conditions below 1200 °C. Results show that the yield of the hydrocarbon species has positive relation to coal volatiles. In fast heating condition CH4 is the major pyrolysis products. In addition, the alkanes generation behavior is quite different from that of olefins and alkynes. In the range of 600–1200 °C, as the pyrolysis temperature increases, the yield of C2H4 and C2H2 increases while CH4 and C2H6 decreases. The yield of C2H2 is significant at the temperature above than 1000 °C. Fourier transform infrared (FTIR) analysis show a close relationship between the coal functional group from 2800 to 3000 cm−1 and the alkanes yield. In the slow heating condition, five CH4 and two C2H6 evolution paths are proposed by the mathematic fitting method. The ethylene in the high temperature produced from the decomposition of C2H6. When the heating rate is low, no C2H2 is detected which illustrates that the formation of acetylene is closely related with the heating rate.