Integrated Process of Coal Pyrolysis with Steam Reforming of Ethane for Improving the Tar Yield
2018
Wu, Yong | Li, Yang | Jin, Lijun | Hu, Haoquan
A new process to integrate coal pyrolysis with steam reforming of ethane (CP-SRE) using Ni/Al₂O₃ as a catalyst was proposed to improve the tar yield of coal. Coal tar of the CP-SRE process was compared to that of pyrolysis in atmospheres of nitrogen (CP-N₂), hydrogen (CP-H₂), and steam reforming of methane (SRM). The results showed a high tar yield in CP-SRE; it is 15.34% on a dry and ash-free basis at a temperature of 600 °C, which is 1.42, 1.09, and 1.04 times the tar yield of CP-N₂, CP-H₂, or CP-SRM, respectively. To understand fraction distribution and structural information on tar in CP-SRE, coal tar was characterized by simulated distillation, ¹H and ¹³C nuclear magnetic resonance, and gel permeation chromatography. It indicated that the tar from CP-SRE presents a lower molecular weight distribution, higher light oil content, lower asphaltene content, and slightly higher amount of uncondensed aromatic protons and quaternary aromatic carbons than that from CP-N₂. The coal tar formation mechanism in CP-SRE was investigated using the isotope trace method with deuterium oxide (D₂O) and deuterated ethane (C₂D₆) as tracer agents. The results indicated that D₂O and C₂D₆ contribute to coal tar formation in the form of activated free radicals, including •D, •CD₃, •C₂D₅, etc.
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