In Situ Catalytic Upgrading of Coal Pyrolysis Tar over Carbon-Based Catalysts Coupled with CO2 Reforming of Methane

In situ catalytic upgrading of tar from the integrated process of CO2 reforming of methane with coal pyrolysis (CRMP) was investigated over carbon-based catalysts to increase the light tar yield. The results showed that the light tar (boiling point of <360 degrees C) content and light tar yield increase when char, modified char (MC), or activated carbon (AC) were used as the catalysts. The effectiveness of tar upgrading was closely related with the properties of carbon catalysts. In comparison to char or MC, AC showed a better catalytic effect in upgrading tar as a result of its higher disorder structure and specific surface area. In comparison to non-upgrading tar, a light tar content of above 88% was obtained and the light tar yield was increased by 45.0% on the AC catalyst at 650 degrees C. The contents of four light fractions increase, along with the obvious decrease of the content of pitch. Deuterium nuclear magnetic resonance (H-2 NMR) spectra analysis of the tar obtained by isotopic trace suggested that carbon based catalysts in the upgrading process catalyze heavy tar cracking and CO2 reforming of methane reaction simultaneously, resulting in their interaction and the high content and yield of light tar. In addition, the AC catalyst amount and flow rates of CO2 and methane affect the tar upgrading.