Catalytic upgrading of volatiles from coal pyrolysis over sulfated carbon-based catalysts derived from waste red oil

Abstract

Sulfated carbon-based catalysts, red oil-derived carbon materials (RDCMs), were prepared by the self-assembly process from industrial alkylation process waste red oil. The performance of catalysts on upgrading of coal pyrolysis volatiles was investigated in a two-stage fixed-bed reactor. Compared with activated carbon (AC) or char, RDCMs exhibited better performance in increasing the yield and fraction of light tar (boiling point <360 °C). The higher specific surface areas and relatively more defects for RDCMs promoted the conversion of more heavy tar into light tar. The high-content doped sulfur in RDCMs contributed to more oxidation reaction in the secondary reaction for producing gaseous products. The pyrolysis water could be activated on the sulfur functional group to form ·H and ·OH radicals, which were able to stabilize the larger radical fragments from tar cracking to form more oxygenated organic compounds. The yield and fraction of light tar after catalytic upgrading using RDCMs (10 wt% of the tested coal) at 500 °C were 7.9 wt% and 80.0%, respectively, which increased by 19.6% and 33.3% in comparison with that from coal pyrolysis without catalyst.