Integrated coal pyrolysis with CO2 reforming of methane over Ni/MgO catalyst for improving tar yield

摘要

A new process to integrate coal pyrolysis with CO2 reforming of methane over Ni/MgO catalyst was put forward for improving tar yield. And several Chinese coals were used to confirm the validity of the process. The experiments were performed in an atmospheric fixed-bed reactor containing upper catalyst layer and lower coal layer to investigate the effect of pyrolysis temperature, coal properties, Ni loading and reduction temperature of Ni/MgO catalysts on tar, water and char yields and CH4 conversion at fixed conditions of 400 ml/min CH4 flow rate, 1:1 CH4/CO2 ratio, 30 min holding time. The results indicated that higher tar yield can be obtained in the pyrolysis of all four coals investigated when coal pyrolysis was integrated with CO2 reforming of methane. For PS coal, the tar, water and char yield is 33.5,25.8 and 69.5 wt.%, respectively and the CH4 conversion is 16.8%, at the pyrolysis temperature of 750 °C over 10 wt.% Ni/MgO catalyst reduced at 850 °C. The tar yield is 1.6 and 1.8 times as that in coal pyrolysis under H2 and N2, respectively.