Pyrolysis of low rank coal by nickel based zeolite catalysts in the two-staged bed reactor

•Catalytic pyrolysis of low rank coal was conducted by Ni based zeolite catalysts in the two-staged bed reactor.•The role of Ni based zeolite catalysts in the coal pyrolysis toward the pyrolysis gas yield and upgraded pyrolysis oil was investigated.•Yield of carbon oxides gases (CO, CO2) especially CO2 gas was decreased significantly as Ni loading increased in the catalysts.•The catalysts reduced the pitch contents in the pyrolysis oil and promoted the total fraction of light pyrolysis oils (BP < 360 °C).

Pyrolysis is an important process in the coal conversion and has a significant effect on the distribution of volatile products. In this work, ZSM-5 zeolite with different Ni loading was studied to upgrade volatile matter using low rank coal (Shengli, Inner Mongolia) in the two-staged bed reactor. All prepared catalysts were characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis and ammonia temperature-programmed desorption (NH3-TPD). The role of Ni metal loading toward the pyrolysis gas yield and upgraded pyrolysis oil was investigated. The yield of non-condensable gases decreases as Ni loading increased in the catalysts, especially the yield of CO2 decreased significantly. Moreover, the catalysts reduced the pitch contents in the pyrolysis oil and promoted the fraction of light pyrolysis oils (BP < 360 °C).