Enhanced production of light tar from integrated process of in-situ catalytic upgrading lignite tar and methane dry reforming over Ni/mesoporous Y

Ni-loaded mesoporous Y zeolite catalysts (Ni/meso-Y1, Ni/meso-Y2 and Ni/meso-Y3) were prepared by deposition-precipitation method, and used for integrated process of in-situ upgrading lignite tar and methane dry reforming (MDR) on a fixed-bed reactor. The results showed that the resultant Ni/mesoporous Y catalysts presented good catalytic upgrading performance in terms of light tar yield and deoxygenation performances. Especially, the Ni/meso-Y3, where support was prepared by steaming-acid leaching-alkaline solution, exhibited better upgrading and deoxygenation performances due to higher mesoporous volume, smaller Ni nanoparticles and mild acidity. The light tar content (boiling point below 360 °C) was improved by about 37.8% and the content of organic oxygen species in lignite tar was decreased by 53.5% over Ni/meso-Y3 in comparison with non-upgrading tar under CH₄/CO₂ atmosphere. Moreover, the upgrading performance under CH₄/CO₂ atmosphere over Ni/meso-Y3 was superior to that under N₂ because MDR and catalytic tar cracking simultaneously occurred over catalysts, promoting the generation of light tar. The regenerated Ni/meso-Y3 exhibited good activity and stability even after four regeneration cycles.