Preparation Of Nickel-loaded On Shengli Lignite For Catalytic Cracking Of Biomass Tar

In this study, we prepared a novel catalyst by loading nickel on Shenli lignite char(Ni/SLC) via ion-exchange and examine the effects of solution p H and carbonization temperature(CT) on the physic-chemical properties of the catalyst.Oxidation of Shengli lignite with H2O2 aqueous solution to obtain nickel loaded on oxidized Shengli lignite char catalyst(Ni/OXSLC). The catalyst was used for corn cob volatiles reforming in a two-stage fixed-bed reactor to study the effects of temperature, steam, and space velocity on gas yields and carbon distributions. The results show that the nickel crystallite size(NCS) and specific surface area(SSA) of the catalyst significantly depended on solution p H and CT. The catalyst prepared in p H 11 at 650 o C reached the maximum SSA of 236.3 m2/g and the nickel particles dispersed quite well in the catalyst with a NCS of 5.6 nm. The pretreatment with H2O2 introduced oxygen functional groups such as-COOH and-OH into Shengli lignite. Ni/OXSLC have bigger SSA and smaller NCS than Ni/SLC, TEM diagrams show the better nickel particles dispersion on Ni/OXSLC catalyst than Ni/SLC.Ni/SLC exhibited higher catalytic activity than Ni/RC and commercial Ni/Al2O3.Ni/SLC effectively improved tar decomposition at 650 o C and SV of 3600 h-1 under inert atmosphere and produced a tar-free syngas in a yield of 44.7 mmol/g. The increase of the NCS during catalytic reforming above 650 o C leads to the catalyst deactivation for tar decomposition. The steam introduced not only promotes the reforming of biomass volatiles, but also suppresses the coke deposition on the catalyst surface by the water-gas shift reactions. The introduction of Ni/OXSLC significantly increased the gas yields, which is 3.4 times higher than that from non-catalytic gasification and 1.1 times higher than that from Ni/SLC catalyst. The study revealed the possibility of using Ni/Char as a potential catalyst for low-temperature gasification of biomass tar.