Catalytic reforming of pyrolysis tar over metallic nickel nanoparticles embedded in pyrochar

Abstract

Metallic nickel (Ni0) nanoparticles could be in situ generated in the carbon matrix of rice husk char (RHC) via a facile one-step pyrolysis. The synthesized RHC Ni has a considerable performance on tar reforming. Tar reforming efficiency is increased with the increases of the used catalyst weight and reforming temperature. In particular, tar reforming efficiency can reach up to 90.5% and 99.8% by using 5g and 10g of RHC Ni, respectively. Tar reforming efficiency can also keep stable after 5 cycles. Besides, RHC Ni showed high tar conversion efficiency, increasing from 92.3% to 100%, when the reforming temperature was increased from 500°C to 900°C. RHC Ni showed a high catalytic activity even at the relatively lower temperatures. Furthermore, the yield of liquid products was decreased from 30.2% to 10.7%, corresponding to tar reforming. Accordingly, the gas yield was increased from 37.5% to 58.0%, in which the main components of syngas are CO and H2. It is noted that the PAHs compounds in tar could be significantly reduced by using the RHC Ni. The surface areas of the used RHC Ni were increased due to the char gasification rate higher than deposition rate. The RHC Ni has a high potential to be used for tar catalytic reforming.