Steam reforming of biomass tar over tyre char for hydrogen production

摘要

Carbonaceous materials have been proven to have a high activity for tar removal. The simultaneous gasification of pyrolysis gases and char has a significant role in increasing the gas yield and decreasing the tar in the product syngas. This study investigates the use of tyre char as a catalyst for hydrogen production and tar reduction during the pyrolysis/reforming of biomass using a two stage fixed bed reactor. The biomass sample was pyrolysed under nitrogen at a pyrolysis temperature of 500 °C. The evolved pyrolysis volatiles were passed to a second stage with steam and the gases were reformed at a temperature of 900 °C with the presence of tyre char as catalyst. The influence of catalyst bed temperature, steam flow rate, reaction time and addition of metals were investigated. Char was characterized using BET surface analysis and scanning electron microscopy (SEM). Raising the steam injection rate and reforming temperature resulted in an increase in hydrogen production as steam reforming and gasification of char increased. Over the ranges of operating conditions examined, the maximum hydrogen content reached 52% and the ratio of H2/CO varied between 1.3 to 2. The presence of steam promotes the char conversion, however, increasing the amount of steam from' 6.64 g/h to 8.64 g/h doesn't contribute to decrease the char yield and the obtained hydrogen yield was almost the same at about 51 vol. %. The results indicate that the char bed exhibited a higher tar reduction than the thermal cracking conditions.