Value addition to rice straw through pyrolysis in hydrogen and nitrogen environments

Abstract

Pyrolysis of rice straw has been carried out under hydrogen atmosphere at 300, 350, 400 and 450 °C and pressures of 1, 10, 20, 30 and 40 bar and in nitrogen atmosphere, experiments have been carried out at the same temperatures. It has been observed that the optimum process conditions for hydropyrolysis are 400 °C and 30 bar pressure and for slow pyrolysis, the optimum temperature is 400 °C. The bio-oil has been characterised using GC-MS, (1)H NMR and FT-IR and bio-char using FT-IR, SEM and XRD. The bio-oil yield under hydrogen pressure was observed to be 12.8 wt.% (400 °C and 30 bar) and yield under nitrogen atmosphere was found to be 31 wt.% (400 °C). From the product characterisation, it was found that the distribution of products is different for hydrogen and nitrogen environments due to differences in the decomposition reaction mechanism.

Keywords: Bio-char; Bio-oil; Hydropyrolysis; Rice straw; Slow pyrolysis.