Catalytic reforming of tar and volatiles from walnut shell pyrolysis over a novel Ni/olivine/La2O3 supported on ZrO2

Abstract

The effect of catalytic reforming of volatiles from pyrolysis of walnut shell using an innovative catalyst was investigated in this study. The analysis was conducted in a two-stage fixed bed reactor operated at 700–1100 °C. The prepared Ni/olivine/La2O3/ZrO2 catalyst had a significant performance on the catalytic tar reforming reactions. In the catalytic reforming of tar, the weight of catalyst is critical. However, it was observed that the tar reforming efficiency increased with increase in catalyst-weight and temperature. In addition, the highest tar reforming efficiency (98.9%) was attained with 20 g of Ni/olivine/La2O3/ZrO2. After 4 cycles of regeneration, tar reforming efficiency was kept stable. The product gas composition was highest at 1100 °C with a very low tar yield, which reduced from 18.1 to 2.1 wt% at 700–1100 °C. At varying reforming conditions, the product gas composition increased. The product-gas distribution varied at different steam flow rates (3–9 mL/h) as well as particle size (0.2–3.5 mm) and the highest yield was achieved with the smallest particle size (0.2 mm) of walnut shell thus confirming the superb catalytic activity of Ni/olivine/La2O3/ZrO2 for tar reformation into gases owing to high dispersion of ZrO2 in the shells.