Pyrolysis of Waste Fryer Grease in a Fixed-Bed Reactor

Abstract

Waste fryer grease (WFG) is an environmentally preferable option for hydrogen production. In the present work, the pyrolysis of waste fryer grease in the absence of catalyst was studied in a fixed-bed reactor. The effects of various operating parameters such as reaction temperature (650−850 °C), carrier gas (N2) flow rate (30−70 mL/min), and reactor inert packing particle size (0.5−2.5 mm) on hydrogen and syngas (i.e., mixture of H2 + CO) production were studied. Quadratic response surface models used in analyzing the product gas and char data showed that temperature was the most important parameter over the wide range of conditions studied. The effect of particle size on the product gas and char yield was not significant. Residence time influenced both hydrogen and syngas composition, but its effect was smaller than that of temperature. Numerical optimization of the responses gave a composition of 17.8 mol % for hydrogen, 26.6 mol % for syngas, and a char yield of 13.7 g/100 g of waste fryer grease. Steam was introduced in the reaction system to increase the hydrogen production. The addition of steam (a steam to carbon ratio of 1.5) caused a drastic increase in the hydrogen production to a maximum of 56.2 mol % and in syngas to a maximum of 82.4 mol %.