Sorption-catalysis-enhanced effects of crab shell derived CaO-based biochar addition on the pyrolysis of waste cooking oil fried sludge

Abstract

In order to promote the yield and calorific value of combustible gas products in the pyrolysis, a CaO-based biochar (CSC) derived from waste crab shell was used as a low-cost sorption-enhanced catalyst to enhance oil-fried sludge (OS) pyrolysis. The effects of CSC addition and pyrolysis temperature on OS pyrolysis characteristics were analyzed in detail. The results indicated that adding CSC significantly enhanced OS pyrolysis and produced more combustible gas products with CO2 removal. At 700 °C, adding CSC promoted the combustible gas yields and greatly reduced CO2 by 96.9 %. And the corresponding LHV of pyrolysis gas products increased by 26.8 % and reached up to 33.7 MJ/N m3. Additionally, TG-FTIR analysis revealed that adding CSC reduced the formation temperature of CH4. Importantly, although there was only 35.5 wt% of Ca in CSC, CSC exhibited almost the same sorption-catalysis-enhanced effects compared to pure CaO. These findings suggest that biochar derived from crab shell has the potential to replace CaO for enhancing sludge pyrolysis into value-added fuel products.