Effect of Calcium-Based Catalysts on Pyrolysis Liquid Products from Municipal Sludge

Aimed to obtain high-quality pyrolysis liquid products, the effects of different calcium-based catalysts and temperatures on liquid products from catalytic pyrolysis of municipal sludge (moisture of 50%) were studied. Results showed that the liquid product yield reached maximum at 600 °C and then decreased. The catalyst capability of catalysts decreased the yield of liquid products in the order of poorly soluble in water (Ca(OH)2, CaCO3, CaO) > soluble in water (CaCl2, Ca(H2PO4)2·H2O). High temperature strengthened the aromatization, and the breaking of the oxygen-containing functional group in liquid products resulted in the decrease of O/C and H/C molar ratios and the increase of four components yield in gaseous products. At 600 °C, the catalysts significantly reduced the O content of liquid products and increased hydrocarbon content. Meantime, CaO additive increased the content of C to 85.34%, and the relative content of aromatics reached 83.99% at 800 °C, which is suitable as chemical raw materials. However, the Ca(OH)2 group had the highest aliphatics content, and the H/C molar ratio was 1.42 at 400 °C, which is suitable as fuel.