Pyrolysis of hydrochar from hydrothermal treatment of kitchen waste: Effects of temperature, catalysts, and KOH addition

The pyrolysis of hydrochar from hydrothermal treatment of kitchen waste was investigated, including the process parameters and characteristics of pyrolysis products. A novel process, KOH-assisted catalytic pyrolysis, was proposed to simultaneously produce oil and char products with high quality. The optimum pyrolysis temperature was 550 ?, at which the three-state products presented better properties. Four zeolite catalysts were investigated to improve the quality of the oil product. SAPO presented the highest promoting effect on aromatic hydrocarbons, whereas HZSM-5 promoted the selectivity of nitrogen components. Upon KOH addition, the selectivity of aromatic hydrocarbons increased from 42.2% to 98.8% for HZSM-5, whereas oxygen-and nitrogen-containing substances disappeared. In addition, the char SBET increased from 7.16 to 1753.57 m(2)/g, with specific capacitance of 206 F/g and methylene blue adsorption capacity of 317.68 mg/g. The results provide a useful back-ground for the development of the treatment of hydrochar.