Experimental study on cotton stalk pyrolysis tar degradation by oxidation in combination with K-containing semi-coke

Abstract

The concept of using partial oxidation coupling with K semi-coke to decompose tar is presented in this research as a way to increase tar energy recovery. According to the results of the partial oxidation of cotton stalk tar, the oxidation accelerated tar cracking and increased CO production as H2 was consumed. The CO content in the gas can reach a maximum of 38 % when the oxygen flow rate is 12.5 mL/min, and the mixture's calorific value can reach 12.5 MJ/Nm3. When tar components are oxidized, the oxygen-containing ones that have a higher activity are more quickly converted into aromatic compounds. Toluene was chosen as the representative compound of oxidized tar, and cotton stalk semi-catalytic coke's properties in the heterogeneous degradation of toluene with or without the presence of K were contrasted. The results reveal that K is easily combined with the oxygen-containing active groups (CO, CO, OH) of semi-coke to boost their activity, resulting in more basic adsorption sites on the semi-coke surface, which strengthens toluene adsorption and accelerates the cracking of the toluene benzene ring and the generation of aliphatic hydrocarbons. The specific surface area and pore development of the semi-coke with K addition were greater than the semi-coke without K addition, which improved the toluene's degradation and condensation reaction while also increasing the amount of carbon on the semi-surface coke's area.