Combustion behaviour and chemical structure changes of enzyme-treated coal

Abstract

As one of the technologies for the improvement in coal quality, biological enzyme technology has received much attention. The enzyme product named 3EC was shown to enhance the power plant performance in our previous full-scale test. In this work, its effect on coal was explored. The results indicated that the enzyme product was beneficial in the removal of organic sulphur from coal, and the catalytic action of 3EC on the cleavage of C–C and C–S bonds was proven based on data from the dibenzothiophene decomposition test. Thus, when it was used to treat coal, the CH3-to-CH2 ratio changed from 0.81 to 0.32 with an increase in treatment time, which indicated that some chemical structures in the enzyme-treated coal changed. Because of these structural changes, the combustion behaviour of coal improved, indicated by the increase in the comprehensive combustion index from 2.958 × 106 to 3.113 × 106 %2 min−2 K−3 and the decrease in activation energy from 32.76 to 30.43 kJ mol−1. In addition, the optimum enzyme treatment time should be 4 days to ensure enough reaction time between the enzyme and the coal.