Gasification of biomass chars in air - Effect of heat treatment temperature

Three biomass materials-coir dust (CD), wheat straw (WS), and potato pulp ( PP)-were pyrolyzed under nitrogen, and the resulting chars were gasified in air at 400 degrees C. In all cases, gasification rate of the chars showed the "normal" dependence on heat treatment temperature (HTT), i.e., a decrea se with increasing HTT, only up to a certain value of HTT (500, 550, and 75 0 degrees C for CD, WS, and PP, respectively), above which the rate dramati cally increased. This contrasts with the monotonic decrease in reactivity r eported for coal chars. The unusual HTT effect is suggested to be due to a change in the chemical state of the indigenous potassium species at the HTT inflection temperature.