Diffusional effects in CO2 gasification experiments with single biomass char particles. 1. Experimental investigation

Kinetic studies were conducted to elucidate the effects of diffusional limitations at particle scale during thermogravimetry analysis (TGA) char reactivity tests. The main objective was to identify the limiting phenomena that may occur during biomass char gasification experiments with CO2. The char used was wood matter from pressed-oil stone (WPOS) (this is also called orujillo). The gasification rates of WPOS were measured at four different particle sizes (0.06, 0.9, 1.2, and 2.1 mm), three CO2 partial pressures (0.20, 0.35, and 0.50 bar), and four temperatures (800, 850, 900, and 950 °C). Literature on single-particle studies and diffusional effects that occur in char gasification kinetic experiments were critically surveyed. We found neither general criteria for a kinetic model to be selected nor a quantitative consensus about the impact of variables such as particle size on the diffusional interferences. Our own experiments indicate the extraordinary importance of the diffusional effects at high tempe...

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