Chemical Engineering Science, Vol.54, No.19, 4125-4136, 1999
A new kinetic model for the NO-carbon reaction
The kinetics of the NO-carbon reaction was studied by thermogravimetric analysis (TGA). The reactivity as a function of carbon conversion was systematically investigated through characterization of the pore structure and carbon active site evolution during reaction. Total surface area measured by CO, adsorption at 273 K gives a relatively constant normalized reactivity over a wide range of carbon conversions. The carbon active surface area (ASA) and unoccupied active surface area (UASA) were estimated from low-temperature NO chemisorption capacities. Large amounts of stable C-O complexes are found to form during the reaction. Results show that ASA or UASA measured in this way do not represent the reactive surface area under gasification conditions. A new kinetic model is introduced by taking into account the contributions from different carbon-oxygen surface complexes during reaction, based on the recently proposed unified kinetic scheme of Yang and coworkers.
Keywords:FLUIDIZED-BED COMBUSTION;CHAR GASIFICATION;NITRIC-OXIDE;ACTIVE-SITES;COAL CHARS;SOLID REACTIONS;OXYGEN;REDUCTION;GAS;RATES