Constant Thickness PorousLayer Model for Reactionbetween Gas and Dense Carbonaceous Materials.

Using oil-sands petroleum coke as the raw material andsulfur dioxideas the activating agent at 700 °C, the process of pore developmentin dense carbonaceous materials was studied. The time dependence ofporosity was established from measured values of specific surfacearea (SSA), which could not be explained using conventional porouslayer theories. Incorporating the Random Pore Model with measurementsof particle size and porous layer thickness, a model was developedbased on the existence of a porous layer of constant thickness. Themodel was found to accurately reproduce experimental time dependenceof SSA. The results confirm a constant thickness of the porous layerfor the activation conditions studied, which results from competingeffects of carbon gasification reaction and penetration of the activatingagent into the carbon particle interior. The model predicts a higherachievable SSA for a greater constant porous layer thickness, smallerinitial particle size, and lower inorganic ash content. This modelwas found to be useful in predicting the maximum porous layer thicknessof a dense material undergoing activation or gasification using onlymeasured values of SSA, pore size distribution, and particle sizeas inputs. [ABSTRACT FROM AUTHOR]