A Non-Driving-Force Approximation for Intraparticle Diffusion in Cyclic Adsorption and Desorption with Short Cycle Times

Simple approximations for intraparticle diffusion rate are obtained for cyclic adsorption-desorption subject to step changes at a cyclic steady state. For slow cycles (0_c→O.l), a linear driving-force approximation with a coefficient JZ² gives good prediction whereas for fast cycles (0_csO.l) a non-driving-force approximation with a constant coefficient (independent of cycle time 8_C) gives satisfactory results. The constant coefficient is an advantage of the non-driving-force approximation over the linear driving-force approximation in which the coefficient increases sharply with decreasing cycle time.