Multicomponent sorption kinetics of ethane and propane in activated carbon: simultaneous adsorption zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF Xijun Hu, Gade N. Department of Chemical Australia Received 17 June 1992 Rao and Duong D. Do* Engineering, University of Queensland, Brisbane, QLD 4072, Extensive experimental data of binary adsorption kinetics of ethane and propane onto Ajax activated carbon are collected by using a ‘differential adsorption bed’ over a range of particle sizes and shapes, bulk concentrations and temperatures. A multicomponent model incorpor- ating macropore, surface and micropore diffusion mechanisms recently proposed by Hu and Do (Chem Eng Sci (in press)) is used to predict the binary adsorption dynamic data by using information of single-component isotherms and dynamics. The multicomponent adsorption equilibrium is calculated by using the ideal adsorbed solution theory (IAST), with the single-component isotherm described by a Unilan equation. The model is found to describe the binary adsorption kinetics well and in particular it accurately predicts the degree of the overshoot of the fast-diffusing/less-strongly adsorbed species. Keywords: activated carbon; adsorption dynamics; ideal adsorbed solution theory Nomenclature Adsorbate concentration in the bulk (kmol rnm3) Imaginary adsorbate concentration inside the microparticle (kmol rnp3) Adsorbate concentration in the macropore (kmol m-‘) Initial adsorbate concentration in the macropore (kmol m-‘) Adsorbed concentration in the particle (kmol rn-‘) Initial adsorbed concentration in the particle (kmol rn-‘) Macropore diffusivity (m’ SC’) Diffusivity of adsorbed species at zero coverage in the particle coordinate (m’ ss’) Diffusivity of adsorbed species at zero coverage in the microparticle coordinate (m’ ss’) Multicomponent equilibrium isotherm function zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC JP Flux through the macropore (kmol mm2s-‘) JP Flux through the solid (kmol rnp2 ss’) NC Number of components r Particle radial position (m) r1 Microparticle coordinate (m) R Particle radius (m) R, Diffusion path length of microparticle (m) s Geometric factor of particle SP Geometric factor of microparticle t Real time (s) Greek symbols 8’ Ratio of zero coverage surface diffusivity in the microparticle coordinate to that in the particle coordinate Lo Particle macropore porosity Introduction Multicomponent systems are always involved in practical adsorption processes. However, in comparison with single-component systems, multicomponent studies are *Author to whom all correspondence should be addressed. far from extensive in terms of the many combinations of multicomponent systems, especially in the exper- imental aspect. Multicomponent diffusion in zeolites has been studied theoretically with or without limited experimental data’-‘. Recently Yang et a1.8 presented some experimental results to study their proposed pre- dictive binary surface diffusion model in zeolite, but only one particle size was considered. In this paper, 0950-4214/93/010039~7 @ 1993 Butterworth-Heinemann Ltd Gas Separation & Purification 1993 Vol 7 No 1 39