Patrick da Silva Bárcia

Single and multicomponent sorption of CO2, CH4 and N2 in a microporous metal-organic framework

Abstract Single and multicomponent fixed-bed adsorption of CO2, N2, and CH4 on crystals of MOF-508b has been studied in this work. Adsorption equilibrium was measured at temperatures ranging from 303 to 343 K and partial pressures up to 4.5 bar. MOF-508b is very selective for CO2 and the loadings of CH4 and N2 are practically temperature independent. The Langmuir isotherm model provides a good representation of the equilibrium data. A dynamic model based on the LDF approximation for the mass transfer has been used to describe with good accuracy the adsorption kinetics of single, binary and ternary breakthrough curves. It was found that the intra-crystalline diffusivity for CO2 is one order of magnitude faster than for CH4 and N2.

Separation of branched hexane isomers using zeolite BEA for the octane improvement of gasoline pool

Abstract A sorption study of single, binary, ternary and quaternary mixtures of hexane (C6) isomers n-hexane (nHEX), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB) and 2,2-dimethylbutane (22DMB) was performed in commercial pellets of zeolite BETA (BEA structure), covering the temperature range between 423 K and 523 K and partial pressures up to 0.3 bar. From these data, single and multicomponent adsorption equilibrium isotherms were collected. An extended tri-site Langmuir model (TSL) was developed to interpret accurately the equilibrium data, and a dynamic adsorption model was developed and tested predicting with a good accuracy the behaviour of multicomponent fixed bed experiments. At the partial pressures studied, the sorption hierarchy in the zeolite BETA is: nHEX>3MP>23DMB>22DMB. BEA structure demonstrates a significant selectivity between C6 isomers, especially at low coverage, giving a good perspective regarding future work.

Separation of branched hexane isomers on zeolite BETA

An experimental study of the single, binary, ternary and quaternary fixed bed adsorption of hexane isomers onto zeolite BETA was performed covering the temperature range between 423 K and 523 K and partial pressures up to 0.3 bar. Adsorption equilibrium isotherms were collected from breakthrough experiments. Based on an analysis of sorption events at the molecular level, a Tri-Site Langmuir model (TSL) was developed to interpret the equilibrium data with good accuracy. At the partial pressures studied, it was found that the degree of branching was related to the affinity; the sorption hierarchy was most favourable towards the linear isomer and least favourable towards the di-branched ones. A mathematical model based on a linear driving force (LDF) was developed and used to test the experimental data. It was found that the model predicted the behaviour of the fixed bed experiments with good accuracy. Zeolite BETA demonstrated significant selectivity between branched C6 isomers (especially at low coverage), thereby suggesting a means of solving this difficult separation problem.