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Single and multicomponent adsorption of hexane isomers in the microporous ZIF-8

Publication . Mendes, Patrícia A.P.; Rodrigues, Alírio; Horcajada, Patricia; Serre, Christian; Silva, José A.C.

Single, binary and ternary breakthrough experiments of hexane (C6) isomers n-hexane (nHEX), 3-methylpentane(3MP), and 2,2-dimethylbutane (22DMB) were performed in the microporous zinc methyl-imidazolate metal–organic framework ZIF-8, covering the temperature range between 313 and 423 K and partial pressures up to 20 kPa. Adsorption equilibrium isotherms for nHEX were collected from single component breakthrough experiments who show that the sorption behavior of linear nHEX is totally different than the one observed for the branched isomers. Indeed, while nHEX is retained in the bed the branched paraffins spontaneously breakthrough leading to an efficient separation with a remarkable working capacity (25 wt%) for nHEX at 313 K and partial pressure 10 kPa. Langmuir isotherm is found to reasonably describe the adsorption equilibrium data of nHEX while the heat of sorption reaches 32.8 kJ/mol with Langmuir equilibrium affinity constants ranging from 1.73 to 0.0624 kPa 1 between 313 and 423 K, respectively. The ternary experiments (nHEX/3MP/22DMB) show a complete separation between nHEX and the branched isomers together with an adsorbed amount of nHEX similar to the one found in single component experiments. In the binary experiments (3MP/22DMB) the separation and sorption capacity is negligible. A fixed bed adsorption dynamic model is used to demonstrate that the complete separation of nHEX from the branched paraffins is due to a spontaneous breakthrough ofthe branched paraffins due to its lower diffusivity values when compared with nHEX.

2014Journal article

Restricted access

Hexane isomers sorption on a functionalized metal-organic framework

Publication . Silva, José A.C.; Mendes, Patricia; Ragon, Florence; Rodrigues, Alírio; Horcajada, Patricia; Serre, Christian

A series of functionalized porous Zr terephthalate MOFs of the UiO-66(Zr) structure type bearing either Br, NH2 or NO2 groups have been synthesized at the multi-gram scale through an atmospheric pressure solvothermal route with the final aim of investigating the influence of functionalization on the separation of hexane isomers (22DMB, 23DMB, 3MP and nHEX). The studies performed in a fixed bed adsorption column with equimolar mixtures at temperatures between 343 and 423 K and partial pressure up to 10 kPa have shown that the Br, NO2 and NH3 forms exhibit an uptake reaching 15%, being the sorption selectivity hierarchy on the whole comparable to the bared UiO-66 solid: 22DMB approximate to 23DMB >> 3MP nHEX. The 22DMB/nHEX selectivity reaches approximately three at low uptake while the 22DMB/3MP selectivity of UiO-66_NO2 is nearly constant (1.3).

2013Journal article

Open access

Functionalization of metal-organic frameworks for hexane isomers separation

Publication . Mendes, Patricia; Rodrigues, Alírio; Ragon, Florence; Horcajada, Patricia; Serre, Christian; Silva, José A.C.

This work shows the effect of incorporating three different organic ligands (NH2-H2BDC, NO2-H2BDC and Br-H2BDC) into UIO-66(Zr) framework viewing the separation of hexane isomers(22DMB, 23DMB, 3MP and nHEX).

2012Conference object

Open access