Competitive adsorption of water vapor with VOCs dichloroethane, ethyl acetate and benzene on MIL-101(Cr) in humid atmosphere

Abstract

It is well-known that water vapor is omnipresent. It would inevitably have a negative influence on VOC adsorption on novel porous materials in actual situations. In this work, the competitive adsorption behavior of water vapor with three VOCs, 1,2-dichloroethane (DCE), ethyl acetate (EA) and benzene, on MIL-101 in a humid atmosphere was investigated by isotherm measurement, breakthrough experiments and TPD experiments. The results showed that adsorption capacities of MIL-101 for DCE, EA and benzene were individually up to 9.71, 5.79 and 3.76 mmol g⁻¹, much higher than those of other conventional adsorbents. Breakthrough experiments indicated that the presence of water vapor in the feed stream resulted in a sharp decrease in the VOCs working capacities of MIL-101 due to competitive adsorption of water vapor on MIL-101 surfaces. The breakthrough times and the working capacities of these VOCs became smaller with an increase in the relative humidity. TPD experiments indicated that the desorption activation energies of water vapor, DCE, EA and benzene on MIL-101 were 72.9, 47.14, 41.9, and 38.16 kJ mol⁻¹, respectively. The stronger interaction of water vapor with MIL-101 formed strong competitive adsorption with VOCs on MIL-101, resulting in the sharp decrease of the VOCs working capacities in a humid atmosphere.