Effect of different micro and micro-mesoporosity in Y zeolites and influence of water on toluene adsorption

VOCs (volatile organic compounds) represent a serious problem in industrial plants, especially in China. Among the VOCs, toluene is a common and toxic agent. Adsorption of released toluene is an interesting and very important aspect to preserve the environment and help companies meeting high environmental standards. Zeolites have a high adsorption capacity and can be used to capture VOCs. FAU (Y) type of zeolite is especially well suited for this purpose, due to the ideal micropore size for toluene adsorption. In this article we propose to find the answer to a question that has not been previously studied: how within one group of zeolites the efficiency of adsorption capacity of toluene changes, if we create a variable mesoporosity? We tested the adsorption capacity of zeolites in two ways. At first, all samples were tested regarding their total adsorption capacity in anhydrous conditions. After selection of the best samples, additional tests of toluene adsorption capacity under wet conditions were carried out. Thus, hydrophilic abilities were checked or in other words, the ability to continue to capture toluene despite the presence of water vapor. This kind of testing conditions brings the laboratory approach closer to real situation in a factory, where obviously there are no ideal conditions. According to the results of this work, the best adsorption capacity of toluene shows zeolite with an approximately equal ratio of micro- and mesopores. Mesopores provide a high toluene diffusion within the zeolite crystal, and the micropore size of Y-zeolite is ideal for capture toluene molecules.

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