Energy-balanced and effective adsorption-catalytic multilayer bed system for removal of volatile organic compounds
Sebastian Jarczewski, Katarzyna Barańska, Marek Drozdek, Marek Michalík, Katarzyna Bizon, Piotr Kuśtrowski
Abstract
A dual-functional adsorption-catalytic system for elimination of volatile organic compounds (VOCs) in a cyclic mode, consisting of various configurations of three components, i.e. carbon adsorbent, inert silica separator and Pt/ZrO2 catalyst, was developed. Both adsorbent and ZrO2 support were synthesized by the nanoreplication method using spherical silica as a template, whereas the Pt active phase was deposited by the polyol approach. Properties of the functional materials were studied by several techniques, including N2 adsorption, SEM-EDS, TGA, XRD, XRF and XPS. It was shown that the inert silica separator played an essential role protecting the carbon adsorbent from undesirable partial oxidation. The highest possible effectiveness of the toluene removal (conversion of 94.5%) was obtained for the configuration with 150 mg of Pt/ZrO2 per 40 mg of the adsorbent. A fair stability of the optimal dual-functional system was proved by performing five consecutive adsorption–desorption-oxidation cycles. The experimental study was complemented by energy demand calculations, which confirmed the superiority of the hybrid system over a classic catalytic flow reactor in terms of energy requirements for the desorption-oxidation step. It was demonstrated that the system might operate autothermally due to a substantial amount of generated heat. Additionally, a simplified dynamic mathematical model of the system was developed, which enabled the identification of key aspects, including directions towards more complex mathematical description, to be taken into account in further research aimed at optimization of the hybrid system. The proposed hybrid dual-functional system can therefore be a step forward in developing cost-effective elimination technologies of VOCs from lean waste gases.