Investigation of Combined Capture–Destruction of Toluene over Pd/MIL-101 and TiO2/MIL-101 Dual Function Materials

Combined capture–destruction strategies offer a sustainable approach to abate volatile organic compounds (VOCs) in a cost-effective manner. In this work, we investigated the potential of metal/MOF and metal oxide/MOF as dual function materials for use in a combined capture–destruction process to abate toluene emissions. Specifically, to enhance the catalytic activity of the MOF, 18 wt % TiO2 and 0.7 wt % Pd were loaded onto the surface of MIL-101­(Cr) and were investigated for their toluene capture and oxidation potential. As a means of achieving complete destruction, a desorption process was facilitated with simultaneous oxidation. The sequential adsorption-oxidation tests revealed that although the capture capacity decreases upon the addition of TiO2 and Pd to the MOF, its catalytic activity increases substantially. At low concentrations of toluene, for example, the 500 ppmv used in this study, bare MIL-101­(Cr) exhibited the highest equilibrium uptake at 5.6 mmol/g at 25 °C, whereas Pd/MIL-101­(Cr) and TiO2/MIL-101­(Cr) exhibited only 3.6 and 1.2 mmol/g uptake capacity, respectively, under the same conditions. On the contrary, Pd/MIL-101­(Cr) outperformed the other materials by displaying a TOF value of 1.32 mmolC7H8/molAS/s, which was 10% and 15% higher than those of TiO2/MIL-101­(Cr) and MIL-101­(Cr), respectively. Overall, the obtained results highlight the efficacy of metal/metal oxide-MOF composites as dual function materials for the efficient capture and destruction of VOCs from ultradilute streams.