Analysis of Sequential Adsorption–Oxidation of VOCs on Atomic Layer-Deposited PtNi/ZrO2–SiO2 Dual-Function Materials

Abstract

To develop efficient dual-function materials (DFMs) for capture and destruction of volatile organic compounds (VOCs), we prepared a series of composite materials comprising PtNi nanoparticles supported on ZrO2-promoted SiO2 (PtNi/ZrO2–SiO2) via atomic layer deposition (ALD) method and investigated them for sequential adsorption and desorption/catalytic oxidation of benzene, as a model VOC compound. ZrO2 was first deposited on a unimodal SiO2 support, followed by deposition of Pt and Ni nanoparticles with varried amount. Dynamic adsorption experiments were conducted using a 500 ppmv-laden feed at 25 °C and 1 atm, followed by in situ catalytic oxidation at 200 °C. Among the DFMs investigated, 1Pt2Ni/ZrSi emerged as the material with overall in situ conversion of ∼96% due to its retaively high PtNi acid sites density compared with other DFMs. Kinetic analysis was conducted on 1Pt2Ni/ZrSi by investigating the effects of feed concentration, regenerative feed flow rate, and oxidation temperature on the benzene conversion in the sequential adsorption–oxidation process. The results of the kinetic analysis revealed that a complete oxidation can be attained over 1Pt2Ni/ZrSi and its performance can be improved upon decreasing adsorptive feed benzene concentration (maximum value of 99.7% at 125 ppmv) and regenerative feed flow rate (100% at 5 mL/min), and increasing oxidation temperature (100% at 200 °C). Overall, the obtained results highlighted the optimal operation conditions for sequential adsorption and oxidation of VOCs over ALD-based DFMs.