Improved Activity and Stability of Chlorobenzene Oxidation Over Transition Metal-Substituted Spinel-Type Catalysts Supported on Cordierite

Abstract

Industrial catalysts usually encounter great challenges in Cl• deactivation, toxic by-products generation, and stability with a long running operation for catalytic oxidation of chlorinated volatile organic compounds (CVOCs). In this research, spinel-type oxides with transition metal substituted as active oxides supported on cordierite (Crd) was identified to catalytic degradation of chlorobenzene (CB). The Cu1.4Mn1.6O4 spinel-type oxides considered as the main active oxides have been identified, which were confirmed by XRD and TEM. The activities of these CuMxMn2-xO4 catalysts were markedly improved by lower calcining temperature and shorter time. CuCe0.25Mn1.75O4/Crd catalyst displayed the highest activity and good stability due to that CeO2 nano-rods structure conducive to increase the Oads amount, the dispersion of active oxides, the strength of weak acidity, the surface areas and pore volume. Moreover, spinel-type with CeO2 doping exhibited high performance in CVOCs elimination attributed to the high storage capacity of oxygen, plentiful oxygen vacancies, good efficiency in breaking C-Cl bond and the easy shuttles between Ce 3+ and Ce 4+ , which were demonstrated by XPS. The results indicate that CeO2, Oads, and •OH have beneficial effects on the removing Cl• into benzene, and then improving the ring-opening of CB for CB degradation.

Research advances in chlorinated benzene-containing compound oxidation catalyzed by metal oxides: activity-enhanced strategies and reaction-facilitated mechanisms

“…Effects of morphology. Manganese oxides with different morphologies such as rod, 85 tubes, 89 lamellar, 89 porous, 53 hollow, 47 spinels, 87 and perovskite 97 structures for CBCs oxidation were investigated. γ-MnO 2 (rod-shaped) exhibited higher activity and stability than α-MnO 2 (tubular) and δ-MnO 2 (lamellar), which were due to abundant surface oxygen vacancies.…”

“…It also proved that the introduction of CeO 2 promoted the ring opening in the presence of adsorbed oxygen and hydroxyl radicals to remove Cl • on benzene. 87 Controlling the morphology to get a more exposed surface of active sites. Adjusting the microstructure is an effective way to improve the activity of catalysts.…”

“…45 However, another view suggests that CB adsorption occurs mainly at oxygen vacancies (in combination with the MvK mechanism), which can accelerate the activation of reactive oxygen species and accelerate the oxidation rate. Oxygen vacancies are increased mainly by introducing metal oxides 50,56,87 or constructing special morphologies 37,125 to introduce defects and oxygen vacancies.…”

“…147 Surface sulfation modification, due to the interaction of sulfate or phosphate with metal ions, can enhance the Brønsted or Lewis acids. 59 The main strategy to promote this pathway is to introduce noble metals 61,75,91,121 or transition metal oxides, 41,47,51,52,60,76,87,90,117,124,128 increase the electron cycling interaction between metal oxides, increase the oxygen vacancy and oxygen mobility, thereby promoting the conversion of free oxygen, adsorbed oxygen, and activated oxygen, and accelerating the breakage of the C-Cl bond and C-C bond.…”

Improved activity and stability for chlorobenzene oxidation over ternary Cu-Mn–O-Ce solid solution supported on cordierite

“…The development and synthesis of monolithic catalysts with excellent oxidation activity and stability are of great signi cance in industrial application. We have studied on the effect of CuA x Mn 2−x O 4 /Cordierite (A = Cr, Fe, Ce; x = 0.25, 0.5, 1) catalysts for catalytic oxidation of CB (Huang et al 2021), previously. It had been demonstrated that CuCe 0.25 Mn 1.75 O 4 /Cordierite catalyst exhibited the high activity and good stability owing to that CeO 2 nano-rods structure conducive to increase the amount of O ads and the strength of weak acidity.…”