Redox-Induced In Situ Growth of MnO₂ with Rich Oxygen Vacancies over Monolithic Copper Foam for Boosting Toluene Combustion

Abstract

Catalytic combustion has been known to be an effective technique in volatile organic compound (VOC) abatement. Developing monolithic catalysts with high activity at low temperatures is vital yet challenging in industrial applications. Herein, monolithic MnO2-Ov/CF catalysts were fabricated via the in situ growth of K2CuFe­(CN)6 (CuFePBA, a family of metal–organic frames) over copper foam (CF) followed by a redox-etching route. The as-synthesized monolith MnO2-Ov-0.04/CF catalyst displays a superior low-temperature activity (T90% = 215 °C) and robust durability for toluene elimination even in the presence of 5 vol % water. Experimental results reveal that the CuFePBA template not only guides the in situ growth of δ-MnO2 with high loading over CF but also acts as a source of dopant to create more oxygen vacancies and weaken the strength of the Mn–O bond, which considerably improves the oxygen activation ability of δ-MnO2 and consequently boosts the low-temperature catalytic activity of the monolith MnO2-Ov-0.04/CF toward toluene oxidation. In addition, the reaction intermediate and proposed mechanism in the MnO2-Ov-0.04/CF mediated catalytic oxidation process were investigated. This study provides new insights into the development of highly active monolithic catalysts for the low-temperature oxidation of VOCs.

Efficient Catalytic Elimination of Chlorobenzene Based on the Water Vapor-Promoting Effect within Mn-Based Catalysts: Activity Enhancement and Polychlorinated Byproduct Inhibition

“…The reactive oxygen mobility and metal reducibility of MnO 2 and M/MnO 2 catalysts were explored by the O 2 -TPD (Figure c) and H 2 -TPR (Figure d), respectively. In O 2 -TPD measurements, oxygen species desorbed sequentially in the order of surface adsorbed oxygen (O ads , <300 °C), surface lattice oxygen (O latt , 300–700 °C), and bulk lattice oxygen (O latt‑bulk , >700 °C). , According to the desorption curves, almost no O 2 signal was detected at the temperature below 300 °C, and O ads was scarce on all sample surfaces. In contrast, considerable amounts of O latt and O latt‑bulk underwent desorption in the corresponding temperature ranges, suggesting the good mobility of the lattice oxygen associated with the manganese oxide.…”

Monolithic Catalysts Supported by Emulsion-Templated Porous Polydivinylbenzene for Continuous Reduction of 4-Nitrophenol

“…Conventionally, active components were loaded onto porous carriers through solution impregnation, sol–gel process, or covering . However, active components are prone to agglomerate during the loading process and migrate when a chemical reaction is catalyzed, causing a remarkable decline in the catalytic activity. , Polymeric porous carriers, especially microporous organic polymers, exhibit advantages in the design of porous structures and the anchor of active components. , …”

“…22 However, active components are prone to agglomerate during the loading process and migrate when a chemical reaction is catalyzed, causing a remarkable decline in the catalytic activity. 6,23 Polymeric porous carriers, especially microporous organic polymers, exhibit advantages in the design of porous structures and the anchor of active components. 18,24 Polymeric porous carriers have been fabricated with a porogen, 14,15 self-assembly process, 16,17,25 hypercross-linked polymer, 18,19 biomass material, 20 etc.…”

“…For a monolithic catalyst, the two main challenges are controlling of porous structures and loading of active components. A series of porous materials, including metal foams, − carbon materials, − ceramic foams, , porous polymers, − etc., have been successfully employed as support materials. Conventionally, active components were loaded onto porous carriers through solution impregnation, sol–gel process, or covering .…”

Multistep Quenching of a Rust-Derived Catalyst for Enhanced Volatile Organic Compound Catalytic Oxidation

“…Volatile organic compounds (VOCs), such as aromatic hydrocarbons and oxygenated VOCs, pose a detriment to the environment and human beings and accelerate the formation of photochemical smog and ozone. − Deep catalytic oxidation of VOCs into CO 2 and H 2 O at lower temperatures is regarded as one of the most effective and economical strategies …”