Removal of VOCs by Ozone: n-Alkane Oxidation under Mild Conditions

Volatile organic compounds (VOCs) have a negative effect on both humans and the environment; therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air; however, in some cases this method requires relatively high temperatures. Thus, the oxidation of short-chain alkanes, which demonstrate the lowest reactivity among VOCs, starts at 250–350 °C. This research deals with the ozone catalytic oxidation (OZCO) of alkanes at temperatures as low as 25–200 °C using an alumina-supported manganese oxide catalyst. Our data demonstrate that oxidation can be significantly accelerated in the presence of a small amount of O3. In particular, it was found that n-C4H10 can be readily oxidized by an air/O3 mixture over the Mn/Al2O3 catalyst at temperatures as low as 25 °C. According to the characterization data (SEM-EDX, XRD, H2-TPR, and XPS) the superior catalytic performance of the Mn/Al2O3 catalyst in OZCO stems from a high concentration of Mn2O3 species and oxygen vacancies.

Oxygen Removal from a Hydrocarbon Containing Gas Stream by Plasma Catalysis

Hydrocarbon exhaust gases containing residual amounts of oxygen may pose challenges for their conversion into value added chemicals downstream, because oxygen may affect the process. This could be avoided by plasma treating the exhaust to convert $$\hbox {O}_2$$ O 2 in presence of hydrocarbons into CO or $$\hbox {CO}_2$$ CO 2 on demand. The underlying reaction mechanisms of plasma conversion of $$\hbox {O}_2$$ O 2 in the presence of hydrocarbons are analysed in a model experiment using a radio frequency atmospheric pressure helium plasma in a plug flow design with admixtures of $$\hbox {O}_2$$ O 2 and of $$\hbox {CH}_4$$ CH 4 . The plasma process is analysed with infrared absorption spectroscopy to monitor $$\hbox {CH}_4$$ CH 4 as well as the reaction products CO, $$\hbox {CO}_2$$ CO 2 and $$\hbox {H}_2$$ H 2 O. It is shown that the plasma reaction for oxygen (or methane removal) is triggered by the formation of oxygen atoms from $$\hbox {O}_2$$ O 2 by electron. Oxygen atoms are efficiently converted into CO, $$\hbox {CO}_2$$ CO 2 and $$\hbox {H}_2$$ H 2 O with CO being an intermediate in that reaction sequence. However, at very high oxygen admixtures to the gas stream, the conversion efficiency saturates because electron induced $$\hbox {O}_2$$ O 2 dissociation in the plasma seems to be counterbalanced by a reduction of the efficiency of electron heating at high admixtures of $$\hbox {O}_2$$ O 2 . The impact of a typical industrial manganese oxide catalyst is evaluated for methane conversion. It is shown that the conversion efficiency is enhanced by 15–20% already at temperatures of 430 K.

Nickle Oxide Regulating Surface Oxygen to Promote Formaldehyde Oxidation on Manganese Oxide Catalyst

Catalytic oxidation is the most effective method to eliminate the in-door formaldehyde, the Mn-based catalyst with low cost and high activity has drawn great attention. Herein, p-type semiconductor NiO doped...