Study of Catalytic Combustion of Chlorobenzene and Temperature Programmed Reactions over CrCeOx/AlFe Pillared Clay Catalysts

Catalytic Combustion of Propane over Ce-Doped Lanthanum Borate Loaded with Various 3d Transition Metals

Ce-doped LaBO3 (Ce0.05La0.95BO3) and a corresponding incorporation with 3d transition metals (TMs) were prepared and evaluated for eliminating propane. Our results showed the catalytic activity toward propane combustion has a close relationship with the loaded TMs, which promoted oxygen vacancies density and further enhanced the reduction and acidity of this material. This eventually led to 90% propane conversion at 718 K for a Cu-loaded Ce0.05La0.95BO3 catalyst. During 10 h of catalytic propane oxidation, the propane-elimination rate was maintained very well, with no degradation of the catalyst.

CO2 Hydrogenation to Synthetic Natural Gas over Ni, Fe and Co–Based CeO2–Cr2O3

CO2 methanation was studied over monometallic catalyst, i.e., Ni, Fe and Co; on CeO2-Cr2O3 support. The catalysts were prepared using one-pot hydrolysis of mixed metal nitrates and ammonium carbonate. Physicochemical properties of the pre- and post-exposure catalysts were characterized by X-Ray Powder Diffraction (XRD), Hydrogen Temperature Programmed Reduction (H2-TPR), and Field Emission Scanning Electron Microscope (FE-SEM). The screening of three dopants over CeO2-Cr2O3 for CO2 methanation was conducted in a milli-packed bed reactor. Ni-based catalyst was proven to be the most effective catalyst among all. Thus, a group of NiO/CeO2-Cr2O3 catalysts with Ni loading was investigated further. 40 % NiO/CeO2-Cr2O3 exhibited the highest CO2 conversion of 97.67% and CH4 selectivity of 100% at 290 °C. The catalytic stability of NiO/CeO2-Cr2O3 was tested towards the CO2 methanation reaction over 50 h of time-on-stream experiment, showing a good stability in term of catalytic activity.

Photocatalytic Activity of Cu2S/WO3 and Cu2S/SnO2 Heterostructures for Indoor Air Treatment

Volatile organic compounds (VOCs) are commonly found in indoor spaces (e.g., homes or offices) and are often related to various illnesses, some of them with carcinogenic potential. The origins of VOC release in the indoor environment are in office products, building materials, electronics, cleaning products, furniture, and maintenance products. VOC removal can be done based on two types of technologies: adsorption in specific materials and decomposition via oxidative processes. The present article reports the development and photocatalytic activity of two heterostructures (Cu2S/WO3 and Cu2S/SnO2) used for indoor air decontamination. The acetaldehyde removal rate is discussed in correlation with the S-scheme mechanisms established between the heterostructure components but also comparatively with the bare catalysts' activity. Acetaldehyde was considered as a VOC reference because it was found by the International Agency for Research on Cancer to be one of the most frequent air toxins with potential carcinogenic effects. The samples contained monoclinic WO3, tetragonal SnO2, and orthorhombic Cu2S crystalline structures. The Cu2S crystallite size in the heterostructure varied from 75.9 to 82.4 Å, depending on the metal oxide substrate. The highest photocatalytic efficiency (75.7%) corresponded to Cu2S/SnO2, with a constant rate of 0.106 s-1 (which was three times faster than WO3 or SnO2 and seven and a half times faster than Cu2S).

Recent advances in volatile organic compounds abatement by catalysis and catalytic hybrid processes: A critical review

Air pollution, particularly for toxic and harmful compounds to humans and the environment, has aroused increasing public concerns. Among air pollutants, volatile organic compounds (VOCs) are the main sources of air pollution. Many attempts have been made to control VOCs using catalysts, plasma, photolysis, and adsorption. Among them, oxidative catalysis by noble metals or transition metal oxides is considered one of the most feasible and effective methods to control VOCs. This paper reviews the experimental achievements on the abatement of VOCs using noble metals, transition metals and modified metal oxide catalysts. Although the catalytic degradation of VOCs appears to be feasible, there are unavoidable problems when only catalysis treatments are applied to the field. Therefore, catalysts including hybrid processes are developed to improve the removal efficiency of VOCs. This review addresses new hybrid treatments to remove VOCs using catalysts, including hybrid treatment combined with plasma, photolysis, and adsorption. The mechanism of the oxidation of VOCs by catalysts is explained by adsorption-desorption principles, such as the Langmuir-Hinshelwood, Eley-Rideal, and Mars-van-Krevelen mechanisms. A π-backbonding interaction between unsaturated compounds and transition metals is introduced to better understand the mechanism of VOC removals. Finally, several factors affecting the catalytic activities, such as support, component ratio, preparation method, metal loading, and deactivation factor, are discussed.