Volatile organic compounds (VOCs) with the properties of volatility, toxicity and diffusivity pose a serious threat to human health and eco-environment. Catalytic oxidation technology has been considered as a highly efficient option for the treatment of VOCs. This review systematically summarizes the recent processes and advances on catalytic elimination of VOCs over nanoparticles catalysts. Firstly, catalytic performances of catalysts for VOC degradation are evaluated and compared on the basis of unified performance metrics. Secondly, catalytic mechanisms of VOC oxidation, based on experimental and theoretical studies, are systematically introduced. Then, catalytic reactors employed in VOC elimination processes are summarized. In particular, photothermocatalysis by integrating (thermo)catalysis with photocatalysis is also elucidated. Lastly, the perspectives to the scientific issues and challenges faced, as well as the future outlooks are proposed. Collectively, this review will provide theoretical and experimental foundation for rational fabrication and application of nanoparticles catalysts toward VOC elimination in future.

Recent advances in VOC elimination by catalytic oxidation technology onto various nanoparticles catalysts: a critical review

In this work, Fe2O3 supported single atom Pt (x Pt1/Fe2O3, x = 0.25 and 0.5 wt%) catalysts (SACs) are synthesized via a novel and simple impregnation-pyrolysis method. HAADF-STEM images show that Pt is atomically dispersed on the surface of Fe2O3. All samples exhibit good light-thermal conversion efficiency, which can increase the surface temperature of catalysts to 210 °C. The 0.5 Pt1/Fe2O3 exhibits the best photothermal catalytic performance (the toluene conversion and CO2 yield are 95 % and 87 %, respectively) for toluene oxidation under the irradiation of simulated sunlight with light intensity of 720 mW/cm2, which is attributed to its good light-thermal conversion efficiency and low temperature reducibility. The Vis-IR light plays a critical role in the photothermal catalytic oxidation of toluene in the whole solar spectrum. Furthermore, the possible photothermal catalytic reaction pathway of toluene oxidation is proposed based on the TD-GC/MS and in-situ DRIFTS experiments.

Simulated solar light driven photothermal catalytic purification of toluene over iron oxide supported single atom Pt catalyst

The controlled oxidation of alcohols to the corresponding ketones or aldehydes via selective cleavage of β-C-H bond of alcohols under mild conditions still remains a significant challenge. Although metal/oxide interface is highly active and selective, the interfacial sites fall far behind the demand, due to large and thick support. Herein, we successfully develop a unique Au-CuO Janus structure (average particle size = 3.8 nm) with ultrathin CuO layer (0.5 nm thickness) via a bimetal in-situ activation and separation strategy. The resulting Au-CuO interfacial sites prominently enhance isopropanol adsorption and decrease the energy barrier of β-C-H bond scission from 1.44 to 0.01 eV due to the strong affinity between O atom of CuO and H atom of isopropanol, compared with Au sites alone, thereby achieving ultrahigh acetone selectivity (99.3%) over 1.1 wt% AuCu0.75/Al2O3 at 100 oC and atmospheric pressure with 97.5% isopropanol conversion. Furthermore, Au-CuO Janus structures supported on SiO2, TiO2 or CeO2 exhibit remarkable catalytic performance, and great promotion in activity and acetone selectivity is achieved as well for other reducible oxides derived from Fe, Co, Ni and Mn. This study helps for developing strategies for maximized interfacial sites construction and structure optimization for β-C-H bond efficient activation.

Synergy in Au-CuO Janus Structure for Catalytic Isopropanol Oxidative Dehydrogenation to Acetone.

Construction of CuO@CuS/PVDF composite membrane and its superiority for degradation of antibiotics by activation of persulfate

Currently, society is facing a great environmental problem, due to the large amount of plastic waste generated, most of which is not subjected to any type of treatment. In this work, polyethylene film waste from the non-selectively collected fraction was catalytically pyrolyzed at 500 °C, 20 °C/min for 2 h, in a discontinuous reactor using nitrogen as an inert gas stream. The main objective of this paper is to find catalysts that decrease the viscosity of the liquid fraction, since this property is quite meaningful in thermal pyrolysis. For this purpose, the three products of catalytic pyrolysis, the gaseous fraction, the solid fraction and the liquid fraction, were separated, obtaining the yield values. After that, the aspect of the liquid fraction was studied, differentiating which catalysts produced a larger quantity of waxy fraction and which ones did not. The viscosity of these samples was measured in order to confirm the catalysts that helped to obtain a less waxy fraction. The results showed that the zeolites Y and the zeolites β used in this study favor the obtaining of a compound with a smaller amount of waxes than for example catalysts such as FCC, ZSM-5 or SnCl2.

Performance of Different Catalysts for the In Situ Cracking of the Oil-Waxes Obtained by the Pyrolysis of Polyethylene Film Waste

We prepare α-Fe2O3 nanosheet supported 0.38, 0.81, and 1.36 wt% Au (average particle size = 4.0 nm) nanocatalysts, and investigate their performance and mechanism for the selective catalytic oxidation of isopropanol to acetone. In the presence of 1.2 vol% isopropanol and 40 vol% O2, 1.36 wt% Au/α-Fe2O3 exhibits excellent catalytic performance, due to its moderate acidic sites and better redox properties, with acetone selectivity and yield being as high as 99% and 95% at 220 oC, respectively. In addition to acetone, little propylene, acetic acid, acetaldehyde, methyl vinyl ketone, 2-butanone, isopropyl ether, isopropyl acetate, 3-penten-2-one, isopropyl acrylate, isopropyl propionate, and 2, 4-dimethylfuran are detected. The possible reaction mechanism is proposed for the selective catalytic oxidation of isopropanol to acetone over the present catalysts. We believe the present selective catalytic oxidation method, rather than the traditional complete catalytic oxidation method, provides an alternative and economic method for VOCs emissions control.

A Resource utilization method for volatile organic compounds emission from the semiconductor industry: Selective catalytic oxidation of isopropanol to acetone Over Au/α-Fe2O3 nanosheets

Xu Yuhan

Papers

A Resource utilization method for volatile organic compounds emission from the semiconductor industry: Selective catalytic oxidation of isopropanol to acetone Over Au/α-Fe2O3 nanosheets