Xue-Jing Yang

Iron Oxychloride (FeOCl): An Efficient Fenton-Like Catalyst for Producing Hydroxyl Radicals in Degradation of Organic Contaminants

An iron oxychloride (FeOCl) catalyst was developed for oxidative degradation of persistent organic compounds in aqueous solutions. Exceptionally high activity for the production of hydroxyl radical (OH·) by H2O2 decomposition was achieved, being 2-4 orders of magnitudes greater than that over other Fe-based heterogeneous catalysts. The relationship of catalyst structure and performance has been established by using multitechniques, such as XRD, HRTEM, and EPR. The unique structural configuration of iron atoms and the reducible electronic properties of FeOCl are responsible for the excellent activity. This study paves the way toward the rational design of relevant catalysts for applications, such as wastewater treatment, soil remediation, and other emerging environmental problems.

Pyrolysis of conjugated nanoporous polycarbazoles to mesoporous N-doped carbon nanotubes as efficient electrocatalysts for the oxygen reduction reaction

Developing new techniques for the synthesis of N-doped carbon nanotubes (N-CNTs) with high porosities and abundant N-doped active sites is significant for energy conversion and utilization. We report herein a novel non-CVD methodology that exploits a conjugated-nanoporous-polymer-driven, self-templated route toward a new family of highly N-doped carbon nanotubes. The utilization of a task-specific tubular nanoporous polycarbazole as a template maintains both high porosity and density of N-doped active sites, while simultaneously affording a hollow nanotube-like morphology of the final N-doped carbons. Attributed to these unique functionalities, the resultant N-CNT-based electrocatalyst exhibits a superior oxygen reduction reaction (ORR) activity with a half-wave potential of 0.88 V (vs. the reversible hydrogen electrode), higher long-term stability, and better methanol tolerance than commercial 20% Pt/C in alkaline media. More importantly, the ORR performance in an acidic medium exceeds that of the most previously reported non-precious carbonaceous catalysts. These findings could provide an alternative approach towards highly efficient non-precious N-CNT-based electrocatalysts for the ORR.

Inlet Particle-Sorting Cyclone for the Enhancement of PM2.5 Separation

Many cities are suffering from severe air pollution from fine particulate matter. Cyclone is an effective separator for particulate pollutant but has low efficiency for those with an aerodynamic diameter of 2.5 μm or less (PM2.5). In this research, four novel inlet particle-sorting cyclones were first developed to enhance the separation of PM2.5. The energy consumption, overall separation efficiency, particle grade efficiency,outlet particle concentration and size distribution were compared with common cyclone (CM-C). It was found that the vertical reverse rotation cyclone (VRR-C), which made the smaller particles enter cyclone from radially outer side and axially lower side at the rectangular inlet, had the best separation performance, especially for PM2.5 separation. The mean diameter of inlet particles was 15.7 μm and the particle concentration was 2000 mg/m3, the overall separation efficiency of the VRR-C reached 98.3%, which was 6.4% higher than that of CM-C. PM2.5 grade efficiency of the VRR-C exceeded 80%, which was 15∼20% higher than that of CM-C. The PM2.5 content at the VRR-C outlet was 30.8 mg/m3, while that of CM-C was still 118.4 mg/m3. The novel inlet particle-sorting cyclone is an effective separation enhancement for PM2.5 source control in the process of industrial production and environment protection.

Degradation of trichloroethylene by hydrodechlorination using formic acid as hydrogen source over supported Pd catalysts

An advanced method for the degradation of trichloroethylene (TCE) over Pd/MCM-41 catalysts through a hydrogen-transfer was investigated. Formic acid (FA) was used instead of gaseous H2 as the hydrogen resource. As a model H-carrier compound, FA has proven to yield less by-products and second-hand pollution during the reaction. Several factors have been studied, including: the property of catalyst supports, Pd loading and size, temperature, initial concentrations of FA and TCE (potential impact on the reaction rates of TCE degradation), and FA decomposition. The intrinsic kinetics for TCE degradation were measured, while the apparent activation energies and the reaction orders with respect to TCE and FA were calculated through power law models. On the basis of kinetics, we assumed a plausible reaction pathway for TCE degradation in which the catalytic degradation of TCE is most likely the rate-determining step for this reaction.

Application of Gas Cyclone–Liquid Jet Absorption Separator for Purification of Tail Gas Containing Ammonia

ABSTRACT In this experiment, with stainless steel gas cyclone–liquid jet absorption separator as carrier, NH3 as experimental gas, and water and H3PO4 solution as absorbents, corresponding NH3 absorption rate change is obtained through the adjustment of experimental parameters, such as NH3 inlet concentration, inlet velocity of mixed gas, injection flow rate of absorbent, temperature of absorbent, and H3PO4 absorbent concentration. The NH3 absorption rate decreases with the increase in NH3 inlet concentration and inlet gas velocity. The NH3 absorption rate will increase first and then tends to remain unchanged after reaching a certain degree with the increase in liquid injection flow rate and absorbent concentration. The NH3 absorption rate will increase first and then decrease with the increase in the absorbent temperature. The maximum NH3 removal efficiencies of water and H3PO4 were 96% and 99%, respectively. GRAPHICAL ABSTRACT

Enhancement of PM2.5 Cyclone Separation by Droplet Capture and Particle Sorting

Fine particulate matter (PM2.5) is one of the most serious environmental pollutants worldwide, and efficient separation technologies are crucial to the control of PM2.5 emission from industrial sources. We developed a novel method to enhance PM2.5 cyclone separation by droplet capture and particle sorting using a vertical reverse rotation cyclone (VRR-C, inlet particle-sorting cyclone). The separation performances of common cyclone (CM-C) without droplets, CM-C with droplets, and VRR-C with droplets were compared in terms of energy consumption, overall separation efficiency, particle grade efficiency, outlet particle concentration, and outlet particle size distribution. The results show that the highest overall separation efficiencies were 51.7%, 89.9%, and 94.5% for CM-C without droplets, CM-C with droplets, and VRR-C with droplets, respectively, when the mean diameter of the inlet particles was 3.2 μm and the inlet particle concentration was 500 mg/m3. The PM2.5 grade efficiency of VRR-C with droplets was as high as 89.8%, which was 6.2% and 49.9% higher than those of CM-C with droplets and CM-C without droplets, respectively. This novel method was first successfully applied to the deep purification of product gas in the methanol-to-olefin (MTO) industry, for which the separation efficiency of fine catalyst particles was considerably improved.

CHAPTER 8:Advances in Catalytic Reactions by Gold-based Catalysts Through the Radical Chain Mechanism

Unlike the published literature, the chapter focuses on recent developments in our understanding of the radicals involved catalytic reactions on heterogeneous gold-based catalysts. This chapter is composed of four parts: (1) selective oxidation of alkanes; (2) selective oxidation of alkenes; (3) selective oxidation of alcohols and aldehydes; and (4) Fenton-like reaction and photocatalytic oxidation. The role of gold in the decomposition of hydrogen peroxide is analysed and the mechanism for the production of hydroxyl radicals (•OH) is envisaged.