T. Gopi

Catalytic activity of Fe/ZrO2 nanoparticles for dimethyl sulfide oxidation

A low-temperature vapor phase catalytic oxidation of dimethyl sulfide (DMS) with ozone over nano-sized Fe2O3-ZrO2 catalyst is carried out at temperatures of 50-200°C. Nanostructured Fe2O3-ZrO2 catalyst (FZN) is prepared by modified sol-gel method using citric acid as a chelating agent and conventional FZ catalyst is prepared with co-precipitation method. The catalysts are characterized using N2-BET surface area and pore size distributions, X-ray diffraction, TPR, TPD of DMS and NH3, SEM and TEM. The effects of operating temperature, ozone/DMS concentration and gas hourly space velocity (GHSV) on DMS removal efficiencies via catalytic ozonation are investigated. Relatively higher amount of ozone decomposition is observed on nanocatalyst compared to the co-precipitate catalyst from 50°C to 150°C. In contrast, at 200°C irrespective of the particle size, both catalysts performed similar activity. It clearly demonstrates that under ozone assisted catalytic oxidation over nanocatalyst offers the 100% of DMS conversion at lower temperature. The synthesized nanocatalyst and ozone are observed highly efficient for low temperature catalytic oxidation of DMS. The stability test shows that the nanocatalyst have relatively high activity and stability under the reaction conditions. A plausible reaction mechanism has been proposed for the oxidation of DMS based on the possible reaction products.

13X分子筛负载Fe催化剂上1,4-二氧六环在空气中完全氧化

Abstract Zeolite-13X-supported Fe (Fe/zeolite-13X) catalysts with various Fe contents were prepared by the wet impregnation method. The catalysts were characterized by N2 adsorption-desorption isotherms to estimate the Brunauer–Emmett–Teller surface areas and Barrett–Joyner–Hanlenda pore size distributions. X-ray diffraction, scanning electron microscopy, temperature-programmed reduction, and temperature-programmed desorption of NH3 were used to investigate the textural properties of the Fe/zeolite-13X catalysts. Their catalytic activities were determined for the complete oxidation of 1,4-dioxane using air as the oxidant in a fixed‐bed flow reactor in the temperature range 100–400 °C. The influences of various process parameters, such as reaction temperature, metal loading, and gas hourly space velocity (GHSV), on the dioxane removal efficiency by catalytic oxidation were investigated. The stability of the catalyst was tested at 400 °C by performing time-on-stream analysis for 50 h. The Fe/zeolite-13X catalyst with 6 wt% Fe exhibited the best catalytic activity among the Fe/zeolite-13X catalysts at 400 °C and a GHSV of 24000 h−1, with 97% dioxane conversion and 95% selectivity for the formation of carbon oxides (CO and CO2). Trace amounts (

A simple and controlled oxidative decontamination of sulfur mustard and its simulants using ozone gas

GRAPHICAL ABSTRACT ABSTRACT A simple and efficient oxidative decontamination method was developed for sulfur mustard (HD), a potential chemical warfare agent. The method involves treatment of chemical warfare agent HD and its simulants, i.e., dimethyl sulfide, diethyl sulfide, and 2-chloroethyl ethyl sulfide with ozone gas at ambient conditions in acetonitrile solvent. Ozone gas readily oxidizes sulfur mustard in a controlled manner to give its corresponding nontoxic sulfoxide. This transformation is selective and takes place even at subzero temperatures. The oxidation products of HD and its simulants were monitored and quantified by gas chromatography and gas chromatography–mass spectrometry.

Vapor Phase Selective Catalytic Oxidation of Cyclohexane over 13X Supported Metal Oxides in the Presence of Ozone

ABSTRACT This article reports the application of ozone for the selective oxidation of cyclohexane over 13X molecular sieve supported various metal oxides at ambient temperatures. From the SEM, XRD and HR-TEM results, the impregnated metal oxides are highly dispersed on the support. The activity results reveal that Co/MS, Mo/MS, Cu/MS, and Ag/MS catalysts produce cyclohexanone/cyclohexanol as selective oxidation products, whereas Ce/MS, Mn/MS, and V/MS catalysts yield, predominantly, CO and CO2. Among them, Co/MS catalyst exhibits better conversion of 12.2% with selectively of 58% to cyclohexanone/cyclohexanol, which is attributed to the simultaneous activation of ozone and cyclohexane (-C-H bond) at ambient conditions.