C. Ramakrishna

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.

Rapid and complete degradation of sulfur mustard adsorbed on M/zeolite-13X supported (M = 5 wt% Mn, Fe, Co) metal oxide catalysts with ozone

Degradation of sulfur mustard (HD) adsorbed on zeolite-13X as well as M/zeolite-13X metal oxide materials (M = 5 wt% Mn, Fe, Co) was studied with and without gaseous ozone as the oxidizing agent under ambient reaction conditions. In the absence of ozone gas HD degradation was very slow over bare zeolite-13X as well as on the metal oxide impregnated zeolite-13X catalysts. Introduction of ozone gas remarkably enhanced the rate of degradation of HD and complete oxidation of HD was achieved on M/zeolite-13X materials in less than 10 minutes of reaction time. The influence of metal content, and catalyst quantity on the distribution of HD degradation products was also investigated. The results revealed that slightly longer reaction times (>5 minutes) and higher catalyst quantity favor the complete oxidation of HD. Carbon oxides were identified as the major degradation products of HD in the presence of ozone. GC-MS techniques were used for the analysis of the gas phase, condensed and surface extracted products. The HD degradation mechanism in the presence and absence of ozone was proposed based on GC-MS analysis results. The M/zeolite-13X catalysts were prepared using a wet impregnation method and characterized by different characterization techniques.

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.