Catalytic abatement of trichloroethylene over Mo and/or W-based bronzes

[EN] In this paper we present the results of the synthesis, characterization and catalytic behaviour of Mo(W)¿Nb¿V¿O mixed metal oxides bronzes for the catalytic oxidation of trichloroethylene. The catalysts were prepared hydrothermally with different Mo/W/Nb/V/P atomic ratio and heat-treated at 500 and 700 °C. They were characterized by several techniques as N2-adsorption, X-ray diffraction, FTIR, SEM-EDS, temperature programmed desorption, temperature programmed reduction, UV¿vis, Fourier transformed infrared spectroscopy of adsorbed pyridine and 18O/16O isotope exchange. X-ray diffraction patterns (XRD) of samples heat-treated at 500 °C suggest the presence of a semi-crystalline material with a diffraction peak at ca. 2¿ = 22.2°, while XRD patterns of samples heat-treated at 700 °C show the formation of a tetragonal tungsten bronze (TTB) structure. The activity for the catalytic abatement of trichloroethylene strongly depends on the heat-treatment temperature and the catalyst composition. Thus, samples with W/(Mo + W) atomic ratios of 0.25-0.75 and heat-treated at 500 °C are the most active ones. The enhanced activity has been related to the remarkable higher surface area of the catalyst and to the catalyst composition which influences the acid characteristics as well as the reducibility and reoxidation of the catalysts. The importance of the oxygen dissociation on the catalyst surface and the diffusion of oxygen species through the catalyst are also discussed.The authors wish to thank DGICYT in Spain (Project CTQ2009-14495 and CSD2009-00050-CONSOLIDER/INGENIO 2010) and Universitat Politecnica de Valencia for the financial support. N.B.R. acknowledges Catedra Cemex Sostenibilidad (UPV) for a fellowship. M.D.S. acknowledges Universitat Politecnica de Valencia for a fellowship.Blanch Raga, N.; Soriano Rodríguez, MD.; Palomares Gimeno, AE.; Concepción Heydorn, P.; Martínez Triguero, LJ.; López Nieto, JM. (2013). Catalytic abatement of trichloroethylene over Mo and/or W-based bronzes. Applied Catalysis B: Environmental. 130-131:36-43. https://doi.org/10.1016/j.apcatb.2012.10.016S3643130-13

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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Environmental Application of Extra-Framework Oxygen Anions in the Nano-Cages of Mayenite

Trichloroethylene (TCE) is a chlorinated volatile organic compound (CVOC), used in the last years in dry-cleaning applications and as degreasing agent. In this study we report on the catalytic oxidation of gaseous trichloroethylene (TCE), in a fixed bed reactor, performed by using mayenite (Ca 12 Al 14 O 33 ) synthetized by using the ceramic method. Results show that mayenite promoted the total oxidation of TCE to carbon dioxide and chlorine in the temperature range 300–500 °C. The catalyst is stable under the investigated reaction conditions showing high recyclability and could be used for several reaction cycles without any loss of activity and selectivity

Environmental Application of Extra-Framework Oxygen Anions in the Nano-Cages of Mayenite

Trichloroethylene (TCE) is a chlorinated volatile organic compound (CVOC), used in the last years in dry-cleaning applications and as degreasing agent. In this study we report on the catalytic oxidation of gaseous trichloroethylene (TCE), in a fixed bed reactor, performed by using mayenite (Ca 12 Al 14 O 33 ) synthetized by using the ceramic method. Results show that mayenite promoted the total oxidation of TCE to carbon dioxide and chlorine in the temperature range 300–500 °C. The catalyst is stable under the investigated reaction conditions showing high recyclability and could be used for several reaction cycles without any loss of activity and selectivity

Cu mixed oxides based on hydrotalcite-like compounds for the oxidation of trichloroethylene

Consolider Ingenio Multicat MAT-2012-3856-C02-01[EN] Different Cu/(Mg or Ni)/Al mixed oxides based on hydrotalcite-like compounds have been studied for the catalytic oxidation of trichloroethylene. The catalysts have been synthesized and characterized by different techniques such as N-2-adsorption, inductively coupled plasma (ICP), X-ray diffraction, and temperature-programmed reduction (TPR). It has been shown that the activity for the catalytic abatement of trichloroethylene depends on the presence of metals with redox properties in the catalyst composition. The best results have been obtained with containing copper mixed oxides, although there is no direct correspondence between the copper content and the catalyst activity. These catalysts are highly active and selective, CO2 and HCl being the main reaction products. A mechanism for the reaction has been proposed.The authors wish to thank CONACYT (project 154060), the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa program (SEV-2012-0267), as well as operating grants Consolider Ingenio Multicat (CSD-2009-00050) and MAT-2012-3856-C02-01 for the financial support. N.B.R. acknowledges Catedra Cemex Sostenibilidad (UPV) for a fellowship. The technical work of Adriana Tejeda in X-ray diffraction is also gratefully recognized.Blanch Raga, N.; Palomares Gimeno, AE.; Martínez Triguero, LJ.; Fetter, G.; Bosch, P. (2013). Cu mixed oxides based on hydrotalcite-like compounds for the oxidation of trichloroethylene. Industrial and Engineering Chemistry Research. 52(45):15772-15779. https://doi.org/10.1021/ie4024935S1577215779524

Promoted Hexagonal Tungsten Bronzes as Selective Catalysts in the Aerobic Transformation of Alcohols: Glycerol and Methanol

M-containing tungsten oxides bronzes (M = Ti, Nb or V) with hexagonal tungsten bronze (HTB) structure have been investigated as catalysts for the aerobic transformation of glycerol and methanol. The catalysts were prepared hydrothermally and characterized by several physico chemical techniques, i.e. N2-adsorption, XRD, Raman spectroscopy and temperature programmed desorption of ammonia. Interesting variations in the thermal stability of the HTB-framework were observed according to the element introduced into the oxide structure. In addition, the incorporation of Ti and Nb modified the acid features of the hexagonal tungsten oxides, whereas V introduced new redox sites. The catalytic results for the aerobic transformation of glycerol and methanol in terms of conversion and nature of reaction products are discussed on the basis of the physico-chemical characteristics of catalysts