The Experts below are selected from a list of 528 Experts worldwide ranked by ideXlab platform
G. N. Baeva - One of the best experts on this subject based on the ideXlab platform.
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Combined XPS and TPR study of sulfur removal from a Pt/BaO/Al_2O_3 NO_ x storage reduction catalyst
Topics in Catalysis, 2007Co-Authors: A. Yu. Stakheev, P. Gabrielsson, I. Gekas, N. S. Teleguina, G. O. Bragina, N. N. Tolkachev, G. N. BaevaAbstract:Pt/Al_2O_3 and Pt/BaO/Al_2O_3 catalysts (1 wt% Pt, 10 wt%BaO) were sulfated under conditions simulating a real NSR catalyst operation. Comparative TPR and XPS studies of sulfur removal from Pt/Al_2O_3 and Pt/BaO/Al_2O_3 catalysts indicate that the sulfur removal from Al_2O_3 surface precedes reductive decomposition of BaSO_4 (250–400 °C). Barium sulfate decomposition started with further increase in desulfation temperature at the point of surface atomic ratio Ba:S = 1 (~450^o). Simultaneously, an intensive formation of Sulfide species on the catalyst surface was observed. Thermodynamic analysis of the desulfation process allows us to hypothesize that Barium Sulfide formation may hinder sulfur removal under reducing conditions.
Do Heui Kim - One of the best experts on this subject based on the ideXlab platform.
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Sulfation and Desulfation Mechanisms on Pt–BaO/Al_2O_3 NO_x Storage-Reduction (NSR) Catalysts
Catalysis Surveys from Asia, 2014Co-Authors: Do Heui KimAbstract:NO_x storage-reduction (NSR) catalyst is regarded as the promising solution to effectively remove NO_x emitted from lean-burn engines. However, sulfur poisoning remains the big obstacle for NSR technology to overcome. Here fundamental studies on NSR catalyst, especially focusing on the various characteristics of sulfur poisoning and regeneration mechanism, were reviewed. Various aspects of sulfation mechanism such as the roles of Pt and Ba, and the types of sulfate species were investigated. It was found that the desulfation of Barium sulfate with H_2 resulted in the transformation into Barium oxide (BaO) or Barium Sulfide (BaS) depending on the amount of Barium loading and the sulfur loading, based on the combined temperature programmed reaction with hydrogen, Sulfur K-edge X-ray absorption near-edge spectroscopy and time-resolved X-ray diffraction results. H_2O played a critical role in converting BaS into BaO, thus promoting the desulfation by producing the additional H_2S. The overall sulfation and desulfation scheme was proposed by integrating the results obtained in this study.
A. Yu. Stakheev - One of the best experts on this subject based on the ideXlab platform.
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Combined XPS and TPR study of sulfur removal from a Pt/BaO/Al_2O_3 NO_ x storage reduction catalyst
Topics in Catalysis, 2007Co-Authors: A. Yu. Stakheev, P. Gabrielsson, I. Gekas, N. S. Teleguina, G. O. Bragina, N. N. Tolkachev, G. N. BaevaAbstract:Pt/Al_2O_3 and Pt/BaO/Al_2O_3 catalysts (1 wt% Pt, 10 wt%BaO) were sulfated under conditions simulating a real NSR catalyst operation. Comparative TPR and XPS studies of sulfur removal from Pt/Al_2O_3 and Pt/BaO/Al_2O_3 catalysts indicate that the sulfur removal from Al_2O_3 surface precedes reductive decomposition of BaSO_4 (250–400 °C). Barium sulfate decomposition started with further increase in desulfation temperature at the point of surface atomic ratio Ba:S = 1 (~450^o). Simultaneously, an intensive formation of Sulfide species on the catalyst surface was observed. Thermodynamic analysis of the desulfation process allows us to hypothesize that Barium Sulfide formation may hinder sulfur removal under reducing conditions.
Richard A Kemp - One of the best experts on this subject based on the ideXlab platform.
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low temperature preparation of crystalline Barium Sulfide
Applied Organometallic Chemistry, 2005Co-Authors: Yongjun Tang, Darren R Dunphy, Richard A KempAbstract:Barium Sulfide (BaS) is a compound with many uses, both commercially and in the scientific research world. Normally, BaS is prepared from the high-temperature reduction of barite (BaSO4) with carbon, a process that eliminates CO2 as a by-product. Temperatures during the reduction step can be as high as 1200 °C. We now demonstrate that Barium disilylamides can be used as precursors to the formation of crystalline BaS in their reactions with hydrogen Sulfide gas. As a major advantage, the temperature of BaS production can be lowered to 25–200 °C. The by-products formed during the reaction are ammonium Sulfides, resulting from the acid–base reaction of the liberated amines with excess H2S. Fortunately, these salts decompose thermally in vacuum under mild conditions. As determined by X-ray powder diffraction, the BaS formed in this reaction is crystalline, in the face-centered cubic space group Fm3m. Copyright © 2005 John Wiley & Sons, Ltd.
Branko Matovic - One of the best experts on this subject based on the ideXlab platform.
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Barium Sulfide under pressure discovery of metastable polymorphs and investigation of electronic properties on ab initio level
Inorganic Chemistry, 2017Co-Authors: Dejan Zagorac, Klaus Doll, Jelena Zagorac, Dragana Jordanov, Branko MatovicAbstract:Barium Sulfide (BaS) is an important precursor to other Barium compounds with applications from ceramics and flame retardants to luminous paints and additives, and recent research shows potential technological applications in electrical and optical devices. Under normal conditions, BaS crystallizes in the NaCl type of structure, and with the increase in pressure BaS undergoes a structural phase transition to a CsCl type modification. This study presents modeling of Barium Sulfide under pressure with special focus on structural aspects and electronic properties. We predict metastable BaS polymorphs which have not yet been observed in the experiment or in previous calculations, and we investigated their vibrational and thermodynamical properties. Furthermore, we investigate the electronic properties of experimentally known structures as well as novel predicted modifications of BaS on ab initio level using Hartree–Fock, GGA-PBE, and the hybrid B3LYP functional. In this way, we address new possibilities of sy...