Combined XPS and TPR study of sulfur removal from a Pt/BaO/Al2O3 NO x storage reduction catalyst

Pt/Al₂O₃ and Pt/BaO/Al₂O₃ 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/Al₂O₃ and Pt/BaO/Al₂O₃ catalysts indicate that the sulfur removal from Al₂O₃ surface precedes reductive decomposition of BaSO₄ (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.     

Integrated DeNO x –DeSoot Catalytic Systems with Improved Low-Temperature Performance

Performance of the combined catalysts [CeO₂–ZrO₂ + FeBETA] and [Mn/CeO₂–ZrO₂ + FeBETA], prepared by mechanical mixing of the component powders, was studied in soot oxidation and NH₃-SCR. [CeO₂–ZrO₂ + FeBETA] catalyst (with component volumetric ratio of 3/1) demonstrated efficient soot oxidation at 400–450 °C and DeNO _x performance similar to that of FeBETA catalyst, despite the fact that the amount of zeolite was reduced by four times indicating a strong synergistic effect between the components. Low-temperature DeNO _x performance of the [CeO₂–ZrO₂ + FeBETA] system can be additionally enhanced by doping the CeO₂–ZrO₂ with Mn. It was found that NO _x conversion over [Mn/CeO₂–ZrO₂ + FeBETA] at 150–250 °C was steadily improved by increasing the Mn loading, and [5.4 % Mn/CeO₂–ZrO₂ + FeBETA] attained NO _x conversion above 90 % at T_react ~190 °C. Comparative studies of soot oxidation and NH₃-SCR over combined catalysts and individual components indicated that the soot oxidation activity is assigned to the soot oxidation over ceria–zirconia component, while enhanced low-temperature SCR performance is a result of a “bi-functional” SCR mechanism comprising NO oxidation to NO₂ over CeO₂–ZrO₂ component followed by fast-SCR over FeBETA.     

An easy way to Pd–Zn nanoalloy with defined composition from a heterobimetallic Pd(μ–OOCMe)4Zn(OH2) complex as evidenced by XAFS and XRD

The heterobimetallic lantern complex Pd(μ-OOCMe)₄Zn(OH₂) was found to be readily reduced with H₂ under fairly mild conditions (150–250 °C, 5–10% H₂/He) both in the carbon-supported and crystalline states to afford a Pd–Zn nanoalloy as evidenced by the ICP elemental analysis, EXAFS, XANES and XRD data.      

Technological value of coal. 2. Coking coal with moderate and low yield of volatiles

The concept of technological value is analyzed. Some characteristics of technological value are refined. The coke group and lean additives are redefined in terms of the metamorphism and vitrinite content of the coal. The technological value is qualitatively assessed in terms of the ranks in those functional groups. A program is proposed for calculating the coal batch used in producing coal of specified strength.     

Electronic state and location of Pt metal clusters in KL zeolite: FTIR study of CO chemisorption

Electronic state and location of Pt metal clusters supported on KL zeolite are studied by FTIR spectroscopy of adsorbed CO. Investigation of the CO adsorption was performed within the wide CO pressure range (from 4×10^?3 to 10² Pa) and supplemented by the study of the CO desorption at elevated temperature. Comparison of the data on CO adsorption and desorption at increased temperature reveals the existence of two groups of Pt particles in the sample. The first group of the particles is localized on the outer surface of the zeolite microcrystals and in the near surface region; they exhibit CO bands at 2060-2050 cm^?1 close to those of Pt supported on conventional supports. The particles of the second group are encaged inside zeolite channels and their electronic structure is presumably strongly perturbed by the zeolite framework. CO adsorbed on the Pt particles of this group exhibits coverage dependent bands at frequencies in the range 1960-1920 cm^?1. The marked downward shift of thevCO band is attributed to the increase of electron density on these particles.     

NO2 formation and its effect on the selective catalytic reduction of NO over Co/ZSM-5

Catalytic performance of Co/ZSM-5 with different metal loadings and of HZSM-5 was compared in the NO + O₂, C₃H₈ + O₂, and NO + C₃H₈ + O₂ reactions. It was found that Co/ZSM-5 catalysts containing only isolated cobalt ions in cationic positions are inactive in NO₂ formation. To achieve appreciable NO conversion in the SCR process over these catalysts higher reaction temperatures are required. These results make it possible to suggest that NO₂ formation is not a prerequisite for the SCR of NO with hydrocarbons over Co/ZSM-5. With increasing Co loading, however, Co/ZSM-5 begins to exhibit activity in NO₂ formation. This is explained by the formation of cobalt oxide particles on the zeolite carrier, which are active in the NO₂ formation. Increase in NO₂ formation strongly enhances catalytic activity in SCR of NO at lower reaction temperatures. Comparison of the C₃H₈ conversion in the C₃H₈ + O₂ and C₃H₈ + O₂ + NO reactions provides evidence that NO₂ activates hydrocarbon molecules resulting in the formation of the reaction intermediates of the SCR process.On leave from N.D. Zelinskii Institute of Organic Chemistry, Leninskii Pr. 47, Moscow, Russia.     

GET 217–2018: State Primary Standard of Unit of Mass Fraction and Unit of Mass (Molar) Concentration of Inorganic Components in Aqueous Solutions Based on Gravimetric and Spectral Methods

Measurement Techniques - The metrological characteristics of GET 217–2018, the State Primary Standard of the unit of mass fraction and unit of mass (Molar) concentration of inorganic...     

Thapsigargin-Stimulated LAD2 Human Mast Cell Line Is a Potent Cellular Adjuvant for the Maturation of Monocyte-Derived Dendritic Cells for Adoptive Cellular Immunotherapy

The preparation of dendritic cells (DCs) for adoptive cellular immunotherapy (ACI) requires the maturation of ex vivo-produced immature(i) DCs. This maturation ensures that the antigen presentation triggers an immune response towards the antigen-expressing cells. Although there is a large number of maturation agents capable of inducing strong DC maturation, there is still only a very limited number of these agents approved for use in the production of DCs for ACI. In seeking novel DC maturation agents, we used differentially activated human mast cell (MC) line LAD2 as a cellular adjuvant to elicit or modulate the maturation of ex vivo-produced monocyte-derived iDCs. We found that co-culture of iDCs with differentially activated LAD2 MCs in serum-containing media significantly modulated polyinosinic:polycytidylic acid (poly I:C)-elicited DC maturation as determined through the surface expression of the maturation markers CD80, CD83, CD86, and human leukocyte antigen(HLA)-DR. Once iDCs were generated in serum-free conditions, they became refractory to the maturation with poly I:C, and the LAD2 MC modulatory potential was minimized. However, the maturation-refractory phenotype of the serum-free generated iDCs was largely overcome by co-culture with thapsigargin-stimulated LAD2 MCs. Our data suggest that differentially stimulated mast cells could be novel and highly potent cellular adjuvants for the maturation of DCs for ACI.     

Statement and personal-computer-aided realization of the conjugate problem of heat transfer in a power-technological boiler with a moving bed of dispersed heat-transfer agent

Consideration is given to the statement of the problem and principles of personal computer-aided realization of the thermal-calculation method for a steam generator-utilizer of the heat of high-temperature coke or other loose medium with known thermophysical properties. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 5, pp. 748–752, September-October, 1997.     

Drying of coking batch by means of secondary energy resources

Preliminary drying of coking batch by means of secondary energy resources generated at coke plants is considered.