Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO2 for no reduction by NH3

Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO₂ for NO reduction by NH₃ was examined in a fixed-bed flow reactor. The deactivation of the catalyst was strongly dependent on reaction temperature. At high reaction temperatures over 300°C, the catalyst did not lose its initial activity up to 50 h of operation, regardless of SO₂ feed concentration from 500 to 20,000 ppm. However, at low reaction temperatures near 250°C, apparent deactivation did occur. Changes in the physicochemical properties such as surface area and sulfur content of deactivated catalyst well correlated with catalyst activity, depending upon reaction temperatures. The deactivation was due to pore blocking and/or filling by deactivating agents, which plugged and/or filled the pores of catalyst. The deactivating agents deposited on the catalyst surface were presumed to be (NH₄)₂SO₄ and/or (NH₄)HSO₄ from the results of TGA and ion-chromatography measurement.     

Control of NO x emissions from diesel engine by selective catalytic reduction (SCR) with urea

Topics in Catalysis - Among the catalysts screened, Cu-ion exchanged ZSM5 zeolite exhibited the highest NO removal activity, particularly at low reaction temperatures below 200 °C,...     

Effect of calcination temperature on the characteristics of SO<Emphasis Type="Italic">sk</Emphasis>4/2-/TiO<Subscript>2</Subscript> catalysts for the reduction of NO by NH<Subscript>3</Subscript>

The catalytic activity of sulfated titania (ST) calcined at a variety of temperatures has been investigated for selective catalytic reduction (SCR) of NO by NH₃. The NO removal activity of ST catalyst mainly depends on its sulfur content, indicating critical role of sulfur species on the surface of TiO₂. The role of sulfur is mainly the formation of acid sites on the catalyst surface. The presence of both BrØnsted and Lewis acid sites on the surface of sulfated titania has been identified by IR study with the adsorption of NH₃ and pyridine on ST. The reduction of the intensity of IR bands representing BrØsted acid sites is more pronounced than that revealing Lewis acid sites as the calcination temperature increases. It has been further clarified by IR study of ST500 catalyst evacuated at a variety of temperatures. The NO removal activity also decreases with the increase of the catalyst calcination temperature. It simply reveals that BrØnsted acid sites induced by sulfate on the catalyst surface are primarily responsible for the enhancement of catalytic activity of ST catalyst containing sulfur for NO reduction by NH₃.     

The Hydrothermal Stability of Paper-Like Ceramic Fiber and Conventional Honeycomb-Type Cordierite Substrates Washcoated with Cu-MFI and V2O5/TiO2 Catalysts for the Selective Reduction of NOx by NH3

A paper-like ceramic fiber was employed as a monolith substrate for removing NO by NH₃. The stronger hydrothermal stability of the ceramic fiber washcoated with V₂O₅/TiO₂ was observed by the pre-calcination of the substrate, mainly due to the well dispersed AlPO₄ formed on the substrate surface improving the washcoating of the catalysts and moderating the phase transformation of TiO₂ from anatase to rutile.     

Promising zeolite-type hydrocarbon trap catalyst by a knowledge-based combinatorial approach

Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst.     

Der f 38 Is a Novel TLR4-Binding Allergen Related to Allergy Pathogenesis from Dermatophagoides farinae

It is difficult to treat allergic diseases including asthma completely because its pathogenesis remains unclear. House dust mite (HDM) is a critical allergen and Toll-like receptor (TLR) 4 is a member of the toll-like receptor family, which plays an important role in allergic diseases. The purpose of this study was to characterize a novel allergen, Der f 38 binding to TLR4, and unveil its role as an inducer of allergy. Der f 38 expression was detected in the body and feces of Dermatophagoides farinae (DF). Electron microscopy revealed that it was located in the granule layer, the epithelium layer, and microvilli of the posterior midgut. The skin prick test showed that 60% of allergic subjects were Der f 38-positive. Der f 38 enhanced surface 203c expression in basophils of Der f 38-positive allergic subjects. By analysis of the model structure of Der p 38, the expected epitope sites are exposed on the exterior side. In animal experiments, Der f 38 triggered an infiltration of inflammatory cells. Intranasal (IN) administration of Der f 38 increased neutrophils in the lung. Intraperitoneal (IP) and IN injections of Der f 38 induced both eosinophils and neutrophils. Increased total IgE level and histopathological features were found in BALB/c mice treated with Der f 38 by IP and IN injections. TLR4 knockout (KO) BALB/c mice exhibited less inflammation and IgE level in the sera compared to wild type (WT) mice. Der f 38 directly binds to TLR4 using biolayer interferometry. Der f 38 suppressed the apoptosis of neutrophils and eosinophils by downregulating proteins in the proapoptotic pathway including caspase 9, caspase 3, and BAX and upregulating proteins in the anti-apoptotic pathway including BCL-2 and MCL-1. These findings might shed light on the pathogenic mechanisms of allergy to HDM.     

Flavonoid glycosides from cowpea seeds (Vigna sinensis K.) inhibit LDL oxidation

Six flavonoid glycosides were isolated from the n-butanol fraction of cowpea seeds (Vigna sinensis K.) through silica gel (SiO₂) and octadecyl silica gel (ODS) column chromatographies. Based on their chemical structures determined via interpretation of spectroscopic data including NMR, MS, and IR, the compounds were identified as kaempferol 3-O-β-d-sophoroside (1), quercetin 3-O-β-d-sophoroside (2), isoquercitrin (3), hyperin (4), catechin 7-O-β-d-glucopyranoside (5), and quercetin 3-O-β-Dglucopyranosyl( 1→6)-O-β-d-galactopyranoside (6). This is the first report of the isolation of these flavonoids from this plant. Among these flavonoids, compound 2, 5, and 6 significantly inhibited LDL oxidation exhibiting 96.0±0.1 (IC₅₀: 3.9 μM), 96.8±1.7 (IC₅₀: 2.9 μM), and 97.4±0.1% (IC₅₀: 3.5 μM) inhibition, respectively, at a concentration of 40 μM.     

Communication enhancer—appliances for better communication in a family

The aim of the exploratory study described in this paper was to develop appliance concepts which can enhance family communication by using digital technologies.     

Selective catalytic reduction of nitrogen oxide by hydrocarbons over mordenite-type zeolite catalysts

The reduction of NO by hydrocarbons such as C₂H₄, C₂H₆, C₃H₆, and C₃H₈ has been investigated over mordenite-type zeolite catalysts including HM, CuHM, NZA (natural zeolite), and CuNZA prepared by an ion-exchange method in a continuous flow fixed-bed reactor. NO conversion over CuNZA catalyst reaches about 94% with 2000 ppm of C₃H₆ at 500°C. As reductants, alkenes seem to exhibit a higher performance for NO conversion than alkanes regardless of the catalysts. No deterioration of the catalytic activity due to carbonaceous deposits for CuNZA was observed above 400°C even after 30 h of on-stream time, but SO₂ in the feed gas stream causes a severe poisoning of the CuNZA catalyst. The effect of H₂O on NO conversion was significant regardless of the catalysts and the reductants employed in this study. However, CuNZA catalyst shows a unique water tolerance with C₃H₆. The reaction path of NO to N₂ is the most important factor for high performance of this catalytic system. NO is directly reduced by a reaction intermediate, C_n′H_m′(O) formed from hydrocarbon and O₂, N₂O is another reaction intermediate which can be easily removed by C_n′H_m′(O).     

Effects of catalyst aging on the activity and selectivity of commercial three-way catalysts

A Pd catalyst is particularly effective for the oxidation of CO and C₃H₆ at low temperatures, while the Pt/Rh/Ce catalyst is active for NO reduction. The TWC activity of both catalysts generally decreased as the catalyst mileage increased. However, the NO reduction activity was less affected by catalyst aging compared to the oxidation reactions. The selectivity of the catalysts in favor of the CO–O₂ reaction (vs. C₃H₆–O₂ reaction) in the O₂ partitioning experiments became less pronounced as the catalyst aged. The NO partitioning experiments reveal the superior capability of H₂ in NO reduction to the other reductants (CO and C₃H₆) examined in the present study. The reactivities of NO with both H₂ and CO were found to decrease upon catalyst aging, resulting in decreased overall NO removal activity.