The present invention disclose catalyst compositions for the selective catalytic reduction of nitrogen oxides, consisting of at least one oxide of vanadium in an amount of 2.0 to 4.0 wt.-%, calculated as V.sub.2O.sub.5 and based on the total weight of the catalyst composition, at least one oxide of tungsten in an amount of 2.5 to 7.2 wt.-%, calculated as WO.sub.3 and based on the total weight of the catalyst composition, at least one oxide of antimony in an amount of 0.6 to 3.4 wt.-%, calculated as Sb.sub.2O.sub.5 and based on the total weight of the catalyst composition, at least one oxide of zirconium in an amount of 0 to 1.0 wt.-%, calculated as ZrO.sub.2 and based on the total weight of the catalyst, and at least one oxide of titanium in an amount of 84.6 to 94.9 wt.-% calculated as TiO.sub.2 and based on the total weight of the catalyst, wherein the weight ratio of the oxides of vanadium, tungsten, antimony, titanium and optionally zirconium, calculated as V.sub.2O.sub.5, WO.sub.3, Sb.sub.2O.sub.5, TiO.sub.2 and optionally ZrC.sub.2, respectively, add up to 100 wt.-%. Furthermore, SCR catalytic articles are disclosed wherein an SCR catalyst composition according to the invention is affixed in the form of a coating. Suitable catalyst carriers are corrugated substrates and cordierite monoliths. The SCR catalytic articles can be used in a method for the reduction of nitrogen oxides in exhaust gases of lean-burn internal combustion engines, and they can furthermore be comprised in an exhaust gas purification system for the treatment of diesel exhaust gas.

A selective catalytic reduction system applying diesel oil as reductant for converting nitrogen oxides by means of a catalyst into diatomic nitrogen and water in a diesel engine is provided. The selective catalytic reduction system includes an oil injection system, a reactor and a number of selective catalytic reduction catalysts provided in a first section. The selective catalytic reduction system includes at least one additional section including a number of selective catalytic reduction catalysts. The at least one additional section is provided in a non-zero from the first section.

The moisture-resistant catalyst for air pollution remediation is a catalyst with moisture-resistant properties, and which is used for removing nitrogen compound pollutants, such as ammonia (NH.sub.3), from air. The moisture-resistant catalyst for air pollution remediation includes at least one metal oxide catalyst, at least one inorganic oxide support for supporting the at least one metal oxide catalyst, and a porous framework for immobilizing the at least one metal oxide catalyst and the at least one inorganic oxide support, where the porous framework is moisture-resistant. As non-limiting examples, the at least one metal oxide catalyst may be supported on the at least one inorganic oxide support by precipitation, impregnation, dry milling, ion-exchange or combinations thereof. The at least one metal oxide catalyst supported on the at least one inorganic oxide support may be physically embedded in the porous framework.

A catalyst powder according to the present invention is a catalyst powder that includes: a core portion that contains ceria and zirconia; and a surface layer portion that is located on the core portion and contains ceria and zirconia. The ratio (M.sub.2/M.sub.1) is 0.30 or more and 0.95 or less, the ratio (M.sub.2/M.sub.1) being the ratio of a mole fraction M.sub.2 (mol %) of cerium in the surface layer portion measured using X-ray photoelectron spectroscopy to a mole fraction M.sub.1 (mol %) of cerium in the entire powder. It is preferable that the ratio (M.sub.4/2/M.sub.3/1) between M.sub.3/1 and M.sub.4/2 is 1.1 or more and 5.0 or less, wherein M.sub.3/1 (=M.sub.3/M.sub.1) represents the ratio between a mole fraction M.sub.3 (mol %) of zirconium in the entire powder and a mole fraction M.sub.1 (mol %) of cerium in the entirety of the powder, and M.sub.4/2 (=M.sub.4/M.sub.2) represents the ratio between a mole fraction M.sub.4 (mol %) of zirconium measured using X-ray photoelectron spectroscopy and a mole fraction M.sub.2 (mol %) of cerium measured using X-ray photoelectron spectroscopy.

A diamond polycrystal is a diamond polycrystal basically composed of a diamond single phase, wherein the diamond polycrystal is composed of a plurality of diamond grains having an average grain size of less than or equal to 30 nm, and the diamond polycrystal has a carbon dangling bond density of more than or equal to 10 ppm.

Catalyst articles comprising palladium and related methods of preparation and use are disclosed. Disclosed is a catalyst article comprising a first catalytic layer formed on a substrate, wherein the first catalytic layer comprises palladium impregnated on a ceria-free oxygen storage component and platinum impregnated on a refractory metal oxide, and a second catalytic layer formed on the first catalytic layer comprising platinum impregnated on an oxygen storage component and rhodium impregnated on a zirconia-coated or yttria-coated alumina. The palladium component of the catalyst article is present in a higher proportion relative to the other platinum group metal components. The catalyst articles provide improved reductions in NOx in exhaust gases, particularly after lean-rich aging.

A novel method and device for the destruction of nitrous oxide in gases such as those resulting from exhaled breath during dental, medical, and veterinary procedures are described. The method employs processing steps including the collection of gases containing constituents such as water vapor, carbon dioxide, oxygen, nitrogen, and nitrous oxide from exhaled breath or from ambient room air, optional removal of moisture from the collected gas, catalytic decomposition of nitrous oxide gas to nitrogen and oxygen, heat exchange to reduce high temperatures in gases exiting the reactor, and sorbents to remove traces of reaction byproducts. Instrumentation and controls are employed to monitor and regulate temperatures, pressures, gas compositions, and flow rates while also providing measures to automatically shut down in the event of off-nominal conditions. The method and device are capable of operating with variable anesthetic or patient exhaled breath flow rates while inducing no significant pressure or vacuum on the patient as they exhale. The method is carried out in a compact device suitable for operation in dental offices, hospitals, and other locations where nitrous oxide is administered as an anesthetic.

A three-way catalyst for purifying exhaust including noble metal components, enables sintering of the noble metal to be suppressed even at high temperature, enables carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) to be removed and a method for purifying exhaust gas. A carrier having a honeycomb structure is coated with two or more layers of the catalyst compositions, an upper layer including a heat resistant inorganic oxide supporting Pd and a La-containing oxide, a lower layer including a heat resistant inorganic oxide supporting Rh. The content of La in terms of La.sub.2O.sub.3 is 9.6 g/L to 23 g/L, the content of Ce in terms of CeO.sub.2 is 5 g/L to 20 g/L, and the content of Ba in terms of BaO is 1.2 g/L or less per unit volume of the honeycomb structure.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

A fuel tank inerting system is disclosed. The system includes a fuel tank and a catalytic reactor with an inlet, an outlet, a reactive flow path between the inlet and the outlet, and a catalyst on the reactive flow path. The catalytic reactor is arranged to receive fuel from a fuel flow path in operative communication with the fuel tank and oxygen from an oxygen source, and to catalytically react a mixture of the fuel and oxygen along the reactive flow path to generate an inert gas. An inert gas flow path provides inert gas from the catalytic reactor to the fuel tank. An adsorbent is disposed along the fuel flow path or along the reactive flow path.