A process is disclosed for limiting the emissions of gases from a porous material in the form of particles comprising a porous inorganic support and at least 0.1% by weight of one or more compounds chosen from organic compounds, halogen compounds, boron compounds and phosphorus compounds. The particles are placed in motion within a hot gas stream traversing them, and a liquid composition containing one or more film-forming polymer(s) is sprayed over the moving particles by means of a twin-fluid atomization nozzle, in which the liquid composition is mixed with a pressurized gas, with a relative atomization pressure of greater than or equal to 0.7100.sup.5 Pa, until a protective layer containing the film-forming polymer(s) and exhibiting a mean thickness of less than or equal to 20 m is obtained on the surface of the said particles. A material resulting from this process is also disclosed.

There is provided a photocatalyst sheet comprising a base material and a photocatalyst layer containing at least a photocatalyst, wherein the photocatalyst layer is firmly adhered to the base material. In an embodiment, there is provided a photocatalyst sheet comprising a base material; and a photocatalyst layer that contains at least a photocatalyst, and is formed on at least one surface of the base material through an aerosol deposition method. This photocatalyst sheet has an excellent photocatalytic activity and an excellent adhesion.

The invention provides a process for limiting self heating of activated particle catalysts wherein the catalyst particles are placed in motion inside a hot gas flow that passes through them and a liquid composition containing one or several film forming polymer(s) is pulverized onto the particles in motion until a protective layer is obtained on the surface of said particles containing said film forming polymer and having an average thickness of less than or equal to 20 ?m. The invention also provides the use of this process to reduce the quantities of toxic gases that may be emitted by the activated catalysts, as well as an activated catalyst for the hydroconversion of hydrocarbons covered with a continuous protective layer that are obtained by this process.

A catalytically active filter for use in hot gas filtration to simultaneously remove solid particles and one or more undesirable compounds from a hot gas stream is partly or fully impregnated with a suitable catalyst. The compounds are selected from HCN, arsenic, organic sulfur compounds and carbonyls. The filter is prepared by making an impregnation liquid, which comprises a catalytically effective amount of at least one active metal and an oxide support, impregnating the filter substrate with the impregnation liquid by dipping it in the liquid or spraying it with the liquid to control the amount of liquid and drying and optionally calcining the impregnated filter.

Catalyst/catalyst support compositions are characterized by a supported cerium oxide, deposited onto a silica, alumina, titanium or zirconium based support, including particles of said supported oxide deposited onto said support, individualized or in the form of aggregates, no greater than 500 nm in size and having, after 6 hours of calcination at a temperature of at least 800 C., a measured reducibility from 30 C. and 900 C. of at least 80%; such compositions are prepared by combining a colloidal dispersion of the supported oxide and a suspension of the support, drying the resulting mixture by atomization and drying the resulting product by calcination.

A circumferential coating material contains colloidal silica, silicon carbide, and titanium oxide different in particle diameters from silicon carbide, coats a circumferential surface of a honeycomb structure monolithically formed by extrusion, including as a main component, cordierite having a porosity of 50 to 75%, and forms a circumferential coating layer. A circumferentially coated honeycomb structure has a honeycomb structure comprising latticed porous partition walls defining and forming a plurality of polygonal cells forming through channels and extending from one end face to the other end face, and a circumferential coating layer formed by coating at least a part of a circumferential surface of the honeycomb structure with the circumferential coating material.

The present invention relates to a high-performance polyoxometalate catalyst and a method of preparing the same. More particularly, the present invention provides a high-performance polyoxometalate catalyst, the activity and selectivity of which may be improved by controlling the content of vanadium and the like and which has superior reproducibility and may unsaturated carboxylic acid from unsaturated aldehyde in a high yield for a long time, a method of preparing the same, and the like.

Articles comprising a catalyst film comprising VOx, MoO.sub.3 or WO.sub.3, and TiO.sub.2 deposited on a substrate are disclosed. The articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases. Methods for producing such articles deposit a catalyst film on the substrate to form a coated substrate, which is then calcined. When used in an SCR process, the coated articles have enhanced activity for NOx conversion, reduced activity for SOx conversion, or both. Light-weight, coated articles having high catalyst loads can be fabricated at the same or reduced dimensions when compared with laminated articles, and increased kNOx/kSOx ratios are available even from coated articles having relatively thin catalyst films. The articles should have particular value for power plant operations, where coal and high-sulfur fuels are commonly used and controlling sulfur trioxide generation is critical.

Disclosed is a catalyst filter, which includes a catalyst support and a nano metallic catalyst sprayed to a surface of the catalyst support. The catalyst filter uses catalyst slurry prepared by using a particulate catalyst, in which a small amount of nano metallic catalyst exhibiting a catalyst performance is sprayed to a surface of the catalyst support, different from an existing patent technique in which catalyst particles are formed and prepared as a support to consume a large amount of catalyst. Therefore, the specific surface area of the catalyst filter is not smaller than the specific surface area of the nano catalyst particles, and thus the catalyst filter may effectively remove and decompose ultra-low concentration gas-state contaminants in an indoor air.

The present invention provides a photocatalytic concrete material sprayed with titanium dioxide/activated zeolite composite material and preparation method thereof, and the photocatalytic concrete material sprayed with titanium dioxide/activated zeolite composite material comprises following raw materials in parts by weight titanium dioxide 0.1-20 parts, activated zeolite molecular sieve 0.1-20 parts, dispersant 0.1-5 parts, emulsifier 0.05-2 parts, coupling agent 0.05-2 parts, cement 40-90 parts, fine sand 40-90 parts and water. In the present invention, the activated zeolite molecular sieve can load titanium dioxide photocatalytic material as a carrier, and can easily adsorb gaseous pollutant of automobile exhaust with huge specific surface area (280.1 m.sup.2/g), thereby increasing photocatalytic degradation efficiency and the efficiency can reach 92%, besides, the present invention has advantages of simple preparation technology, cheap raw materials and low preparation cost, so the present invention is suitable for industrial production.