A catalyst may suppress pressure loss and coaking and produce a target substance in high yield when a gas-phase catalytic oxidation reaction of a material substance is conducted using the catalyst to produce the target substance. A ring-shaped catalyst may have a straight body part and a hollow body part, which is used when a gas-phase catalytic oxidation reaction of a material substance is conducted to produce a target substance, wherein a length of the straight body part is shorter than a length of the hollow body part and at least at one end part, a region from an end part of the straight body part to an end part of the hollow body part is concavely curved.

Methods of treating hydroconversion catalysts used for cracking of hydrocarbons are described. A method can include mixing an inactive hydroconversion catalyst with a solid hydrocarbon containing material having a melting point of 50° C. or greater. The inactive hydroconversion catalyst/solid hydrocarbon containing material mixture can be contacted with a gaseous stream that includes hydrogen (H.sub.2) and a sulfur-containing compound under conditions sufficient to sulfide the catalyst and carbonize at least a portion of the hydrocarbon containing material on the sulfided catalyst to obtain a treated sulfided hydroconversion catalyst.

Systems for treating wastewater containing organic nitrogen compounds are disclosed. The systems include a wet air oxidation unit having an oxidation zone, a catalytic zone, and a metal-based catalyst. Methods of treating wastewater containing organic nitrogen compounds are also disclosed. The methods include contacting the wastewater with an oxidant to produce a mixed liquor, contacting the mixed liquor with a metal-based catalyst to catalyze ammonia and produce a gas containing nitrogen and a liquid effluent containing nitrogen. Methods of retrofitting a wet air oxidation unit including providing a metal-based catalyst are also disclosed. Methods of facilitating treatment of wastewater in a wet air oxidation unit including providing a metal-based catalyst are also disclosed.

Systems for treating wastewater containing organic nitrogen compounds are disclosed. The systems include a wet air oxidation unit having an oxidation zone, a catalytic zone, and a metal-based catalyst. Methods of treating wastewater containing organic nitrogen compounds are also disclosed. The methods include contacting the wastewater with an oxidant to produce a mixed liquor, contacting the mixed liquor with a metal-based catalyst to catalyze ammonia and produce a gas containing nitrogen and a liquid effluent containing nitrogen. Methods of retrofitting a wet air oxidation unit including providing a metal-based catalyst are also disclosed. Methods of facilitating treatment of wastewater in a wet air oxidation unit including providing a metal-based catalyst are also disclosed.

A photocatalytic device includes a substrate having a surface, and an array of conductive projections supported by the substrate and extending outward from the surface of the substrate. Each conductive projection of the array of conductive projections has a semiconductor composition. The semiconductor composition establishes a photochemical diode. The surface may be nonplanar such that subsets of the array of conductive projections are oriented at different angles.

Provided is a titanium oxide composition that has a high capability to decompose odor-causing substances, is less likely to cause re-emission of an odor-causing substance(s) due to adsorption of water, and exhibits an excellent particle dispersion stability. The titanium oxide composition contains titanium oxide particles, a component A and a component B. The component A is at least one kind selected from a group of sepiolite and attapulgite, and the component B is at least one kind selected from a group of high silica zeolite and hydrophobic silica. A mass ratio of the component A to the titanium oxide particles is 0.75 to 3.25, and a mass ratio of the component B to the component A is 0.25 to 3.0. Also provided is a member having such titanium oxide composition on its surface.

Provided is a titanium oxide composition that has a high capability to decompose odor-causing substances, is less likely to cause re-emission of an odor-causing substance(s) due to adsorption of water, and exhibits an excellent particle dispersion stability. The titanium oxide composition contains titanium oxide particles, a component A and a component B. The component A is at least one kind selected from a group of sepiolite and attapulgite, and the component B is at least one kind selected from a group of high silica zeolite and hydrophobic silica. A mass ratio of the component A to the titanium oxide particles is 0.75 to 3.25, and a mass ratio of the component B to the component A is 0.25 to 3.0. Also provided is a member having such titanium oxide composition on its surface.

Water purification particles have porous particles and photocatalyst particles formed of titanium-based compound particles that are supported on the porous particles, have absorption at a wavelength of 500 nm in a visible absorption spectrum, and have an absorption peak at 2,700 cm.sup.−1 to 3,000 cm.sup.−1 in an infrared absorption spectrum, and a metal compound having a metal atom and a hydrocarbon group is bonded to the surface of each of the titanium-based compound particles through an oxygen atom.

Water purification particles have porous particles and photocatalyst particles formed of titanium-based compound particles that are supported on the porous particles, have absorption at a wavelength of 500 nm in a visible absorption spectrum, and have an absorption peak at 2,700 cm.sup.−1 to 3,000 cm.sup.−1 in an infrared absorption spectrum, and a metal compound having a metal atom and a hydrocarbon group is bonded to the surface of each of the titanium-based compound particles through an oxygen atom.

A method of preparing hydrodesulfurization catalysts having cobalt and molybdenum sulfide deposited on a support material containing mesoporous silica. The method utilizes a sulfur-containing silane that dually functions as a silica source and a sulfur precursor. The method involves an one-pot strategy for hydrothermal treatment and a single-step calcination and sulfidation procedure. The application of the hydrodesulfurization catalysts in treating a hydrocarbon feedstock containing sulfur compounds to produce a desulfurized hydrocarbon stream is also specified.