The invention relates to a catalyst arrangement for preparing phthalic anhydride by gas-phase oxidation of aromatic hydrocarbons, which comprises a reactor having a gas inlet end for a feed gas and a gas outlet end for a product gas and also a first catalyst zone made up of catalyst bodies and at least one second catalyst zone made up of catalyst bodies, where the first catalyst zone is arranged at the gas inlet end and the second catalyst zone is arranged downstream of the first catalyst zone in the gas flow direction and the length of the first catalyst zone in the gas flow direction is less than the length of the second catalyst zone in the gas flow direction, characterized in that the first catalyst zone has a higher gap content compared to the second catalyst zone.

The present invention relates to a method for producing a carbon nanotube aggregate whose bulk density is easily controllable. Therefore, the present invention provides a carbon nanotube aggregate suitable for use in various fields.

Disclosed is method for removing carbonyl sulphide and/or carbon disulphide from a sour gas stream. The method comprises subjecting the gas stream to simultaneous contact with an absorption liquid, such as an aqueous amine solution, and with a catalyst suitable for hydrolyzing carbonyl sulphide and/or carbon disulphide. To this end, the invention also provides a reactor system wherein both an absorption liquid and a catalyst are present. In a preferred embodiment, the catalyst is a heterogeneous catalyst present on or in an absorption column, either coated on the trays of a column with trays, or contained in the packing of a packed column.

Disclosed is method for removing carbonyl sulphide and/or carbon disulphide from a sour gas stream. The method comprises subjecting the gas stream to simultaneous contact with an absorption liquid, such as an aqueous amine solution, and with a catalyst suitable for hydrolyzing carbonyl sulphide and/or carbon disulphide. To this end, the invention also provides a reactor system wherein both an absorption liquid and a catalyst are present. In a preferred embodiment, the catalyst is a heterogeneous catalyst present on or in an absorption column, either coated on the trays of a column with trays, or contained in the packing of a packed column.

This exhaust gas purifying catalyst is provided with a substrate and a catalyst layer formed on a surface of the substrate. The catalyst layer contains zeolite particles that support a metal, and a rare earth element-containing compound that contains a rare earth element. The rare earth element-containing compound is added in such an amount that the molar ratio of the rare earth element relative to Si contained in the zeolite is 0.001 to 0.014 in terms of oxides.

Provided is an SCR catalyst for removing nitrogen oxides (NO.sub.x) from exhaust gas, comprising: 0.01-70 wt % of zeolite having an average pore size of 5 Å or more; 25-90 wt % of titanium dioxide (TiO.sub.2); and 4-10 wt % of vanadium pentoxide (V.sub.2O.sub.5). The SCR catalyst according to the present invention exhibits denitrification performance in a low-temperature area that is superior to that of a conventional SCR catalyst, has improved tolerance for a sulfur compound, and also has an excellent regeneration rate.

Provided is an SCR catalyst for removing nitrogen oxides (NO.sub.x) from exhaust gas, comprising: 0.01-70 wt % of zeolite having an average pore size of 5 Å or more; 25-90 wt % of titanium dioxide (TiO.sub.2); and 4-10 wt % of vanadium pentoxide (V.sub.2O.sub.5). The SCR catalyst according to the present invention exhibits denitrification performance in a low-temperature area that is superior to that of a conventional SCR catalyst, has improved tolerance for a sulfur compound, and also has an excellent regeneration rate.

Disclosed are gas-phase ODH and OCP processes for converting alkanes (e.g., C.sub.2H.sub.6 and C.sub.3H.sub.8) to alkenes (e.g., C.sub.2H.sub.4 and C.sub.3H.sub.6) or oxygenates (e.g., methanol, ethanol, isopropanol, or propylene oxide) or converting alkenes (e.g., ethylene and propene) and oxygenates (e.g., methanol, ethanol, isopropanol or propylene oxide) to longer carbon-chain alkenes or longer carbon-chain alkanes with or without solid catalysts.

Disclosed are gas-phase ODH and OCP processes for converting alkanes (e.g., C.sub.2H.sub.6 and C.sub.3H.sub.8) to alkenes (e.g., C.sub.2H.sub.4 and C.sub.3H.sub.6) or oxygenates (e.g., methanol, ethanol, isopropanol, or propylene oxide) or converting alkenes (e.g., ethylene and propene) and oxygenates (e.g., methanol, ethanol, isopropanol or propylene oxide) to longer carbon-chain alkenes or longer carbon-chain alkanes with or without solid catalysts.

A nitric acid production process, comprising tertiary abatement of N2O and NOx on a tail gas withdrawn from an absorption stage, said abatement including passing the tail gas over a sequence of a deN2O stage comprising a Fe-z catalyst and a deNOx stage comprising a V2O5-TiO2 catalyst in the presence of gaseous ammonia, wherein the tail gas at the inlet of deN2O stage and the tail gas at the inlet of deNOx stage have a temperature greater than 400° C.