A method for cleaning an off-gas from viscose production, essentially containing H.sub.2S and CS.sub.2, comprises passing the gas through a catalytic reactor containing a direct oxidation type catalyst, such as V.sub.2O.sub.3 on silica, to convert H.sub.2S in the gas to elemental sulfur, SO.sub.2 or mixtures thereof, either via the oxygen present in the gas or via oxygen added to the gas stream. Elemental sulfur and SO.sub.2 are removed from the effluent gas from the catalytic reactor, and the unconverted CS.sub.2 is recycled to the viscose production process.

There is provided a catalyst that exhibits a high denitration efficiency at a relatively low temperature and does not cause oxidation of SO.sub.2 in a selective catalytic reduction reaction that uses ammonia as a reducing agent. A denitration catalyst molded in a block shape contains 43 wt % or more of vanadium pentoxide. The denitration catalyst has a BET specific surface area of 30 m.sup.2/g or more and is used for denitration at 200 C. or lower.

The present disclosure provides msect-4 molecular sieves with OFF and ERI topologies, a preparation method therefor, and applications thereof. An eight-membered ring small pore molecular sieve used as a raw material is dispersed in an aqueous phase. Following that, caustic potash, an aluminum source, and an organic structure-directing agent (OSDA) are added. The pH value is then adjusted to be greater than 10, and a silicon source is introduced to attain the desired silicon-aluminum ratio, followed by stirring reaction, aging, crystallization, filtration, washing, ammonia exchange reaction, drying, and calcination. The msect-4 molecular sieves with OFF and ERI topologies, the preparation method therefor, and applications exhibit excellent hydrothermal stability, a plurality of adsorption sites exposed by a regular bone-like structure, and a large specific surface area. Consequently, this molecular sieves find applicability across various technical fields including selective catalytic reduction, passive adsorption, and catalytic cracking, and has broad application prospects.

The present invention relates to a catalytic article for purifying an exhaust gas containing nitrogen oxides, which comprises a first region containing a vanadium-based SCR catalyst, a second region containing a metal-promoted molecular sieve catalyst, and a third region containing a vanadium-based SCR catalyst, wherein at least part of the second region is located downstream of at least part of the first region and upstream of at least part of the third region in the exhaust gas flow direction, provided that no part of the second region is located upstream of the first region or downstream of the third region. The present invention also relates to a method and a system for treatment of an exhaust gas containing nitrogen oxides by selective catalytic reduction using the catalytic article.

The invention provides a method for regenerating a deNO.sub.X catalyst comprising contacting the catalyst with steam at a temperature in the range of from 250 to 390 C. The invention further provides a method of reducing the amount of nitrogen oxide components in a process gas stream comprising: a) contacting the process gas with a deNO.sub.X catalyst which results in the conversion of nitrogen oxide components as well as a decline in the NO.sub.X conversion over the deNO.sub.X catalyst; and b) regenerating the deNO.sub.X catalyst to improve the NO.sub.X conversion by contacting the deNO.sub.X catalyst with steam at a temperature in the range of from 250 to 390 C.

The present invention is directed towards the use of an ion-exchanged zeolite containing ASC as a trap for volatile vanadium compounds in a downstream position of a vanadium containing SCR-catalyst.

A gasoline particulate filter for an exhaust system of a gasoline internal combustion engine includes a substrate and a catalytic coating disposed on the substrate. The catalytic coating has a carrier and at least one catalytically active ingredient. The catalytic coating has a carrier loading less than or equal to 0.5 g/in.sup.3 (0.03 g/cm.sup.3), and a catalytically active ingredient loading greater than or equal to 0.01 g/ft.sup.3 (0.35 g/m.sup.3) and less than 2 g/ft.sup.3 (70.63 g/m.sup.3).

A diesel engine has an exhaust aftertreatment system which has a vanadium SCR catalyst for reducing some NOx in engine-out diesel exhaust and a trap for trapping any sublimated vanadium which may be present in exhaust which has been treated by a diesel oxidation catalyst, a diesel particulate filter, and a main SCR catalyst which are between the vanadium SCR catalyst and the trap.

The present invention relates to a method for regenerating a catalyst that can effectively remove a poison bound to a catalyst without chemical injury while minimizing the loss of catalytically active components through a process with improved efficiency, whereby the regenerated catalyst may exhibit excellent denitrification performance.

The invention discloses a preparation method and application of a denitration catalyst with wide operating temperature for flue gas, which utilizes an organic vanadium compound as a vanadium precursor, and titanium dioxide powder or titanium tungsten powder as a carrier, and is prepared by mechanical ball milling method and heat treatment to obtain a catalyst, which denitration of fixed source flue gas under wide temperature range. Compared with the existing arts, the present invention includes minor modifications to the traditional vanadium tungsten titanium catalyst system and adopts the mechanical ball milling method, the activity and resistance to sulfur and water poisoning are improved significantly, thus providing a preparation technology of SCR denitration powder catalyst which is green, highly efficient, low cost and simple in operation. Through the interaction of the organic vanadium precursor with the carrier, the vanadium surface atom concentration of the catalyst is higher, the species of polymeric vanadium is more, and the vanadium oxide is more easily reduced, thereby obtaining higher denitrification activity at low temperature. The denitration catalyst of the present invention has relatively higher activity at 200-450 C. while having good resistance to sulfur and water poisoning.