Provided is a combustion system using a catalyst having better denitration efficiency at low temperatures, during a selective catalytic reduction reaction in which ammonia is used as a reducing agent. This combustion system comprises: a combustion device that combusts fuel; an exhaust path through which flows exhaust gas generated from the combustion of fuel in the combustion device; a dust collection device that is arranged on the exhaust path and collects ash dust/dust in the exhaust gas; and a denitration device that is arranged on the exhaust path and removes nitrogen oxides from the exhaust gas by means of a denitration catalyst, wherein the denitration device is arranged downstream of the dust collection device on the exhaust path, and the denitration catalyst contains vanadium oxide including vanadium pentoxide and has a defect site in which an oxygen atom is deficient in a crystal structure of the vanadium pentoxide.

Catalyst regeneration processes that include measures for controlling emissions generated during the regeneration are described. The present invention further relates to catalytic processes for producing various chlorinated aromatic compounds that include provisions for controlling emissions during catalyst regeneration.

A process and a process plant for production of elemental sulfur from a feedstock gas including from 15 vol % to 100 vol % H2S and a stream of sulfuric acid, the process including a) providing a Claus reaction furnace feed stream with a substoichiometric amount of oxygen, b) directing s to a reaction furnace operating at elevated temperature, c) cooling, d) directing to contact a material catalytically active in the Claus reaction, e) withdrawing a Claus tail gas and elemental sulfur, f) directing to a means for sulfur oxidation, g) directing to contact a material catalytically active in SO2 oxidation to SO3, h) converting to concentrated sulfuric acid, i) recycling to the Claus reaction furnace, wherein an amount of combustibles, in the Claus tail gas, is oxidized in the presence of a material catalytically active in sulfur oxidation, at an inlet temperature below 400° C.

The present invention relates to a selective catalytic reduction (SCR) catalyst comprising a support, vanadium and antimony, a catalytic article comprising the SCR catalyst, and an exhaust treatment system for an internal combustion engine comprising the SCR catalyst. In one embodiment, the invention provides an SCR catalyst for reduction of 5 nitrogen oxides, comprising: a support, and an active material on the support; wherein the support, calculated as its oxide, is present in the SCR catalyst in an amount of 40 to 99% by weight, relative to the total weight of the SCR catalyst; the active material comprises vanadium and antimony; the vanadium, calculated as V.sub.2O.sub.5, is present in the SCR catalyst in an amount of 1 to 15% by weight, relative to the total weight of the SCR catalyst; the 10 antimony, calculated as Sb.sub.2O.sub.3, is present in the SCR catalyst in an amount of 0.5 to 20% by weight, relative to the total weight of the SCR catalyst; wherein the SCR catalyst, after hydrothermally aged at 550° C. for 100 hours with 10% water, has a 200-300° C. denitrification efficiency of at least 60%, with 60,000h.sup.−1 space velocity and an ammonia to NOx molar ratio of 1:11

An object of the present invention is to provide a heating carrier that does not heat all of exhaust gas flowing into a catalyst converter, but directly supplies, to a catalyst layer, thermal energy in the form of an instantaneous pulse to effectively activate a catalyst during a cold start-up period, and thus may reduce emission pollutants with a small amount of energy, and an exhaust gas reduction carrier having the heating carrier. In order to accomplish the object, the heating carrier of the present invention may include a main body of which the inside is formed to have a honeycomb structure, the main body being formed of a conductive ceramic material that is a nonmetallic heating element; and a catalyst layer formed by coating a first catalyst on a surface of the main body.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall defining a plurality of cells serving as fluid through channels extending from a first end face to a second end face, and having a circumferential wall disposed so as to encompass the circumference of the partition wall, wherein a thickness of the partition wall is 50 to 132 μm, a porosity of the partition wall is 40 to 55%, an open frontal area of pores on the surface of the partition wall per unit surface area of the partition wall is 10 to 15%, and a percentage (S.sub.0˜10/S.sub.all×100%) of the ratio of an opening area S.sub.0˜10 of the pores having an opening diameter of 10 μm or less to a total opening area S.sub.all of the pores opened to the surface of the partition wall is 90% or more.

A wall-flow honeycomb catalyst for dust removal and low-temperature denitrification of flue gas, and a preparation process thereof are provided. The catalyst is prepared from the following raw materials in parts by weight: calcined titanium dioxide: 30 to 60 parts; crude titanium dioxide: 30 to 50 parts; boehmite: 3 to 5 parts; fused silica powder: 2 to 4 parts; binder: 0.5 to 2 parts; lubricant: 0.5 to 2 parts; vanadium-molybdenum composite oxide: 5 to 10 parts; and water: 150 to 200 parts; and the vanadium-molybdenum composite oxide is obtained by dissolving ammonium metavanadate and ammonium molybdate in an oxalic acid solution and spray-drying a resulting solution. The preparation process of the catalyst of the present disclosure is simple and low in cost.

Chromium particulate emissions in flue gas can be reduced or minimized by incorporating a thin layer bed of a catalyst within the flue gas flow path of a furnace, boiler, or other furnace environment that includes Cr-containing surfaces. The thin layer bed of catalyst can correspond to, for example, a honeycomb monolith with catalyst supported on the monolith surface, so as to provide a high contact area while forcing all of the flue gas to pass through the catalyst bed. The honeycomb monolith structure and the depth of the bed can be selected to provide a reduced or minimized pressure drop across the catalyst bed, such as a pressure drop of 0.25 kPa (1.0 inches of water) or less. Exposing the Cr-containing flue gas to the thin layer catalyst bed can result in a treated flue gas with a lower content of Cr.

The present invention relates to an aqueous suspension comprising water, a source of one or more of a vanadium oxide and a tungsten oxide, and particles of an oxidic support; wherein the particles of the aqueous suspension exhibit a polymodal particle size distribution characterized by a particle size distribution curve comprising a first peak with a maximum M(I) in the range of from 0.5 to 15 micrometers and a second peak with a maximum M(II) in the range of from 1 to 40 micrometers, wherein (M(I)/μm):(M(II)/μm)<1:1.

The invention belongs to the field of nitrogen oxide control in environmental protection science and technology, and particularly relates to the field of regeneration and utilization of SCR denitration catalyst with calcium poisoning, that is a neutral complex cleaning liquid and a regeneration method for denitration catalyst with calcium poisoning. The present invention uses a neutral polyether surfactant as a regeneration and calcium removal reagent to achieve a poisoned catalyst regeneration method with high calcium removal rate, low loss rate of active components and excellent recovery of denitrification activity; wherein the content of the polyether surfactant is in the range of 0.1-1 wt %; by the regeneration method of the present invention, the loading of active components which is required in the conventional regeneration process can be omitted, while the corrosion of equipment and catalyst can be reduced, thus capable of regenerating the denitration catalyst with high efficiency.