A method for flue gas denotation includes the step of, in the presence of ammonia, enabling flue gas in a denitration reactor to pass through a plurality of catalyst beds from the bottom to the top to participate in a denitration reaction. Each catalyst bed contains a catalyst support component and a granular denitration catalyst stacked on the catalyst support component, and, in every single catalyst bed, the granular denitration catalyst moves along a same direction on the catalyst support component. Between every two adjacent catalyst beds, the granular denitration catalyst falls from the tail of a previous catalyst support component to the head of a next catalyst support component, making the granular denitration catalyst travel along the catalyst support components reciprocatively.

A method for treating exhaust gas from an internal combustion engine including, determining if a steady state condition exist and perturbing a reductant injection corresponding the steady state. Measuring a first and a second NOx values corresponding to the steady state and resulting from the perturbation, and computing a gradient of the NO.sub.x values relative to the steady state respectively. The method also includes comparing the gradient of the second NO.sub.x value with one of the first NO.sub.x value, if the gradient of the first NOx value is within a selected range of the gradient of the second NOx value, identifying poor efficiency operation for the engine and setting an estimated reductant storage at zero. Otherwise if the gradient of the second NOx value exceeds a selected threshold, identifying a reductant slip condition and setting the estimated storage at maximum, if not, making no corrections in estimated storage.

A process for the cleaning of a lean gas stream contaminated with volatile organic compounds (VOCs) and/or sulfur-containing compounds comprises the steps of adding ozone to the contaminated lean gas stream, subjecting the ozone-containing lean gas stream to ultraviolet irradiation, thereby transforming VOCs to particles, maintaining the irradiated gas stream in a stay zone for a sufficient time to allow aerosol particle growth, and passing the gas stream through a catalytic bag filter at a temperature down to room temperature to remove the formed particles and eliminate any remaining ozone. The bag filter has been made catalytic by impregnation with one or more metal oxides in which the metals are selected from V, W, Pd and Pt, supported on TiO.sub.2.

A process for cleaning process gas removes sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter (PM) to produce a tail gas substantially free of these pollutants. The process oxidizes and absorbs SOx and NOx for storage as liquid acids. In some embodiments a PM removal stage and/or a SOx removal stage are provided in a close-coupled higher-pressure environment upstream from a turbocharger turbine. The process has example application in cleaning exhaust gases from industrial processes and large diesel engines such as ship engines.

To be able to produce an SCR catalyst (2), in particular one having a zeolite fraction (Z) as catalytically active fraction, in a reliable process and at the same time achieve good catalytic activity of the catalyst (2), an inorganic binder fraction (B) which is catalytically inactive in the starting state and has been treated to develop catalytic activity is mixed into a catalyst composition (4). The inorganic binder component for the binder fraction (B) is, in the starting state, preferably porous particles (10), in particular diatomaceous earth, which display mesoporosity. To effect catalytic activation, the individual particles (10) are either coated with a catalytically active layer (12) or transformed into a catalytically active zeolite (14) with maintenance of the mesoporosity.

In a process for the removal of siloxanes from biogas streams, especially a landfill gas stream or a gas stream from anaerobic digesters, the gas stream is first passed through a conventional siloxane removing unit to remove the majority of the siloxanes and subsequently passed over a selected catalyst with polishing effect, thereby removing remaining traces of siloxanes. The catalyst with polishing effect is chosen from i.a. zeolites, porous silica, titania and various metals on alumina or titania.

For a denitration catalyst used for a denitration treatment of a combustion exhaust gas, for example, from a coal-fired boiler or the like, such a denitration catalyst is provided that has a sufficient mechanical strength capable of retaining the catalyst shape, has a better catalyst performance than the ordinary denitration catalyst containing crystals of zirconium oxide, is low in production cost. In the denitration catalyst comprising, as a base material, a honeycomb structure consisting of an inorganic fiber sheet, titania, vanadium oxide and/or tungsten oxide, and a zirconium compound (except for crystalline zirconium dioxide) as a shape-retaining binder are supported on the honeycomb structure.

Use of a ternary vanadate of formula (I): Fe.sub.x MeI.sub.y MeII.sub.z VO.sub.4 wherein MeI and MeII are different from each other and each stand for an element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Er, Gd, Tb, Dy, Ho, Tm, Yb, Lu, Al, Bi and Sb and wherein x=0.05-0.9; y=0.05-0.9; z=0.05-0.9; x+y+z=1, as a catalyst for the oxidation of carbonaceous compounds in combustion engines.

In a process for the removal of soot from a sulfurous gas stream, a process gas containing O.sub.2 and more than 500 ppm SO.sub.2 and/or SO.sub.3 together with soot is brought into contact with a VK type catalyst in a reactor, said catalyst comprising vanadium pentoxide (V.sub.2O.sub.5), sulfur in the form of sulfate, pyrosulfate, tri- or tetrasulfate and one or more alkali metals, such as Na, K, Rb or Cs, on a porous carrier, preferably a silicon dioxide carrier.

A reducing agent injection device includes a honeycomb structure and a urea spraying device spraying a urea water solution in mist form. A pair of electrode members is formed in the honeycomb structure. The honeycomb structure of the reducing agent injection device, the hydraulic diameter HD, defined as HD=4?S/C, when the area of the cross section of one of the cells in the cross section perpendicular to the cell extending direction is S, and the peripheral length of the cross section of one of the cells is C, is 0.8 to 2.0 mm. Also, the open frontal area OFA of the honeycomb structure in the cross section perpendicular to the cell extending direction is 45 to 80%.