A honeycomb structural body 20 comprises a porous partition portion 22 which forms a plurality of cells each functioning as a flow path of a fluid, and in the partition portion 22, the average pore diameter is 10 to 20 m, and a wet area rate R (=S/V) which is the rate of a wet area S of pores to a volume V of the partition portion 22 is 0.000239 m.sup.1 or more.

The disclosure is directed to an exhaust gas heating unit for an exhaust gas system of an internal combustion engine. The exhaust gas heating unit includes at least one electrically conductive heating conductor element, wherein the at least one electrically conductive heating conductor element is configured from bent flat strip material. The exhaust gas system conducts exhaust gas defining an exhaust gas primary flow direction (H). The heating conductor element can have a plurality of broad sides arranged to be substantially parallel to the exhaust gas primary flow direction (H) and a plurality of end faces arranged substantially orthogonally to the exhaust gas primary flow direction (H).

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.

The present disclosure provides a method for recycling soil contaminated with mercury and dioxin. The method includes: desorbing mercury and dioxin from the contaminated soil by an indirect rotary furnace; condensing the mercury and discharging it by a condensing and discharging unit; and a secondary indirect burner for decomposing dioxin at a high temperature, so as for the concentration of the contaminants in the exhaust being examined to meet regulation standards and the treated soil to meet the current regulations. The present disclosure also provides an apparatus for recycling contaminated soil containing mercury and dioxin.

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction (NH.sub.3-SCR) catalyst. The modified LNT comprises platinum, palladium, barium, and a ceria-containing material, and has a platinum:palladium molar ratio of at least 3:1. The modified LNT stores NO.sub.x at temperatures below about 200? C. and releases the stored NO.sub.x at temperatures above about 200? C. The urea injection system injects urea at temperatures above about 180? C.

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 is obtained by coating a substrate with a catalyst component. The catalyst component contains 43 wt % or more of vanadium pentoxide and has a BET specific surface area of 30 m.sup.2/g or more. The denitration catalyst is used for denitration at 200 C. or lower.

A combustion system operated at low cost is provided. A combustion system 1 includes a combustion device 10 that burns fuel, an exhaust line L1 through which exhaust gas flows, the exhaust gas being generated through combustion of the fuel in the combustion device 10, a dust collector 50 that is disposed in the exhaust line L1 and that collects dust in the exhaust gas, and a denitration device 90 that is disposed in the exhaust line L1 and that removes nitrogen oxide from the exhaust gas using a denitration catalyst. The denitration device 90 is disposed downstream from the dust collector 50 in the exhaust line L1. The denitration catalyst contains 43 wt % or more of vanadium pentoxide and has a BET specific surface area of 30 m.sup.2/g or more.

An exhaust gas purifying device includes a first SCR catalyst converter, an oxidation catalyst converter, a filter section, and a second SCR catalyst converter arranged in series to a flow direction of an exhaust gas. The first SCR catalyst converter includes a pillar-shaped honeycomb structure a cell density of which is from 31 to 78 cells/cm.sup.2, a porosity of the partition walls of which is from 50 to 65%, and in which a first SCR catalyst is loaded onto the surfaces of the partition walls and inner portions of pores formed in the partition walls, and an amount of the first SCR catalyst to be loaded onto the surfaces of the partition walls and the inner portions of the pores is from 200 to 500 g/L and an amount of the first SCR catalyst to be loaded onto the inner portions of the pores is from 5 to 80 g/L.

The invention is a method and a sulfuric acid plant design for reduction of start-up SO.sub.2, SO.sub.3 and H.sub.2SO.sub.4 emissions in sulfuric acid production, in which SO2 is converted to SO.sub.3 in n successive catalyst beds, where n is an integer >1. The final catalytic beds are used as absorbents for SO.sub.2 to SO3 during the start-up procedure, and one or more of the m beds downstream the first bed are purged, either separately or simultaneously, with hot gas, where m is an integer >1 and m<n, during the previous shut-down. Also, one separate purge with hot gas is used on the final bed.

Method and system for removal of particles such as soot, ash and heavy metals, and optionally additionally NO.sub.X and SO.sub.X being present in exhaust gas from an engine or process equipment.