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.

There is provided a method for recycling 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 method for recycling a denitration catalyst includes a step of removing a used denitration catalyst from a denitration device and then coating the used denitration catalyst 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, and the denitration catalyst after recycling is used for denitration at 200? C. or lower.

There is provided a method for recycling 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 method for recycling a denitration catalyst includes a step of spraying an aqueous solution with a pH of 7 or more onto a used denitration catalyst while the denitration catalyst is set in a denitration device to remove a surface of the denitration catalyst. 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. The denitration catalyst after recycling is used for denitration at 200? C. or lower.

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 contains 3.3 wt % or more of vanadium oxide in terms of vanadium pentoxide and has a BET specific surface area of 10 m.sup.2/g or more.

A combustion system for ships operated at low cost is provided. A combustion system 1 for ships includes an internal combustion engine 20 that burns fuel, an exhaust line L2 through which exhaust gas flows, the exhaust gas being generated through combustion of the fuel in the internal combustion engine 20, an exhaust heat recovery device 40 that is disposed in the exhaust line L2 and that recovers exhaust heat from the exhaust gas discharged from the internal combustion engine 20, and a denitration device 50 that is disposed in the exhaust line L2 and that removes nitrogen oxide from the exhaust gas using a denitration catalyst. The denitration device 50 is disposed downstream from the exhaust heat recovery device 40 in the exhaust line L2. 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.

A configuration for a power supply of a component in an exhaust gas system includes at least one electrical contact disposed at an exhaust gas line. The at least one electrical contact is surrounded by an electrical insulation material.

An electrically heatable honeycomb body assembly includes an electrical connection of sheet metal layers at a connection pin. A honeycomb body has a metal casing with an inner periphery, through which the connection pin is led in a bushing and electrically insulated. The sheet metal layers are alternately coarsely structured and finely structured or smooth sheets together forming a stack with uppermost and lowermost layers and channels for an axial gas flow between the layers. The connection pin runs radially approximately perpendicular to the layers and is metallically connected to at least two or all of the layers through at least one intermediate piece. The uppermost sheet metal layer preferably runs approximately parallel to the metal casing over at least 35% of the inner periphery and is separated therefrom only by an air gap. Simple production of an operationally safe and very uniformly electrically heatable honeycomb body is provided.