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 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.

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.

A method includes at least two-stage process for the oligomerization of short-chain olefins in the presence of a catalyst, wherein the regeneration of the catalyst is stage-customized.

A method of synthesizing a smart paper transformer is provided. The method comprises combining paper with HAuCl.sub.4 and stirring together in an aqueous solution to form a pulp. The pulp is treated with NaBH.sub.4 aqueous solution. The treated pulp is then washed and centrifuged with water a number of times to form a gold nanosponge (AuNS) catalyst pulp.

Articles comprising a catalyst film comprising VOx, MoO.sub.3 or WO.sub.3, and TiO.sub.2 deposited on a substrate are disclosed. The articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases. Methods for producing such articles deposit a catalyst film on the substrate to form a coated substrate, which is then calcined. When used in an SCR process, the coated articles have enhanced activity for NOx conversion, reduced activity for SOx conversion, or both. Light-weight, coated articles having high catalyst loads can be fabricated at the same or reduced dimensions when compared with laminated articles, and increased kNOx/kSOx ratios are available even from coated articles having relatively thin catalyst films. The articles should have particular value for power plant operations, where coal and high-sulfur fuels are commonly used and controlling sulfur trioxide generation is critical.

A used denitration catalyst is regenerated by means of a method comprising bringing the used denitration catalyst comprising titanium oxide as an essential ingredient into contact with a suspension of particles comprising manganese oxide, subjecting the resulting product to a liquid draining, and subjecting the liquid-drained product to a drying process, additionally, further comprising impregnating a solution comprising a compound containing at least one element selected from the group consisting of vanadium, molybdenum and tungsten into the denitration catalyst after the drying process, and subjecting the impregnated product to a drying treatment.

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 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.

The invention relates to a process for rejuvenating an at least partially spent hydrotreating and/or hydrocracking catalyst, said catalyst comprising a group VIII metal, a group VIB metal and an oxide support, said process comprising the following steps: a) the catalyst is regenerated, b) said regenerated catalyst is then brought into contact with an impregnation solution consisting of a mixture of water, at least one precursor of a group VIB metal, at least one precursor of a group VIII metal and at least one organic compound, the amount of organic compound introduced into the regenerated catalyst being optimized with respect to the metals already present in the regenerated catalyst and with respect to the amount of metals introduced via the impregnation solution, c) a drying step is then carried out without subsequently calcining it.