Methods and systems are provided for maintaining efficiency of a catalyst that is positioned in an exhaust system downstream of an internal combustion engine. In one example, the catalyst may be heated via supplying fuel to a cylinder that does not combust the fuel. The fuel may be oxidized at the catalyst via excess oxygen in the exhaust system.

The present invention is an in-situ cleaning procedure for the recovery of catalytic activity of a based alumina HDS catalyst, molybdenum, nickel coated coke and contaminants and it has an HDS activity seriously diminished. The catalyst under study had between 13 and 18 wt % total carbon. Reformate, half the total volume, industrial toluene=35 volume % and Iso-propylic alcohol, 15 volume %, in order to reactivate a deactivated catalyst, a solvent mixture with the following volumetric ratio is prepared. Or it can also be used only reformate (100% volume). The solvent mixture is passed using a LHSV of 2 hr1 for 72 hours at 50 C. or also using a recirculating three 24-hour cycles at 50 C. Option lasts 24 hours pure reformate LHSV=2h1 to 50 C. The washed catalyst is fed back to the load reaction conditions maintained for 36 hours at 340 C., to initiate HDS activity balances. During this treatment oxides of molybdenum and nickel in the active phase are re-sulfided by increasing the HDS activity. The In-Situ Cleaning procedure to reactivate deactivated hydrotreating catalysts used to partially remove the carbon and increase the active phase of molybdenum di-sulphide, and also retrieve specific area, and hydrogenation sites that promote higher hydrodesulfurization activity of gasoil after this treatment.

The invention relates to a method for catalytically producing formic acid and regenerating the catalyst used in the process. A vanadyl ion, vandate ion, or polyoxometallate ion, which is used as the catalyst, of the general formula [PMo.sub.xV.sub.yO.sub.40].sup.n is brought into contact with an alpha hydroxyl aldehyde, an alpha hydroxy carboxylic acid, a carbohydrate, a glycoside, or a polymer, which contains a carbon chain and which comprises at least one OH group that is bound to the carbon chain as a substituent in a repeating manner and/or an O, N, or S atom contained in the carbon chain in a repeating manner, in a liquid solution (12) in a vessel (10) at a temperature above 70 C. and below 160 C., wherein 6x11, 1y6, 3<n<10, and x+y=12, where n, x, and y is each a whole number. The catalyst reduced in the process is returned to its starting state by oxidation. For this purpose, the solution (12) is brought into contact with a gas (18) which contains a volume percent of oxygen of at least 18% at a pressure of at least 2 bar and maximally 16 bar by means of a mixing device or via a liquid-non-permeable gas-permeable membrane. CO and/or CO.sub.2 resulting during the reaction and merging with the gas (18) is discharged in such a quantity that the volume percent of CO and CO.sub.2 combined does not exceed 80% in the gas (18).

The invention relates to a method for catalytically producing formic acid and regenerating the catalyst used in the process. A vanadyl ion, vandate ion, or polyoxometallate ion, which is used as the catalyst, of the general formula [PMo.sub.xV.sub.yO.sub.40].sup.n is brought into contact with an alpha hydroxyl aldehyde, an alpha hydroxy carboxylic acid, a carbohydrate, a glycoside, or a polymer, which contains a carbon chain and which comprises at least one OH group that is bound to the carbon chain as a substituent in a repeating manner and/or an O, N, or S atom contained in the carbon chain in a repeating manner, in a liquid solution (12) in a vessel (10) at a temperature above 70 C. and below 160 C., wherein 6x11, 1y6, 3<n<10, and x+y=12, where n, x, and y is each a whole number. The catalyst reduced in the process is returned to its starting state by oxidation. For this purpose, the solution (12) is brought into contact with a gas (18) which contains a volume percent of oxygen of at least 18% at a pressure of at least 2 bar and maximally 16 bar by means of a mixing device or via a liquid-non-permeable gas-permeable membrane. CO and/or CO.sub.2 resulting during the reaction and merging with the gas (18) is discharged in such a quantity that the volume percent of CO and CO.sub.2 combined does not exceed 80% in the gas (18).

The present invention provides techniques that selectively recover Re from reductive amination catalysts. In particular, the present invention allows Re to be recovered selectively relative to Ni, Co, and/or Cu, and particularly Ni, that are often present on reductive amination catalysts. The present invention uses a combination of oxidation and extraction techniques to selectively recover Re relative to Ni, Co, and/or Cu. Advantageously, the recovery is selective even when using aqueous solutions for extraction.

The present invention provides techniques that selectively recover Re from reductive amination catalysts. In particular, the present invention allows Re to be recovered selectively relative to Ni, Co, and/or Cu, and particularly Ni, that are often present on reductive amination catalysts. The present invention uses a combination of oxidation and extraction techniques to selectively recover Re relative to Ni, Co, and/or Cu. Advantageously, the recovery is selective even when using aqueous solutions for extraction.

A method of equipment decontamination may include: introducing a cleaning stream comprising hydrogen and a solvent comprising a fatty acid methyl ester and an oxygenated solvent, or alternatively comprising a carrier fluid and a hydrocarbon solvent, into the equipment; and introducing a stream comprising nitrogen into the equipment, wherein the equipment comprises deposits and other contaminants.

A method of equipment decontamination may include: introducing a cleaning stream comprising hydrogen and a solvent comprising a fatty acid methyl ester and an oxygenated solvent, or alternatively comprising a carrier fluid and a hydrocarbon solvent, into the equipment; and introducing a stream comprising nitrogen into the equipment, wherein the equipment comprises deposits and other contaminants.

A method of equipment decontamination may include: introducing a cleaning stream comprising hydrogen and a solvent comprising a fatty acid methyl ester and an oxygenated solvent, or alternativelycomprising acarrier fluid and a hydro-carbon solvent, into the equipment; and introducing a stream comprising nitrogen into the equipment, wherein the equipment comprises deposits and other contaminants.

A method of equipment decontamination may include: introducing a cleaning stream comprising hydrogen and a solvent comprising a fatty acid methyl ester and an oxygenated solvent, or alternativelycomprising acarrier fluid and a hydro-carbon solvent, into the equipment; and introducing a stream comprising nitrogen into the equipment, wherein the equipment comprises deposits and other contaminants.