A process for the regeneration of a supported noble metal catalyst comprising contacting the catalyst with a liquid aqueous system at a temperature in the range of from 90 to 160 C., wherein the pH of the aqueous system is outside the range of from 6 to 8, separating the aqueous system from catalyst; and subjecting the catalyst to calcination.

A method for regenerating a carbonyl sulfide (COS) hydrolysis catalyst for hydrolyzing COS which is contained in a gas obtained by gasifying a carbon material, wherein a spent COS hydrolysis catalyst is immersed in an acid solution for a prescribed time thereby removing poisoning substances adhering to the surface of the COS hydrolysis catalyst; and thus regenerating the COS hydrolysis catalyst.

A method for regenerating a carbonyl sulfide (COS) hydrolysis catalyst for hydrolyzing COS which is contained in a gas obtained by gasifying a carbon material, wherein a spent COS hydrolysis catalyst is immersed in an acid solution for a prescribed time thereby removing poisoning substances adhering to the surface of the COS hydrolysis catalyst; and thus regenerating the COS hydrolysis catalyst.

A process is provided for preparing a spent noble metal fixed-bed catalyst for precious metals recovery, comprising: a) adding the catalyst to a caustic solution to wash the spent catalyst and to make a wash slurry having an alkaline pH, wherein the spent catalyst has been in contact with chloroaluminate ionic liquid catalyst, and wherein the spent catalyst comprises from 5 to 35 wt % chloride; and b) filtering the wash slurry and collecting: i) a filter cake having from at least 70 wt % of the chloride in the spent catalyst removed and having the noble metals retained, and ii) a wash filtrate. Also provided is a filter cake comprising a washed consolidated cake having 40 to 75 wt % solids, a cake moisture content from 25 to less than 60 wt %, 0.1 to 1.5 wt % total noble metals, and a residual chloride content of from zero to less than 4 wt %.

A process is provided for preparing a spent noble metal fixed-bed catalyst for precious metals recovery, comprising: a) adding the catalyst to a caustic solution to wash the spent catalyst and to make a wash slurry having an alkaline pH, wherein the spent catalyst has been in contact with chloroaluminate ionic liquid catalyst, and wherein the spent catalyst comprises from 5 to 35 wt % chloride; and b) filtering the wash slurry and collecting: i) a filter cake having from at least 70 wt % of the chloride in the spent catalyst removed and having the noble metals retained, and ii) a wash filtrate. Also provided is a filter cake comprising a washed consolidated cake having 40 to 75 wt % solids, a cake moisture content from 25 to less than 60 wt %, 0.1 to 1.5 wt % total noble metals, and a residual chloride content of from zero to less than 4 wt %.

The following invention relates to methods for reprocessing SCR catalysts. In a first embodiment, the invention relates to a method for reprocessing SCR catalysts, wherein an oxygen-containing compound of titanium and tungsten or molybdenum is removed from the catalyst and is then reacted with a vanadium compound. In a second embodiment, the invention relates to a method for removing titanium oxide and vanadium, molybdenum, and tungsten compounds from SCR catalysts and to a method for reusing these compounds in such catalysts.

A process for regenerating a silica-supported depleted alkali metal catalyst is described. The level of alkali metal on the depleted catalyst is at least 0.5 mol % and the silica support is a zero-gel. The process comprises the steps of contacting the silica supported depleted alkali metal catalyst with a solution of a salt of the alkali metal in a solvent system that has a polar organic solvent as the majority component. A re-impregnated catalyst prepared by the process of the invention any comprising a silica zero-gel support and a catalytic metal selected from an alkali metal in the range 0.5-5 mol % on the catalyst, wherein the surface area of the silica support is <180 m.sup.2/g is also described. The invention is applicable to a process for preparing an ethylenically unsaturated acid or ester comprising contacting an alkanoic acid or ester of the formula R.sup.1CH.sub.2COOR.sup.3, with formaldehyde or a suitable source of formaldehyde.

A metal contaminated spent catalyst or regenerated catalyst from a biomass conversion unit may be subjected to an ammonium wash in order to remove potassium. The ammonium wash may include ammonium sulfate, ammonium nitrate, ammonium hydroxide, ammonium acetate, ammonium phosphates, and mixtures thereof. Acidity and catalytic activity of the biomass conversion catalyst is restored by the removal of potassium contaminants.

Methods, systems, and compositions related to the recycling and/or recovery of activating materials from activated aluminum are disclosed. In one embodiment, an aqueous solution's composition may be controlled to maintain aluminum ions dissolved in solution during reaction of an activated aluminum. In another embodiment, aluminum hydroxide containing the activating materials may be dissolved into an aqueous solution to isolate the activating materials.

Methods, systems, and compositions related to the recycling and/or recovery of activating materials from activated aluminum are disclosed. In one embodiment, an aqueous solution's composition may be controlled to maintain aluminum ions dissolved in solution during reaction of an activated aluminum. In another embodiment, aluminum hydroxide containing the activating materials may be dissolved into an aqueous solution to isolate the activating materials.