Catalysts, in particular clay catalysts, use in alkylation reaction of aromatic compounds, e.g., aromatic amines, that have lost activity during use, are regenerated by contacting the used catalyst with a mixture of a minor amount of an acid, in a mixture with water and an organic solvent. The regeneration process is readily incorporated into an alkylation process for aromatic amines.

A process for rejuvenating an at least partially spent catalyst resulting from a hydrodesulfurization process of a sulfur-containing olefinic gasoline cut, where the at least partially spent catalyst result is from a fresh catalyst a metal from group VIII, a metal from group VIb, and an oxide support, where the process includes a) regenerating the at least partially spent catalyst in an oxygen-containing gas stream at a temperature between 350° C. and 550° C., b) the regenerated catalyst is brought into contact with an impregnation solution containing a compound containing a metal from group VIb, the molar ratio of the metal from group VIb added per metal from group VIb already present in the regenerated catalyst being between 0.15 and 2.5 mol/mol, c) a drying stage is carried out at a temperature of less than 200° C., and
the use of the rejuvenated catalyst in a hydrodesulfurization process.

In accordance with one or more embodiments of the present disclosure, a method for regenerating and rejuvenating a spent catalyst comprising coke and contaminant metals includes washing the spent catalyst with a solvent; drying, at least partially, the spent catalyst; partially combusting the spent catalyst to remove a portion of the coke, thereby producing a partially de-coked catalyst; acid washing the partially de-coked catalyst; and fully combusting the partially de-coked catalyst, thereby producing a regenerated and rejuvenated catalyst. The portion of the coke removed during the partial combustion is greater than or equal to 10 wt. % and less than or equal to 60 wt. %. No rare earth elements are added to the partially de-coked catalyst prior to the fully combusting the partially de-coked catalyst.

In accordance with one or more embodiments of the present disclosure, a method for regenerating and rejuvenating a spent catalyst comprising coke and contaminant metals includes washing the spent catalyst with a solvent; drying, at least partially, the spent catalyst; partially combusting the spent catalyst to remove a portion of the coke, thereby producing a partially de-coked catalyst; acid washing the partially de-coked catalyst; and fully combusting the partially de-coked catalyst, thereby producing a regenerated and rejuvenated catalyst. The portion of the coke removed during the partial combustion is greater than or equal to 10 wt. % and less than or equal to 60 wt. %. No rare earth elements are added to the partially de-coked catalyst prior to the fully combusting the partially de-coked catalyst.

A catalyst which comprises an amorphous support based on alumina, a C1-C4 dialkyl succinate, citric acid and optionally acetic acid, phosphorus and a hydrodehydrogenating function comprising at least one element from group VIII and at least one element from group VIB; the most intense bands comprised in the Raman spectrum of the catalyst are characteristic of Keggin heteropolyanions (974 and/or 990 cm.sup.−1), C1-C4 dialkyl succinate and citric acid (in particular 785 and 956 cm.sup.−1). Also a process for preparing said catalyst in which a catalytic precursor in the dried, calcined or regenerated state containing the elements of the hydrodehydrogenating function, and optionally phosphorus, is impregnated with an impregnation solution comprising at least one C1-C4 dialkyl succinate, citric acid and optionally at least one compound of phosphorus and optionally acetic acid, and is then dried. Further, the use of said catalyst in any hydrotreatment process.

A catalyst which comprises an amorphous support based on alumina, a C1-C4 dialkyl succinate, citric acid and optionally acetic acid, phosphorus and a hydrodehydrogenating function comprising at least one element from group VIII and at least one element from group VIB; the most intense bands comprised in the Raman spectrum of the catalyst are characteristic of Keggin heteropolyanions (974 and/or 990 cm.sup.−1), C1-C4 dialkyl succinate and citric acid (in particular 785 and 956 cm.sup.−1). Also a process for preparing said catalyst in which a catalytic precursor in the dried, calcined or regenerated state containing the elements of the hydrodehydrogenating function, and optionally phosphorus, is impregnated with an impregnation solution comprising at least one C1-C4 dialkyl succinate, citric acid and optionally at least one compound of phosphorus and optionally acetic acid, and is then dried. Further, the use of said catalyst in any hydrotreatment process.

Provided are a denitration catalyst regeneration method and a denitration catalyst regeneration system, which are capable of recovering denitration performance to a high level and reducing the SO.sub.2 oxidation rate of a catalyst. A denitration catalyst regeneration method according to the present invention includes: a chemical solution cleaning step for immersing a denitration catalyst in a chemical solution containing a fluorine compound and an inorganic acid; a step for extracting the denitration catalyst from the chemical solution; and a finish washing step for washing the denitration catalyst extracted from the chemical solution with a finish cleaning solution containing an organic acid.

Provided are a denitration catalyst regeneration method and a denitration catalyst regeneration system, which are capable of recovering denitration performance to a high level and reducing the SO.sub.2 oxidation rate of a catalyst. A denitration catalyst regeneration method according to the present invention includes: a chemical solution cleaning step for immersing a denitration catalyst in a chemical solution containing a fluorine compound and an inorganic acid; a step for extracting the denitration catalyst from the chemical solution; and a finish washing step for washing the denitration catalyst extracted from the chemical solution with a finish cleaning solution containing an organic acid.

A method and system for renewing spent fluid catalytic cracking (SFCC) catalysts are disclosed which comprises: treating SFCC catalysts using a static reactor designed to uniformly distribute with an oxalic acid solution and its reflux to obtain leached SFCC catalysts; washing with aqueous solution and filtering to collect cleaned and treated SFCC catalyst; and c) executing the cleaned and treated SFCC catalyst with thermal treatment to obtain renewed FCC catalysts.

A method and system for renewing spent fluid catalytic cracking (SFCC) catalysts are disclosed which comprises: treating SFCC catalysts using a static reactor designed to uniformly distribute with an oxalic acid solution and its reflux to obtain leached SFCC catalysts; washing with aqueous solution and filtering to collect cleaned and treated SFCC catalyst; and c) executing the cleaned and treated SFCC catalyst with thermal treatment to obtain renewed FCC catalysts.