Realized is a method for restoring the activity of a catalyst for producing a carbonate ester by a simple technique with no use of a complicated step such as calcining or the like to allow the catalyst to be reusable, and a method for producing a carbonate ester at a high yield by use of the catalyst thus regenerated. The above-described problem has been solved by a method for regenerating a catalyst containing CeO.sub.2, the catalyst being usable for a carbonate ester generation reaction of generating a carbonate ester from carbon dioxide and an alcohol, the method comprising (a) a separation step of separating the catalyst as a crude catalyst from a reaction solution of carbon dioxide and the alcohol; and (b) a catalyst processing step of washing the crude catalyst with a washing alcohol to provide a purified catalyst.

The invention relates to a hydrocarbon hydroprocessing catalyst comprising a support based on at least one refractory oxide, at least one metal from group VIII and at least one metal from group VIB. The inventive catalyst is characterized in that it also comprises at least one organic compound having formula (I) or (II): ##STR00001##
in which each R.sub.1 represents independently an alkyl group at C.sub.1-18, an alkenyl group at C.sub.2-18, an aryl group at C.sub.6-18, a cycloalkyl group at C.sub.3-8, an alkylaryl or arylalkyl group at C.sub.7-20, or the two R.sub.1 groups together form a divalent group at C.sub.2-18, and R.sub.2 represents an alkylene group at C.sub.1-18, an arylene group at C.sub.6-18, a cycloalkylene group at C.sub.3-7, or a combination of same. The invention also relates to a method of preparing one such catalyst and to the use thereof for hydroprocessing or hydrocracking.

The invention relates to a hydrocarbon hydroprocessing catalyst comprising a support based on at least one refractory oxide, at least one metal from group VIII and at least one metal from group VIB. The inventive catalyst is characterized in that it also comprises at least one organic compound having formula (I) or (II): ##STR00001##
in which each R.sub.1 represents independently an alkyl group at C.sub.1-18, an alkenyl group at C.sub.2-18, an aryl group at C.sub.6-18, a cycloalkyl group at C.sub.3-8, an alkylaryl or arylalkyl group at C.sub.7-20, or the two R.sub.1 groups together form a divalent group at C.sub.2-18, and R.sub.2 represents an alkylene group at C.sub.1-18, an arylene group at C.sub.6-18, a cycloalkylene group at C.sub.3-7, or a combination of same. The invention also relates to a method of preparing one such catalyst and to the use thereof for hydroprocessing or hydrocracking.

The present invention relates to a catalyst system for olefin metathesis, the catalyst system comprising: a) a first system zone substantially comprising a layered double hydroxide; and b) a second system zone comprising a metathesis catalyst.

The present invention relates to a catalyst system for olefin metathesis, the catalyst system comprising: a) a first system zone substantially comprising a layered double hydroxide; and b) a second system zone comprising a metathesis catalyst.

Catalytic preparation of hydrogen and aldehyde(s) from alcohols, including bioalcohols, without production of carbon monoxide or carbon dioxide.

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.

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.

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.