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.

The invention relates to a catalyst regeneration process for a tar reforming catalyst within a catalyst bed in a tar reformer. The process comprises the steps of:—Admitting a main gas stream with controlled temperature and oxygen content to an inlet into the tar reformer;—Passing the main gas stream through the catalyst bed to form an oxygen depleted gas stream;—Exiting the oxygen depleted gas stream from the tar reformer; and—Recycling at least a part of the oxygen depleted gas stream exiting from the tar reformer back into said main gas stream upstream said tar reformer. The temperature of said main gas stream at the inlet is controlled to be within the range from about 500° C. to about 1000° C.

The invention relates to a catalyst regeneration process for a tar reforming catalyst within a catalyst bed in a tar reformer. The process comprises the steps of:—Admitting a main gas stream with controlled temperature and oxygen content to an inlet into the tar reformer;—Passing the main gas stream through the catalyst bed to form an oxygen depleted gas stream;—Exiting the oxygen depleted gas stream from the tar reformer; and—Recycling at least a part of the oxygen depleted gas stream exiting from the tar reformer back into said main gas stream upstream said tar reformer. The temperature of said main gas stream at the inlet is controlled to be within the range from about 500° C. to about 1000° C.

A method of producing olefins by catalytic cracking of hydrocarbons is disclosed. The method may include catalytic cracking hydrocarbons in a feed stream that includes the hydrocarbons and the dry gas diluent. The catalytic cracking may be carried out in a process using a train of fixed bed reactors while one or more other trains of fixed bed reactors are being regenerated or are on standby after being regenerated. When the train of fixed bed reactors being used needs regenerating, it is taken out of service and the one or more other trains of fixed bed reactors put in service to carry out the catalytic cracking process. Dry gas instead of steam may be used to reduce the partial pressure of hydrocarbons.

Provided is an SCR catalyst for removing nitrogen oxides (NO.sub.x) from exhaust gas, comprising: 0.01-70 wt % of zeolite having an average pore size of 5 Å or more; 25-90 wt % of titanium dioxide (TiO.sub.2); and 4-10 wt % of vanadium pentoxide (V.sub.2O.sub.5). The SCR catalyst according to the present invention exhibits denitrification performance in a low-temperature area that is superior to that of a conventional SCR catalyst, has improved tolerance for a sulfur compound, and also has an excellent regeneration rate.

The present invention relates to a method for producing long-chain alkylbenzene by reacting an aromatic hydrocarbon and a long-chain olefin, wherein the reaction is carried out in the presence of a solid acid catalyst, the aromatic hydrocarbon is selected from the group consisting of benzene, toluene and xylene, the long-chain olefin is selected from the group consisting of C.sub.8-C.sub.26 alkenes, the catalyst is a HMCM-22 type molecular sieve solid acid catalyst modified with heteroatom(s), the heteroatom(s) is/are selected from the group consisting of boron, gallium, indium, chromium, molybdenum, tungsten, manganese and phosphorus, and the molar ratio of silicon atoms to heteroatoms in the solid acid catalyst is in the range of 1:0.01-0.03. The invention also relates to a method for regenerating the solid acid catalyst used in the reaction.

Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.

Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium 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.