Abstract: Molecular sieve catalysts, such as alumino-silicate zeolites, used in hydrocarbon conversion and separation processes, are restored after their recommended use-cycle service, by novel methods of regeneration and metal redispersion, or rejuvenation.An additive compound is injected into the catalyst during regeneration, or coke removal. The additive is of a molecular diameter large enough to prevent the additive from being captured by a cell of the catalyst, and is preferably of a pH which promotes adsorption of the additive onto the zeolite material.Metal-coated zeolite catalysts are rejuvenated, preferably after regeneration, by injecting a halogen compound followed by the above additive compound, and then heating the catalyst to a high temperature. This procedure is effective in re-dispersing metal agglomerates uniformly throughout the catalyst to restore the original metal coating.

Abstract: Platinum-alumina catalysts deactivated by accumulations of sulfur and carbonaceous deposits are treated for removal of sulfur by contacting the deactivated catalyst with a hydrogen-rich gas, water or water precursor, a solution of liquid chlorinated hydrocarbon containing one to eight carbon atoms per molecule, in an oxygen-containing organic compound containing one to eight carbon atoms per molecule prior to contacting the deactivated catalyst with oxygen-containing regeneration gas for removal of coke deposits from the catalyst.

Abstract: An isomerization process for the production of desired isomers of aromatic hydrocarbons containing eight carbon atoms per molecule, i.e., para-xylene and ortho-xylene, from a mixture of aromatic hydrocarbons containing eight carbon atoms per molecule wherein yields of the desired carbon, are increased by incorporating an aliphatic hydrocarbon, e.g., n-pentane, in the feedstock for the process.