Abstract: A reactivated catalyst having optimum activity for hydrocracking and other acid catalyzed chemical conversion processes is prepared by contacting its deactivated counterpart, which contains a crystalline molecular sieve, a Group VIII noble metal hydrogenation component and carbonaceous deposits, with a gas containing molecular oxygen, preferably air, at a temperature between 950.degree. and 1200.degree. F., preferably between about 1050.degree. and 1150.degree. F., for a time sufficient to remove at least a portion of the carbonaceous deposits. When the reactivated catalyst contains a dealuminated Y zeolite that has been ion-exchanged with both noble metal and rare earth metal cations, its activity for hydrocracking in an ammonia-deficient atmosphere can be further increased by a rejuvenation procedure in which the reactivated catalyst is contacted with an aqueous ammonia solution in which an ammonium salt has been dissolved.

Abstract: A reactivated catalyst having optimum activity for hydrocracking and other acid catalyzed chemical conversion processes is prepared by contacting its deactivated counterpart, which contains a crystalline molecular sieve, a Group VIII noble metal hydrogenation component and carbonaceous deposits, with a gas containing molecular oxygen, preferably air, at a temperature between 950.degree. and 1200.degree. F., preferably between about 1050.degree. and 1150.degree. F., for a time sufficient to remove at least a portion of the carbonaceous deposits. When the reactivated catalyst contains a dealuminated Y zeolite that has been ion-exchanged with both noble metal and rare earth metal cations, its activity for hydrocracking in an ammonia-deficient atmosphere can be further increased by a rejuvenation procedure in which the reactivated catalyst is contacted with an aqueous ammonia solution in which an ammonium salt has been dissolved.

Abstract: A catalytic hydrotreating process wherein silicon-containing contaminants contained in a hydrocarbon feedstream are deposited onto a hydrotreating catalyst bed during hydrotreating in a manner providing improved catalyst stability. Hydrotreating catalysts having relatively high activities and low surface areas are located downstream of upstream hydrotreating catalysts having relatively low activities and high surface areas.

Abstract: A catalyst useful for promoting the conversion of organonitrogen and organosulfur compounds in a hydrocarbon-containing feedstock is regenerated in a method wherein a deactivated catalyst is contacted with a controlled amount of water prior to combustion of sulfur contaminants from the catalyst.

Abstract: A catalyst composition composed of a crystalline aluminosilicate Y zeolite, normally having a silica-to-alumina mole ratio of about 6.2 or above, in combination with a porous, inorganic refractory oxide. The Y zeolite contains ion-exchanged rare earth cations and ion-exchanged Group VIII noble metal cations. The combination of the zeolite and the refractory oxide contains between 4.5 weight percent and about 6.0 weight percent water. Such a catalyst containing the recited amount of water has been found to have consistently high activities when used as a catalyst in a hydrocracking process. The Y zeolites used as part of the catalyst are typically prepared by contacting an ammonium-exchanged Y zeolite with an aqueous solution of ammonium fluorosilicate.

Abstract: A catalyst composition composed of a crystalline aluminosilicate Y zeolite, normally having a silica-to-alumina mole ratio of about 6.2 or above, in combination with a porous, inorganic refractory oxide. The Y zeolite contains ion-exchanged rare earth cations and ion-exchanged Group VIII noble metal cations. The combination of the zeolite and the refractory oxide contains between 4.5 weight percent and about 6.0 weight percent water. Such a catalyst containing the recited amount of water has been found to have consistently high activities when used as a catalyst in a hydrocracking process. The Y zeolites used as part of the catalyst are typically prepared by contacting an ammonium-exchanged Y zeolite with an aqueous solution of ammonium fluorosilicate.

Abstract: In the pressure testing of catalyst-loaded reactors with nitrogen gas at elevated temperatures, it is found that certain types of zeolite catalysts are substantially degraded in activity. The catalysts concerned comprises a Group VIII noble metal in an oxidized state, dispersed on a crystalline hydrogen zeolite, e.g., Y zeolite. It has now been discovered however that if such catalysts are first prereduced with a dilute, non-combustible mixture of nitrogen and hydrogen, damage on subsequent pressure testing with nitrogen is prevented or drastically reduced. Following pressure testing, the catalyst is activated by dehydration in a stream of hydrogen at elevated temperatures and pressures.