A method for producing a base oil having a high ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality by hydroisomerization dewaxing a selected Fischer-Tropsch wax under hydroisomerization conditions including a hydrogen to feed ratio from about 712.4 to about 3562 liter H.sub.2/liter oil.

Systems and methods are provided for hydroprocessing a petroleum fraction, such as a bottoms fraction from a fuels hydrocracking process, to generate a lubricant base oil. The aromatic content of such a petroleum fraction can be reduced using a aromatic saturation stage with multiple catalyst beds, or alternatively using a reactor (or reactors) with multiple aromatic saturation stages. The catalysts in the various beds or stages can be selected to provide different types of aromatic saturation activity. An initial bed or stage can provide activity for saturation of 1-ring aromatics in the petroleum fraction. One or more subsequent beds or stages, operating at successively lower temperature, can then be used to reduce the multiple-ring aromatic content of the petroleum fraction.

Described are processes to produce base oils with one more improved properties, e.g., lower aromatics, economically and/or efficiently. In some embodiments the processes comprise a step that reduces the amount of residual refractory sulfur compounds prior to or simultaneous with a hydrofinishing step which advantageously provides base oils with lower aromatics than comparable processes.

A catalyst system for dewaxing of a hydrocarbon feedstock comprising at least two catalytic sections, the first section comprising a first dewaxing catalyst and a subsequent section comprising a second dewaxing catalyst, wherein the first dewaxing catalyst is a ZSM-12 zeolite based catalyst and the second dewaxing catalyst is a EU-2 and/or ZSM-48 zeolite based catalyst. The catalyst system displays enhanced performance when compared to systems containing either ony ZSM-12 based catalyst or EU-2/ZSM-48 based catalyst only.

Methods are provided for forming noble metal catalysts comprising both platinum and a second Group VIII metal, such as palladium, with improved aromatic saturation activity. Instead of impregnating a catalyst with both platinum and another Group VIII metal at the same time, a sequential impregnation can be used, with the Group VIII metal being impregnated prior to platinum. It has been discovered that by forming a Group VIII metal-impregnated catalyst first, and then impregnating with platinum, the distribution of platinum throughout the catalyst can be improved. The improved distribution of platinum can result in a catalyst with enhanced aromatic saturation activity relative to a catalyst with a similar composition formed by simultaneous impregnation.

Provided is a process for preparing base oil from a waxy hydrocarbon feedstock by contacting the hydrocarbon feedstock in a hydroisomerization zone under hydroisomerization conditions. The reaction is in the presence of hydrogen and an inert gas, with the total pressure in the hydroisomerization zone being at least 400 psig. A product from the hydroisomerization zone is collected and separated into base oil products and fuel products. The inert gas can comprise any suitable inert gas, but is generally nitrogen, methane or argon. Nitrogen is used in one embodiment.

Provided in one embodiment is an improved and more flexible process for preparing a finished base oil or a white oil product comprising passing a dewaxed base oil product to a distillation column and separating the dewaxed base oil product into fuel and base oil product streams. The base oil product streams are tested to determine if they meet desired specifications. Base oil product streams that meet the desired minimum base oil specifications are passed to a hydrofinishing reactor to prepare a white oil product, or passed to direct sale.

A method is disclosed for preparing an aviation fuel composition by subjecting a feedstock of biological and/or recycled origin to cracking in a cracking unit and to fractionation in a fractionation unit to obtain a kerosene fraction. The obtained kerosene fraction is subjected to hydrotreatment in a hydrotreatment unit to form a first jet fuel component. The formed first jet fuel component is mixed with a further jet fuel component to form a fuel composition having a wear scar diameter of 0.78 mm or less, as measured with BOCLE lubricity test method according to ASTM D5001. The feedstock contains one or more of tall oil pitch (TOP), a mixture of sludge palm oil, palm fatty acid distillate and animal fat (FATS), and used lubricant oil (ULO).

A catalyst system for dewaxing of a hydrocarbon feedstock comprising a mixture of a first dewaxing catalyst composition and a second dewaxing catalyst composition, wherein the first dewaxing catalyst composition is a ZSM-12 zeolite based catalyst composition and the second dewaxing catalyst composition is a EU-2 and/or ZSM-48 zeolite based catalyst composition, and wherein a concentration gradient of the mixture is achieved within a single catalyst bed, such that the concentration of the first dewaxing catalyst is decreasing and the concentration of the second dewaxing catalyst is increasing through the catalyst bed; and a process for dewaxing of a hydrocarbon feedstock comprising contacting the hydrocarbon feedstock with said catalyst system.

An improved hydroisomerization catalyst system and process for making a base oil product using a combined catalyst system comprising SSZ-91 molecular sieve and SSZ-95 molecular sieve. The catalyst system and process generally involves the use of a catalyst comprising an SSZ-91 molecular sieve and a separate catalyst comprising an SSZ-95 molecular sieve to produce dewaxed base oil products by sequentially contacting the catalysts with a hydrocarbon feedstock. The catalyst system and process provide improved base oil yield along with other beneficial base oil properties.