Lubricating Base Oil Production via Mixed Metal Sulfide Hydrocracking
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Solution Overview
Problem
Conventional methods for producing high viscosity lubricating base oils face challenges in maintaining high selectivity and yield, particularly due to the concentration of heteroatoms like sulfur and nitrogen in heavier petroleum fractions, which reduces the yield of high viscosity products.
Innovation Solution
A process involving a hydrocracking reaction zone with a self-supported mixed metal sulfide catalyst, followed by dewaxing and hydrofinishing, to produce a lubricating base oil with a viscosity index greater than 95 and a viscosity at 100°C of 10 cSt or greater, while reducing nitrogen and sulfur content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional processing methods are used on heavier petroleum fractions to produce high viscosity base oils, then the concentration of heteroatoms (sulfur and nitrogen) is reduced, but the yield of high viscosity products decreases
Solution Approach 1:
The patent changes the operational parameters of the hydrocracking process, specifically using a two-stage hydrocracking process with controlled conversion levels (10-30% in first stage, additional conversion in second stage), temperature ranges (350-450°C), and pressure conditions (50-200 atm) to optimize both yield and purity of high viscosity base oils while removing heteroatoms
Solution Approach 2:
The patent divides the hydrocracking process into multiple stages (first hydrocracking stage with 10-30% conversion, second hydrocracking stage for additional conversion, dewaxing stage, hydrofinishing stage) to achieve both high yield and high purity separately at each stage, preventing the trade-off between yield and purity
2Productivity
If catalyst selectivity is improved to increase conversion to desired product, then yield of lubricating base oil increases, but selectivity maintenance becomes more difficult due to heteroatom concentration
Solution Approach 1:
The patent performs preliminary hydrocracking (10-30% conversion) and dewaxing before the final hydrofinishing stage, removing heteroatoms and wax components in advance to prevent catalyst fouling and maintain high selectivity in subsequent processing stages
Solution Approach 2:
The patent uses multiple catalysts as intermediaries at different stages: hydrocracking catalysts (Ni-Mo, Co-Mo, Ni-W, Co-W) in first and second hydrocracking stages, dewaxing catalysts (Pt, Pd, or Ni on molecular sieves), and hydrofinishing catalysts to progressively transform the feedstock while maintaining selectivity at each step
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process effectively increases the yield of high viscosity lubricating base oils by improving catalyst selectivity and reducing impurities, resulting in a product with enhanced properties.
Implementation Method 1
the lubricating oil feedstock is hydrocracked with a hydrogen-containing treat gas stream under hydrocracking conditions to form a hydrocrackate
Implementation Method 2
the liquid fraction is dewaxed in the presence of a hydrogen-containing treat gas stream over a shape selective intermediate pore size molecular sieve catalyst at hydroisomerization conditions
Implementation Method 3
the dewaxed effluent is provided to a hydrofinishing reaction zone for hydrogenating the dewaxed effluent over a hydrofinishing catalyst
Implementation Method 4
The hydrocrackate is separated into at least a gaseous product that contains ammonia, and a liquid fraction that boils above the initial boiling point of the feedstock; and has a nitrogen content of less than 50 ppm
Implementation Method 5
a sulfur content of greater than 0.1 wt. %
Data Source
AI summary
A process is provided for producing a heavy lubricating base oil by hydrocracking a lubricating oil feedstock at high yield. The lubricating oil feedstock contains a hydroprocessed stream that is difficult to process using a conventional catalyst system. The catalyst used in the process includes a mixed metal sulfide catalyst that comprises at least one Group VIB metal and at least one Group VIII metal. The process also provides for hydroisomerization and hydrofinishing process steps to prepare the lubricating base oil.