Mixed Metal Sulfide Catalyst for Deep Hydroprocessing
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Solution Overview
Problem
There is a need for improved self-supported mixed metal sulfide catalysts with enhanced catalytic activity and resistance to deactivation for the hydroprocessing of refractory hydrocarbon feeds, particularly those with high aromatic content, to meet stringent emission requirements and produce low-aromatic products.
Innovation Solution
A self-supported catalyst comprising molybdenum sulfide, nickel sulfide, and tungsten sulfide with specific molar ratios and a multi-phased structure, optimized to achieve higher hydrogenation, hydrodesulfurization, and hydrodenitrogenation activities, characterized by enhanced reaction rate constants and surface area retention during hydrotreating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-metal sulfide catalysts (molybdenum or tungsten) are used, then the catalyst structure is simple and easy to manufacture, but the catalytic activity and resistance to deactivation are insufficient for deep hydrogenation of refractory feeds
Solution Approach 1:
The patent combines multiple metal sulfides (molybdenum sulfide, tungsten sulfide, and nickel sulfide) into a single catalyst system. This merging of different metallic components creates synergistic effects that enhance both hydrogenation and hydrogenolysis activities, providing improved catalytic performance and resistance to deactivation while processing refractory hydrocarbon feeds
Solution Approach 2:
The invention employs a composite catalyst structure consisting of mixed metal sulfides with specific molar ratios (Ni:Mo:W between 1:1:1 and 1:2:1). This composite material approach allows the catalyst to exhibit properties that neither single-metal nor simple binary sulfides can achieve alone, particularly in terms of balanced hydrogenation-hydrogenolysis functionality and stability
2Productivity
If catalysts with high hydrogenation activity are used to meet aromatic saturation requirements, then deep hydrogenation is achieved, but the balance between hydrogenation and hydrogenolysis functions is compromised
Solution Approach 1:
The patent creates different functional zones within the catalyst structure by incorporating specific metal sulfide components in optimized ratios. The nickel sulfide provides hydrogenation activity, while molybdenum and tungsten sulfides contribute to hydrogenolysis. This local differentiation of functional properties within the composite catalyst enables simultaneous optimization of both reaction pathways
Solution Approach 2:
The invention optimizes the molar ratios of metal components (Ni:Mo:W between 1:1:1 and 1:2:1) to achieve the desired balance between hydrogenation and hydrogenolysis. By adjusting these compositional parameters, the catalyst can be tuned to provide appropriate activity for both aromatic saturation and sulfur removal, adapting to different feedstock requirements
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 catalyst exhibits significantly improved HDS and HDN reaction rate constants, maintaining high surface area and activity even after exposure to refractory feeds, effectively meeting the demands for deep hydrogenation and desulfurization in producing ultra-low sulfur diesel and other refined products.
Implementation Method 1
Hydrodesulfurization is accomplished most efficiently through a combination of: 1) hydrogenation (HYD), which releases sulfur atoms after saturating the ring structure of parent aromatic compounds and 2) hydrogenolysis (HYL), which breaks the bond between a sulfur atom and the carbon atom(s) in the sulfur containing molecule
Implementation Method 2
hydrogenolysis (HYL), which breaks the bond between a sulfur atom and the carbon atom(s) in the sulfur containing molecule
Implementation Method 3
High hydrodenitrogenation (HDN) activity is typically associated with aromatic saturation activity of nickel tungsten sulfides catalysts
Implementation Method 4
hydrogenation (HYD), which releases sulfur atoms after saturating the ring structure of parent aromatic compounds
Implementation Method 5
A lower number of layers in stacks implies the presence of smaller crystals of molybdenum, tungsten or molybdenum tungsten sulfides, which can result in larger surface areas available for catalysis
Data Source
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AI summary
The invention relates to a self-supported mixed metal sulfide (MMS) catalyst for hydrotreating hydrocarbon feedstock and to a method for preparing the catalyst. The catalyst can be any of: a bi-metallic catalyst consisting essentially of nickel sulfide and tungsten sulfide, with Ni:W in a mole ratio of 1:3 to 4:1, on a transition metal basis; a bi-metallic catalyst consists essentially of molybdenum sulfide and tungsten sulfide, with at least 0.1 mol% of Mo and at least 0.1 mol% of W, on a transition metal basis; or a tri-metallic catalyst ratios with components Ni:Mo:W in a region defined by five points ABCDE of a ternary phase diagram: A (Ni=0.72, Mo=0.00, W=0.25), B (Ni=0.25, Mo=0.00, W=0.75), C (Ni=0.25, Mo=0.25, W=0.50), D (Ni=0.60, Mo=0.25, W=0.15), E (Ni=0.72, Mo=0.13, W=0.15). The catalyst is characterized as having multiple phases for enhanced HYD and HYL activities, and outstanding HDN and HDS performance.