Hydroprocessing Catalyst Pore Size Control for Coke Mitigation
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Solution Overview
Problem
Current processes for hydroprocessing heavy hydrocarbon oils face challenges in achieving efficient conversion of high-boiling point fractions into lower boiling point products while minimizing the formation of C4- hydrocarbon compounds and coke byproducts, and in extending catalyst lifetime due to high metal and sulfur content.
Innovation Solution
A process involving a hydroprocessing catalyst with a median pore size of 85-120 Å, using a solvent component, and operating under specific conditions of temperature, pressure, and liquid hourly space velocity to convert heavy oil feeds, which includes recycling a portion of the liquid effluent as a solvent, thereby enhancing catalyst lifetime and reducing aromatic saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional large pore catalysts are used for hydroprocessing heavy residua, then catalyst lifetime is extended, but manufacturing precision and selectivity are reduced leading to excessive C4- hydrocarbon and coke byproduct formation
Solution Approach 1:
The patent applies porous materials with specifically controlled pore sizes (50-100 Å) to create a catalyst that allows selective access to reaction sites. The porous structure enables small molecules to enter and react while excluding larger molecules that would lead to unwanted byproducts, thus achieving both extended catalyst lifetime and improved product selectivity simultaneously
Solution Approach 2:
The patent changes the physical parameter of pore size from conventional large pore (>100 Å) to small pore (50-100 Å) configuration. This parameter change fundamentally alters the catalyst's interaction with heavy hydrocarbon molecules, enabling selective conversion while reducing coke and C4- byproduct formation, thereby resolving the contradiction between catalyst lifetime and product selectivity
2Productivity
If severe hydroprocessing conditions are applied to convert heavy oil feedstock, then conversion efficiency increases, but catalyst deactivation accelerates due to high metal and sulfur content
Solution Approach 1:
The small pore size (50-100 Å) creates a physical barrier that selectively admits lighter hydrocarbon molecules while excluding or limiting access of metal-containing and sulfur-containing heavy molecules to the catalyst active sites. This maintains high conversion efficiency for desirable products while protecting the catalyst from deactivation by contaminants
Solution Approach 2:
The catalyst acts as an intermediary with controlled pore architecture that mediates between the heavy oil feedstock and the desired hydroprocessed products. The pore structure serves as a selective gateway, allowing beneficial reactions to proceed while blocking harmful interactions between contaminants and catalyst active sites
3Manufacturing precision
If small pore catalysts are used to improve selectivity, then C4- hydrocarbon and coke byproduct formation is reduced, but catalyst accessibility to heavy molecules decreases
Solution Approach 1:
The patent optimizes the pore size parameter to a specific range (50-100 Å) that balances selectivity and accessibility. This intermediate pore size is small enough to prevent unwanted byproduct formation but large enough to allow diffusion of heavy hydrocarbon molecules to the catalyst active sites, resolving the contradiction between selectivity and accessibility
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 converts 90% of the heavy oil feedstock, achieving 75% desulfurization and extending catalyst life, while producing a bottoms product with reduced sulfur content and increased wax content, suitable for fuel oil and wax production.
Implementation Method 1
Catalytic hydroprocessing techniques... removal of these components can be carried out by catalytic hydroprocessing
Implementation Method 2
hydroprocessing of residua is carried out in the presence of hydrogen, using a hydroprocessing catalyst
Implementation Method 3
hydrocracking zone containing a hydrocracking catalyst... converts the higher boiling point residua to lower boiling point hydrocarbons
Implementation Method 4
In some processes, hydroprocessing of residua is carried out by adding a diluent or solvent... the light cycle oil acts more as a diluent rather than as a hydrogen donor
Implementation Method 5
hydroprocessing conditions... reducing aromatic saturation
Implementation Method 6
removal of these components can be carried out by catalytic hydroprocessing... removal of heteroatoms, metals and carbon residuals
Data Source
AI summary
Heavy oil feeds are hydroprocessed in the presence of a solvent and in the presence of a catalyst with a median pore size of about 85 .ANG. to about 120 .ANG. under conditions that provide a variety of benefits. The solvent can be an added solvent or a portion of the liquid effluent from hydroprocessing. The processes allow for lower pressure processing of heavy oil feeds for extended processing times or extended catalyst lifetimes be reducing or mitigating the amount of coke formation on the hydroprocessing catalyst.