Two-Stage Diesel Aromatics Saturation Process
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Solution Overview
Problem
Existing processes struggle to effectively remove organic nitrogen and polyaromatic compounds from distillate feedstocks to produce diesel products with high Cetane Index, as they focus primarily on desulfurization and do not adequately address denitrogenation and aromatics saturation, especially with high concentrations of polyaromatics and sulfur.
Innovation Solution
A process involving two reaction zones with specific catalysts for hydrodenitrogenation and polyaromatics saturation, followed by a high-pressure interstage stripper and further monoaromatics saturation, using base metal catalysts to enhance the Cetane Index of diesel products, while reducing nitrogen, sulfur, and aromatics content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing processes focus primarily on desulfurization with single-stage reactors, then sulfur removal is achieved, but nitrogen removal and polyaromatics saturation are insufficient, resulting in low Cetane Index
Solution Approach 1:
The single-stage reactor is divided into two separate reaction zones with different catalysts and operating conditions. The first zone uses a desulfurization catalyst for sulfur and nitrogen removal, while the second zone uses a saturation catalyst for polyaromatics conversion, enabling simultaneous achievement of denitrogenation and aromatics saturation for high Cetane Index
Solution Approach 2:
Different sections of the reaction system are given different local qualities: the first reaction zone is optimized for hydrodenitrogenation with specific catalyst composition and operating conditions, while the second reaction zone is optimized for polyaromatics saturation with different catalyst and conditions, allowing each zone to perform its specific function effectively
2Manufacturing precision
If high-pressure conditions are used throughout the process, then polyaromatics saturation is improved, but energy consumption and equipment complexity increase
Solution Approach 1:
The process uses dynamic pressure conditions rather than uniform high pressure throughout. The first reaction zone operates at moderate pressure for desulfurization and denitrogenation, while the second reaction zone operates at higher pressure for polyaromatics saturation, optimizing energy consumption while achieving the required aromatics saturation level
Solution Approach 2:
The pressure conditions are segmented into two stages: moderate pressure in the first zone for sulfur and nitrogen removal, and high pressure in the second zone for polyaromatics conversion, allowing energy-intensive high-pressure conditions to be applied only where necessary for aromatics saturation
3Productivity
If noble metal catalysts are used for polyaromatics saturation, then reaction efficiency is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metal catalysts with base metal catalysts (such as nickel, cobalt, or iron-based catalysts) in the second reaction zone that, while potentially having shorter lifespan or requiring more careful management, significantly reduce manufacturing costs while maintaining adequate reaction efficiency for polyaromatics saturation
Solution Approach 2:
The catalyst composition parameter is changed from noble metals to base metals, and the operating conditions (temperature, pressure, LHSV) are optimized for the base metal catalyst to achieve effective polyaromatics saturation at lower cost, balancing reaction efficiency with manufacturing cost
4Device complexity
If single reactor stage is used, then process complexity is reduced, but ability to simultaneously remove nitrogen and saturate polyaromatics is insufficient
Solution Approach 1:
The single reactor is segmented into two reaction zones with different catalyst beds and operating conditions. The first zone handles desulfurization and denitrogenation, while the second zone handles polyaromatics saturation, enabling simultaneous achievement of multiple product quality requirements (low nitrogen, low sulfur, high Cetane Index) within a single reactor vessel, thus increasing product quality without requiring multiple separate reactors
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 yields diesel products with significantly improved Cetane Index, reduced nitrogen and sulfur concentrations, and lower aromatics content, meeting stringent quality standards without the use of expensive noble metal catalysts.
Implementation Method 1
contacting a distillate feedstock with a first catalyst contained within a first reaction zone to provide for the hydrodenitrogenation of organic nitrogen compounds and the saturation of polyaromatic compounds
Implementation Method 2
The treated effluent is passed to a high pressure interstage stripper, comprising a stripper vessel which defines a lower section, including a stripping zone, and an upper section, including a phase separation zone
Implementation Method 3
The stripped liquid fraction is contacted with a second catalyst contained within a second reaction zone to provide for the saturation of monoaromatics
Data Source
AI summary
A process for making high cetane diesel. The process includes contacting a distillate feedstock in a hydrodenitrogenation and polyaromatics saturation zone and passing the resulting treated effluent to a high pressure stripping zone. The stripped liquid fraction from the high pressure stripping zone is contacted with a base metal catalyst under monoaromatics saturation conditions to yield a reactor product. The reactor product undergoes a separation to provide a hydrogen portion and a dearomatized distillate portion with the hydrogen portion being recycled and introduced into the high pressure stripping zone.