Mild Hydrotreating Hydrocracking for Low Sulfur Diesel
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Solution Overview
Problem
Current hydroprocessing methods for upgrading distillate feedstocks, such as Light Cycle Oil, to produce diesel and naphtha products face challenges in achieving low sulfur content and high octane values, with high severity hydrotreating leading to excessive hydrogen consumption and modest diesel quality improvements.
Innovation Solution
Implementing a combination of mild hydrotreating and hydrocracking processes, allowing organic nitrogen to 'slip' from the hydrotreating to the hydrocracking catalyst bed, which suppresses hydrogenation and retains aromatic compounds, thereby improving the quality of naphtha and diesel products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high severity hydrotreating is used to reduce sulfur content, then sulfur levels in diesel are reduced, but hydrogen consumption increases excessively and cetane improvement is modest
Solution Approach 1:
The hydrotreating process is divided into two distinct zones: a first catalyst bed for sulfur removal and a second catalyst bed for nitrogen removal. This segmentation allows each zone to perform its specific function efficiently, reducing overall hydrogen consumption while achieving the desired sulfur reduction in diesel fuel.
Solution Approach 2:
The invention changes the operational parameters by using different catalysts in sequential beds with specific activity levels. The first bed uses a catalyst with high sulfur removal activity, while the second bed uses a catalyst optimized for nitrogen removal. This parameter differentiation enables selective removal of contaminants without excessive hydrogen consumption.
2Manufacturing precision
If high severity hydrotreating is used to upgrade distillate quality, then sulfur content is reduced, but cetane number improvement is modest
Solution Approach 1:
The hydrotreating process is divided into two distinct zones: a first catalyst bed for sulfur removal and a second catalyst bed for nitrogen removal. This segmentation allows each zone to perform its specific function efficiently, reducing overall hydrogen consumption while achieving the desired sulfur reduction in diesel fuel.
Solution Approach 2:
The invention changes the operational parameters by using different catalysts in sequential beds with specific activity levels. The first bed uses a catalyst with high sulfur removal activity, while the second bed uses a catalyst optimized for nitrogen removal. This parameter differentiation enables selective removal of contaminants without excessive hydrogen consumption.
3Quantity of substance
If conventional hydrocracking is used to produce naphtha, then aromatic compounds are hydrogenated to cycloalkanes, but octane number is reduced
Solution Approach 1:
The invention applies preliminary action by removing nitrogen compounds from the feedstock before hydrocracking in a separate second catalyst bed. This preliminary nitrogen removal prevents catalyst deactivation and allows subsequent hydrocracking to proceed with better aromatic retention, thereby maintaining higher octane numbers in the produced naphtha.
Solution Approach 2:
The invention changes the operational parameters by using different catalysts in sequential beds with specific activity levels. The first bed uses a catalyst with high sulfur removal activity, while the second bed uses a catalyst optimized for nitrogen removal. This parameter differentiation enables selective removal of contaminants without excessive hydrogen consumption.
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
This approach enhances the octane number of naphtha and reduces sulfur levels in diesel, meeting ultra low sulfur standards while optimizing hydrogen usage and aromatic retention, resulting in higher-value fuel components.
Implementation Method 1
organic nitrogen beneficially suppresses the hydrogenation function of the hydrocracking catalyst, thereby increasing aromatic retention in the upgraded hydrocarbon product
Implementation Method 2
The retained aromatics are generally mono-ring alkyl benzene compounds, having desirable octane values, which result from the cracking of 2-ring and multi-ring aromatic compounds present in the distillate feedstock
Data Source
AI summary
Methods are disclosed for the hydrotreating and hydrocracking of highly aromatic distillate feeds such as light cycle oil (LCO) to produce ultra low sulfur gasoline and diesel fuel. Optimization of hydrotreater severity improves the octane quality of the gasoline or naphtha fraction. In particular, the operation of the hydrotreater at reduced severity to allow at least about 20 ppm by weight of organic nitrogen into the hydrocracker feed is shown to lead to these important benefits. Post-treating of the hydrocracker effluent over an additional hydrotreating catalyst bed may be desired to meet specifications for ultra low sulfur fuel components.