Catalytic Distillation for Low-Sulfur Gasoline Octane Preservation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing reformulated gasolines with low sulfur content, such as catalytic cracking gasolines, face challenges in reducing sulfur levels while preserving octane numbers and efficiently processing diolefins, often requiring high hydrogen consumption and significant investment, with existing processes either degrading octane numbers or failing to achieve very low sulfur levels in the light fraction.
Innovation Solution
A process involving a distillation column with a catalyst comprising nickel and molybdenum, operating in sulfide form, where gasoline is treated with hydrogen to selectively convert mercaptans into heavier sulfur compounds, separating a desulfurized light fraction from a heavy fraction, while also hydrogenating diolefins and isomerizing olefins to maintain octane numbers and reduce sulfur content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrodesulfurization is applied to catalytic cracking gasoline, then sulfur content is reduced, but octane number drops significantly due to olefin saturation
Solution Approach 1:
The gasoline feedstock is divided into light fraction (boiling point <120°C) and heavy fraction (boiling point ≥120°C). The light fraction is selectively treated in a distillation column with catalyst positioned above the feed injection point, allowing desulfurization of only the light fraction while leaving the heavy fraction untreated, thus preserving overall octane number
Solution Approach 2:
The catalyst is positioned in a specific location (above the feed injection point) within the distillation column to create a localized reaction zone. This ensures that demercaptanization occurs only in the light fraction as it passes through the catalytic bed, while the heavy fraction bypasses the catalyst, achieving selective treatment with different quality outcomes for different fractions
2Manufacturing precision
If fractionation into multiple fractions is performed, then desulfurization efficiency improves, but device complexity and investment cost increase
Solution Approach 1:
The distillation column and catalytic reactor are merged into a single integrated unit. The catalyst is positioned within the distillation column above the feed injection point, combining the separation and reaction functions in one device, thereby reducing the number of separate units needed and simplifying the overall process
Solution Approach 2:
The distillation column performs multiple functions: it separates the gasoline into light and heavy fractions based on boiling point, and simultaneously serves as the reaction vessel where the catalytic demercaptanization occurs. This multi-functional design reduces the need for separate fractionation and treatment units
3Duration of action of moving object
If catalyst is positioned below feed injection point, then contact time increases, but light fraction with low sulfur content cannot be effectively separated
Solution Approach 1:
Instead of placing the catalyst below the feed injection point (conventional approach), the catalyst is invertedly positioned above the feed injection point. This reversal allows the light fraction to contact the catalyst as it rises through the column, enabling effective demercaptanization while maintaining the ability to separate the treated light fraction at the column top
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 process achieves a sulfur content of less than 50 ppm in the light gasoline fraction with high conversion efficiency (>90%) and minimal hydrogen consumption, preserving octane numbers and reducing the need for additional hydrodesulfurization steps, thus meeting stringent environmental standards with reduced investment costs.
Implementation Method 1
a stage for treating gasoline in the presence of hydrogen in a distillation column (2) comprising at least one reaction zone (3) including at least one catalyst, with the catalyst being in sulfide form and comprising a substrate, at least one element that is selected from group VIII, and at least one element that is selected from group VIb
Implementation Method 2
The gasoline that distills at the top of the catalytic column is brought into contact with the catalyst of the reaction zone (3) and the hydrogen in such a way as to provide desulfurized light gasoline
Implementation Method 3
Gasoline is injected into the distillation column at a level located below the reaction zone (3) in such a way as to separate a desulfurized light gasoline at a point located above the reaction zone and a heavy gasoline comprising the majority of the sulfur-containing compounds at the bottom of the column
Data Source
AI summary
This invention relates to a process for treatment of a gasoline that comprises diolefins, olefins and sulfur-containing compounds including mercaptans, consisting of a stage for treatment of the gasoline in a distillation column (2) comprising at least one reaction zone (3) including at least one catalyst that makes it possible to carry out the addition of mercaptans to the olefins that are contained in the gasoline that distills toward the top of the catalytic column.