Bifunctional Catalyst for Deep Desulfurization and Octane Preservation
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Solution Overview
Problem
Current hydrodesulfurization catalysts, such as CoMo based catalysts, face challenges in achieving deep desulfurization of FCC gasoline while maintaining high octane numbers and reducing olefin content, which is essential for meeting stringent gasoline quality standards.
Innovation Solution
A bifunctional catalyst with a modified carrier composed of γ-Al2O3 and an acidic molecular sieve, adjusted with a binder, and loaded with VIB and VIII Group elements, enhances hydrodesulfurization and olefin isomerization efficiency by optimizing the Brønsted to Lewis acid sites ratio, allowing for deep desulfurization and olefin reduction without significant octane number loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a traditional CoMo based HDS catalyst is used for desulfurization of FCC gasoline, then good thermal stability and low price are achieved, but deep desulfurization is difficult to achieve and a large number of olefins are saturated causing large loss of octane number
Solution Approach 1:
The patent uses a composite catalyst carrier combining γ-Al2O3 and acidic molecular sieve (such as H-ZSM-5, H-Beta, or H-Y) to create a bifunctional catalyst. This composite structure provides both hydrodesulfurization activity from CoMo species and olefin isomerization activity from the acidic molecular sieve, enabling deep desulfurization while preserving octane number through selective olefin conversion to iso-olefins rather than complete saturation
Solution Approach 2:
The bifunctional catalyst performs multiple functions simultaneously: hydrodesulfurization to remove sulfur, olefin isomerization to maintain octane number, and selective hydrogenation. The acidic molecular sieve component provides shape-selective catalysis that directs olefin conversion toward isomerization products with higher octane numbers, while the CoMo component handles sulfur removal, achieving multiple goals in a single catalyst system
2Quantity of substance
If other kinds of hydrodesulfurization catalysts are developed to pursue high desulfurization rate, then sulfur content is reduced, but it is still difficult to meet the strict requirements of maintaining octane number while reducing olefin and desulfurizing FCC gasoline
Solution Approach 1:
The acidic molecular sieve component introduces localized acid sites with specific properties within the catalyst structure. These acid sites are concentrated in the molecular sieve crystallites, providing shape-selective catalysis that promotes olefin isomerization specifically, while the rest of the catalyst maintains hydrodesulfurization activity. This localized functional differentiation enables selective olefin conversion that preserves overall octane number
3Quantity of substance
If olefin content is reduced through saturation to meet gasoline quality standards, then sulfur content and olefin content are controlled, but octane number decreases significantly
Solution Approach 1:
Instead of completely saturating olefins through hydrogenation (the conventional approach), the patent uses the acidic molecular sieve to promote olefin isomerization, converting normal olefins to iso-olefins. This inverted approach maintains the olefin content necessary for high octane number while still reducing problematic olefin species. The iso-olefins produced have similar or higher octane numbers than the original olefins, thus avoiding significant octane loss
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 bifunctional catalyst achieves desulfurization rates of 90% or higher and olefin saturation of 30% or more, with minimal octane number loss, producing ultra-low sulfur or sulfur-free gasoline that meets strict quality standards.
Implementation Method 1
The modified catalyst carrier is a composite carrier prepared through mixing γ-Al2O3 and an acidic molecular sieve by a binder and calcining... adjust the ratio of Brønsted sites (BAS) to Lewis acid sites (LAS) on a surface of the bifunctional catalyst
Implementation Method 2
A bifunctional catalyst with hydrodesulfurization activity and isomerization activity... realize the purposes of deep desulfurization, olefin reduction and octane number preservation
Implementation Method 3
The modified catalyst carrier is a composite carrier prepared through mixing γ-Al2O3 and an acidic molecular sieve by a binder and calcining... olefin isomerization conversion of the bifunctional catalyst increased
Data Source
AI summary
Provided are an in situ bifunctional catalyst for deep desulfurization and increasing octane number of gasoline, and its preparation method and application. The bifunctional catalyst includes a modified catalyst carrier and a loaded active metal, where the modified catalyst carrier is a composite carrier prepared through mixing γ-Al2O3 and an acidic molecular sieve by a binder and calcining. When the bifunctional catalyst provided by the present application is used for hydrodesulfurization of gasolines, deep desulfurization, olefin reduction and octane number preservation can be realized simultaneously, thereby obtaining a high-quality oil product.