Selective Hydrogenation Catalyst for Low-Sulfur Gasoline
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Solution Overview
Problem
Current processes for producing low-sulfur gasoline, particularly from catalytic cracking, face challenges in selectively hydrogenating diolefins while minimizing the hydrogenation of mono-olefins to preserve octane number and reduce hydrogen consumption, as well as effectively managing sulfur compounds to meet stringent environmental standards.
Innovation Solution
A process involving selective hydrogenation of polyunsaturated compounds in gasoline using a catalyst with specific characteristics, such as a specific surface area of 200-270 m^2/g, a molybdenum-to-nickel ratio, and sulfidation rates, which enables the hydrogenation of diolefins, weighting of light sulfur compounds, and isomerization of external olefins to internal olefins, followed by hydrodesulfurization to achieve low sulfur content while maintaining octane levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-selective hydrogenation is used to desulfurize gasoline, then sulfur content is reduced, but octane number is significantly lost and hydrogen consumption is high
Solution Approach 1:
The patent applies parameter changes by carefully controlling reaction conditions (temperature between 50-150°C, pressure, space velocity) to achieve selective hydrogenation of diolefins while minimizing mono-olefin hydrogenation. The catalyst composition (Group VIb metal at 1-20 wt%, Group VIII metal at 1-15 wt%) is optimized to promote diolefin saturation while preserving mono-olefins, thus reducing hydrogen consumption compared to non-selective hydrogenation.
Solution Approach 2:
The patent implements local quality by designing a catalyst with specific properties (Group VIb and Group VIII metals on porous support with controlled surface area 200-500 m²/g) that creates different reactivity zones. This enables selective hydrogenation of diolefins while leaving mono-olefins largely unaffected, achieving local selectivity in the hydrogenation process to reduce unnecessary hydrogen consumption.
2Quantity of substance
If non-selective hydrogenation is used to desulfurize gasoline, then sulfur content is reduced, but octane number is significantly lost
Solution Approach 1:
The patent uses parameter changes by operating at moderate temperatures (50-150°C) and optimizing catalyst composition to achieve selective hydrogenation. This prevents excessive hydrogenation of mono-olefins that would lead to paraffin formation and octane loss, while still effectively removing sulfur compounds through the modified feed composition.
Solution Approach 2:
The patent applies preliminary action by performing selective hydrogenation of diolefins before the main hydrodesulfurization process. This pre-treatment step modifies the feed composition by saturating diolefins while preserving mono-olefins, creating a more favorable feed for subsequent HDS that maintains higher octane numbers.
3Stability of the object's composition
If selective hydrogenation of diolefins is performed, then octane number is preserved, but the process complexity increases
Solution Approach 1:
The patent applies merging by combining the selective hydrogenation function and hydrodesulfurization function into a single integrated process step. By using a bifunctional catalyst (Group VIb + Group VIII metals) that performs both diolefin hydrogenation and sulfur removal, the process avoids the need for separate treatment units, thereby reducing overall process complexity while maintaining octane number.
Solution Approach 2:
The patent implements universality by designing a single catalyst system that performs multiple functions: selective hydrogenation of diolefins, hydrodesulfurization of sulfur compounds, and potential isomerization of olefins. This multi-functional catalyst simplifies the process equipment requirements compared to using separate catalysts for each function.
4Use of energy by moving object
If polyunsaturated compounds are present in gasoline, then hydrogenation potential is high, but polymerization gum formation increases and catalyst deactivation occurs
Solution Approach 1:
The patent applies preliminary action by performing selective hydrogenation of diolefins (polyunsaturated compounds) before hydrodesulfurization. This pre-saturation step converts reactive diolefins into stable mono-olefins, eliminating the source of polymerization gum formation and protecting the downstream HDS catalyst from deactivation while still utilizing the hydrogenation potential.
Solution Approach 2:
The patent implements preliminary anti-action by selectively hydrogenating diolefins to prevent their polymerization into gums. By addressing the polyunsaturated compounds first, the process prevents the harmful polymerization reactions that would otherwise occur, protecting catalyst reliability and system operation.
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 effectively reduces sulfur content to less than 50 ppm, preferably less than 10 ppm, while limiting the loss of octane number and hydrogen consumption, and improves the isomerization of mono-olefins, thereby enhancing the efficiency of the desulfurization process.
Implementation Method 1
the hydrogenation of the polyunsaturated compounds into monounsaturated compounds
Implementation Method 2
the isomerization of the monounsaturated compounds comprising an external C=C double bond into their isomer with an internal C=C double bond
Implementation Method 3
the weighting of the saturated light sulfur compounds by reaction with the unsaturated compounds
Implementation Method 4
the reactions of reduction of sulfur to hydrogen sulphide (H2S)
Data Source
AI summary
Selective hydrogenation of gasoline comprising polyunsaturated compounds and sulfurous light compounds, comprises conjointly hydrogenating the polyunsaturated compounds into monounsaturated compounds, weighting sulfurous saturated light compounds by reacting with unsaturated compounds, and isomerizing the monounsaturated compounds comprising an external double bond into their isomer having an internal double bond, where: the process is performed using a catalyst containing at least one VIb group metal and at least one VIII group metal deposited on a porous support. Selective hydrogenation of gasoline comprising polyunsaturated compounds and sulfurous light compounds, comprises conjointly hydrogenating the polyunsaturated compounds into monounsaturated compounds, weighting sulfurous saturated light compounds by reacting with unsaturated compounds, and isomerizing the monounsaturated compounds comprising an external double bond (C=C) into their isomer having an internal double bond (C=C), where: the process is performed using a catalyst containing at least one group VIb metal and at least one group VIII metal deposited on a porous support; the weight content of the group VIb element with respect to the weight of the catalyst is 6-18 wt.%; the weight content of the oxide of the group VIII element with respect to the weight of the catalyst is 4-12 wt.%; the specific surface area of the catalyst is 200-270 m 2>/g; the density of the group VIb element, expressed as the ratio of the weight content of oxide of the group VIb element to the specific surface area of the catalyst, is 4-6.10 -> 4> g/m 2>; the molar ratio between the group VIII metal and the group VIb metal is 0.6-3 mol/mol. An independent claim is included for desulfurization of gasoline comprising sulfurous light compounds comprising performing selective hydrogenation, separating the gasoline in two fractions respectively including a light gasoline and a heavy gasoline, and processing the separated heavy gasoline on a catalyst allowing to at least partially decompose the sulfur compounds into hydrogen sulfide.