Mild Hydrodesulfurization with Gas Phase Oxidation for Ultra-Low Sulfur Fuels
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Solution Overview
Problem
Current methods for desulfurizing hydrocarbon fuels to ultra-low sulfur levels are costly and inefficient, particularly in removing refractory sulfur-containing compounds, as they require severe operational conditions and involve subjecting entire fuel streams to oxidation reactions, leading to high capital and operating costs and undesired side reactions.
Innovation Solution
An integrated process combining mild hydrodesulfurization and gas phase oxidative desulfurization, where the fuel stream is fractionated to separate labile and refractory sulfur compounds, allowing for targeted desulfurization of refractory compounds in a gas phase catalytic oxidation zone, reducing equipment capacity and avoiding unnecessary oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If severe operational conditions are used to remove refractory sulfur-containing compounds, then sulfur removal efficiency is improved, but capital and operating costs increase
Solution Approach 1:
The fuel stream is divided into two fractions based on boiling point: a first fraction containing refractory sulfur compounds (boiling at or above target cut point) and a second fraction containing labile sulfur compounds (boiling below target cut point). This segmentation allows each fraction to be treated with appropriate desulfurization methods, improving overall efficiency while reducing costs.
Solution Approach 2:
Different desulfurization approaches are applied to different fractions: the first fraction undergoes gas phase catalytic oxidation specifically targeted at refractory sulfur compounds, while the second fraction is removed separately without oxidation. This local quality approach ensures that harsh oxidation conditions are applied only where necessary, minimizing costs while maintaining high sulfur removal efficiency.
2Manufacturing precision
If the entire fuel stream is subjected to oxidation reactions, then sulfur removal is improved, but undesired side reactions increase
Solution Approach 1:
The second fraction containing labile sulfur compounds is extracted and removed from the oxidation process entirely. Only the first fraction containing refractory sulfur compounds is subjected to gas phase catalytic oxidation. This extraction prevents labile compounds from undergoing unnecessary oxidation, eliminating undesired side reactions while maintaining effective sulfur removal from the refractory fraction.
Solution Approach 2:
The fuel stream is segmented into fractions that are then treated differently: the first fraction undergoes oxidation while the second fraction is removed separately. This segmentation ensures that oxidation reactions occur only where necessary, preventing undesired side reactions in the labile fraction while effectively removing sulfur from the refractory fraction.
3Productivity
If equipment capacity is increased to handle entire fuel streams, then desulfurization capability is improved, but capital investment increases
Solution Approach 1:
The fuel stream is segmented into fractions that are processed separately. The oxidation reactor only needs to handle the first fraction containing refractory sulfur compounds, which is a smaller volume than processing the entire fuel stream. This segmentation reduces the required equipment capacity and associated capital investment while maintaining effective desulfurization capability for the target compounds.
Solution Approach 2:
Instead of applying oxidation to the entire fuel stream, the process applies oxidation only to the portion (first fraction) that contains refractory sulfur compounds requiring removal. This partial action approach reduces equipment capacity requirements and capital investment while achieving the necessary desulfurization capability for the problematic fraction.
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 minimizes costs and optimizes desulfurization by operating under milder conditions, selectively removing refractory sulfur compounds, and producing hydrocarbon fuels with ultra-low sulfur levels while avoiding harsh oxidation side reactions.
Implementation Method 1
contacting the fuel stream with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to remove labile organosulfur compounds
Implementation Method 2
mild hydrodesulfurization of a fuel stream to remove labile organosulfur compounds
Implementation Method 3
gas phase oxidative desulfurization of a targeted fraction to remove refractory organosulfur compounds
Implementation Method 4
converting the refractory organosulfur compounds into sulfur dioxide and useful oxygenated products as well as sulfur-deficient hydrocarbons
Implementation Method 5
a flashing column downstream of the hydrodesulfurization reaction zone to separate the hydrotreated effluent into two hydrocarbon fuel fractions
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Desulfurization of hydrocarbonfeedsis achieved by first contacting the entire feed with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone operating under mild conditions to remove the labile organosulfur compounds. A flashing column downstream of the hydrodesulfurization reaction zone fractionates the effluent at a target cut point temperature to obtain two hydrocarbon fuel fractions. A first fraction boiling at or above the target cut point temperature contains the remaining refractory organosulfur compounds. A second fraction boiling below the target cut point temperature is substantially free of organosulfur compounds, since the organosulfur compounds boiling in the range of this fraction were the labile organosulfur compounds which were initially removed by mild hydrodesulfurization. The first fraction is contacted with a gaseous oxidizing agent over an oxidation catalyst having a formula CuxZn1-xA12O4 in a gas phasecatalytic oxidation reaction zone to convert the refractory organosulfur compounds to SOx and low sulfur hydrocarbons. The by-product SOx is subsequently removed, producing a stream containing a reduced level of organosulfur compounds.