Mesoporous Trapping Mass for Selective Mercaptan Capture
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Solution Overview
Problem
Current desulfurization processes for gasoline cuts, particularly those from catalytic cracking units, face challenges in selectively removing mercaptan-type compounds without hydrogenating monoolefins, leading to octane number loss and excessive hydrogen consumption.
Innovation Solution
A process utilizing a trapping mass with a specific porosity and metal content, comprising mesoporous and macroporous structures with a high specific surface area, to selectively trap mercaptans in hydrocarbon feedstocks, thereby preserving the octane number and reducing hydrogen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If catalytic hydrodesulfurization is used to remove sulfur compounds, then sulfur content is reduced, but monoolefins are hydrogenated leading to octane number loss
Solution Approach 1:
The desulfurization process is divided into two distinct stages: first, catalytic hydrodesulfurization to remove sulfur compounds; second, adsorption on a specialized mass to remove recombination mercaptans. This segmentation allows each stage to be optimized independently, preventing excessive hydrogenation of monoolefins while achieving deep desulfurization.
Solution Approach 2:
A specialized adsorbent mass with specific pore structure (mesopores and macropores) and metal content is introduced as an intermediary between the hydrodesulfurization catalyst and the feedstock. This intermediary selectively adsorbs mercaptan compounds without catalyzing hydrogenation of monoolefins, thus protecting the octane number while enabling deep desulfurization.
2Quantity of substance
If catalytic hydrodesulfurization is used to achieve deep desulfurization, then sulfur content is reduced to very low levels, but hydrogen consumption increases excessively
Solution Approach 1:
The process segments the sulfur removal function from the hydrogen consumption function. The first hydrodesulfurization stage consumes hydrogen to convert sulfur compounds to H2S, while the second adsorption stage removes recombination mercaptans without requiring additional hydrogen, thus reducing overall hydrogen consumption for deep desulfurization.
Solution Approach 2:
The adsorbent mass acts as an intermediary that removes mercaptans through physical adsorption rather than requiring hydrogenation. This intermediary mechanism eliminates the need for additional hydrogen input in the second stage, significantly reducing total hydrogen consumption compared to conventional single-stage hydrodesulfurization.
3Quantity of substance
If conventional hydrodesulfurization is used, then sulfur is removed non-selectively, but monoolefins are hydrogenated leading to high loss of octane number
Solution Approach 1:
The adsorbent mass is designed with local quality differentiation: it has high affinity for mercaptan compounds through specific pore structure and metal content, while being inert toward monoolefins. This local selectivity allows the system to remove sulfur compounds without hydrogenating unsaturated hydrocarbons, preserving the octane number.
Solution Approach 2:
The specialized adsorbent serves as an intermediary that provides selective removal of mercaptans through adsorption, decoupling the sulfur removal function from the hydrogenation function. This intermediary prevents the non-selective hydrogenation that occurs in conventional hydrodesulfurization, thereby preserving the octane number while achieving effective sulfur removal.
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 proposed process effectively traps mercaptans, achieving deep desulfurization while minimizing the hydrogenation of monoolefins, thus preserving the octane number and optimizing hydrogen usage.
Implementation Method 1
a process for trapping mercaptans contained in a sulfur-containing hydrocarbon feedstock... in the presence of a trapping mass comprising an active phase based on at least one group VIII, IB or IIB metal, and a mesoporous or macroporous support
Data Source
AI summary
Process for trapping mercaptans contained in a sulfur-containing hydrocarbon feedstock, in the presence of a trapping mass comprising an active phase based on at least one group VIII, IB or IIB metal, and a mesoporous or macroporous support, said trapping mass comprising a specific surface area of between 120 m2/g and 350 m2/g, and:the volume of mesopores with a diameter greater than or equal to 2 nm and less than 50 nm corresponds to between 40% and 70% by volume of the total pore volume of said trapping mass;the volume of macropores with a diameter greater than or equal to 50 nm corresponds to between 30% and 60% by volume of the total pore volume of said trapping mass.