Rejuvenated Catalyst for Selective Hydrodesulfurization
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Solution Overview
Problem
Current hydrodesulfurization processes for gasoline cuts face challenges in achieving high selectivity and activity while minimizing the hydrogenation of olefins, leading to a significant drop in octane number and increased catalyst replacement costs due to reduced activity and selectivity of rejuvenated catalysts.
Innovation Solution
A process involving a rejuvenated catalyst with specific metal compositions, an oxide support, and organic compounds containing oxygen, nitrogen, or sulfur, which is sulfidated and used in a hydrodesulfurization reaction at controlled temperatures and pressures to maintain catalyst activity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional hydrodesulfurization processes are used to remove sulfur from gasoline, then sulfur content is reduced, but octane number drops significantly due to hydrogenation of olefins
Solution Approach 1:
The patent applies parameter changes by precisely controlling reaction conditions (temperature between 200-400°C, pressure between 1-3 MPa, hourly space velocity between 1-10 h⁻¹, hydrogen/gasoline ratio between 100-1200 Sl/l) to favor hydrodesulfurization over hydrogenation. The catalyst composition is also modified with specific metal ratios (Co/Mo or Ni/Mo between 0.5-2.0) and organic compounds to change the catalytic properties and achieve selective sulfur removal while preserving olefins.
Solution Approach 2:
The patent uses composite catalyst materials comprising metal group VIII (Co or Ni), metal group VIb (Mo), oxide support (alumina, silica, or silica-alumina), and organic compounds containing oxygen, nitrogen, and/or sulfur. This composite structure enables simultaneous hydrodesulfurization activity and olefin preservation, resolving the contradiction between sulfur removal and octane maintenance.
2Ease of manufacture
If catalysts are regenerated to reduce replacement costs, then economic efficiency improves, but catalyst activity and selectivity decrease
Solution Approach 1:
The patent applies preliminary action by adding organic compounds (such as carboxylic acids, alcohols, or their derivatives) to the regenerated catalyst before actual use. This pre-treatment restores the catalyst's active sites and chemical properties, ensuring high activity and selectivity are recovered before the catalyst is put into service for hydrodesulfurization.
Solution Approach 2:
The patent changes the chemical parameters of the regenerated catalyst by introducing organic compounds that modify the catalyst surface properties. This restores the catalyst's effectiveness, maintaining high hydrodesulfurization activity and olefin selectivity even after regeneration, thereby resolving the reliability issue.
3Productivity
If process conditions are optimized for high hydrodesulfurization activity, then sulfur removal efficiency improves, but olefin hydrogenation increases
Solution Approach 1:
The patent applies local quality by creating different functional zones within the catalyst structure. The catalyst contains specific active sites (metal sulfides of Co-Mo or Ni-Mo) that are highly selective for sulfur removal, while the organic compounds and support structure provide selective properties that discourage olefin hydrogenation. This localized functional differentiation enables high productivity with minimal substance loss.
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: catalyst composition (metal ratios, organic compound addition), reaction temperature (200-400°C), pressure (1-3 MPa), and space velocity (1-10 h⁻¹). These parameter changes create optimal conditions where hydrodesulfurization proceeds rapidly while olefin hydrogenation is suppressed, resolving the contradiction between productivity and substance conservation.
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 process effectively transforms organosulfur compounds into hydrogen sulfide while limiting olefin hydrogenation, maintaining catalyst activity and selectivity, thus reducing the need for frequent catalyst replacement and minimizing octane loss.
Implementation Method 1
process for the hydrodesulfurization of a sulfur-containing olefinic gasoline cut in which said gasoline cut, hydrogen and a rejuvenated catalyst are brought into contact
Implementation Method 2
limiting the hydrogenation of the olefins present
Data Source
AI summary
The invention relates to a process for the hydrodesulfurization of a sulfur-containing olefinic gasoline cut in which said gasoline cut, hydrogen and a rejuvenated catalyst are brought into contact, said hydrodesulfurization process being carried out at a temperature of between 200° C. and 400° C., a total pressure of between 1 and 3 MPa, an hourly space velocity, defined as being the flow rate by volume of feedstock relative to the volume of catalyst, of between 1 and 10 h−1 and a hydrogen/gasoline feedstock ratio by volume of between 100 and 1200 Sl/l, said rejuvenated catalyst resulting from a hydrotreating process and comprises at least one metal from group VIII, at least one metal from group VIb, an oxide support and at least one organic compound containing oxygen and/or nitrogen and/or sulfur.