Flash Alumina Catalyst for Hydrodesulfurization
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Solution Overview
Problem
Existing hydrodesulfurization processes for gasoline cuts from fluidized-bed catalytic cracking units face challenges in reducing sulfur content without significantly reducing the octane number, due to the hydrogenation of olefins.
Innovation Solution
A catalyst comprising an alumina support obtained by dehydration of aluminum hydroxide or oxyhydroxide, combined with metals from group VIb (such as molybdenum), group VIII (such as cobalt), and phosphorus, with specific molar ratios, is used in the hydrodesulfurization process to improve catalytic activity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrodesulfurization catalysts are used to reduce sulfur content, then sulfur removal efficiency is improved, but octane number decreases due to olefin hydrogenation
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by incorporating phosphorus in a specific molar ratio (0.2-0.35) relative to group VIb metals, and by using alumina with controlled surface area (150-300 m²/g) and pore volume (0.4-1.2 cm³/g). These parameter changes optimize the catalyst's selectivity for hydrodesulfurization while suppressing olefin hydrogenation, thus reducing sulfur content without significantly decreasing octane number
Solution Approach 2:
The patent creates a composite catalyst system combining group VIb metals (Mo, W), group VIII metals (Co, Ni), and phosphorus on an alumina support. This composite structure synergistically enhances hydrodesulfurization activity while improving selectivity. The phosphorus-modified alumina support with specific physical properties works together with the metal-phosphorus active phase to achieve both high sulfur removal and olefin preservation
2Productivity
If phosphorus is added to improve hydrodesulfurization activity, then desulfurization efficiency is improved, but selectivity for olefin preservation deteriorates
Solution Approach 1:
The patent precisely controls the molar ratio of phosphorus to group VIb metals within 0.2-0.35, and the alumina support surface area within 150-300 m²/g. This dual parameter optimization ensures that phosphorus enhances hydrodesulfurization activity through appropriate metal-phosphorus complex formation, while the controlled alumina surface area prevents excessive phosphorus aggregation that would harm selectivity. The balanced parameters achieve both high productivity and precision
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 catalyst achieves better conversion of feedstock with improved catalytic activity and selectivity, effectively reducing sulfur content while minimizing the hydrogenation of olefins and thus preserving the octane number.
Implementation Method 1
an alumina support obtained by dehydration of an aluminum hydroxide or oxyhydroxide at a temperature of between 400 and 1200° C.
Implementation Method 2
hydrodesulfurization of a sulfur-containing olefinic gasoline cut in which said gasoline cut, hydrogen and a catalyst are brought into contact
Implementation Method 3
limit the hydrogenation of the unsaturated compounds present
Data Source
AI summary
The invention relates to a method for hydrodesulfurization of a sulfur-containing olefinic gasoline cut wherein said gasoline cut, hydrogen and a catalyst comprising an alumina support obtained by dehydration of an aluminum hydroxide or oxyhydroxide at a temperature of between 400° C. and 1200° C. and for a time of between 0.1 seconds and 5 seconds, at least one metal from group VIB, at least one metal from group VIII, and phosphorus are brought into contact, the molar ratio between the phosphorus and the metal from group VIB being between 0.2 and 0.35.