Thioetherification Guard Bed for Mercaptan Removal
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Solution Overview
Problem
Conventional methods, such as caustic scrubbers and adsorption techniques, are ineffective in removing mercaptans from charge gas streams, which can poison noble metal catalysts and reduce the effectiveness of hydrogenation reactors, especially in processes requiring low mercaptan levels.
Innovation Solution
A thioetherification process using a catalyst comprising palladium and silver to convert mercaptans into less volatile thioethers, which are then separated from the charge gas stream through distillation, effectively reducing mercaptan concentrations from up to 1000 ppm to less than 5 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional caustic scrubber technology is used to remove sulfur compounds from charge gas streams, then H2S and CO2 are effectively removed, but mercaptans remain in the stream and can poison noble metal catalysts
Solution Approach 1:
A guard bed containing a zeolite material is introduced as an intermediary component between the caustic scrubber and the hydrogenation catalyst. This guard bed specifically adsorbs mercaptans from the charge gas stream, preventing them from reaching and poisoning the noble metal catalyst while allowing other components to pass through
Solution Approach 2:
The guard bed utilizes a zeolite material with specific porous structure and surface properties that enable selective adsorption of mercaptan molecules. The porous structure provides high surface area for adsorption while the zeolite's molecular sieve properties allow size-selective and polarity-selective removal of mercaptans
2Object-affected harmful factors
If a zeolite guard bed is used to remove mercaptans from charge gas streams, then catalyst poisoning is prevented, but the high reactivity of the charge gas feed fouls the bed rapidly
Solution Approach 1:
The operating parameters of the guard bed are optimized by controlling temperature, pressure, and space velocity to enhance mercaptan adsorption capacity. The guard bed is positioned in a temperature zone that maximizes adsorption while minimizing fouling reactions, and the space velocity is adjusted to ensure sufficient contact time for mercaptan removal before the gas reaches the catalyst
3Reliability
If mercaptan levels are reduced to less than 5 ppm for CD-Hydro and olefin metathesis processes, then catalyst deactivation is minimized, but conventional removal methods are ineffective at achieving such low levels
Solution Approach 1:
The guard bed utilizes a zeolite material with specific porous structure and surface properties that enable selective adsorption of mercaptan molecules. The porous structure provides high surface area for adsorption while the zeolite's molecular sieve properties allow size-selective and polarity-selective removal of mercaptans, achieving concentrations below 5 ppm
Solution Approach 2:
The guard bed employs a composite zeolite material that combines multiple functional properties: high surface area for adsorption, molecular sieve capabilities for size-selective separation, and surface chemistry tailored for mercaptan affinity. This composite approach enables the guard bed to achieve ultra-low mercaptan levels that single-function materials cannot achieve
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 process enhances the efficiency and longevity of sulfur-sensitive catalysts and reactors by significantly reducing mercaptan levels, improving the performance of CD-Hydro and olefin metathesis processes by minimizing catalyst deactivation and reducing absorbent volume requirements.
Implementation Method 1
a catalyst which is capable of catalyzing the thioetherification of mercaptans to thioethers
Implementation Method 2
a distillation unit comprising an upper section and a lower section which is capable of separating lower boiling point hydrocarbons from the thioethers
Data Source
AI summary
This invention relates to thioetherification processes for the removal of mercaptans in charge gas streams. In particular, the invention relates to thioetherification processes for the removal of mercaptans using a catalyst comprising palladium and silver.