Selective Hydrogenation for Olefinic Gasoline Hydrotreatment
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Solution Overview
Problem
Current hydrodesulphurization processes are hindered by the deactivation of catalysts due to the presence of carbon oxides in hydrogen, which affects the selective hydrogenation of polyunsaturated compounds and the conversion of saturated sulphur compounds, leading to reduced catalytic activity and increased sulphur content in gasoline.
Innovation Solution
A process utilizing hydrogen with a limited CO+CO2 content of less than 1000 ppmv, preferably less than 500 ppmv, for selective hydrogenation and subsequent hydrodesulphurization stages, employing catalysts like nickel or cobalt sulphides on inert supports, to achieve high catalytic efficiency and reduce sulphur content in gasoline without hydrogenating olefins, thereby maintaining octane number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydrogen with high CO and CO2 content is used in hydrodesulphurization process, then hydrogen source versatility and cost are improved, but catalyst deactivation increases and sulphur removal efficiency decreases
Solution Approach 1:
The patent applies preliminary action by introducing a selective hydrogenation stage before the hydrodesulphurization stage. This preliminary hydrogenation step selectively converts polyunsaturated compounds (diolefins and acetylenics) into saturated compounds, removing the harmful substances that would cause catalyst deactivation in the subsequent hydrodesulphurization process. This allows the use of hydrogen with higher CO and CO2 content from varied sources while maintaining catalyst reliability.
2Reliability
If selective hydrogenation of polyunsaturated compounds is performed, then catalyst reliability is improved, but olefin hydrogenation increases and octane number decreases
Solution Approach 1:
The patent applies local quality by using a catalyst with specific composition (sulphurized compound containing nickel, cobalt, or iron) that exhibits selective catalytic activity. This catalyst is designed to selectively hydrogenate polyunsaturated compounds (diolefins and acetylenics) while minimizing hydrogenation of mono-unsaturated olefins. The local quality of the catalyst surface and its selective interaction with different hydrocarbon types enables this differentiation, maintaining olefin content and octane number while removing harmful polyunsaturates.
3Quantity of substance
If deep desulphurization is implemented, then sulphur content is reduced, but process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the desulphurization process into two distinct sequential stages: (1) a selective hydrogenation stage that converts polyunsaturated compounds to saturated compounds, and (2) a hydrodesulphurization stage that removes sulphur compounds. This segmentation allows each stage to be optimized independently - the first stage prepares the feedstock by removing catalyst-poisoning polyunsaturates, while the second stage efficiently removes sulphur. This segmented approach achieves deep desulphurization (reducing sulphur to below 10 ppm) while maintaining manageable process complexity through modular design.
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 achieves substantial hydrogenation of polyunsaturated compounds (>70%) with minimal hydrogenation of mono-unsaturated compounds and effective conversion of sulphur compounds, enabling the production of low-sulphur gasoline while maintaining the octane number, using varied and cost-effective hydrogen sources.
Implementation Method 1
a selective hydrogenation stage comprising the hydrogenation of polyunsaturated compounds (diolefins and acetylenics) present in the olefinic gasoline on a catalyst comprising, on an inert support, a sulphurized compound
Implementation Method 2
the hydrogenation of polyunsaturated compounds (diolefins and acetylenics) present in the olefinic gasoline
Implementation Method 3
a stage of selective conversion of the saturated sulphur compounds of this same gasoline, or of part of the selectively hydrogenated gasoline
Data Source
AI summary
The invention relates to a process for the hydrotreatment of an olefinic gasoline comprising at least one selective hydrogenation stage, and generally of simultaneous conversion of mercaptans by weight increase, in which the makeup hydrogen used in this stage or these stages has a reduced CO+CO2 content, preferably comprised between 5 and 200 ppmv. Most often, the CO content is comprised between 1 and 20 ppmv. The process typically makes it possible to hydrorefine an olefinic gasoline by more or less eliminating the diolefins and sulphur compounds.