Nickel-Molybdenum Catalyst Pretreatment for Selective Hydrogenation
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Solution Overview
Problem
Existing catalysts used for selective hydrogenation of unsaturated hydrocarbons in aromatic fractions suffer from high aromatic loss and short durability, making them inefficient for long-term operation.
Innovation Solution
A three-step pretreatment process for a nickel-molybdenum catalyst, involving sulfidation, oxidation (calcination), and reduction, is employed to enhance its selective hydrogenation activity while minimizing aromatic loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing catalysts are used for selective hydrogenation of unsaturated hydrocarbons in aromatic fractions, then hydrogenation activity is achieved, but aromatic loss increases and durability decreases
Solution Approach 1:
The catalyst undergoes preliminary treatment steps (sulfidation followed by oxidation) before actual hydrogenation operation. This preliminary action modifies the catalyst surface properties and metal oxidation state, creating optimal conditions for selective hydrogenation that minimizes aromatic ring saturation while maintaining high activity for unsaturated hydrocarbon conversion.
Solution Approach 2:
The invention changes the oxidation state parameter of the catalyst through controlled oxidation treatment after sulfidation. By adjusting the oxidation conditions and timing, the catalyst achieves an optimal oxidation state that enhances selectivity for unsaturated hydrocarbons over aromatic compounds, thereby reducing aromatic loss while maintaining hydrogenation activity.
2Productivity
If existing catalysts are used for selective hydrogenation, then unsaturated hydrocarbons are removed, but catalyst durability decreases
Solution Approach 1:
The dual treatment process of sulfidation followed by oxidation serves as a preliminary activation step that stabilizes the catalyst structure and surface properties before prolonged operation. This preliminary action creates a more durable catalyst that maintains its hydrogenation activity and selectivity over extended periods, reducing deactivation and extending service life.
3Productivity
If conventional hydrogenation is performed without selective pretreatment, then unsaturated hydrocarbons are converted, but aromatic hydrocarbons are also hydrogenated causing product loss
Solution Approach 1:
The invention changes the catalyst's chemical state through controlled oxidation after sulfidation, creating a surface environment that favors hydrogenation of unsaturated hydrocarbons while being less active toward aromatic ring saturation. This parameter change in oxidation state enables selective conversion that preserves aromatic hydrocarbons while effectively removing unsaturated components.
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 pretreated catalyst effectively removes unsaturated hydrocarbons from aromatic fractions with minimal aromatic loss, maintaining high hydrogenation activity even during long-term operation.
Implementation Method 1
sulfidation, oxidation (calcination), and reduction
Implementation Method 2
sulfidation, oxidation (calcination), and reduction
Implementation Method 3
selective hydrogenation of unsaturated hydrocarbons in an aromatic fraction
Data Source
AI summary
Disclosed is a method for providing improved hydrogenation activity by pretreating a catalyst in a three-step manner before selective hydrogenation of unsaturated hydrocarbons in an aromatic fraction in the presence of an oxide-type bimetallic (particularly nickel-molybdenum) supported catalyst.