Selective Hydrogenation Catalyst with Ionic Liquids
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Solution Overview
Problem
Conventional methods for selective hydrogenation of acetylene in front-end processes face challenges such as thermal runaway, requiring strict temperature control and lengthy startup procedures, and often necessitate pre-charging with CO and inert gases, which are costly and pose safety concerns.
Innovation Solution
A method using a catalyst composition comprising a porous support, palladium, and at least one ionic liquid, allowing for selective hydrogenation of acetylene at high throughput with low CO concentrations without thermal runaway, and enabling rapid reactor startup without pre-charging with CO or inert gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional palladium-shell catalysts are used for front end selective hydrogenation, then acetylene conversion can be achieved, but thermal runaway occurs requiring strict temperature control and limiting productivity
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating ionic liquids (0.1-10 wt%) alongside palladium and promoters on the support. This compositional parameter change modifies the catalyst's electronic and geometric properties, enabling higher acetylene conversion rates while maintaining thermal stability and preventing runaway reactions.
Solution Approach 2:
The patent creates a composite catalyst material combining palladium, promoters (Cu, Zn, Al, Ga, In, or La), and ionic liquids on a support. This composite structure synergistically combines the high activity of Pd with the thermal stability and electronic modulation provided by the ionic liquid component, resolving the contradiction between high productivity and thermal safety.
2Reliability
If reactor startup is performed at low temperature to avoid thermal runaway, then safety is maintained, but acetylene reduction is incomplete and production time is extended
Solution Approach 1:
The ionic liquid component in the catalyst changes the temperature-dependent activity profile, allowing the reactor to be started at higher temperatures without thermal runaway risk. This parameter change enables complete acetylene reduction during startup while maintaining safety, thereby reducing startup time.
Solution Approach 2:
The catalyst composition self-regulates the reaction temperature through the thermal properties of the ionic liquid, which acts as an internal thermal buffer. This self-service mechanism eliminates the need for external temperature control during startup, allowing faster initiation while maintaining safety.
3Reliability
If conventional startup procedures with CO pre-charging are used, then thermal runaway is prevented, but costs increase and safety risks are introduced
Solution Approach 1:
The patent extracts and eliminates the need for CO pre-charging and inert gas pressurization steps from the startup procedure. The ionic liquid-containing catalyst inherently provides thermal runaway prevention, removing the requirement for these complex preliminary steps and simplifying the overall startup process while maintaining safety.
Solution Approach 2:
The catalyst composition provides self-contained thermal runaway prevention through the thermal and chemical properties of the ionic liquid, eliminating the need for external CO pre-charging systems and complex startup procedures. The system serves itself by using the catalyst's intrinsic properties to ensure safe operation.
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 method achieves high acetylene conversion with minimal ethylene conversion to ethane, reducing the risk of thermal runaway and simplifying the startup process, thereby improving operational efficiency and safety while reducing costs.
Implementation Method 1
contacting a catalyst composition comprising a porous support, palladium, and at least one ionic liquid with a process gas comprising ethylene, acetylene, hydrogen and carbon monoxide; wherein at least 90% of the acetylene present in the process gas is hydrogenated
Implementation Method 2
the activity of the hydrogenation catalyst under the process conditions must be carefully limited to avoid thermal runaway (an uncontrolled feedback loop, in which heat from the exothermic hydrogenation reaction increases the catalyst temperature, in turn increasing the rate of the hydrogenation reaction)
Data Source
AI summary
The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; acetylene, present in the process gas in an amount of at least 1 ppm; and 0 to 190 ppm or at least 600 ppm carbon monoxide. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway.