OCM Catalyst Composition with Stable Promoter Support
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Solution Overview
Problem
The oxidative coupling of methane (OCM) process faces challenges with low carbon efficiency due to the oxidation of desired C2+ hydrocarbons to carbon dioxide, and alkali metal promoters in catalysts tend to evaporate at reaction temperatures, reducing catalyst performance over time.
Innovation Solution
A catalyst composition is developed with a specific formula [(AMz)1-eAEaRE1bRE2cATdOx)][(MmOn)f(AMz)e][MmOn]1-f, incorporating alkali metals, alkaline earth metals, and rare earth elements, supported on a metal oxide that reacts with the alkali metal at high temperatures to form a stable oxide reaction product, preventing promoter leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkali metal promoters are used to improve carbon efficiency and C2+ hydrocarbon selectivity, then carbon efficiency is improved, but catalyst stability deteriorates due to evaporation at reaction temperatures
Solution Approach 1:
The patent combines alkali metal promoters with alkaline earth metals and rare earth elements to form a composite catalyst system. This composite structure allows the alkali metal to provide high carbon efficiency while the other components mitigate evaporation, achieving both improved reliability and extended duration of action.
Solution Approach 2:
The patent modifies the chemical composition parameters of the catalyst by introducing specific ratios of alkaline earth metals and rare earth elements alongside the alkali metal promoter. These parameter changes alter the thermal stability characteristics, reducing evaporation rates while maintaining the carbon efficiency benefits.
2Productivity
If OCM reaction is conducted at high temperatures to improve methane conversion, then productivity is improved, but alkali metal promoter evaporation increases reducing catalyst stability
Solution Approach 1:
The composite catalyst system with multiple metal components creates a more stable chemical environment at high temperatures. The interactions between alkali metal, alkaline earth metal, and rare earth element compounds reduce the volatility of individual components, allowing high-temperature operation with maintained composition stability.
Solution Approach 2:
The alkaline earth metals and rare earth elements act as intermediary components that stabilize the alkali metal promoter at high temperatures. These intermediaries form stable phases or interactions that prevent excessive evaporation, enabling sustained high-temperature productivity.
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 composition achieves high carbon efficiency and stability, maintaining improved methane and oxygen conversion over extended periods, enhancing the commercial viability of the OCM process by reducing carbon dioxide selectivity and increasing C2+ hydrocarbon selectivity.
Implementation Method 1
supported on a metal oxide that reacts with the alkali metal at high temperatures to form a stable oxide reaction product
Implementation Method 2
oxidatively coupled, in presence of certain methane coupling catalysts, commercially high value chemicals, such as ethylene and other C2+ hydrocarbons
Implementation Method 3
alkali metals on account of their strong basicity can assist in mitigating the formation of certain intermediate oxide species such as oxidized methyl radicals
Data Source
AI summary
The invention relates to a composition containing a catalyst having high catalytic stability for conducting oxidative coupling of methane (OCM) at high carbon efficiency, while improving both methane and oxygen conversion. Particularly, the inventive catalyst is a metal oxide supported catalyst, which contains an alkali metal promoter and a mixed metal oxide component having at least one alkali earth metal and at least one rare earth metal. The metal oxide support is selected in a manner, such that at least a portion of the metal oxide support is capable of reacting with at least a part or whole of the alkali metal promoter under conditions of calcination during catalyst preparation. The invention further provides a method for preparing such a metal oxide supported catalyst composition, using a calcination process. Additionally, the invention further describes a process for producing C2+ hydrocarbons, using such a catalyst composition.