Oxygen-Free Methane Conversion Catalysts
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Solution Overview
Problem
Current methods for converting methane to value-added products, such as olefins, face challenges including high temperature oxidative conditions, carbon deposition, and low selectivity, particularly in direct conversion processes like oxidative coupling of methane and selective partial oxidation of methane, which hinder industrial scalability and efficiency.
Innovation Solution
A method for oxygen-free direct conversion of methane to olefins using metal-doped silicon-based catalysts in an amorphous molten state, where metal elements are lattice-doped into silicon-based materials, enabling continuous flow reactions without molecular oxygen, elemental sulfur, or sulfur oxide compounds, resulting in high olefin and aromatic selectivity with minimal coke deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxidative coupling of methane or selective partial oxidation of methane is used for direct conversion, then olefin production is achieved, but carbon deposition occurs and selectivity decreases
Solution Approach 1:
The patent removes oxygen from the reaction system entirely, extracting the harmful oxidative environment that causes carbon deposition. By using an oxygen-free atmosphere with inert gases (nitrogen, carbon dioxide, or their mixtures), the process eliminates the root cause of carbon deposition while maintaining olefin production through non-oxidative coupling mechanisms.
Solution Approach 2:
The patent changes the chemical environment parameter from oxidative to non-oxidative by replacing oxygen-containing atmospheres with oxygen-free inert gases. This parameter change fundamentally alters the reaction pathway, preventing carbon deposition while enabling sustained olefin production through controlled non-oxidative coupling of methane.
2Productivity
If high temperature oxidative conditions are used for direct conversion, then methane conversion is achieved, but catalyst life decreases due to deactivation
Solution Approach 1:
The patent implements an inert atmosphere by using oxygen-free gases (nitrogen, carbon dioxide, or their mixtures) to create a chemically stable environment. This inert environment protects the catalyst from oxidative deactivation and carbon deposition, extending catalyst life while maintaining high methane conversion rates through controlled non-oxidative reactions.
Solution Approach 2:
The patent converts the typically harmful effect of high temperatures (which cause catalyst deactivation and carbon deposition in oxidative environments) into a benefit by combining them with an oxygen-free atmosphere. The high temperature enables efficient methane activation and coupling, while the inert atmosphere prevents the harmful side effects, resulting in both high conversion and extended catalyst life.
3Manufacturing precision
If oxidative coupling conditions are used, then ethylene selectivity is improved, but over oxidation to CO2 increases
Solution Approach 1:
The patent extracts oxygen from the reaction system, eliminating the possibility of over-oxidation to CO2. By using an oxygen-free inert atmosphere, the process prevents the formation of CO2 while maintaining high ethylene selectivity through controlled non-oxidative coupling reactions, where methane molecules couple to form ethylene without excessive oxidation.
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 approach achieves high olefin selectivity (30-90%) and aromatic co-product selectivity (10-70%) with extended catalyst life (>100 hours), zero coke deposition, and easy product separation, making it suitable for industrial applications by maintaining stability under redox and hydrothermal conditions at high temperatures.
Implementation Method 1
A method for oxygen-free direct conversion of methane to olefins using metal-doped silicon-based catalysts in an amorphous molten state
Data Source
AI summary
A process of methane catalytic conversion produces olefins, aromatics, and hydrogen under oxygen-free, continuous flowing conditions. Such a process has little coke deposition and realizes atom-economic conversion. Under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750-1200° C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000-30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30-90%. And selectivity of aromatics is 10-70%. The catalyst for this methane conversion has a SiO2-based matrix having active species that are formed by confining dopant metal atoms in the lattice of the matrix.