Pt-Bi/ZSM-5 Catalyst Non-Oxidative Methane Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for the oxidative coupling of methane face challenges in achieving high carbon selectivity and conversion to valuable C2 hydrocarbons, with existing non-oxidative methods limited by catalyst deactivation and coke formation, making them industrially uneconomic.
Innovation Solution
A bimetallic catalyst comprising platinum and bismuth supported on ZSM-5 zeolite is used to selectively convert methane to ethane with high carbon selectivity (>90%) and moderate temperature stability, preventing coke formation and maintaining catalyst activity for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oxidative coupling of methane is used to produce C2 hydrocarbons, then carbon selectivity towards C2 species can be improved, but carbon selectivity towards CO/CO2 increases unavoidably
Solution Approach 1:
The patent inverts the conventional oxidative coupling approach by using non-oxidative conditions. Instead of oxidizing methane and accepting CO/CO2 as unavoidable byproducts, the invention uses a bimetallic Pt-Bi catalyst to couple methane molecules directly through a different mechanism that produces C2 hydrocarbons without significant oxidation, thereby eliminating the trade-off between C2 selectivity and CO/CO2 formation
Solution Approach 2:
The patent changes the fundamental reaction parameter from oxidative to non-oxidative conditions. By switching from oxidation-based coupling to catalytic coupling under non-oxidative atmosphere, the reaction pathway is altered to avoid over-oxidation to CO/CO2 while maintaining high C2 selectivity through the specific Pt-Bi catalyst system
2Loss of substance
If non-oxidative coupling of methane is used to improve carbon atom economy, then catalyst deactivation and coke formation occur, limiting catalyst lifetime
Solution Approach 1:
The patent employs a composite bimetallic catalyst system consisting of platinum and bismuth metals supported on a carrier. This composite structure combines the benefits of both metals: platinum provides catalytic activity for methane activation while bismuth prevents coke formation and catalyst deactivation, thereby maintaining both high carbon atom economy and extended catalyst lifetime simultaneously
Solution Approach 2:
Bismuth acts as an intermediary element in the catalytic system. It mediates between the methane activation function of platinum and the prevention of coke deposition. The bismuth component interacts with the platinum sites to modify the reaction pathway and prevent carbonaceous deposits that would otherwise deactivate the catalyst, thus preserving catalyst lifetime while maintaining high carbon efficiency
3Productivity
If high temperature is used in oxidative coupling of methane, then reaction rate increases, but energy consumption and equipment requirements increase
Solution Approach 1:
The patent changes the temperature parameter from high (>700°C in conventional OCM) to moderate (250-700°C) range. This parameter change is enabled by the novel non-oxidative mechanism and bimetallic catalyst, which provide sufficient activity at lower temperatures, thereby reducing energy consumption while maintaining acceptable reaction rates and 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 method achieves stable methane conversion to ethane with carbon selectivity greater than 90% and methane conversion of 2-3% at moderate temperatures (500-700°C), demonstrating improved carbon atom economy and catalyst stability compared to existing technologies.
Implementation Method 1
Catalytic transformation of methane to value-added chemicals plays an important role in methane utilization. Non-oxidative coupling of methane (NOCM) to form C2 hydrocarbons has been considered since the 1990s. A bimetallic catalyst comprising platinum and bismuth supported on ZSM-5 zeolite is used to selectively convert methane to ethane with high carbon selectivity (>90%)
Implementation Method 2
It has been reported that C2H6 and H2 were immediately produced when CH4 was fed continuously over a commercial 6% wt Pt/SiO2 catalyst at low temperature 250° C. This indicates that methane can be activated at temperature lower than typically used in OCM (>700° C.)
Data Source
AI summary
A method for producing hydrocarbons and hydrogen from methane. The method includes packing a catalyst comprising platinum, bismuth and a support material into a reactor; introducing a reactant mixture containing methane into the reactor such that the reactant mixture containing methane is in close contact with the reactant mixture; and heating the reactant mixture containing methane to a temperature for a period of time.