Segmented Catalyst System for Methane Oxidative Coupling
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Solution Overview
Problem
Catalysts for the oxidative coupling of methane (OCM) reaction face a trade-off between low temperature activity and high coupling selectivity, with low temperature catalysts risking decreased selectivity at higher temperatures and high selectivity catalysts requiring high temperatures.
Innovation Solution
An olefin production device and method utilizing a first catalyst with zirconium or alkaline earth metal oxides supported on a substrate, followed by a second catalyst with tungsten oxide or alkali metal carbonates, where the reaction heat from the first catalyst is used to achieve high methane conversion and selectivity in the second catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a low temperature catalyst is used for OCM reaction, then the reaction can proceed at low temperatures below 700°C, but the coupling selectivity may decrease at high temperatures
Solution Approach 1:
The catalyst system is segmented into two distinct catalysts with different functions: the first catalyst (low temperature type) activates methane at lower temperatures, while the second catalyst (high selectivity type) ensures high coupling selectivity. This segmentation allows each catalyst to operate in its optimal temperature range, resolving the contradiction between low temperature operation and high selectivity maintenance.
Solution Approach 2:
The invention changes the temperature parameter dynamically by using the first catalyst at lower temperatures (below 700°C) for methane activation, then allowing the gas to be heated before entering the second catalyst which operates at higher temperatures for high selectivity coupling. This parameter change strategy enables both low temperature operation and high coupling selectivity.
2Manufacturing precision
If a high coupling selectivity catalyst is used for OCM reaction, then high coupling selectivity is achieved, but the reaction requires high temperatures
Solution Approach 1:
The catalyst system is segmented into two distinct catalysts with different functions: the first catalyst (low temperature type) activates methane at lower temperatures, while the second catalyst (high selectivity type) ensures high coupling selectivity. This segmentation allows each catalyst to operate in its optimal temperature range, resolving the contradiction between low temperature operation and high selectivity maintenance.
Solution Approach 2:
The first catalyst performs preliminary methane activation at lower temperatures before the gas enters the second catalyst. This preliminary action prepares the reactants in a state that allows the second catalyst to achieve high coupling selectivity at elevated temperatures, effectively separating the temperature requirement from the selectivity requirement.
3Device complexity
If a single catalyst is used for OCM reaction, then the device complexity is reduced, but it is difficult to achieve both high methane conversion and high coupling selectivity simultaneously
Solution Approach 1:
The invention merges two catalysts with complementary functions into a single reactor system. The first catalyst provides low-temperature activity for methane activation, while the second catalyst provides high-temperature selectivity for coupling reactions. This merging allows the system to achieve both high methane conversion and high coupling selectivity that would be difficult to obtain with a single catalyst.
Solution Approach 2:
The catalyst system uses composite material strategy by combining two different catalyst types (low temperature catalyst and high selectivity catalyst) in sequence within the reactor. This composite approach leverages the strengths of each catalyst type to achieve superior overall performance in terms of both conversion and selectivity.
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 configuration allows for high methane conversion and coupling selectivity by controlling the outlet temperature of the first catalyst and supplying the gas to the second catalyst, optimizing reaction conditions.
Implementation Method 1
a first reaction step of producing an olefin from methane in the raw material gas by oxidative coupling reaction using a first catalyst
Implementation Method 2
a second reaction step of producing an olefin from methane in the raw material gas that has undergone the first reaction step by oxidative coupling reaction using a second catalyst
Data Source
AI summary
An olefin production device for producing an olefin from a raw material gas containing methane and oxygen includes a reactor containing: a first catalyst; and a second catalyst disposed downstream of the first catalyst in a flow direction of the raw material gas. The first catalyst is a catalyst in which a zirconium salt or carbonate of an alkali metal, an oxide of an alkaline earth metal, an oxide of one kind of lanthanoid element, a composite oxide containing a lanthanoid element, or a combination thereof is supported on a support. The second catalyst is a catalyst containing a tungsten oxide, phosphate, or carbonate of an alkali metal.