Three-Phase Lanthanum Oxycarbonate Catalyst for Low-Temperature OCM
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Solution Overview
Problem
Existing catalysts for the oxidative coupling of methane (OCM) require high reaction temperatures, have low C2 hydrocarbon concentrations, and struggle to achieve high methane conversion with high selectivity for C2 hydrocarbons, limiting commercialization.
Innovation Solution
A lanthanum oxycarbonate catalyst with coexisting hexagonal, monoclinic, and tetragonal phases is prepared by controlling the addition rate of an alkali solution to a mixed solution containing a lanthanum source and a doping element, allowing for high C2 hydrocarbon yield at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional OCM catalysts are used, then methane conversion can be achieved, but high reaction temperature (700-900°C) is required
Solution Approach 1:
The patent employs a composite catalyst system containing three distinct crystal phases (hexagonal, monoclinic, and tetragonal) of lanthanum oxycarbonate. Each phase contributes different catalytic properties, and their synergistic interaction enables effective methane conversion at lower temperatures (450-650°C) compared to conventional single-phase catalysts that require 700-900°C
Solution Approach 2:
The patent changes the crystal phase composition parameters of lanthanum oxycarbonate by controlling the addition rate of alkali solution during preparation. This parameter change transforms the catalyst from requiring high temperature operation to operating effectively at lower temperatures while maintaining methane conversion activity
2Productivity
If high methane conversion rate is achieved, then more C2 hydrocarbons are produced, but selectivity of C2 hydrocarbons becomes low
Solution Approach 1:
The three-phase composite structure provides multiple active sites with different selectivity characteristics. The hexagonal phase, monoclinic phase, and tetragonal phase work synergistically to promote C2 hydrocarbon formation while suppressing side reactions, maintaining high selectivity even at high conversion rates
Solution Approach 2:
Different crystal phases are distributed within the catalyst structure, with each phase providing localized catalytic functionality. The hexagonal phase may favor certain C2 products while the monoclinic and tetragonal phases contribute to overall conversion, creating local quality variations that optimize both selectivity and productivity
3Quantity of substance
If conventional catalysts are used, then C2 hydrocarbons are produced, but the concentration of C2 hydrocarbons in the product is low
Solution Approach 1:
The multi-phase composite catalyst enhances C2 hydrocarbon concentration in the product stream by providing synergistic catalytic effects that favor C2 product formation and minimize byproduct generation, achieving higher C2 concentration compared to conventional single-phase catalysts
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 achieves high yield of C2 hydrocarbons at 450-650°C with improved selectivity, addressing the limitations of existing OCM catalysts.
Implementation Method 1
adding an alkali solution to a mixed solution containing a lanthanum source and a compound containing a doping element to make the pH value of the mixed system greater than 9
Implementation Method 2
monoclinic phase lanthanum oxycarbonate containing a doping element, and tetragonal phase lanthanum oxycarbonate containing a doping element
Implementation Method 3
The catalyst achieves high yield of C2 hydrocarbons at 450-650°C with improved selectivity, addressing the limitations of existing OCM catalysts
Data Source
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AI summary
The present invention relates to the technical field of lanthanum oxycarbonate, and discloses a lanthanum oxycarbonate catalyst, a preparation method and an application thereof. The lanthanum oxycarbonate catalyst comprises hexagonal phase lanthanum oxycarbonate, monoclinic phase lanthanum oxycarbonate containing a doping element and tetragonal phase lanthanum oxycarbonate containing a doping element. When the catalyst of the present invention is used for methane oxidative coupling reaction, it has a high C2 hydrocarbon yield at low temperature.