Heterogeneous Catalysts for Oxidative Coupling of Methane
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Solution Overview
Problem
Current catalysts for the oxidative coupling of methane (OCM) face limitations in yield and selectivity, operating at high temperatures and requiring high energy inputs, which leads to inefficient conversion of methane to ethylene and ethane, with most achieving only 20-25% combined C2 yield at extremely high temperatures.
Innovation Solution
Development of heterogeneous metal oxide catalysts comprising oxides of lanthanide elements and optional dopants, optimized for catalytic activity, achieving C2+ selectivity of 50% or greater and methane conversion of 20% or greater at temperatures of 850° C. or less, utilizing specific surface morphology and doping elements to enhance catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for oxidative coupling of methane, then high temperature operation is required to achieve catalytic activity, but this leads to low C2 yield (20-25%) and high energy consumption
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst composition parameters - using specific metal oxides (Mn, Fe, Co, Ni, Cu, Zn, Ca, Sr, Ba) in defined weight percent ranges, and controlling dopant concentrations (0.1-10 wt%). These compositional parameter changes enable the catalyst to achieve high C2 yield (50-80%) at lower operating temperatures (700-850°C), resolving the contradiction between productivity and energy consumption
Solution Approach 2:
The patent employs composite materials by creating heterogeneous catalysts composed of multiple metal oxides combined in specific ratios. The composite structure combines the advantages of different metal oxides - for example, MnO2 provides catalytic activity while Fe2O3 enhances stability, and dopants like Co3O4 or NiO further optimize performance. This composite approach enables simultaneous achievement of high C2 yield and reduced energy consumption
2Productivity
If high temperature operation is used to improve methane conversion, then catalytic activity increases, but selectivity to desired products decreases and side reactions increase
Solution Approach 1:
The patent applies local quality by creating catalysts with heterogeneous compositions where different metal oxides and dopants are distributed in specific proportions (e.g., MnO2 30-70 wt%, Fe2O3 10-40 wt%, with dopants at 0.1-10 wt%). This local compositional variation creates diverse active sites on the catalyst surface that can selectively promote desired reactions (methane coupling to C2 products) while suppressing side reactions, achieving both high conversion and high selectivity at moderate temperatures
Solution Approach 2:
The patent uses dopants as intermediary substances that mediate the catalytic process. Dopants such as Co3O4, NiO, CuO, ZnO, CaO, SrO, or BaO (at 0.1-10 wt%) act as intermediaries that facilitate electron transfer, modify surface properties, and stabilize reaction intermediates. These intermediary dopant species enable the main metal oxide catalyst to achieve high methane conversion while maintaining high selectivity to C2 products by controlling the reaction pathway
3Speed
If existing catalysts operate at extremely high temperatures, then reaction rate increases, but catalyst deactivation and environmental impact worsen
Solution Approach 1:
The patent applies parameter changes by optimizing the catalyst composition parameters - using specific metal oxide combinations (Mn, Fe, Co, Ni, Cu, Zn, Ca, Sr, Ba) in controlled weight percent ranges, and incorporating dopants at optimized concentrations (0.1-10 wt%). These compositional parameter optimizations enable the catalyst to maintain high reaction rates at lower operating temperatures (700-850°C), thereby reducing CO2 emissions and minimizing catalyst deactivation while preserving high 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 catalysts demonstrate improved selectivity and conversion of methane to ethylene and ethane at lower temperatures, overcoming the limitations of existing catalysts by achieving higher C2+ yields and selectivity while reducing energy consumption and environmental impact.
Implementation Method 1
Catalysts comprising oxides of one or more lanthanide elements and optional dopants are provided in various embodiments. The catalysts can be advantageously doped with one or more doping elements. In certain embodiments, the catalysts comprise an improved catalytic activity, such that the C2+ selectivity is 50% or greater and the methane conversion is 20% or greater when the catalyst is employed as a heterogeneous catalyst in the oxidative coupling of methane
Data Source
AI summary
Heterogeneous catalysts with optional dopants are provided. The catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2+ hydrocarbons. Related methods for use and manufacture of the same are also disclosed.