Mn-Na2WO4/SiO2 Catalyst with Rare Earth Oxides for Methane Coupling
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Solution Overview
Problem
Current catalyst systems for oxidative coupling of methane face challenges such as susceptibility to deactivation under high reactor severity, high selectivity for ethyne, reduced activity rates, and inefficient carbon dioxide production, which affects ethylene production costs and environmental sustainability.
Innovation Solution
A catalyst composition blending an alkaline earth metal with rare earth elements and a transition metal element having redox properties and an alkali metal tungstate compound, optimized to maintain high ethylene selectivity while reducing ethyne and carbon dioxide selectivity, and enhancing catalytic stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Mn-Na2WO4/SiO2 catalyst system is used to achieve high C2+ hydrocarbon selectivity, then ethylene production is improved, but the catalyst becomes susceptible to deactivation under high reactor severity
Solution Approach 1:
The patent combines Mn-Na2WO4/SiO2 catalyst with rare earth metal oxides (La2O3, CeO2, Pr6O11) to create a composite catalyst system. This merging integrates the high C2+ hydrocarbon selectivity of Mn-Na2WO4/SiO2 with the thermal stability and resistance to deactivation provided by rare earth metal oxides, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The invention uses composite catalyst materials consisting of Mn-Na2WO4/SiO2 supported on rare earth metal oxides. The composite structure leverages the synergistic effects of different materials: Mn-Na2WO4/SiO2 provides high ethylene selectivity while rare earth metal oxides provide structural stability and resistance to sintering under high reactor severity conditions.
2Productivity
If catalyst selectivity is increased for C2+ hydrocarbons, then ethylene production is improved, but ethyne selectivity also increases which is harmful to downstream processes
Solution Approach 1:
The patent modifies the local catalytic properties by incorporating rare earth metal oxides with specific oxygen storage and release capabilities. These materials create localized active sites that favor ethylene formation over ethyne, allowing high C2+ hydrocarbon selectivity while suppressing the formation of harmful ethyne by adjusting the local chemical environment around the active sites.
3Productivity
If reactor severity is increased to improve catalytic activity rate, then production efficiency is improved, but catalyst deactivation occurs more rapidly
Solution Approach 1:
The rare earth metal oxides act as a protective cushion for the Mn-Na2WO4/SiO2 catalyst before deactivation occurs. They provide thermal stability and prevent sintering of the active phases under high reactor severity conditions, cushioning the catalyst against rapid deactivation and extending its operational lifespan while maintaining high activity rates.
4Productivity
If oxidative coupling of methane is performed to produce ethylene, then valuable chemicals are produced, but large amounts of carbon dioxide are formed reducing environmental sustainability
Solution Approach 1:
The patent changes the chemical parameters of the reaction by incorporating rare earth metal oxides that modify the oxidation pathways. These materials promote partial oxidation reactions that produce less CO2 compared to complete combustion, thereby reducing carbon dioxide emissions while maintaining high ethylene production rates through optimized oxygen activation and distribution.
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 composition achieves significant improvements in ethylene selectivity, catalytic activity, and stability, enabling cost-effective ethylene production with reduced carbon dioxide emission and prolonged catalyst lifespan.
Implementation Method 1
a second catalyst component comprising a transition metal element having redox property
Implementation Method 2
catalyst composition blending an alkaline earth metal with rare earth elements and a transition metal element having redox properties and an alkali metal tungstate compound, optimized to maintain high ethylene selectivity
Data Source
AI summary
A catalyst composition, suitable for producing ethylene and other C2+ hydrocarbons, from methane. The composition comprises a blended product of two distinct catalyst components, blended at such synergistic proportions that results in a catalyst having high ethylene selectivity while maintaining low ethyne selectivity and sufficient catalytic activity rate. The invention further provides a method for preparing such a catalyst composition and a process for producing ethylene and other C2+ hydrocarbons, using such a catalyst composition.