Rh-R-Mo-V Composite Oxide Catalyst for Methane Selective Oxidation
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Solution Overview
Problem
Current catalysts for methane selective oxidation fail to produce industrially acceptable yields of aldehydes and alcohols due to the inert nature of methane, requiring high activation temperatures that lead to further oxidation of products like CO, CO2, and H2O, and lack effectiveness in producing ethanol and acetaldehyde.
Innovation Solution
A composite oxide with the formula RhR x Mo y V z O δ-α, where R is Ni, Co, or a combination of Ni and Co, supported on inorganic refractory oxides, is developed to catalyze the selective oxidation of methane to ethanol and acetaldehyde, utilizing in-situ crystallization and specific reaction conditions to enhance methane activation and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If elevated temperatures are used to activate methane, then methane activation is improved, but product selectivity deteriorates due to further oxidation
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating specific ratios of Rh, Mo, V, and promoter metals (Ni, Co, or their combinations) to create a catalyst that can activate methane at lower temperatures while maintaining product selectivity. The formula RhR x Mo y V z O δ-α with specific compositional ranges represents this parameter change approach.
Solution Approach 2:
The patent uses a composite oxide catalyst combining multiple metal elements (Rh, Mo, V, and promoters) in a specific composite structure. This composite material approach allows the catalyst to simultaneously provide methane activation capability and product protection, resolving the contradiction between activation rate and selectivity.
2Productivity
If high reaction temperatures are applied, then methane conversion is improved, but harmful oxidation products increase
Solution Approach 1:
The patent changes the operational parameters by enabling effective methane conversion at lower temperatures (300-600°C) through the specialized catalyst composition, thereby reducing the formation of harmful oxidation products while maintaining productivity.
Solution Approach 2:
The patent converts the high reactivity that causes over-oxidation into a benefit by using it for the desired selective oxidation to ethanol and acetaldehyde. The catalyst directs the reactive oxygen species to produce valuable products rather than harmful CO and CO2.
3Quantity of substance
If existing catalyst compositions are used, then formaldehyde production is achieved, but ethanol and acetaldehyde production is insufficient
Solution Approach 1:
The patent creates a universal catalyst composition that can produce multiple products (formaldehyde, ethanol, and acetaldehyde) from methane oxidation. The specific Rh-R-Mo-V oxide structure provides multi-functionality, allowing the same catalyst to generate different oxidation products depending on reaction conditions.
Solution Approach 2:
The patent changes the catalyst composition parameters by incorporating specific promoter metals and ratios that enable the production of higher oxidation state products (ethanol and acetaldehyde) in addition to formaldehyde, expanding the catalyst's product range.
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 composite oxide achieves improved methane conversion and selectivity to ethanol and acetaldehyde, with up to 17% conversion and 78% selectivity, while operating at reduced reaction pressures, making it suitable for industrial-scale production.
Implementation Method 1
the composite oxide is capable of acting as a catalyst for co-producing ethanol and acetaldehyde by a methane selective oxidation reaction
Implementation Method 2
utilizing in-situ crystallization and specific reaction conditions to enhance methane activation and selectivity
Data Source
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AI summary
This invention relates to a composite oxide, production and use thereof as a methane selective oxidizing catalyst. The composite oxide has a composition as illustrated by the formula RhRxMoyVzOδ-α, wherein the symbols are as defined in the specification. When used as a methane selective oxidizing catalyst, the present composite oxide provides a high methane conversion and a high selectivity to the aimed products.