Mixed Oxide Catalyst Selectivity for Acrolein Production
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Solution Overview
Problem
Current mixed oxide catalysts based on molybdenum for alkane gas-phase oxidation primarily produce acrylic acid with minimal formation of acrolein or methacrolein, limiting the yield of these valuable unsaturated aldehydes and acids.
Innovation Solution
A mixed oxide catalyst with the formula (Mo1Cr0.005-0.1P0.01-0.1Te0.01-0.8)Ox, incorporating elements like Si, Al, Ti, and Zr, is used for the catalytic gas-phase oxidation of alkanes, allowing for the formation of acrolein and acrylic acid with improved selectivity and yield, particularly when thermally treated under specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional Mo-V-Te catalysts are used for propane oxidation, then acrylic acid is formed with high selectivity, but acrolein formation is suppressed (0-30% selectivity)
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by introducing Cr and P elements in specific ratios (Cr: 0.005-0.1, P: 0.01-0.1 relative to Mo), which fundamentally alters the catalyst's selectivity characteristics to produce acrolein as the main product rather than acrylic acid
Solution Approach 2:
The patent creates a composite oxide catalyst system (Mo-Cr-P-Te) that combines multiple metal oxides with complementary properties, where Cr and P work synergistically with Mo and Te to achieve both high acrolein selectivity and acceptable acrylic acid formation
2Productivity
If catalyst loading is increased to improve productivity, then space-time yield increases, but selectivity may deteriorate due to side reactions
Solution Approach 1:
The patent optimizes the Cr and P content within specific ranges (0.005-0.1 and 0.01-0.1 respectively) to balance activity and selectivity, ensuring that even at high loadings the catalyst maintains high acrolein selectivity by preventing excessive over-oxidation to CO2 and CO
Solution Approach 2:
The patent employs a porous catalyst structure with controlled surface area and pore distribution, which enhances mass transfer and allows high productivity while maintaining selectivity by controlling reactant access to active sites and product diffusion
3Productivity
If thermal treatment conditions are optimized to enhance catalyst activity, then conversion efficiency improves, but catalyst stability may be compromised
Solution Approach 1:
The patent specifies precise thermal treatment parameters (temperature range, atmosphere, duration) to achieve optimal catalyst activation while preserving structural stability, balancing the competing requirements of high activity and long-term durability
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 higher activity and selectivity for acrolein production, even at high specific loadings, and can convert isobutane to methacrolein and methacrylic acid, offering enhanced productivity and selectivity compared to prior art.
Implementation Method 1
The invention relates to the use of mixed oxide catalysts for the catalytic gas-phase oxidation of alkanes
Implementation Method 2
The catalyst can be used to convert propane into acrolein and acrylic acid or isobutane into methacrolein and methacrylic acid, with acrolein or methacrolein being formed at least as the main product
Data Source
AI summary
The invention relates to mixed oxide catalysts for the catalytic gas phase oxidation of alkanes, or mixtures of alkanes and olefins, for the production of aldehydes and carboxylic acids with air or oxygen in the presence of inert gases at elevated temperatures and pressure, and a method for the production of catalysts.