Supported Composite Oxide Catalyst for Low-Temperature Methanol Oxidation
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Solution Overview
Problem
Existing catalysts for the selective oxidation of methanol to formaldehyde suffer from low methanol conversion, low formaldehyde selectivity, and short catalyst life due to the need for high reaction temperatures and molybdenum sublimation, leading to deactivation.
Innovation Solution
A supported composite oxide catalyst with the formula FeMoaSibXcOd, where X is an alkali or alkaline earth metal, is prepared by a method involving the use of an acidic surfactant solution, hydrolysis, crystallization, and calcination of iron and molybdenum compounds, with a modifying metal compound added in a mixed solution, resulting in a catalyst with a large active surface area and uniform distribution of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high reaction temperature is used to improve methanol conversion and formaldehyde yield, then productivity is improved, but catalyst stability deteriorates due to molybdenum sublimation and deactivation
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by introducing a specific composite oxide structure containing Fe, Mo, Si, and alkali/alkaline earth metals in defined ratios. This compositional parameter change enables the catalyst to achieve high methanol conversion at lower temperatures while preventing molybdenum sublimation, thus resolving the contradiction between productivity and catalyst stability.
Solution Approach 2:
The patent employs a composite oxide material system combining multiple metal elements (Fe, Mo, Si, and promoter metals) in a specific structural arrangement. This composite material approach creates synergistic effects that enhance catalytic activity at low temperatures while improving thermal stability and preventing component loss, thereby achieving both high productivity and reliability.
2Productivity
If high reaction temperature is used to improve formaldehyde yield, then productivity is improved, but catalyst life deteriorates due to deactivation
Solution Approach 1:
The patent modifies the catalyst's chemical composition parameters by incorporating promoter metals (Al, La, Ce, Bi, Mn) and binder metals (Ti, Zr) in optimized amounts. These parameter changes enhance the catalyst's resistance to deactivation mechanisms, allowing it to maintain high formaldehyde yield over extended periods without requiring high reaction temperatures that would accelerate degradation.
Solution Approach 2:
The patent utilizes a multi-component composite oxide structure where different elements perform specialized functions: Fe and Mo provide catalytic activity, Si provides structural stability, and promoter/binder metals enhance durability. This composite material design extends catalyst life while maintaining high productivity through synergistic interactions among components.
3Ease of manufacture
If conventional co-precipitation method is used to prepare catalyst, then ease of manufacture is improved, but manufacturing precision deteriorates due to random mixture and segregation
Solution Approach 1:
The patent applies preliminary action by forming a precursor structure with controlled composition before final calcination. The precursor is prepared through a specific hydrolysis and aging process that pre-arranges the metal elements in a uniform distribution, preventing segregation during subsequent treatment steps and ensuring precise component distribution in the final catalyst.
Solution Approach 2:
The patent changes the preparation process parameters by introducing controlled hydrolysis conditions, aging time, and calcination temperature profiles. These parameter adjustments transform the random mixture obtained by conventional co-precipitation into a uniformly distributed composite structure, achieving high manufacturing precision while maintaining ease of manufacture through a systematic process.
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 exhibits high methanol conversion and formaldehyde selectivity at low temperatures, with improved catalyst stability and reduced molybdenum loss, extending its service life.
Implementation Method 1
dissolving an iron-containing compound and a complexing agent in the acidic aqueous solution, adding tetra-C1-4 alkyl orthosilicate, followed by hydrolysis, crystallization and calcination to obtain a precursor
Implementation Method 2
The catalyst exhibits high methanol conversion and formaldehyde selectivity at low temperatures
Data Source
AI summary
In a supported composite oxide catalyst and preparation and use thereof, the catalyst has the general formula: FeMoaSibXcOd, wherein X is a modified metal and is selected from alkali metals or alkaline earth metals; a=0.5-5, b=10-50, c=0.001-0.1, and d is the amount of oxygen element satisfying the chemical valence. The catalyst is prepared with the following method: (i) providing an acidic aqueous solution of a surfactant; (ii) dissolving an iron-containing compound and a complexing agent in the acidic aqueous solution, adding tetra C1-4 alkyl orthosilicate, and performing hydrolysis, crystallization and calcination to obtain a precursor; and (iii) forming a mixed liquid of the precursor, a molybdenum-containing compound and a modifying metal compound, drying same and calcinating the resultant, so as to obtain the supported composite oxide catalyst.