VPO Catalyst Pore Structure for Maleic Anhydride Diffusion
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Solution Overview
Problem
Existing VPO catalysts face limitations in catalytic performance due to internal diffusion resistance, which can be exacerbated by using small catalyst granules and inadequate pore structure, leading to operational difficulties and suboptimal production of maleic anhydride.
Innovation Solution
Development of a VPO catalyst with an improved micro-pore structure, characterized by a total pore volume of at least 0.27 cc/g, with micro-pores having a diameter of 0.6 microns or less, and optionally macro-pores between 0.6 to 10 microns, where the micro-pore volume comprises at least 55% of the total pore volume, achieved by contacting the catalyst with organic solvents to increase pore size and volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If small catalyst granules are used to reduce internal diffusion resistance, then diffusion resistance is reduced, but pressure drop through the fixed bed increases leading to operational difficulties
Solution Approach 1:
The patent applies porous materials by developing a catalyst with optimized pore structure, specifically creating a hierarchical pore system with both micro-pores (0.01-0.6 microns) and macro-pores (0.6-10 microns). The macro-pores serve as transport channels that reduce diffusion resistance without requiring smaller granule sizes, thereby avoiding the pressure drop issue while still improving mass transfer to active sites located in micro-pores.
Solution Approach 2:
The patent transitions from considering only granule size (one dimension) to incorporating pore structure dimensions (micro-pores and macro-pores). By adding the dimensional aspect of pore architecture, the solution addresses diffusion resistance through internal pore pathways rather than external granule size reduction, thus avoiding the operational difficulties associated with small granules.
2Volume of stationary object
If macro-pores are formed using pore building agents, then pore volume is increased, but the process requires additional steps including adding agents and calcination
Solution Approach 1:
The patent extracts the pore building agent step from the traditional process. Instead of adding external agents and performing calcination, the invention utilizes the natural porosity inherent in the catalyst precursor particles and optimizes it through controlled preparation methods, eliminating the need for separate agent addition and thermal treatment steps.
Solution Approach 2:
The catalyst precursor particles themselves provide the pore structure needed. The preparation process leverages the self-organizing properties of the precursor particles to form an optimized pore network without requiring external pore building agents or additional processing steps, making the system self-sufficient.
3Productivity
If traditional VPO catalysts are used, then catalyst structure is simple, but internal diffusion resistance limits catalytic performance
Solution Approach 1:
The patent creates a composite pore structure combining micro-pores and macro-pores within the catalyst body. This hierarchical composite architecture integrates the high surface area benefit of micro-pores with the efficient mass transport capability of macro-pores, resolving the diffusion resistance issue while enhancing overall catalytic performance.
Solution Approach 2:
The patent applies different pore size qualities to different functional requirements: micro-pores (0.01-0.6 microns) provide high surface area for catalytic activity, while macro-pores (0.6-10 microns) provide efficient transport pathways. This local differentiation of pore qualities optimizes both reaction and mass transfer functions simultaneously.
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
This approach enhances catalytic performance by increasing yield, selectivity, and conversion efficiency, while reducing internal diffusion resistance, thereby improving the productivity and operability of the catalyst in maleic anhydride production.
Implementation Method 1
contacting the catalyst with organic solvents to increase pore size and volume
Implementation Method 2
catalyst for the catalytic oxidation of hydrocarbons to produce a carboxylic acid anhydride
Data Source
AI summary
Embodiments of the present invention disclose improved micro-pore catalyst structures containing catalytic material comprised of mixed oxides of vanadium and phosphorus and using such improved micro-pore catalyst structures for the production of maleic anhydride.