VPO Catalyst Preparation via Controlled Water Reduction
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Solution Overview
Problem
VPO catalysts have low intrinsic activity and high costs due to the high cost of starting materials, requiring improvement in catalysis performance, selectivity, and service life for the oxidation of hydrocarbons like butane to maleic anhydride.
Innovation Solution
A process for producing a VPO catalyst with a molybdenum and vanadyl pyrophosphate phase, involving a reaction mixture with controlled water content, where vanadium pentoxide is reduced in the presence of phosphoric acid and an aromatic alcohol, followed by filtration, drying, and activation, without removing water during the reduction step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water is removed during the reduction step to improve catalyst purity, then the catalyst performance improves, but the process complexity and energy consumption increase
Solution Approach 1:
The patent extracts the harmful effect of water by allowing it to remain in the system during reduction, then removes it only in the final drying step. This selective extraction approach improves catalyst performance while minimizing process complexity by avoiding intermediate water removal steps.
Solution Approach 2:
The patent performs preliminary reduction in the presence of water, then follows with a single drying step to remove water before activation. This preliminary action approach allows the reduction to proceed optimally without water interference, then consolidates water removal into one step, reducing overall process complexity.
2Device complexity
If the reduction is carried out in the presence of water to simplify the process, then the process complexity decreases, but the catalyst selectivity deteriorates
Solution Approach 1:
The patent converts the traditionally harmful effect of water during reduction into a beneficial feature by allowing water to remain present during the reduction step. This simplifies the process while the subsequent drying step ensures high catalyst selectivity by removing water before activation, thus converting what was previously a harmful factor into a process simplification opportunity.
3Productivity
If the drying temperature is increased to improve catalyst activation, then the catalyst activity improves, but the catalyst stability deteriorates due to phase transformation
Solution Approach 1:
The patent optimizes the drying temperature parameter to a specific range (100-200°C) that balances catalyst activation and stability. This parameter change approach ensures sufficient moisture removal for high catalyst activity while maintaining the vanadyl pyrophosphate phase structure for long-term stability, avoiding the harmful effects of higher temperatures.
4Productivity
If a large amount of catalyst is used to compensate for low intrinsic activity, then the conversion sufficient is achieved, but the cost increases
Solution Approach 1:
The patent changes key process parameters including drying temperature (100-200°C), activation temperature (200-400°C), and the composition ratios of starting materials to optimize catalyst performance. These parameter changes result in high intrinsic catalyst activity that achieves sufficient conversion with reduced catalyst amounts, thereby lowering overall process cost.
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 process enhances catalyst performance by maintaining the effectiveness of the molybdenum promoter, reducing by-product formation, and improving stability, leading to improved activity and selectivity in the production of maleic anhydride.
Implementation Method 1
reducing the V(V) compound with the reducing agent, at least in part, to vanadyl hydrogen phosphate
Implementation Method 2
drying the intermediate at a temperature of no more than 350 °C to obtain a dried intermediate
Implementation Method 3
activating the dried intermediate at a temperature above 200 °C
Data Source
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AI summary
The invention relates to a process for the production of a VPO catalyst containing molybdenum and a vanadyl pyrophosphate phase, comprising the steps of: a) providing a reaction mixture comprising a V(V) compound, a P(V) compound, a Mo compound, a reducing agent, and a solvent; b) reducing the V(V) compound with the reducing agent, at least partially, to vanadyl hydrogen phosphate to obtain an intermediate suspension; c) filtering the intermediate suspension from step b) to obtain an intermediate; d) drying the intermediate at a temperature of at most 350 °C to obtain a dried intermediate; and e) activating the dried intermediate at a temperature above 200 °C, characterized in that in step a) a maximum of 0.2 wt% water, based on the weight of the reaction mixture, is present and no water is removed during the reduction in step b).The invention further relates to a VPO catalyst that can be produced by the process according to the invention, and to a catalyst containing the molybdenum-containing vanadium-phosphorus mixed oxide.