Catalyst Shutdown Sequence for Oxidized Organic Compounds
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Solution Overview
Problem
Catalytic gas-phase oxidation reactions in the production of oxidized organic compounds, such as acrylic acid, face challenges in maintaining catalyst performance during shutdown and startup, leading to reduced yield and prolonged recovery times, with existing methods either causing catalyst degradation or failing to prevent explosive conditions.
Innovation Solution
A method involving the sequential supply of inert gas and molecular oxygen-containing gas during shutdown to remove residual reactants and by-products, maintaining catalyst oxidation state and preventing degradation, while ensuring safety by avoiding explosive compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the catalytic gas-phase oxidation reaction is stopped by simply stopping reactant supply, then the shutdown operation is simple, but the catalyst performance deteriorates due to reduction and takes long to recover
Solution Approach 1:
The patent applies preliminary action by performing oxidation treatment of the catalyst with oxygen-containing gas before the actual shutdown. This preliminary oxidation maintains the catalyst in its active oxidized state, preventing reduction during the shutdown period and enabling quick recovery upon restart without complex recovery procedures
Solution Approach 2:
The patent uses oxygen-containing gas (such as air or pure oxygen) to create an oxidizing atmosphere during shutdown to prevent catalyst reduction. This controlled atmosphere maintains the catalyst in its active state, solving the contradiction between simple shutdown operation and catalyst performance stability
2Reliability
If oxygen-containing gas is supplied during shutdown to maintain catalyst oxidation state, then catalyst performance is maintained, but explosive conditions may occur with residual reactants
Solution Approach 1:
The patent segments the shutdown procedure into distinct sequential steps: first nitrogen purging to remove explosive atmospheres, then oxygen-containing gas supply for catalyst oxidation, and finally reactant supply resumption. This segmentation eliminates the harmful effect of explosive conditions while maintaining catalyst performance
Solution Approach 2:
The patent applies preliminary anti-action by first purging the system with nitrogen to remove residual reactants and create a non-explosive atmosphere before introducing oxygen-containing gas for catalyst oxidation. This preliminary protective action prevents explosive conditions while enabling catalyst maintenance
3Object-affected harmful factors
If nitrogen is supplied during shutdown to prevent explosion, then safety is improved, but catalyst oxidation state deteriorates leading to performance loss
Solution Approach 1:
The patent segments the shutdown gas supply into two distinct phases: first nitrogen supply for safety and explosive atmosphere prevention, then oxygen-containing gas supply for catalyst oxidation state maintenance. This sequential segmentation resolves the contradiction by addressing both safety and catalyst performance in separate steps
Solution Approach 2:
The patent uses periodic action by alternating between nitrogen purging (for safety) and oxygen-containing gas supply (for catalyst maintenance) during the shutdown period. This periodic gas supply strategy ensures both safety and catalyst performance are maintained throughout the shutdown
4Productivity
If the reaction is restarted immediately after shutdown, then productivity is maintained, but catalyst performance has not recovered leading to reduced yield
Solution Approach 1:
The patent performs preliminary oxidation treatment of the catalyst with oxygen-containing gas during the shutdown period, before restart is attempted. This preliminary action ensures the catalyst is in its active oxidized state when restart occurs, enabling immediate high-yield operation without recovery delays
Solution Approach 2:
The patent maintains continuity of useful action by keeping the catalyst in its active oxidized state throughout the shutdown period through oxygen-containing gas supply. This continuous maintenance of catalyst activity ensures seamless transition to high-yield production upon restart, combining productivity and yield
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 stabilizes catalyst performance upon restart, maintaining high yield and safety by managing catalyst oxidation state and preventing explosive risks, thereby enhancing production efficiency and extending stable operation.
Implementation Method 1
supplying an inert gas and then a molecular oxygen-containing gas to a reactor (100) when stopping operation of a catalytic gas-phase oxidation reaction step
Implementation Method 2
supplying a molecular oxygen-containing gas to the reactor (100) when stopping operation of the catalytic gas-phase oxidation reaction step
Data Source
AI summary
The object of the present invention is to provide, in the production of a useful oxidized organic compound by a catalytic gas-phase oxidation reaction on an industrial scale, a manufacturing method which, even when operation has been temporarily interrupted for periodic inspection or emergency shutdown, fully avoids the danger of an explosion due to reaction feedstock gases and the like remaining inside the reaction apparatus, and which, when operation is restarted, is able to shorten, relative to the prior art, the period required for the reaction to return to a stable steady state, and moreover which, after operation has restarted, does not undergo a decrease in yield, and allows a high yield to be stably maintained over a long period, whereby the production efficiency can be greatly increased. The disclosed invention is a method for manufacturing an oxidized organic compound which includes a step of forming an oxidized organic compound, in use of a fixed-bed reactor having a reaction tube packed with an oxide catalyst, by supplying at least one type of organic compound as a reaction feedstock gas and using a molecular oxygen-containing gas to carry out a catalytic gas-phase oxidation reaction; and a step of stopping the catalytic gas-phase oxidation reaction. In the manufacturing method, when stopping the catalytic gas-phase oxidation reaction, the supply of the reaction feedstock gas is stopped, after which an inert gas is supplied to the reactor, then a molecular oxygen-containing gas is supplied, subsequent to which the supply of the molecular oxygen-containing gas to the reactor is stopped.