Multiphase Reactor Liquid Injection for Catalyst Longevity
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Solution Overview
Problem
Continuous multiphase reaction systems involving gas and liquid phase reactants with a solid catalyst face challenges such as substoichiometric gas to liquid reactant ratios, leading to undesirable side reactions and catalyst deactivation, particularly in plug flow or quasi-plug flow reactors, where maintaining optimal reactant concentrations is difficult due to limited axial mixing and high liquid substrate concentrations.
Innovation Solution
Introducing a liquid phase reactant at a targeted concentration at the reactor inlet and at multiple downstream locations along the axial flow direction, with optional gaseous feed additions to maintain a desired gas/liquid ratio, minimizing catalyst requirements and extending the effective reaction period by controlling liquid substrate concentration without dilution, thereby optimizing the reaction system's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous multiphase reaction system operates with limited axial mixing (plug flow or quasi-plug flow), then the reaction efficiency and productivity are improved, but the liquid substrate concentration becomes non-uniform along the reactor length, leading to substoichiometric gas to liquid reactant ratios and undesirable side reactions
Solution Approach 1:
The reactor is divided into multiple zones along the axial direction, with liquid reactant injection points strategically positioned to create localized reaction zones. This segmentation allows different sections of the reactor to maintain optimal reactant concentrations independently, preventing substoichiometric conditions while preserving the overall plug flow characteristics for high productivity.
Solution Approach 2:
Liquid reactant is introduced at specific downstream locations before the gas reactant is completely consumed, ensuring that the liquid substrate concentration is replenished in advance. This preliminary action prevents the formation of substoichiometric gas to liquid ratios and avoids undesirable side reactions catalyzed by excess liquid phase components at the catalyst interface.
2Productivity
If the liquid substrate concentration is maintained at high levels to improve reaction rate, then productivity increases, but gas reactant is consumed in undesirable side reactions before reaching the catalyst surface
Solution Approach 1:
The liquid substrate concentration is optimized locally at different positions along the reactor. By introducing liquid reactant at specific downstream locations, the concentration is maintained at optimal levels near the catalyst surface where the reaction occurs, rather than uniformly throughout the entire reactor. This local optimization ensures high reaction rates while preventing gas reactant consumption in side reactions that occur when liquid substrate concentration is excessively high.
3Productivity
If well-mixed slurry reactors are used to facilitate effective temperature control and intensive mass transfer, then the reaction performance is improved, but catalyst separation and recovery becomes difficult due to catalyst attrition
Solution Approach 1:
Instead of using well-mixed slurry reactors where catalyst particles are mobile and cause attrition, the invention inverts the approach by using a fixed-bed reactor configuration. The catalyst remains stationary in a fixed bed, eliminating attrition and simplifying separation. Liquid reactant is introduced in a controlled manner to achieve intensive mass transfer without the harmful effects of catalyst movement, thus resolving the contradiction between mass transfer efficiency and catalyst separation complexity.
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 maintains optimal reactant concentrations along the reactor length, reducing catalyst usage, minimizing side reactions, and enhancing productivity and selectivity, while avoiding the need for significant product recycling and dilution, thus improving process economics and catalyst longevity.
Implementation Method 1
Multiphase processes involving the reaction of gas and liquid phase reactants on a solid catalyst
Implementation Method 2
the claimed invention relates specifically to such a continuous multiphase reaction process for the hydrogenation of one or more sugars to sugar alcohols
Implementation Method 3
introducing a liquid phase reactant into a reactor in a targeted concentration at the inlet and at one or more downstream locations along the reactor in the axial direction of fluid flow
Data Source
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AI summary
A process is described for improving the performance of certain multiphase reaction systems including a solid catalyst, one or more reactants in the gas phase and one or more reactants in the liquid phase, wherein a targeted maximum concentration of a reactant in the liquid phase is identified for providing improved value in terms of byproduct formation, catalyst deactivation and yields of desired products, and this targeted concentration is closely approached and preferably achieved, but not substantially exceeded, downstream in a continuous process or later in time from the initiation of a batch in a semibatch mode of operation of such processes.