Heteropolyacid Catalyst Drying for Ethene Dehydration
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Solution Overview
Problem
High-temperature operation in ethanol dehydration processes using heteropolyacid catalysts leads to catalyst deactivation due to undesirable side reactions and carbon build-up, which reduces productivity and increases replacement costs, affecting the economic viability of the process.
Innovation Solution
A process involving a low-temperature drying step for the heteropolyacid catalyst followed by operation at intermediate pressures within a specific range, allowing for increased reaction temperatures without exacerbating deactivation, thereby extending catalyst lifetime and enhancing ethene productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dehydration reaction is conducted at high temperature to increase ethene productivity, then productivity is improved, but catalyst deactivation occurs due to side reactions and carbon build-up
Solution Approach 1:
The catalyst is pre-dried at a specific temperature range (100-200°C) before the high-temperature dehydration reaction to remove water molecules bound to the heteropolyacid component. This preliminary action creates an optimized initial state that enables the catalyst to maintain stability during subsequent high-temperature operation, allowing ethene productivity to be improved without excessive catalyst deactivation
Solution Approach 2:
The invention changes the temperature parameter for catalyst drying from the conventional high temperature (at least 220°C as taught in WO 2011/104495) to a lower specific range (100-200°C). This parameter change optimizes the hydration state of the heteropolyacid component, enabling the catalyst to achieve better performance in terms of both productivity and stability during the dehydration reaction
2Object-generated harmful factors
If the catalyst is dried at high temperature (at least 220°C) to remove bound water, then ethane selectivity is improved, but catalyst deactivation is exacerbated during high-temperature operation
Solution Approach 1:
The invention changes the drying temperature parameter from high temperature (at least 220°C) to a lower specific range (100-200°C). This parameter change achieves the optimal balance between removing excessive bound water (improving ethane selectivity) and preserving catalyst stability (extending catalyst lifetime), as demonstrated by the extended catalyst lifetime of at least 100 hours in the dehydration reaction
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 significantly reduces catalyst deactivation, extends catalyst lifetime, and increases ethene productivity, providing economic benefits by minimizing replacement costs and maintaining high product output.
Implementation Method 1
a process for producing ethene by the vapour phase dehydration of ethanol using a heteropolyacid catalyst
Implementation Method 2
drying of the heteropolyacid catalyst at a specific range of temperature prior to use... the heteropolyacid component will almost certainly be exposed to water (such as moisture in the atmosphere) under conditions at which it may become bound to the heteropolyacid component
Implementation Method 3
drying a supported heteropolyacid catalyst in a reactor under a stream of inert gas at a temperature of from above 100 °C to 200 °C
Data Source
Figure 1~2
Figure 3
AI summary
The present invention provides a process for the preparation of ethene by vapour phase chemical dehydration of a feed comprising ethanol and optionally water and/or ethoxyethane, said process comprising contacting a dried supported heteropolyacid catalyst in a reactor with the feed-stream having feed temperature of at least 200 °C; wherein the pressure inside the reactor is at least 0.80 MPa but less than 1.80 MPa; and before the supported heteropolyacid catalyst is contacted with the feed-stream having a feed temperature of at least 200 °C, the process is initiated by: (i) drying a supported heteropolyacid catalyst in a reactor under a stream of inert gas having a feed temperature of from above 100 °C to 200 °C; and (ii) contacting the dried supported heteropolyacid catalyst with an ethanol-containing vapour stream having a feed temperature of from above 100 °C to 160 °C.