Catalyst Stability via Moisture-Controlled Wet Reduction
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Solution Overview
Problem
Platinum-based catalysts used in hydrocarbon dehydrogenation processes experience stability issues due to wet reduction when exposed to hydrogen gas with high moisture content, leading to premature deactivation.
Innovation Solution
A method is implemented to control the moisture content of the hydrogen gas by passing it through a drier or using an inert gas stream, maintaining it at or below 4000 ppmv, and heating it to specific temperatures to prevent catalyst deactivation, while also replenishing spent catalyst with fresh catalyst stored in a reduction zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrogen gas with high moisture content is used in the reduction zone, then the reduction process is simpler, but the catalyst stability decreases due to wet reduction
Solution Approach 1:
The patent changes the moisture content parameter of the hydrogen gas from high (conventional) to controlled at or below 4000 ppmv. This parameter modification prevents wet reduction of the catalyst while maintaining the reduction process functionality, thereby resolving the contradiction between process simplicity and catalyst stability.
Solution Approach 2:
The patent introduces a drier as an intermediary device between the hydrogen gas source and the reduction zone. This intermediary component removes excess moisture from the hydrogen gas, allowing the reduction process to proceed while protecting the catalyst from wet reduction damage.
2Reliability
If moisture content of hydrogen gas is reduced to at or below 4000 ppmv, then catalyst stability increases, but process complexity increases due to need for drier or inert gas stream
Solution Approach 1:
The patent uses dry hydrogen gas (with moisture controlled at or below 4000 ppmv) to create an inert-like environment in the reduction zone that prevents wet reduction. This controlled atmosphere approach protects the catalyst while using a relatively simple drying method rather than complex inert gas systems.
3Ease of operation
If fresh catalyst is stored in reduction zone for extended periods, then catalyst availability for replenishment improves, but catalyst stability deteriorates due to wet reduction over time
Solution Approach 1:
The patent applies preliminary action by controlling the moisture content of hydrogen gas before it contacts the stored catalyst in the reduction zone. By pre-drying the hydrogen gas to at or below 4000 ppmv moisture content, the catalyst can be stored for extended periods without undergoing wet reduction, thus maintaining both availability and stability.
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 increases the stability and lifespan of the catalyst, with catalyst stability ranging from 112 to 157.5 hours, depending on the moisture and temperature conditions, compared to conventional processes where stability decreases substantially.
Implementation Method 1
The moisture content of the gas may be reduced to at or below about 4000 ppmv by passing the gas through a drier
Implementation Method 2
storing fresh catalyst in a reduction zone, passing a gas through the reduction zone
Implementation Method 3
introducing hydrocarbons and hydrogen gas into a reactor positioned downstream from the reduction zone to facilitate a dehydrogenation reaction
Data Source
AI summary
The present invention provides a method of increasing stability of a catalyst used in a dehydrogenation process. The method includes storing fresh catalyst in a reduction zone, passing a gas through the reduction zone, introducing hydrocarbons and hydrogen gas into a reactor positioned downstream from the reduction zone to facilitate a dehydrogenation reaction, and replenishing spent catalyst in the reactor with fresh catalyst from the reduction zone. The gas has a moisture content at or below about 4000 ppmv and a temperature at or below about 290° C. The reactor includes catalyst for increasing the rate of the dehydrogenation reaction. The moisture content of the gas may be reduced to at or below about 4000 ppmv by passing the gas through a drier or by using an inert gas stream. The temperature of the gas may also be reduced.