Reactor Purification Zone Absorbent for Catalyst Poisoning
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Solution Overview
Problem
Industrial-scale chemical operations face challenges with catalyst poisoning due to low levels of impurities like sulfur, halogen, phosphorous, and selenium in feedstreams, which affect catalyst performance and shorten catalyst lifespan in processes such as olefin epoxidation, despite existing improvements in reactor designs and purification methods.
Innovation Solution
A reactor system incorporating a purification zone with an absorbent containing silver and an alkali or alkaline earth metal on a gamma alumina support, followed by a reaction zone with a silver catalyst on a carrier with a low surface area, effectively reduces impurities and enhances catalyst performance by positioning the purification zone either outside or inside the reactor vessel upstream from the reaction tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional purification methods are used to remove impurities from feedstream, then some impurity reduction is achieved, but catalyst poisoning still occurs due to remaining trace impurities
Solution Approach 1:
The patent applies preliminary action by positioning a purification zone with absorbent material upstream from the catalyst in the reaction tubes. This absorbent material selectively adsorbs trace impurities (sulfur, halogen, phosphorous, arsenic, selenium) from the feedstream before the purified feed contacts the catalyst, preventing catalyst poisoning and extending catalyst lifespan.
Solution Approach 2:
The patent uses an intermediary substance (absorbent material containing alkali metal, alkaline earth metal, or rare earth metal) as a mediator between the impure feedstream and the catalyst. This intermediary selectively binds harmful impurities through adsorption, allowing the catalyst to operate with purified feed while the absorbent captures and retains the poisonous elements.
2Productivity
If catalyst is continuously operated to maximize productivity, then production efficiency increases, but catalyst activity decreases over time due to impurity accumulation
Solution Approach 1:
The purification zone with absorbent material is positioned upstream from the catalyst to perform preliminary removal of impurities before they can accumulate on the catalyst surface. This allows continuous operation at high productivity while preventing the degradation that would otherwise limit catalyst lifetime.
Solution Approach 2:
The patent extracts harmful impurities from the feedstream using the absorbent material in the purification zone. By taking out sulfur, halogen, phosphorous, arsenic, and selenium impurities before they reach the catalyst, the system maintains high productivity without the negative effects of impurity accumulation on catalyst activity.
3Duration of action of stationary object
If feedstream is highly purified to protect catalyst, then catalyst lifespan extends, but process complexity and cost increase
Solution Approach 1:
The patent merges the purification function directly into the reactor system by incorporating the purification zone with absorbent material upstream from the catalyst within the same reactor vessel. This integrated design eliminates the need for separate external purification units, reducing overall process complexity while achieving effective impurity removal to extend catalyst lifespan.
Solution Approach 2:
The absorbent material serves as a simple intermediary that provides effective purification through selective adsorption. This single-component approach (using alkali metal, alkaline earth metal, or rare earth metal-based absorbents) achieves high purification effectiveness without requiring complex multi-stage purification systems.
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 described reactor system significantly reduces impurity levels, improving catalyst selectivity and activity, and extending the catalyst's operational time within the reactor system by effectively removing sulfur- and halogen-containing impurities, thereby enhancing the overall efficiency of olefin oxide production.
Implementation Method 1
a purification zone (32) containing an absorbent (35) positioned upstream from the reaction tubes (19)
Implementation Method 2
a reaction zone (26) containing a catalyst (36)
Data Source
Figure 1
Figure 2
AI summary
The present invention provides a reactor system comprising: - one or more purification zones comprising an absorbent which comprises silver, an alkali or alkaline earth metal, and a support material having a surface area of more than 20 m2/g, and - a reaction zone comprising a catalyst, which reaction zone is positioned downstream from the one or more purification zones; an absorbent; a process for reacting a feed comprising one or more feed components; and a process for preparing a 1,2-diol, a 1,2-diol ether, a 1,2-carbonate, or an alkanolamine.