Modified Aluminosilicate Catalyst for Alcohol Dehydration
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Solution Overview
Problem
Zeolite-based catalysts for alcohol dehydration and skeletal isomerization face challenges with rapid deactivation and limited regenerability, particularly due to steaming and leaching treatments that alter the catalyst's selectivity and framework, making it difficult to achieve high selectivity and stability for linear olefin production.
Innovation Solution
A modified crystalline aluminosilicate catalyst composition with a Si/Al framework molar ratio greater than 10, combined with a silica binder, is prepared through a process involving calcination, steaming at controlled temperatures and pressures, and shaping, which maintains the catalyst's acidity and selectivity without leaching, ensuring efficient dehydration and skeletal isomerization of alcohols to olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steaming and leaching treatments are applied to zeolite-based catalysts, then catalyst activity is improved, but catalyst stability and selectivity deteriorate due to framework alteration
Solution Approach 1:
The patent applies steaming treatment at controlled temperatures (400-600°C) to modify the catalyst's physical and chemical properties. This thermal treatment alters the zeolite framework in a controlled manner to enhance activity while maintaining stability, resolving the contradiction between improved productivity and preserved reliability.
Solution Approach 2:
The invention uses composite catalyst compositions combining zeolite-based materials with other components that provide both high activity and improved stability. The composite structure allows the catalyst to achieve high conversion rates while resisting deactivation and maintaining selectivity over extended operation periods.
2Device complexity
If conventional dehydration catalysts like alumina are used, then catalyst simplicity is maintained, but product selectivity deteriorates leading to isobutene-rich products
Solution Approach 1:
The patent employs composite catalyst systems that combine multiple materials with complementary properties. These composite catalysts achieve high selectivity for linear butenes (n-butene isomers) while maintaining structural integrity and avoiding the complexity of multi-step processing required by conventional approaches.
Solution Approach 2:
The invention creates catalysts with spatially differentiated properties, where specific regions of the catalyst possess tailored acidity and pore structure characteristics. This local optimization enables selective production of linear butenes from isobutanol while maintaining overall catalyst simplicity and avoiding excessive complexity in the catalyst design.
3Manufacturing precision
If high Si/Al ratio crystalline silicates are used to improve selectivity, then linear butene selectivity is improved, but catalyst regenerability deteriorates
Solution Approach 1:
The patent optimizes the Si/Al ratio parameter within a specific range (greater than 10) to achieve the right balance between selectivity and regenerability. By carefully controlling this compositional parameter, the catalyst maintains high linear butene selectivity while preserving the framework stability necessary for effective regeneration through standard steaming and calcination procedures.
Solution Approach 2:
The invention creates catalysts with optimized local acid site distribution and pore structure characteristics that enable high selectivity for linear butenes. The localized structural features are designed to maintain catalyst activity and selectivity while allowing for effective regeneration, resolving the contradiction between manufacturing precision and ease of repair.
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 modified catalyst composition achieves complete conversion of C2-C7 alcohols to corresponding olefins with improved selectivity and regenerability, maintaining activity and selectivity towards linear olefins, thus enhancing process efficiency and reducing downstream separation costs.
Implementation Method 1
dehydration of alcohols to produce alkenes have been known for a long time. Solid acid catalysts are widely used for alcohol dehydration
Implementation Method 2
dehydration and skeletal isomerization of alcohols on acidic catalysts to make corresponding olefins
Implementation Method 3
steaming at temperatures above 400° C. leads to a modification of the acidity of the catalyst and to the removal of aluminium from the crystalline silicate framework
Implementation Method 4
it is necessary to treat the catalyst via a leaching to remove the aluminium and to increase the ratio Si/Al
Implementation Method 5
The process for preparing a catalyst composition containing a modified crystalline aluminosilicate... comprises the following steps: a) providing a crystalline aluminosilicate... b) optionally calcining said crystalline aluminosilicate
Data Source
AI summary
Process for preparing a catalyst composition containing a modified crystalline aluminosilicate and a binder, wherein the catalyst composition comprises from 5 to 95% by weight of crystalline aluminosilicate as based on the total weight of the catalyst composition, the process being remarkable in that it comprises a step of steaming said crystalline aluminosilicate:at a temperature ranging from 100° C. to 380° C.;under a gas phase atmosphere containing from 5 wt % to 100 wt % of steam;at a pressure ranging from 2 to 200 bars;at a partial pressure of H2O ranging from 2 to 200 bars; andsaid steaming being performed during at least 30 min and up to 144 h;and in that the process also comprises a step of shaping, or of extruding, the crystalline aluminosilicate with a binder, wherein the binder is selected to comprise at least 85 wt % of silica as based on the total weight of the binder, and less than 1000 ppm by weight as based on the total weight of the binder of aluminium, gallium, boron, iron and/or chromium.