Amorphous Alumina Catalyst Macroporosity for C4 Alcohol Dehydration
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Solution Overview
Problem
Existing catalysts used for dehydration and skeletal isomerization of C4 monohydric alcohols suffer from deactivation due to coking, leading to reduced activity and selectivity over time, as coke deposits block active sites and modify the catalyst's pore structure, limiting access to molecules.
Innovation Solution
A method employing an alumina-based catalyst with high open macroporosity, allowing increased volume for catalytic coke while maintaining active sites, achieved through specific pore distribution and promoter addition, which enhances catalyst durability and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts (alumina, zeolites, mineral acids) are used for dehydration of C4 alcohols, then the reaction activity is initially high, but the catalyst deactivates over time due to coking that blocks active sites and modifies pore structure
Solution Approach 1:
The patent employs an amorphous solid catalyst with specific porosity characteristics (high open macroporosity volume between 0.1-0.3 mL/g and controlled mesoporosity) to resolve the contradiction between initial activity and long-term stability. The porous structure allows coke deposits to be accommodated within the pore volume rather than blocking external active sites, thereby maintaining catalytic activity over extended periods while preserving reaction productivity
Solution Approach 2:
The patent changes the physical-chemical parameters of the catalyst by controlling the pore size distribution (macropores >0.1 μm and mesopores 3.6-100 nm) and surface area (100-300 m²/g) to optimize both activity and stability. This parameter optimization allows the catalyst to maintain high reaction activity while resisting deactivation through coking
2Object-affected harmful factors
If pore volume is increased to reduce coke blocking, then access to active sites is improved, but the number of active sites decreases and activity is reduced
Solution Approach 1:
The patent applies local quality by creating different pore size regions within the catalyst structure: macropores (volume 0.1-0.3 mL/g) that accommodate coke deposits and mesopores (surface area 100-300 m²/g) that provide active sites. This spatial differentiation allows coke to be sequestered in larger pores while maintaining accessible active sites in the mesoporous network, thereby preserving catalytic activity
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 method improves catalyst cycle time and activity over time by minimizing the loss of active sites, achieving longer durability and increased selectivity for C4 olefins production without a significant drop in activity.
Implementation Method 1
The dehydration of C4 monohydric alcohols has been investigated for many years, mainly as a route of synthesis or purification of isobutene. Catalysts based on mineral acid, FeCl2 salt, metal oxides such as alumina or zeolite have been used in this application.
Implementation Method 2
By 'open macroporosity' is meant the pore spaces connected to the porous network and accessible to the wetting fluids used in the methods of measuring porosity such as mercury porosimetry.
Data Source
AI summary
The present invention relates to a method of producing C4 olefins, from a feed of C4 monohydric alcohol, in which a reaction of dehydration of the monohydric alcohol to at least one olefin, and a reaction of skeletal isomerization of at least one of the olefins produced in one and the same reaction vessel, are carried out in the presence of an alumina-based catalyst with adapted porosity.