1,5-Pentanediol Production via THFA Dehydration and Hydration
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Solution Overview
Problem
Current methods for producing 1,5-Pentanediol (1,5-PD) from tetrahydrofurfural alcohol are inefficient due to low selectivity and high costs associated with noble metal catalysts, requiring high temperatures and additional steps for acid neutralization and separation.
Innovation Solution
A method involving the dehydration of tetrahydrofurfural alcohol to dihydropyran, followed by hydration to 2-hydroxytetrahydropyran in the absence of catalysts or acids, and subsequent ring-opening using inexpensive base metal catalysts like Co/TiO2 or NiMo/C, achieving high yields of 1,5-PD at mild conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional direct hydrogenation of furfural and hydrogenolysis of tetrahydrofurfural alcohol is used, then 1,5-PD can be produced, but the selectivity and conversion are low and high temperature (≥250°C) is required
Solution Approach 1:
The invention changes the chemical structure parameter by converting THFA to DHP (introducing a double bond), which fundamentally alters the reaction pathway. This allows the hydrogenation to proceed at much lower temperatures (60-150°C) while achieving high conversion and selectivity to 1,5-PD, resolving the contradiction between productivity and temperature requirements
Solution Approach 2:
The invention performs preliminary dehydration of THFA to DHP before the hydrogenation step. This preliminary structural modification activates the molecule for subsequent low-temperature hydrogenation, enabling high productivity under mild conditions without requiring high-temperature processing
2Ease of manufacture
If base metal catalysts are used in conventional route, then cost is reduced, but high temperature (≥250°C) is required which increases energy cost
Solution Approach 1:
By changing the substrate structure from THFA to DHP through dehydration, the invention enables base metal catalysts (Ni, Co, Fe) to function effectively at low temperatures (60-150°C). This simultaneously achieves low catalyst cost and low energy consumption, resolving the contradiction between ease of manufacture and energy use
3Productivity
If homogeneous acid catalyst is used for hydration, then DHP can be converted to intermediate, but acid neutralization and separation steps are required
Solution Approach 1:
The invention extracts and eliminates the homogeneous acid catalyst from the system by using a solid acid catalyst instead. This allows the catalyst to be easily separated from the reaction mixture through filtration, removing the need for acid neutralization and complex separation steps while maintaining high hydration efficiency
Solution Approach 2:
The invention introduces a solid acid catalyst as an intermediary that facilitates the hydration reaction without requiring subsequent neutralization. The solid catalyst acts as a mediator that can be easily removed by filtration, simplifying the process while maintaining high productivity
4Temperature
If noble metal catalysts are used, then hydrogenolysis can proceed at lower temperature, but catalyst cost increases significantly
Solution Approach 1:
The invention changes the substrate from THFA to DHP, which has a double bond that is highly reactive toward hydrogenation. This structural parameter change enables base metal catalysts to achieve effective hydrogenolysis at low temperatures (60-150°C), eliminating the need for expensive noble metal catalysts while maintaining low temperature operation
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 method results in over 90% overall yield of 1,5-PD with significantly reduced catalyst costs, eliminating the need for noble metals and acid neutralization steps, thereby lowering production costs and energy requirements.
Implementation Method 1
In a first step THFA is dehydrated using a metal-oxide catalyst, such as γ-Al2O3, to yield dihydropyran (DHP)
Implementation Method 2
The DHP is then hydrated in water at low temperatures (e.g., about 70 °C to about 100 °C), preferably in the absence of catalysts and in the absence of added homogenous acid, to yield 2-hydroxytetrahydropyran (2-HY-THP)
Implementation Method 3
2-HY-THP is a highly reactive alternative (as compared to THFA) for a subsequent hydrogenolysis reaction step in which the 2-HY-THP is ring-opened to yield 1,5-PD. This can be accomplished using a number of different metallic catalysts.
Data Source
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AI summary
A method of making 1,5-pentanediol from tetrahydrofurfural alcohol. The method includes the steps of dehydrating tetrahydrofurfural alcohol (THFA) to dihydropyran (DHP); hydrating at least a portion of the DHP to 2-hydroxy-tetrahydropyran (2-HY-THP) in the absence of homogeneous acid; and hydrogenating at least a portion of the 2-HY-THP to 1,5-pentanediol. The method can be conducted entirely in the absence of noble metal catalysts.