Transfer Hydrogenation via Reactive Distillation
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Solution Overview
Problem
The transfer-hydrogenation process faces challenges due to unfavorable reaction equilibrium between alcohol and carbonyl compounds, often requiring a large excess of donor alcohol, which increases costs and complexity due to the need for separation, recovery, and recycling of the excess alcohol.
Innovation Solution
The process involves continuously removing low-boiling carbonyl products during the reaction using reactive or catalytic distillation, integrating chemical reaction steps with product separation in a single unit operation, employing a Group 8 to 11 metal catalyst, and optionally using aldol condensation to recycle reactants, thereby driving the equilibrium and simplifying product separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large excess of donor alcohol is employed to favor higher conversion of the acceptor, then conversion efficiency is improved, but process cost and complexity increase due to the need for separation, recovery, and recycling of the excess alcohol
Solution Approach 1:
The patent removes the low-boiling carbonyl product from the reaction zone continuously during the reaction by distillation. This extraction of the product from the reaction equilibrium drives the reaction forward to higher conversion without requiring excess donor alcohol, thereby avoiding the complexity of separating and recycling large amounts of unreacted alcohol.
Solution Approach 2:
The patent combines the chemical reaction step with the product separation step into a single integrated reactive distillation process. The transfer-hydrogenation reaction occurs in the reaction zone while simultaneously distilling off the low-boiling carbonyl product, merging reaction and separation operations to improve conversion without the need for separate recovery and recycling units.
2Productivity
If a large excess of donor alcohol is employed to favor higher conversion, then conversion efficiency is improved, but process cost increases due to the need for separation, recovery, and recycling
Solution Approach 1:
The patent continuously extracts the low-boiling carbonyl product from the reaction mixture via distillation during the reaction. This removal of product shifts the equilibrium toward higher conversion of the acceptor carbonyl compound, eliminating the need to use a large excess of donor alcohol and thereby reducing the quantity of alcohol that would otherwise need to be separated and recycled.
3Productivity
If reactive distillation is used to remove low-boiling carbonyl products, then conversion efficiency is improved without excess alcohol, but process complexity increases due to integration of reaction and separation
Solution Approach 1:
The patent integrates the transfer-hydrogenation reaction and the distillation separation into a single reactive distillation process. The reaction zone where alcohol and carbonyl compounds react is combined with the distillation zone that continuously removes low-boiling carbonyl products. This merging allows the system to achieve high conversion efficiency while using stoichiometric or near-stoichiometric amounts of donor alcohol, avoiding the need for separate excess alcohol management 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
This approach allows for efficient conversion of carbonyl compounds without the need for excess alcohol, reducing costs and complexity by continuously removing products, enhancing reaction efficiency, and producing higher molecular weight alcohols with improved selectivity and yield.
Implementation Method 1
contacting a first carbonyl compound with a first alcohol compound in the presence of a transfer-hydrogenation catalyst
Implementation Method 2
a transfer-hydrogenation process, and more particularly, to the field of catalytic hydrogen transfer from alcohol compounds to carbonyl compounds
Implementation Method 3
removing the second carbonyl compound from the first reaction zone during step (a)
Implementation Method 4
integrating chemical reaction steps with product separation in a single unit operation
Data Source
AI summary
A transfer-hydrogenation process for preparing a carbonyl compound and an alcohol compound comprises the steps of (a) contacting a first carbonyl compound with a first alcohol compound in the presence of a transfer-hydrogenation catalyst in a first reaction zone at conditions effective to form a second carbonyl compound from the first alcohol compound and a second alcohol compound from the first carbonyl compound, and (b) removing the second carbonyl compound from the first reaction zone during step (a). The first carbonyl compound is a saturated aldehyde or ketone, or an α,β-unsaturated aldehyde or ketone. The first alcohol compound is a primary or secondary alcohol. The second alcohol compound is α,β-saturated. The transfer-hydrogenation catalyst includes a Group 8 to 11 metal. This process is useful for preparing and higher value alcohols, such as butanol or 2-ethylhexanol, from the corresponding carbonyl compounds by engaging lower alcohol (C2-C4) feedstocks instead of hydrogen (H2).