Hydroformylation Using Dense Propane Solvent
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Solution Overview
Problem
The hydroformylation of allyl alcohol often requires the use of inert organic solvents, which are costly and difficult to separate and recycle, and existing processes struggle to achieve high linear to branched product ratios efficiently.
Innovation Solution
A process using a liquefiable petroleum gas, such as dense propane, as both a volumetric expansion medium and solvent, allowing for hydroformylation in the substantial absence of additional solvents, with the ability to recover the solvent overhead and adjust the H2/CO ratio to achieve high linear to branched aldehyde product ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional liquid phase hydroformylation with homogeneous catalyst systems is used, then the reaction can proceed at high pressures and temperatures, but substantial amounts of inert organic solvent/diluent are required which are costly to separate and recycle
Solution Approach 1:
The patent employs supercritical carbon dioxide as the reaction medium, utilizing phase transition properties to achieve a dense fluid state that dissolves reactants and catalysts effectively. The supercritical state allows for high reaction efficiency while eliminating the need for substantial inert organic solvents, as CO2 can be easily separated by pressure reduction and recycled
Solution Approach 2:
The patent changes the physical parameters of the reaction medium by using supercritical conditions (high pressure and temperature) of carbon dioxide. This parameter change transforms CO2 from a gaseous state to a supercritical fluid state, enabling it to function as an effective reaction medium without requiring additional inert organic solvents, thus reducing solvent loss and recycling costs
2Productivity
If high pressures of synthesis gas are used to achieve high conversion, then reaction rate increases, but separation and recovery of products becomes more difficult
Solution Approach 1:
The patent utilizes phase transition of carbon dioxide from supercritical to gaseous state by pressure reduction. This phase change enables easy separation of dissolved gases (H2, CO) and products from the reaction medium, simplifying the separation and recovery process while maintaining high conversion rates achieved through high pressure reaction conditions
3Stability of the object's composition
If traditional solvents are used to dissolve catalysts and reactants, then homogeneous reaction mixtures can be formed, but the solvents must be recovered and recycled which adds process complexity
Solution Approach 1:
The patent uses supercritical carbon dioxide to form homogeneous reaction mixtures with catalysts and reactants. The homogeneous mixture is maintained during reaction, and upon pressure reduction, CO2 transitions to gaseous state, automatically separating from products and eliminating the need for complex solvent recovery and recycling systems
Solution Approach 2:
The supercritical carbon dioxide medium performs self-service by automatically separating from the reaction products through pressure reduction. The CO2 gas evolves and leaves the system, taking with it any volatile impurities, while products remain in the liquid phase for easy collection, eliminating the need for external solvent recovery 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 enables efficient recovery of hydroformylation products with a high linear to branched aldehyde ratio, reducing the need for additional solvent recovery steps and improving the environmental and safety profiles, while maximizing the production of desired linear aldehydes like 4-hydroxybutyraldehyde.
Implementation Method 1
an inert compressed gas serves as both a volumetric expansion medium in the manner of the above-summarized '234 Subramaniam patent, for causing a volumetric expansion of a liquid including and preferably comprised substantially entirely of the olefinic substrate
Implementation Method 2
forming a homogeneous reaction mixture including the olefinic feedstock, a hydroformylation catalyst and a single inert solvent
Implementation Method 3
recovering substantially all of the solvent overhead as a vapor by reducing the pressure and degassing the product mixture
Implementation Method 4
reacting the olefinic feedstock with carbon monoxide and with hydrogen in the presence of the catalyst under elevated temperature and pressure conditions sufficient to carry out a hydroformylation
Data Source
Figure 1~2
Figure 3
AI summary
Allyl alcohol, particularly from biobased sources such as glycerol, is hydroformylated to products including 4-hydroxybutyraldehyde and 4-hydroxy-2-methylpropionaldehyde by forming a homogeneous reaction mixture including allyl alcohol, a rhodium-based hydroformylation catalyst and a near critical liquefiable petroleum gas or mixture of such gases, reacting the near critical liquefiable petroleum gas (or gas mixture)-expanded allyl alcohol substrate with carbon monoxide and with hydrogen in the presence of the catalyst, and recovering substantially all of the petroleum gas or gases overhead by reducing the pressure and degassing the product mixture. Dense propane is especially useful as a single inert solvent/diluent, and substantially no other solvent/diluent is needed.