Reactive Distillation for Diol Esterification
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Solution Overview
Problem
Current methods for producing 1,3-butadiene, such as steam-cracking of hydrocarbons and fermentation followed by pyrolysis, face issues with high energy consumption, equipment oversizing, and degradation reactions due to the use of homogeneous catalysts and excessive acetic acid, leading to reduced yields and increased costs.
Innovation Solution
A method involving reactive distillation with a heterogeneous acid catalyst, optimizing the carboxylic acid/diol molar ratio and operating conditions to minimize excess carboxylic acid and degradation reactions, while using a mixed reaction/separation zone in a reactive distillation column to produce high-purity diesters with reduced energy consumption and equipment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a homogeneous catalyst (sulfuric acid) is used in reactive distillation, then the esterification reaction proceeds efficiently, but degradation reactions occur at temperatures above 150°C leading to reduced yield and formation of by-products like methyl ethyl ketone
Solution Approach 1:
The patent changes the catalyst from homogeneous (sulfuric acid) to heterogeneous (solid acid catalyst), which fundamentally alters the reaction system's behavior. This parameter change allows the reaction to proceed efficiently while preventing degradation reactions, as the heterogeneous catalyst can be easily separated and does not promote unwanted side reactions at elevated temperatures.
Solution Approach 2:
The patent segments the reactive distillation column into distinct zones: a reaction zone with the heterogeneous catalyst and a separation zone without catalyst. This segmentation allows the reaction to occur in the presence of catalyst while preventing catalyst-induced degradation in the separation zone where temperatures may be higher.
2Object-generated harmful factors
If a large excess of acetic acid is introduced to minimize degradation reactions, then the thermal profile is reduced, but equipment is oversized and energy consumption increases
Solution Approach 1:
The patent changes the catalyst type to heterogeneous, which fundamentally alters the reaction kinetics and allows for stoichiometric or near-stoichiometric amounts of acetic acid to be used. This eliminates the need for large excess acetic acid, thereby reducing equipment size and energy consumption for heating and separation.
Solution Approach 2:
The patent extracts the catalyst from the liquid phase (homogeneous) and places it in the solid phase (heterogeneous) within the column. This allows for precise control of acetic acid dosage and eliminates the need to use large excesses to control degradation, as the heterogeneous catalyst provides selective catalysis without promoting unwanted side reactions.
3Object-generated harmful factors
If a large excess of acetic acid is used to control the thermal profile, then degradation is minimized, but the distillation column and associated equipment are oversized
Solution Approach 1:
The patent changes the catalyst from homogeneous to heterogeneous, which fundamentally alters the reaction system's thermal profile and kinetics. This allows for reduced acetic acid excess, thereby reducing the volume of equipment needed for heating, reaction, and separation operations.
Solution Approach 2:
By extracting the catalyst into the solid phase and confining it to specific zones in the column, the patent enables better control of the thermal profile without requiring large excesses of acetic acid. This leads to more compact equipment design.
4Quantity of substance
If the carboxylic acid/diol molar ratio is optimized to between 2 and 6, then excess carboxylic acid is minimized and costs are reduced, but maintaining high purity diester becomes more challenging
Solution Approach 1:
The patent segments the column into a reaction zone with heterogeneous catalyst and a separation zone without catalyst. This segmentation allows for optimized molar ratios (2-6) in the reaction zone while achieving high purity diester in the separation zone through enhanced mass transfer and phase separation, without requiring excessive acetic acid.
Solution Approach 2:
The patent changes to heterogeneous catalysis, which provides better selectivity and control over the esterification reaction. This allows for optimized molar ratios to be used while maintaining high diester purity, as the heterogeneous catalyst promotes the desired reaction without promoting side reactions that would compromise purity.
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 enhances the yield and purity of diesters, reduces operating costs, and minimizes degradation reactions, improving the overall efficiency of the esterification process and subsequent pyrolysis step for producing 1,3-butadiene.
Implementation Method 1
esterification step, fed with at least said diol feedstock and with said carboxylic acid feedstock... said esterification step comprising at least one reactive distillation column... consisting of a mixed reaction/separation zone located between two separation zones... said mixed zone comprising an acid heterogeneous catalyst
Implementation Method 2
reactive distillation column operated at a temperature of between 40 and 280° C., at a pressure of between 0.01 and 0.5 MPa... producing at least one distillate that comprises water and a diol-diester residue
Implementation Method 3
reactive distillation column operated at a temperature of between 40 and 280° C.... producing at least one distillate that comprises water
Data Source
AI summary
The invention relates to a conversion method that is fed with a diol feedstock that comprises at least 90% by weight of diol and a carboxylic acid feedstock that comprises at least 80% by weight of carboxylic acid. The method comprising at least:An esterification step which is fed with at least the diol feedstock and at least the carboxylic acid feedstock, wherein the carboxylic acid/diol molar ratio at the inlet of the esterification step is between 2 and 6, the esterification step comprises at least one reactive distillation column that has a mixed reaction/separation zone located between two separation zones; andA water elimination step that is fed with distillate from the esterification step that comprises water and producing at least one water effluent.