1,4-Cyclohexanedimethanol Production via Recycled Alcohol Esterification
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Solution Overview
Problem
The existing process for producing 1,4-cyclohexanedimethanol involves challenges such as high energy consumption, equipment costs, and purification complexities due to the use of dimethyl terephthalate as a starting material, which forms solids and requires additional processing steps.
Innovation Solution
A process involving the esterification of terephthalic acid with (4-methylcyclohexyl)methanol to form bis(4-methylcyclohexyl)methyl) terephthalate, followed by hydrogenation to produce 1,4-cyclohexanedimethanol, where the by-products are recycled and the purification is simplified by separating into distinct layers for efficient recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dimethyl terephthalate is used as starting material, then 1,4-cyclohexanedimethanol can be produced, but high energy consumption and equipment costs occur due to high pressure and temperature esterification
Solution Approach 1:
The patent changes the esterification parameters by using (4-methylcyclohexyl)methanol instead of methanol, allowing the reaction to proceed under milder conditions with lower energy consumption while still producing the desired terephthalate diester intermediate
Solution Approach 2:
The patent uses a readily available alcohol ((4-methylcyclohexyl)methanol) that simplifies the overall process by eliminating the need for high-pressure equipment, trading the cost of a slightly more complex alcohol for the elimination of expensive high-pressure processing infrastructure
2Reliability
If dimethyl terephthalate is used as starting material, then 1,4-cyclohexanedimethanol can be produced, but equipment costs increase due to requirement of specialized high pressure equipment
Solution Approach 1:
The patent changes the reaction conditions from high-pressure esterification to mild-temperature esterification by selecting a different alcohol reactant, thereby eliminating the need for specialized high-pressure equipment and simplifying the overall process infrastructure
3Reliability
If dimethyl terephthalate is used as starting material, then 1,4-cyclohowanedimethanol can be produced, but purification complexity increases due to solid formation and plugging
Solution Approach 1:
The patent changes the physical state of the esterification product from solid to liquid by using (4-methylcyclohowexyl)methanol instead of methanol, preventing solid formation and plugging problems while simplifying the purification process through liquid-liquid separation
Solution Approach 2:
The patent exploits phase behavior by designing a process where the esterification product remains liquid under reaction conditions and subsequently separates into distinct liquid layers during purification, avoiding solid formation and enabling easy phase separation
4Reliability
If dimethyl terephthalate is used as starting material, then 1,4-cyclohowanedimethanol can be produced, but additional processing steps are required to remove partial esterification products and catalysts
Solution Approach 1:
The patent extracts and removes catalysts and partial esterification products through liquid-liquid separation and distillation steps, utilizing the different solubilities and volatilities of components to achieve purification without complex processing
Solution Approach 2:
The patent uses water as an intermediary medium in the liquid-liquid separation process, where water facilitates the separation of organic layers containing the product from catalysts and impurities, simplifying the purification pathway
5Loss of substance
If dimethyl terephthalate is used as starting material, then 1,4-cyclohowanedimethanol can be produced, but methanol recovery and recycling require additional purification and processing steps
Solution Approach 1:
The patent designs a process where the alcohol used in esterification ((4-methylcyclohowexyl)methanol) is regenerated in situ through the hydrogenation process, eliminating the need for separate recovery and recycling operations and improving overall processing efficiency
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 reduces energy consumption, equipment costs, and simplifies purification by recycling by-products, enhancing the overall efficiency and cost-effectiveness of the 1,4-cyclohexanedimethanol production process.
Implementation Method 1
contacting bis(4-methylcyclohexyl)methyl) terephthalate with hydrogen in a first hydrogenation zone in the presence of a catalyst effective for hydrogenation of an aromatic ring
Implementation Method 2
contacting the effluent from the first hydrogenation zone with hydrogen in the presence of an ester hydrogenation catalyst in a second hydrogenation zone to produce a hydrogenation product comprising 1,4-cyclohowanedimethanol
Implementation Method 3
allowing the distillation bottoms to form a lower layer comprising a majority of the 1,4-cyclohowanedimethanol in the distillation bottoms and a upper layer comprising a majority of the 4,4'-oxybis(methylene)bis(methylcyclohowane)
Data Source
AI summary
Disclosed is a process for the preparation of 1,4-cyclohexanedimethanol from terephthalic acid. Terephthalic acid is esterified with (4-methylcyclohexyl)methanol and the terephthalate ester hydrogenated to 1,4-cyclohexanedimethanol in a 2-stage process. The (4-methylcyclohexyl)methanol that is formed during the hydrogenation step is recycled to the esterification reaction. After removal of the (4- methylcyclohexyl)methanol from the crude hydrogenation product, the 1,4- cyclohexanedimethanol product can be recovered and purified by a phase separation and distillation.