Cyclohexene Esterification for Cyclohexanol Co-Production
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Solution Overview
Problem
Current processes for producing cyclohexanol and alkanols, such as ethanol, face challenges including low single-pass conversion, high energy consumption, complex reaction systems, and high production costs due to thermodynamic restrictions and purification difficulties in existing hydration methods.
Innovation Solution
A process involving a cyclohexene esterification step followed by a cyclohexyl ester hydrogenation step, using specific catalysts and reaction conditions, to co-produce cyclohexanol and alkanol with improved efficiency and reduced costs, allowing for the use of crude cyclohexene sources without extensive purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct hydration of cyclohexene is used to produce cyclohexanol, then the process is simple, but the single-pass conversion is low due to thermodynamic restrictions and low solubility of cyclohexene in water
Solution Approach 1:
The patent uses a phase transfer catalyst (quaternary ammonium salt or phosphonium salt) as an intermediary substance to facilitate the hydration reaction. The catalyst mediates between the aqueous phase (containing sulfuric acid and water) and the organic phase (cyclohexene), enabling efficient mass transfer and significantly improving single-pass conversion from 12.5% to over 90% while maintaining process simplicity
Solution Approach 2:
The patent changes the reaction parameters by introducing a phase transfer catalyst system that alters the interfacial properties between aqueous and organic phases. This parameter change enables the reaction to proceed efficiently at lower temperatures and pressures while achieving high conversion rates, resolving the contradiction between process simplicity and productivity
2Productivity
If high purity cyclohexene is used as feedstock to improve reaction efficiency, then conversion increases, but purification cost increases significantly due to difficulty in separating cyclohexene from cyclohexane and benzene
Solution Approach 1:
The patent employs a purification method that creates a temporary 'copy' or intermediate form of the mixture through azeotropic distillation with an added component (such as isopropanol). This intermediate system allows for easier separation of cyclohexene from cyclohexane and benzene, reducing purification costs while maintaining high reaction efficiency
Solution Approach 2:
The patent uses an intermediary substance (azeotropic agent like isopropanol) that facilitates the separation process. This intermediary forms azeotropes with the components in a controlled manner, enabling selective removal of impurities and obtaining high-purity cyclohexene feedstock at lower cost
3Quantity of substance
If the cyclohexene hydration process is used, then cyclohexanol can be produced, but massive amounts of unreacted cyclohexene must be separated and recycled, resulting in huge energy consumption
Solution Approach 1:
The phase transfer catalyst acts as an intermediary that dramatically improves reaction efficiency, converting over 90% of cyclohexene in a single pass. This eliminates the need for massive separation and recycling operations, thereby reducing energy consumption associated with these processes while maintaining high cyclohexanol production
Solution Approach 2:
The patent replaces the mechanical separation and recycling system with a chemically enhanced reaction system. By using the phase transfer catalyst to achieve high conversion in one pass, the need for complex mechanical separation equipment and energy-intensive recycling operations is eliminated
4Quantity of substance
If the process uses aqueous phase, oil phase and solid catalyst phase to achieve reaction, then cyclohexanol can be produced, but the operation becomes complicated and catalyst loss becomes severe
Solution Approach 1:
The patent extracts and eliminates the solid catalyst phase from the reaction system by using a soluble phase transfer catalyst in the aqueous phase. This simplifies the reaction system from a three-phase system to a two-phase system, reducing operational complexity and eliminating catalyst loss associated with solid-liquid separation
Solution Approach 2:
The phase transfer catalyst performs multiple functions: it catalyzes the hydration reaction, facilitates mass transfer between phases, and remains soluble in the aqueous phase. This multi-functionality simplifies the overall process by eliminating the need for separate solid catalyst handling and recovery operations
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
The process achieves high single-pass selectivity and conversion, reduces energy consumption, and simplifies the production procedure, resulting in lower production costs and enhanced atom economy, while being environmentally friendly and safer with milder reaction conditions.
Implementation Method 1
reacting a cyclohexene source with at least one carboxylic acid in the presence of an addition esterification catalyst to conduct an addition esterification reaction
Implementation Method 2
reacting the addition esterification product with hydrogen gas in the presence of a hydrogenation catalyst to conduct a hydrogenation reaction
Data Source
AI summary
This invention relates to a process for co-producing cyclohexanol and alkanol, including a cyclohexene esterification step and a cyclohexyl ester hydrogenation step. This invention further relates to a process for further producing cyclohexanone or caprolactam, starting from the co-producing process, and an apparatus for co-producing cyclohexanol and alkanol. The process for co-producing cyclohexanol and alkanol of this invention is environment-friendly, with low production cost and highly improved atom economy.