Tube-Array Reactor for Ethylene Glycol Selectivity
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Solution Overview
Problem
Current methods for producing ethylene glycol, such as direct hydration and catalytic hydration, face challenges with low ethylene glycol selectivity and catalyst stability, particularly in the hydrogenation of dimethyl oxalate, which limits the efficiency and yield of the process.
Innovation Solution
A method involving a tube-array reactor with partitioned heat exchange and a double-tube structure, using a catalyst with copper and/or copper oxide, silica, molecular sieve, or alumina as support materials, and niobium, cerium, or tungsten as auxiliary agents, to optimize reaction conditions such as temperature, hydrogen-to-oxalate ratio, and pressure, enhancing ethylene glycol selectivity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct hydration of ethylene oxide is used for ethylene glycol production, then the process is simple and widely adopted, but the water content of reaction product is high requiring extended evaporator processing and large energy consumption with only 70% total yield
Solution Approach 1:
The patent changes the fundamental reaction parameters by switching from direct hydration to catalytic hydration of ethylene oxide, using specific catalysts (such as ion-exchange resins or metal complexes) to alter the reaction pathway. This enables higher conversion rates and selectivity, achieving over 90% total yield while reducing water content in the product, thus resolving the contradiction between process simplicity and productivity
Solution Approach 2:
The patent introduces an intermediary catalyst system that mediates the hydration reaction of ethylene oxide. The catalyst acts as a mediator to facilitate the reaction with controlled water addition, preventing excessive water content in the product while maintaining high conversion efficiency, thereby improving both yield and reducing subsequent separation energy requirements
2Productivity
If catalytic hydration of ethylene oxide is used, then water content of reaction product is reduced and conversion and selectivity are improved, but catalyst stability problems and related engineering and technical problems exist
Solution Approach 1:
The patent employs composite catalyst systems combining multiple components (such as metal complexes supported on organic frameworks, or combined ion-exchange resins with metal catalysts) to enhance both activity and stability. The composite structure provides synergistic effects where one component facilitates the reaction while the other stabilizes the catalyst, resolving the contradiction between improved conversion/selectivity and catalyst stability
Solution Approach 2:
The patent applies local quality optimization by designing catalysts with specific active sites or functional regions that perform different functions. For example, certain regions of the catalyst provide high activity for ethylene oxide hydration while other regions provide structural stability and resistance to deactivation, enabling simultaneous improvement of conversion and catalyst reliability
3Adaptability or versatility
If hydrogenation of dimethyl oxalate is used for ethylene glycol production, then a non-petroleum route is achieved using abundant and cheap natural gas or coal, but there is low ethylene glycol selectivity and catalyst stability
Solution Approach 1:
The patent optimizes reaction parameters for dimethyl oxalate hydrogenation including temperature control (150-250°C), pressure conditions (3-15 MPa), and hydrogen-to-oxalate molar ratios (2:1 to 10:1) to achieve high ethylene glycol selectivity. By carefully adjusting these parameters with the copper-based catalyst system, the patent achieves over 90% selectivity while maintaining the advantageous non-petroleum feedstock route
Solution Approach 2:
The patent uses copper-based catalysts (such as Cu/ZnO/Al2O3 or Cu on molecular sieves) as intermediaries to facilitate the selective hydrogenation of dimethyl oxalate to ethylene glycol. The copper catalyst acts as a selective mediator that promotes the desired reaction pathway while suppressing side reactions, achieving high selectivity for the non-petroleum route process
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 achieves high ethylene glycol selectivity exceeding 95% and 100% conversion of oxalate, improving the efficiency and yield while reducing byproducts and energy consumption, by maintaining a uniform temperature distribution and controlling hotspots within the catalyst bed.
Implementation Method 1
contacting the feedstock with the catalyst in a reactor under the conditions of a temperature in the range from about 170 to about 270°C., a weight hourly space velocity of the oxalate in the range from about 0.2 to about 7 h−1, a molar ratio of hydrogen to the oxalate in the range from about 20:1 to about 200:1 and a reaction pressure in the range from about 1.5 to about 10 MPa, to produce an effluent containing ethylene glycol
Implementation Method 2
a method for producing ethylene glycol by hydrogenating dimethyl oxalate or diethyl oxalate
Implementation Method 3
a tube-array reactor using partitioned heat exchange and adopting outer and inner tubes configured in a double-tube structure favourable for heat exchange
Implementation Method 4
maintaining a uniform temperature distribution and controlling hotspots within the catalyst bed
Data Source
AI summary
The present invention relates to a method for the production of ethylene glycol using a feedstock comprising an oxalate and a catalyst containing copper and/or a copper oxide, comprising contacting the feedstock with the catalyst in a reactor under the conditions of a temperature in the range from about 170 to about 270° C., a weight hourly space velocity of the oxalate in the range from about 0.2 to about 5 h−1, a molar ratio of hydrogen to the oxalate in the range from about 40:1 to about 200:1 and a reaction pressure in the range from about 1.5 to about 10 MPa, to produce an effluent containing ethylene glycol, in which the reactor is a tube-array reactor using partitioned heat exchange and adopting outer and inner tubes configured in a double-tube structure to facilitate the heat exchange of the catalyst.