Air-lift Reactor Flared Downcomer for Phenol Selectivity
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Solution Overview
Problem
The existing processes for producing phenol from cumene suffer from secondary reactions that result in undesired by-products, such as dicumyl peroxide and dimethyl benzyl alcohol, which complicate downstream processing and reduce selectivity and efficiency in phenol production.
Innovation Solution
The process involves an air-lift reactor with a flared downcomer for improved oxidation selectivity and a loop reactor with series heat exchangers for controlled acid cleavage, allowing for higher phenol selectivity and reduced management costs by optimizing temperature control and recirculation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional air-lift reactor is used for cumene oxidation, then the oxidation reaction can proceed, but selectivity to cumene hydroperoxide decreases due to secondary reactions producing by-products like dicumyl peroxide and dimethyl benzyl alcohol
Solution Approach 1:
The patent applies parameter changes by modifying the downcomer geometry (adding flares with specific A1/A2 ratios between 1.1-2.0) and optimizing operational parameters (O2/cumene molar ratio of 0.05-0.15, temperature 40-70°C, residence time 1-10 hours) to enhance oxidation selectivity and minimize by-product formation through controlled reaction conditions
2Productivity
If conventional loop reactor is used for acid cleavage of cumene hydroperoxide, then phenol can be produced, but the extremely exothermic reaction requires complex temperature control and neutralization procedures
Solution Approach 1:
The patent applies segmentation by dividing the acid cleavage process into multiple stages with sequential acid addition and interstage cooling, where the reaction mass is circulated through heat exchangers between acid addition steps, allowing better control of the exothermic reaction and simplified temperature management
Solution Approach 2:
The patent uses acetone as an intermediary substance that serves dual purposes: it is a product of the cleavage reaction and simultaneously acts as a cooling medium to absorb excess heat from the exothermic reaction, simplifying temperature control without requiring complex external cooling systems
3Productivity
If CHP concentration to 70-90% is performed between oxidation and acid cleavage, then the acid cleavage efficiency improves, but the process requires additional concentration step and equipment
Solution Approach 1:
The patent extracts the concentration step from the overall process by conducting acid cleavage directly on diluted CHP solutions (30-70% concentration), eliminating the need for separate concentration equipment and operations while maintaining high phenol production efficiency through the segmented acid addition approach
4Device complexity
If downcomer without flares is used in air-lift reactor, then the reactor structure is simpler, but the oxidation selectivity and temperature control are inferior
Solution Approach 1:
The patent applies local quality by adding flares only to the downcomer portion of the air-lift reactor rather than modifying the entire reactor structure, creating localized flow patterns that enhance mass and heat transfer in the critical oxidation zone while maintaining overall structural simplicity
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 selectivity of phenol production, simplifies process management, and reduces costs by improving temperature control and recirculation efficiency, while minimizing the formation of unwanted by-products.
Implementation Method 1
the cumene is oxidized to cumene hydroperoxide (CHP)
Implementation Method 2
The reagents, cumene and a gas containing oxygen, preferably air, are fed to the base of the reactor in continuous and are recycled, again continuously, in the interior through the downcomer
Implementation Method 3
the heat of reaction is removed with cooling water, fed and dischrged through (4) and (5), flowing on the shell side
Implementation Method 4
the acid cleaved reaction, which is extremely exothermic
Implementation Method 5
the CHP is acid cleaved into phenol and acetone with an acid, generally sulfuric acid
Data Source
AI summary
Process for the production in continuous or semi-continuous of phenol/acetone from cumene, via cumene hydroperoxide (CHP), which comprises: a. producing CHP in an air-lift reactor in which at least the upper and/or lower part of the downcomer has a flaring; b. cleaving the cumene hydroperoxide by means of acid treatment in a loop reactor comprising two heat exchangers connected in series and wherein the feedings of CHP and fresh acetone are in pairs and each pair is positioned up-stream of each exchanger.