Phenol Production Process with Nitrogen Impurity Removal
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Solution Overview
Problem
The existing processes for producing phenol through the Hock process face challenges with acetone imbalance and propylene supply issues, as well as contamination of nitrogen impurities in the cumene recycle streams, which deactivates the zeolite catalyst used in the alkylation step.
Innovation Solution
A modified process that involves alkylating benzene with isopropanol, oxidizing cumene to cumene hydroperoxide, treating unreacted cumene to remove nitrogenous impurities, and recycling the purified cumene stream, while also hydrogenating excess acetone to produce isopropanol for recycling, thereby minimizing catalyst poisoning and optimizing the use of propylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional caustic washing is used to prevent organic acid build-up during cumene oxidation and phenol recovery, then corrosion is controlled, but nitrogen compounds (corrosion inhibitors) are transferred into the cumene recycle streams, causing nitrogen impurities in the acetone product that deactivate the zeolite catalyst
Solution Approach 1:
The patent extracts and removes nitrogenous impurities from the cumene recycle streams through specific treatment steps (such as washing with water or selective adsorbents) before recycling the cumene back to the oxidation reactor. This separation removes the harmful nitrogen compounds that would otherwise be transferred into the acetone product and deactivate the catalyst, while maintaining the beneficial corrosion control function of caustic washing.
Solution Approach 2:
The patent introduces an intermediary treatment step between the caustic washing and cumene recycling processes. This intermediary step (such as a water wash column or adsorption bed) acts as a mediator that removes nitrogen compounds from the cumene stream without interfering with the corrosion inhibition function, thereby preventing nitrogen impurity transfer to the acetone product.
2Productivity
If excess acetone is produced from phenol production via the Hock process, then phenol supply meets demand, but acetone creates a supply-demand imbalance and disrupts the economics of phenol production
Solution Approach 1:
The patent recovers and reuses the excess acetone produced from phenol production by hydrogenating it back to isopropanol, which is then fed back to the alkylation reactor to produce more cumene. This circular process converts the unwanted byproduct (acetone) back into a useful intermediate (isopropanol), eliminating the supply-demand imbalance and improving process economics.
Solution Approach 2:
The patent establishes a continuous cycle where excess acetone is continuously converted back to isopropanol and fed back to cumene production. This continuous recovery and recycling process ensures that the acetone byproduct does not accumulate or create economic disruption, but instead maintains a steady flow of materials through the process system.
3Productivity
If propylene feedstock is used for cumene production, then phenol can be produced via the Hock process, but propylene supply is limited and costs are likely to increase
Solution Approach 1:
The patent changes the feedstock parameter from propylene to isopropanol for cumene production. By using isopropanol (which can be derived from acetone, a byproduct of phenol production itself), the process eliminates dependence on external propylene supplies and their associated cost increases and supply constraints, while maintaining phenol production capability.
Solution Approach 2:
The patent makes the phenol production process more self-sufficient by using acetone (an internal byproduct) to generate isopropanol, which then serves as the alkylating agent for cumene production. This multi-functional approach allows the same phenol plant to produce its own feedstock, reducing external dependencies on propylene and creating a more resilient supply chain.
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 nitrogen impurities in the isopropanol product, extends zeolite catalyst life, and minimizes the need for propylene feedstock, addressing the acetone imbalance and supply issues in phenol production.
Implementation Method 1
alkylating benzene with isopropanol using a zeolite catalyst under liquid phase conditions to synthesize cumene
Implementation Method 2
oxidizing the cumene from step (a) with molecular oxygen into cumene hydroperoxide
Implementation Method 3
subjecting cumene hydroperoxide to acid cleavage to synthesize phenol and acetone
Implementation Method 4
hydrogenating the acetone from step (c) with hydrogen gas under liquid phase conditions into isopropanol
Implementation Method 5
attempts to remove these impurities from the acetone and isopropanol feeds with conventional solid acid adsorbents
Data Source
AI summary
In a process for producing phenol, benzene is contacted with a C3 alkylating agent comprising isopropanol under alkylation conditions such that at least part of the isopropanol reacts with the benzene to produce cumene. At least part of the resultant cumene is then oxidized in the presence of an oxidizing gas to produce an oxidation effluent comprising cumene hydroperoxide, unreacted cumene and a spent oxidizing gas. The unreacted cumene is separated from the oxidation effluent and is treated to remove nitrogenous impurities therefrom and produce a purified cumene stream, which is recycled to the oxidization step. At least part of the cumene hydroperoxide from the oxidation effluent is cleaved to produce a cleavage effluent comprising phenol and acetone. The phenol is recovered phenol from the cleavage effluent, whereas at least part of the acetone from the cleavage effluent is hydrogenated to produce isopropanol for recycle to the alkylation step.