Extractive Distillation for Aromatic Purity and Hydrogen Reduction
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Solution Overview
Problem
Existing processes for obtaining pure aromatics from hydrocarbon fractions require significant amounts of hydrogen and complex equipment, as they need to hydrogenate non-aromatic compounds, leading to inefficient hydrogen use and increased gas production.
Innovation Solution
A process that involves initial extractive distillation to separate non-aromatic compounds from aromatic-rich hydrocarbon fractions, followed by hydrodealkylation in a single column, reducing hydrogen consumption and gas production by eliminating the need for hydrogenating non-aromatics, and allowing for higher aromatic throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrodealkylation is performed on hydrocarbon fractions containing non-aromatic compounds, then aromatic products are obtained, but hydrogen consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by performing extractive distillation before hydrodealkylation to separate non-aromatic compounds from the feedstock. This pre-separation step removes paraffins and naphthenes that would otherwise consume hydrogen during subsequent hydrodealkylation, thereby reducing overall hydrogen consumption while maintaining aromatic product yield
Solution Approach 2:
The process is segmented into two distinct stages: (1) extractive distillation to separate non-aromatics from aromatic-rich fractions, and (2) hydrodealkylation of the purified aromatic fraction. This segmentation allows each stage to be optimized independently, with the first stage removing hydrogen-consuming impurities and the second stage focusing solely on aromatic dealkylation
2Quantity of substance
If non-aromatic compounds are hydrogenated during hydrodealkylation, then complete conversion is achieved, but gas production increases
Solution Approach 1:
The patent applies the extraction principle by using extractive distillation to remove non-aromatic compounds (paraffins, naphthenes) from the hydrocarbon fraction before hydrodealkylation. By extracting these components in advance, they are prevented from undergoing hydrogenation reactions that would generate excessive gas, thus reducing harmful gas production while maintaining complete conversion of the desired aromatic compounds
3Use of energy by moving object
If extractive distillation is performed before hydrodealkylation, then hydrogen consumption is reduced, but equipment complexity increases
Solution Approach 1:
The patent merges the extractive distillation unit with the hydrodealkylation process into an integrated flowsheet. The extractive distillation column is positioned directly upstream of the hydrodealkylation reactor, creating a compact arrangement where the two units work in sequence. This integration reduces equipment complexity compared to separate standalone units while achieving the dual benefit of non-aromatic removal and aromatic dealkylation
4Quantity of substance
If conventional hydrodealkylation processes are used, then aromatic production is achieved, but plant complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating extractive distillation as a pre-treatment step before hydrodealkylation. This pre-separation of non-aromatic compounds simplifies the overall plant configuration by eliminating the need for complex downstream separation units and reducing the number of processing steps required to achieve pure aromatic products
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 process significantly reduces hydrogen usage and gas production, achieving high-purity aromatic products with increased aromatic throughput and simplified equipment requirements.
Implementation Method 1
an initial extractive distillation is carried out to separate non-aromatic compounds from aromatic-rich hydrocarbon fractions
Implementation Method 2
separate non-aromatic compounds from aromatic-rich hydrocarbon fractions
Implementation Method 3
the alkylated benzene derivatives of the aromatic fractions being converted to benzene or lower alkylated benzene derivatives by hydrodealkylation
Data Source
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AI summary
The invention relates to a method for obtaining a pure product which contains aromatic compounds. The pure product is obtained by extractive distillation of a benzene which is rich in aromatic compounds, and olefins, diolefins and polyolefins being removed. The extractive distillation is followed by hydration of the resulting product stream which is rich in aromatic compounds and low in olefins, the alkylated aromatic compounds, especially toluol and xylols being dealkylated, and the paraffinic dealkylation products being reacted to give methane so that due to the nature of the hydration step after the extractive distillation the amount of hydrogen can be considerably reduced since the mixture of aromatic compounds is free of olefins and no hydrogen is required for olefin hydration. The invention also relates to a device for carrying out said method, preferably a column being used for extractive distillation which column allows an extractive distillation with solvent recirculation, thereby eliminating the need for an additional stripping column for removing the extracted solvent.