Coal Tar Phenol Purification via Extraction and Adsorption
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Solution Overview
Problem
Current methods for removing nitrogen and sulfur contaminants from crude phenols in coal tar are inefficient, as they either destroy phenols or fail to effectively reduce contaminant levels, hindering the upgrading process of these valuable compounds.
Innovation Solution
A process combining acid-base liquid extraction followed by an adsorption process using multiple adsorbent zones, including clays and zeolites, to selectively remove nitrogen and sulfur contaminants from coal-derived phenol streams, preserving the phenols and achieving low contaminant levels below 100 ppmw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrotreating is used to remove nitrogen and sulfur contaminants from crude phenols, then contaminant removal is achieved, but phenols are destroyed
Solution Approach 1:
The process segments contaminant removal into two distinct stages: extraction with aqueous alkali solution for bulk removal, and adsorption with specific adsorbents for trace removal. This segmentation allows each stage to target specific contaminant levels without affecting phenols excessively, resolving the contradiction between thorough contaminant removal and phenol preservation
Solution Approach 2:
The patent introduces aqueous alkali solution and solid adsorbents as intermediary substances that selectively interact with nitrogen and sulfur contaminants without reacting with phenols. These intermediaries mediate the separation process, enabling contaminant removal while preserving the desired phenolic compounds
2Manufacturing precision
If catalytic hydrodesulfurization is used to remove sulfur from phenols, then sulfur removal is achieved, but the process is inhibited by phenols like cresol
Solution Approach 1:
The patent extracts sulfur-containing compounds from the phenolic mixture using aqueous alkali solution before the adsorption step. This preliminary extraction removes the bulk of sulfur contaminants and reduces phenol concentration that would otherwise inhibit the desulfurization process, enabling effective sulfur removal without inhibition
3Quantity of substance
If extraction with aqueous sodium hydroxide followed by neutralization is used, then phenols are recovered, but nitrogen and sulfur contaminants remain
Solution Approach 1:
The patent continues the purification action by adding an adsorption step after the traditional extraction and neutralization process. This continuous purification approach maintains phenol recovery while further reducing nitrogen and sulfur contaminants to acceptable levels, completing the useful action of purification
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 effectively reduces nitrogen and sulfur contaminants to below 10 ppmw, allowing for efficient upgrading of phenols with a phenolic recovery rate of 75% or more, while avoiding the destruction of phenols that occurs in hydrotreating processes.
Implementation Method 1
a adsorption process using a plurality of adsorbent zones, including at least one clay adsorbent zone and at least one zeolite adsorbent zone
Implementation Method 2
phenols in coal tar distillate were extracted with an aqueous alkali solution
Data Source
AI summary
A process for removing contaminants from coal-derived phenols is described. The process combines an extraction process with at least two adsorption zones containing adsorbents. Liquid-liquid and acid base extraction processes can be used. The adsorbents can be clays and/or zeolites. The process can be used to reduce organonitrogen compounds and organosulfur compounds to levels below 10 ppmw and to generate a colorless product.