Ionic Liquid Extraction for Vacuum Gas Oil Desulfurization
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Solution Overview
Problem
Current processes for removing sulfur and nitrogen compounds from vacuum gas oil (VGO) are inefficient, particularly in reducing refractory species, which remain after hydrotreating, and require costly hydrogen use in hydrotreating steps.
Innovation Solution
A process involving the use of VGO-immiscible phosphonium ionic liquids to selectively extract highly aromatic polar nitrogen species followed by sulfur species, either before or after hydrotreating, to enhance the efficiency of sulfur removal and reduce contaminant levels in VGO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrotreating is used to remove sulfur and nitrogen compounds from VGO, then contaminant content is reduced, but hydrogen is consumed and the process becomes more expensive
Solution Approach 1:
The patent applies liquid-liquid extraction using ionic liquids to selectively remove sulfur and nitrogen compounds from VGO. The ionic liquid phase selectively extracts these contaminants from the hydrocarbon phase, providing an alternative to hydrotreating that avoids hydrogen consumption while achieving contaminant removal.
Solution Approach 2:
The patent introduces ionic liquids as intermediary substances that facilitate contaminant removal. The ionic liquids act as mediators between the VGO and the contaminants, selectively interacting with sulfur and nitrogen compounds to transfer them from the hydrocarbon phase to the ionic liquid phase.
2Quantity of substance
If conventional extraction methods are used to remove sulfur compounds, then some sulfur is removed, but refractory nitrogen species remain and extraction efficiency is limited
Solution Approach 1:
The patent modifies the extraction process by changing the chemical parameters of the extracting agent. By using specifically designed ionic liquids with particular cations and anions, the process achieves enhanced selectivity and efficiency in removing both sulfur and nitrogen compounds, overcoming the limitations of conventional extraction methods.
Solution Approach 2:
The patent employs composite ionic liquid systems that combine different cations and anions to create extracting agents with optimized properties. These composite ionic liquids provide simultaneous capability to extract both sulfur and nitrogen compounds, improving overall extraction efficiency and reliability.
3Manufacturing precision
If serial extraction is performed to first remove nitrogen species then sulfur species, then selectivity is improved, but process complexity increases
Solution Approach 1:
The patent develops ionic liquids that possess multi-functional extraction capabilities. The ionic liquid system can simultaneously and selectively extract both nitrogen and sulfur compounds in a single operation, eliminating the need for separate serial extraction steps and reducing process complexity while maintaining high selectivity.
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 significantly reduces sulfur content by at least 10 wt% and nitrogen content in VGO, improving downstream processing conditions and reducing emissions, while also making hydrotreating easier by addressing refractory species.
Implementation Method 1
contacting the vacuum gas oil with a VGO-immiscible phosphonium ionic liquid to produce a processed vacuum gas oil and VGO-immiscible phosphonium ionic liquid mixture, and separating the mixture to produce a processed vacuum gas oil effluent and a VGO-immiscible phosphonium ionic liquid effluent comprising the sulfur and nitrogen compounds
Data Source
AI summary
A process for removing a nitrogen compound and a sulfur compound from a hydroprocessed vacuum gas oil feed includes contacting the hydroprocessed vacuum gas oil feed comprising the nitrogen compound and the sulfur compound with a VGO-immiscible phosphonium ionic liquid to produce a hydroprocessed vacuum gas oil and VGO-immiscible phosphonium ionic liquid mixture, and separating the mixture to produce a hydroprocessed vacuum gas oil effluent having a reduced nitrogen compound and sulfur compound content relative to the vacuum gas oil feed. It was found that the amount of the sulfur compound being removed was significantly improved by first removing the nitrogen compounds, especially polar nitrogen compounds.