Composite solvent for liquefied petroleum gas sweetening and its preparation method and application

Abstract

The invention provides a liquefied petroleum gas sweetening composite solvent and its preparation method and application. The composite solvent comprises the following composition: 5-30wt.% inorganic strong base, 0.5-5wt.% sulfone solvent, 2.5-10wt. % ketone solvent, 0-2.5wt.% carboxylate, and the balance is water. The present invention forms a high-efficiency composite solvent by screening suitable organic additives and lye, can more significantly improve the effect of sulfur removal from mercaptans, and is especially applicable to deep sweetening treatment of coking liquefied gas with ultra-high mercaptan content.

Description

technical field [0001] The invention relates to a product refining process, in particular to a composite solvent for sweetening liquefied petroleum gas and its preparation method and application, belonging to the technical field of petroleum processing. Background technique [0002] As an important petrochemical product, liquefied petroleum gas (LPG) can not only be directly used as civil fuel, but also be used as chemical raw material for further processing to produce high value-added products, so it has attracted widespread attention. However, unrefined LPG carries a certain amount of small molecule mercaptans, which are odorous, toxic and corrosive, which will not only pollute the environment, but also cause great harm to the deep processing of liquefied gas, such as corrosion of equipment and catalyst poisoning Wait. Especially the liquefied gas (coking liquefied gas) from the coking unit has mercaptan content about 10 times that of the liquefied gas (catalytically crac...

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Problems solved by technology

[0011] Utilize the dethiol preparation in the research and process published online above, and introduce alcohol amine to improve the reaction and solubility of mercaptan and alkali. Although the removal rate of mercaptan has been improved to a certain extent, the extraction agent still needs to consume more High concentration of lye can guarantee the desulfurization effect, while large dose and high concentration of lye will slow down the oxidation of mercaptide (such as sodium mercaptide) to disulfide in the catalyst regeneration process, resulting in the desulfurization of the entire desulfurization agent. The regeneration speed is slow, and the sulfur removal is not complete, which will easily cause problems such as the decrease of the alkali amount in the circulation system and the frequent replacement of the alkali solution; in addition, alkali embrittlement may occur when the regeneration temperature is high, causing equipment corrosion; alcohol amines in the system also It will cause the accumulation of impurities due to its own oxidation; on the other hand, it is necessary to continue to use a liquid catalyst in the extractant, which is easy to aggregate and deactivate at a higher alkali concentration, which will also lead to problems such as shortened cycle life of the extractant

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