Study On Oxidative Desulfurization Of High Sulfur Petroleum Coke Catalyzed By Polyoxometalate Ionic Liquid

As a by-product of the refining industry,petroleum coke has the characteristics of low ash content?<1.2 wt%?and high carbon content?<85 wt%?,which can become the main raw material for the production of carbon products?such as carbon anodes?.However,with the decline of crude oil quality,more than 10 million tons of high-sulfur petroleum coke?sulfur content>3 wt%?is produced by refining and chemical industry every year.High-sulfur petroleum coke cannot be used to produce carbon products due to its high sulfur content,and it can only be classified as waste that causes environmental problems.Therefore,reducing the sulfur content in high-sulfur petroleum coke is of great significance to the environmental protection and economic development.Currently,high temperature desulfurization is the main industrial method applied to reduce the sulfur content in petroleum coke,which requires higher temperature,large energy consumption and high production cost.In order to respond to the national new requirements for energy conservation and environmental protection,a simple and easy new method for desulfurization of petroleum coke is explored in this paper under mild condition.Previous studies have shown that oxidative desulfurization can efficiently remove thiophene sulfides under mild reaction conditions.Therefore,a variety of polyoxometalate ionic liquids?POM-ILs?as catalysts are designed and synthesized in this paper,using H₂O₂ as an oxidant,to explore the oxidative desulfurization performance of high-sulfur petroleum coke and thiophene sulfides.The main contents are as follows:?1?An imidazole-type POM-ILs[Bmim]₃PW₁₂O₄₀ was synthesized as the catalyst and the oxidative desulfurization of high-sulfur petroleum coke with H₂O₂ as an oxidant was studied in this paper.At 80^oC,the sulfur content in high-sulfur petroleum coke can be reduced from 4.46 wt%to 2.85 wt%after 5 h.The characterizations of product structure show that the sulfide in petroleum coke is oxidized to sulfone,sulfoxide and sulfate.?2?Four types of quaternary ammonium POM-ILs with different carbon chain length were simply prepared as catalysts,and the effect of carbon chain length on the catalytic performance of quaternary ammonium POM-ILs was also explored.The results show that the catalyst with the shortest carbon chain has the best activity.At70^oC,the sulfur content in high-sulfur petroleum coke can be reduced from 4.46 wt%to 2.76 wt%after 5 h.At the same time,different thiophene sulfides were added into the solvent benzene to simulate the aromatic environment of petroleum coke,and the respective sulfate conversion rate is investigated.As a result,the sulfate conversion rate of 4-MDBT is the lowest.?3?Pyridine-type POM-IL[PSPy]₃PW₁₂O₄₀ was synthesized as a catalyst,and its effect on the sulfate conversion rate of 4-MDBT was investigated.At 70^oC,the sulfate conversion rate of 4-MDBT can reach to 31.66%after 6 h.At the same time,the desulfurization system was applied to the desulfurization of real high-sulfur petroleum coke,and the sulfur content can be reduced from 4.46 wt%to 2.41 wt%.