CN-121991716-A - Desulfurization method for high-sulfur petroleum coke

Abstract

The invention belongs to the field of high-end carbon material preparation, and relates to a method for desulfurizing high-sulfur petroleum coke. The core of the invention is to construct a three-step closed cycle system of desulfurization, acidification and regeneration. The system takes magnesium oxide as a circulating medium, firstly, magnesium oxide reacts with sulfur in petroleum coke at high temperature to be converted into magnesium sulfide, then sulfur is released and recovered through an acidification step, meanwhile, magnesium is converted into an intermediate product magnesium hydroxide, and finally, the magnesium medium is recovered to activity through a thermal regeneration step to obtain magnesium oxide, so that the circulation is completed.

Inventors

• ZHU LIJUN
• BAI YAN
• Li Menying
• YANG JUNWEI

Assignees

• 中国石油大学(华东)

Dates

Publication Date

20260508

Application Date

20251226

Claims (1)

1. 1. A petroleum coke desulfurization and sulfur recovery method based on magnesium oxide chemical circulation is characterized by comprising three steps of high-temperature calcination desulfurization, acidification sulfur release and sulfur recovery, magnesium agent regeneration and cyclic utilization which are sequentially carried out; wherein, the high temperature calcination desulfurization step includes: Crushing and grinding the high-sulfur petroleum coke to 20-40 mesh granularity, and uniformly mixing the crushed high-sulfur petroleum coke and magnesia powder according to a preset proportion to obtain a mixed material; placing the mixed material in inert or weak reducing atmosphere, and carrying out calcination desulfurization reaction at the temperature of 700-1000 ℃ for 1-5 hours; the magnesia powder comprises recycled magnesia and/or supplementary fresh magnesia; The feeding ratio of magnesium oxide to sulfur in petroleum coke is 1.05:1 to 1.2:1 calculated by the mol ratio of magnesium element to sulfur element; the step of acidifying sulfur release and sulfur recovery comprises: Acidifying the magnesium sulfide-containing solid product obtained after calcining and desulfurizing with hydrochloric acid solution, wherein the reaction temperature is between normal temperature and 80 ℃, and stirring at the same time; collecting gas generated by the reaction, washing, condensing and drying to obtain pure hydrogen sulfide gas; Introducing the hydrogen sulfide gas into a sulfur recovery device, and converting the hydrogen sulfide gas into elemental sulfur for recovery; The magnesium agent regeneration and recycling steps comprise: adding sodium hydroxide solution into the magnesium chloride-containing solution generated after the acidification reaction, and adjusting the pH value of the system to 11-13 to precipitate magnesium ions in the form of magnesium hydroxide; filtering and washing the magnesium hydroxide slurry to obtain a magnesium hydroxide filter cake; Thermally decomposing the magnesium hydroxide filter cake at 350-500 ℃ to regenerate magnesium oxide; and returning the magnesium oxide obtained by regeneration to the high-temperature calcining desulfurization step for recycling.

Description

Desulfurization method for high-sulfur petroleum coke Technical Field The invention belongs to the field of high-end carbon material preparation, and relates to a method for desulfurizing high-sulfur petroleum coke. Background Petroleum coke is a byproduct of delayed coking of heavy residual oil in the crude oil refining process, and the annual yield of the petroleum coke is more than 1 hundred million tons. As a substance with high carbon and high heat value, the petroleum coke is a high-quality fuel and a raw material for preparing carbon materials such as graphite electrodes, prebaked anodes for aluminum and the like. However, with the trend of heavy and inferior global crude oil resources being increased, the sulfur content of part of petroleum coke is more than 3%, and part of petroleum coke is even as high as 6% -8%, which is called high sulfur coke, and the yield ratio is remarkably increased. The direct combustion or use of high sulfur coke releases a large amount of sulfur dioxide (SO 2), which is one of the main causes of acid rain and atmospheric pollution. When used in electrode materials, sulfur content can lead to product expansion, strength degradation, and resistivity increase, severely affecting downstream product quality and performance. Therefore, the core bottleneck is the lack of efficient and economical desulfurization technology for large-scale, high value-added utilization of high sulfur petroleum coke. At present, the desulfurization research and application technology for petroleum coke is mainly divided into a physical method, a chemical method and a biological method. For example, the high-temperature calcination method, the high-sulfur coke is used for thermal decomposition of organic sulfur into H 2 S, COS and the like to escape under the inert atmosphere of 1200-1400 ℃. However, the method has extremely high energy consumption and large equipment investment, and the sulfur is discharged in the form of sulfur-containing tail gas with low concentration and complex components, so that a huge tail gas treatment device such as Claus+ tail gas treatment is needed, and the system is complex and has high cost. And the graphitization structure of the petroleum coke is easy to change in the high-temperature process, the yield is reduced, and the performance of the petroleum coke as a carbon material is affected. Wet acid-base chemical desulfurization is carried out by reacting strong base (NaOH, KOH) or strong acid (HNO 3、H2O2/acid system) with sulfur under normal pressure or pressure. The method has the advantages of high reagent consumption and high cost. A large amount of wastewater containing high-concentration salt or organic matters is produced, the treatment difficulty is high, and secondary pollution is easy to cause. The method has limited removal effect on inorganic sulfur (such as FeS 2), and the strong oxidizing acid is easy to break the carbon skeleton, so that carbon loss is caused. In addition, biological desulfurization is to use specific microorganisms (such as thermophilic bacteria) to catalyze and oxidize sulfur in petroleum coke. The reaction rate in the process is very slow, the treatment period is as long as weeks or even months, the control requirements on temperature, pH, nutrition conditions and the like are harsh, and the industrialized amplification difficulty is very high. The desulfurization depth of the biological method is limited, and the culture and maintenance cost of the strain is not very good. Therefore, it is difficult for the biological method to satisfy the demands of industrial large-scale treatment in terms of efficiency, stability and economy. Magnesium oxide (MgO) is used as an alkaline metal oxide, and has wide sources, relatively low cost, and the characteristics of generating magnesium sulfide (MgS) with thermodynamic stability by reacting with H 2 S, and the like, and is applied to the fields of gas desulfurization, flue gas desulfurization and the like. There have been some studies and studies on the use of the mixed MgO with petroleum coke for desulfurization, such as co-pyrolysis. However, this technical path remains at the level of "single use" or "waste disposal", with two fundamental bottlenecks: Firstly, the economic bottleneck is that magnesium sulfide (MgS) generated after the desulfurization reaction is regarded as solid waste. This not only causes waste of valuable magnesium resources (MgO), but also creates a new solid waste disposal problem (MgS generates extremely toxic H 2 S when meeting water or acid, belonging to hazardous waste). The high unit consumption cost of desulfurizing agent makes the technology economically incompatible with the large-scale petroleum coke treatment requirements. Secondly, the recycling bottleneck is that sulfur in petroleum coke is fixed in MgS and is not converted into a form (such as elemental sulfur or sulfuric acid) which is easy to separate and utilize in a high-value mode. From the point of