CN-122012142-A - Deep denitrification method for preparing light fuel oil by coal tar hydrogenation

CN122012142ACN 122012142 ACN122012142 ACN 122012142ACN-122012142-A

Abstract

The invention relates to the technical field of coal tar hydrogenation, and particularly discloses a deep denitrification method for preparing light fuel oil by coal tar hydrogenation. The method comprises the steps of filtering coal tar, dehydrating, demetallizing and deasphalting, performing a first-stage hydrogenation reaction under a conventional catalyst, entering a second hydrogenation reactor filled with an N-P co-doped ordered mesoporous carbon supported Zr 3+ doped Ni 2 P catalyst, performing hydrocracking and in-situ regeneration assisted by oxygen, and finally performing deep adsorption through a nitric acid modified ZSM-5 and alumina composite adsorbent to obtain light fuel oil. The invention adopts a multistage synergistic process of stepwise impregnation and in-situ regeneration of the catalyst and the B-Si double auxiliary agent and deep denitrification of the composite adsorbent, strengthens the hydrodenitrogenation activity and the catalyst stability, effectively reduces the total nitrogen content of the product and improves the yield of the light fraction of gasoline and diesel oil. The method has high denitrification depth and long catalyst life, can realize the efficient recycling of the coal tar, and is suitable for industrial production.

Inventors

WANG YANG
YANG LIANG
MA WENCHAO
SONG CHAOFAN
HU DIANLU
LIU LIANGGUO
WANG XIAOBING

Assignees

新疆汇安能源有限公司

Dates

Publication Date: 20260512
Application Date: 20260324

Claims (10)

1. The deep denitrification method for preparing the light fuel oil by hydrogenating the coal tar is characterized by comprising the following steps of: s1, pretreating a coal tar raw material, then sending the pretreated coal tar raw material into a first hydrogenation reactor, carrying out hydrogenation reaction under a first reaction condition, and carrying out gas-liquid separation after the reaction is finished to obtain a first effluent; S2, carrying out hydrocracking reaction on the first effluent in a second hydrogenation reactor filled with a catalyst under a second reaction condition to obtain a second effluent, wherein in the hydrocracking reaction process, introducing oxygen-containing gas flow into the reactor, and carrying out in-situ regeneration on the catalyst; S3, sending the second effluent into an adsorption reactor, filling a composite adsorbent in the adsorption reactor, and enabling the second effluent to be in contact with the composite adsorbent under a third operation condition to obtain the light fuel oil after deep denitrification.
2. The deep denitrification process for preparing light fuel oil by hydrogenating coal tar according to claim 1, wherein in S1, the pretreatment comprises at least one of filtration, dehydration, demetallization and deasphalting.
3. The deep denitrification method for preparing light fuel oil by hydrogenating coal tar according to claim 1, wherein in S1, the first reaction condition comprises a reaction temperature of 260-350 ℃, a reaction pressure of 6-12MPa, a volume space velocity of 0.8-1.5h -1 and a hydrogen-oil volume ratio of (800-2000): 1.
4. The deep denitrification method for preparing light fuel oil by hydrogenating coal tar according to claim 1, wherein in S1, the reaction is finished until the total nitrogen content of the first effluent is reduced to 2000-5000ppmw.
5. The deep denitrification method for preparing light fuel oil by coal tar hydrogenation according to claim 1 is characterized in that in S2, the catalyst comprises a carrier, an active component and a double auxiliary agent, wherein the carrier comprises Zr 3+ doped Ni 2 P, the double auxiliary agent comprises a boron source and a silicon source, the preparation method of the catalyst comprises the steps of taking organic sugar as a carbon source, mesoporous silicon as a template agent, mixing the organic sugar with nitrogen source and phosphorus source dissolved in deionized water to obtain a mixed solution A, evaporating in a water bath, calcining at high temperature, removing the template agent to obtain an N-P co-doped ordered mesoporous carbon carrier, dissolving zirconium salt and nickel salt in deionized water to obtain a mixed solution B, adding the N-P co-doped ordered mesoporous carbon carrier, performing a hydrothermal reaction, adding the phosphorus source after the reaction, heating up to react, separating and drying to obtain a mixture C, sequentially dipping the mixture C in a boron source solution and a silicon source solution step by step, and drying to obtain the catalyst.
6. The deep denitrification method for preparing light fuel oil by coal tar hydrogenation according to claim 5, wherein in S2, the organic sugar comprises any one of glucose, fructose and sucrose, the mesoporous silicon comprises any one of MCM-41 mesoporous silicon, SBA-15 mesoporous silicon and MCM-48 mesoporous silicon, the nitrogen source comprises any one of urea, melamine and ammonium chloride, the phosphorus source comprises any one of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate, the zirconium salt comprises any one of zirconium chloride, zirconium nitrate and zirconium sulfate, the nickel salt comprises any one of nickel nitrate, nickel chloride and nickel acetate, the boron source solution comprises any one of boric acid solution, sodium borate solution and potassium borate solution, and the silicon source solution comprises any one of ethyl orthosilicate solution, sodium silicate solution and sodium methyl silicate solution.
7. The deep denitrification method for preparing light fuel oil by coal tar hydrogenation according to claim 5 is characterized in that in S2, the water bath evaporating temperature is 60-90 ℃ and the water bath evaporating time is 2-6h, the high-temperature calcining temperature is 500-800 ℃ and the water heating reaction time is 3-8h, the water heating reaction temperature is 120-180 ℃ and the water heating reaction time is 4-12h, the heating reaction temperature is 200-300 ℃ and the reaction time is 2-5h, the drying roasting drying temperature is 80-120 ℃ and the drying time is 2-4h, the step impregnating temperature is 25-60 ℃ and the impregnating time is 2-6h, the mass ratio of impregnating solid to liquid is 1 (3-8), the roasting temperature of drying roasting is 300-500 ℃ and the roasting time is 2-5h.
8. The deep denitrification method for preparing light fuel oil by hydrogenating coal tar according to claim 5, wherein in S2, the second reaction condition comprises a reaction temperature of 360-420 ℃, a reaction pressure of 8-15MPa, a liquid hourly space velocity of 0.3-1.5h -1 and a hydrogen-oil volume ratio of (600-1200): 1.
9. The deep denitrification method for preparing light fuel oil by coal tar hydrogenation according to claim 1, wherein in S3, the composite adsorbent is obtained by roasting and compositing ZSM-5 molecular sieve impregnated by nitric acid with alumina precursor, wherein the mass concentration of nitric acid is 10-20wt%, the mass ratio of ZSM-5 molecular sieve impregnated by nitric acid to alumina precursor is (3-4): 1, and the roasting temperature is 500-650 ℃ and the time is 2-8h.
10. The deep denitrification method for preparing light fuel oil by hydrogenating coal tar according to claim 1, wherein in S3, the third operation condition comprises an operation temperature of 80-120 ℃, an operation pressure of 0.8-1.5MPa and a volume space velocity of 1.0-2.0h -1 .

Description

Deep denitrification method for preparing light fuel oil by coal tar hydrogenation Technical Field The application relates to the technical field of coal tar hydrogenation, in particular to a deep denitrification method for preparing light fuel oil by coal tar hydrogenation. Background Coal tar is a key byproduct generated in the pyrolysis, gasification and coking processes of coal, has extremely complex components, and is rich in polycyclic aromatic hydrocarbon, sulfur/nitrogen/oxygen-containing heteroatom compounds, nickel, vanadium, iron and other metal impurities. As important heavy carbon resources, the efficient clean conversion of the heavy carbon resources has important significance for improving the overall economy and environmental protection of the coal chemical industry. The coal tar is converted into clean light fuel oil with high cetane number by hydro-upgrading technology, and is one of the main ways for realizing the high-value utilization of the coal tar. However, high concentrations of metals and polycyclic aromatic hydrocarbons in the feedstock pose serious challenges to the hydrogenation process in that metal impurities (especially alkali metals and alkaline earth metals) tend to cause irreversible poisoning of the subsequent fixed bed hydrogenation catalyst, increased bed pressure drop, and greatly shortened device operating cycles, while polycyclic aromatic hydrocarbons are not only difficult to saturate, but also exacerbate catalyst soot deactivation during deep hydrogenation processes, and consume large amounts of hydrogen. At present, pretreatment of coal tar in industry mainly depends on conventional physical separation methods such as centrifugation, filtration, electrostatic desalting, solvent extraction and the like. Although the technologies can remove part of solid particles and inorganic salts, the selective removal efficiency of metal impurities and polycyclic aromatic hydrocarbons existing in the form of oil-soluble complex is limited, and the oil phase loss or secondary pollution is easily caused. In addition, in the prior art, an independent protection reactor is arranged in front of a hydrogenation main reactor, and a general demetallization agent and an adsorbent are filled. The passive adsorption protection strategy has the problems of limited metal capacity, low adsorption selectivity, strong aromatic adsorption reversibility and the like, and the protective agent needs to be replaced or regenerated once saturated, so that the operation cost is high, and the problem of poisoning of impurities on the main catalyst is difficult to fundamentally solve. Therefore, developing a novel pretreatment technology which can efficiently remove key toxic impurities in coal tar and can be in seamless connection with a subsequent hydrogenation process becomes a key for breaking through the bottleneck of the current coal tar hydro-upgrading technology and realizing the upgrading of the coal tar hydro-upgrading technology to the direction of producing clean oil products with ultra-high cetane number. Disclosure of Invention According to the method, the coal tar raw material is pretreated and then sent to a first hydrogenation reactor for hydrogenation reaction, a first effluent is obtained through gas-liquid separation, then the first effluent is sent to a second hydrogenation reactor filled with a specific catalyst for hydrocracking reaction, an oxygen-containing gas flow is introduced to conduct in-situ regeneration on the catalyst to obtain a second effluent, and finally the second effluent is sent to an adsorption reactor filled with a composite adsorbent for contact reaction, so that deep denitrification of the coal tar is realized, and a light fuel oil product is prepared. In order to achieve the above purpose, the application adopts the following technical scheme: the application provides a deep denitrification method for preparing light fuel oil by coal tar hydrogenation, which comprises the following steps: s1, pretreating a coal tar raw material, then sending the pretreated coal tar raw material into a first hydrogenation reactor, carrying out hydrogenation reaction under a first reaction condition, and carrying out gas-liquid separation after the reaction is finished to obtain a first effluent; S2, carrying out hydrocracking reaction on the first effluent in a second hydrogenation reactor filled with a catalyst under a second reaction condition to obtain a second effluent, wherein in the hydrocracking reaction process, introducing oxygen-containing gas flow into the reactor, and carrying out in-situ regeneration on the catalyst; S3, sending the second effluent into an adsorption reactor, filling a composite adsorbent in the adsorption reactor, and enabling the second effluent to be in contact with the composite adsorbent under a third operation condition to obtain the light fuel oil product after deep denitrification. According to the application, S1 is used for removing sol