Method for two-stage catalytic direct liquefaction of coal and application thereof
阅读说明：本技术 煤两段催化直接液化的方法及其应用 (Method for two-stage catalytic direct liquefaction of coal and application thereof ) 是由 王洪学 谢晶 李导 舒歌平 杨葛灵 单贤根 吴剑平 于 2020-07-21 设计创作，主要内容包括：本发明涉及煤炭直接液化领域,公开了一种煤两段催化直接液化的方法及其应用。该方法包括以下步骤：1)将含有第一催化剂、硫助剂、煤粉和供氢溶剂的煤浆与氢气进行一段液化反应；2)在第二催化剂存在下,将步骤1)得到产物与氢气进行二段液化反应,其中,所述第一催化剂为铁系催化剂,所述第二催化剂的活性成分选自钴、钼、镍、钨和铁中的一种或多种。采用该方法进行煤直接液化可以提高煤转化率、油收率和液化粗油的液化供氢性能。(The invention relates to the field of direct coal liquefaction, and discloses a method for two-stage catalytic direct coal liquefaction and application thereof. The method comprises the following steps: 1) carrying out a first-stage liquefaction reaction on coal slurry containing a first catalyst, a sulfur auxiliary agent, coal powder and a hydrogen supply solvent and hydrogen; 2) and (2) carrying out a two-stage liquefaction reaction on the product obtained in the step 1) and hydrogen in the presence of a second catalyst, wherein the first catalyst is an iron catalyst, and the active component of the second catalyst is one or more selected from cobalt, molybdenum, nickel, tungsten and iron. The method for directly liquefying coal can improve the coal conversion rate, the oil yield and the liquefaction hydrogen supply performance of the liquefied crude oil.)
1. A two-stage catalytic direct coal liquefaction method is characterized by comprising the following steps:
1) carrying out a first-stage liquefaction reaction on coal slurry containing a first catalyst, a sulfur auxiliary agent, coal powder and a hydrogen supply solvent and hydrogen;
2) in the presence of a second catalyst, the product obtained in the step 1) and hydrogen are subjected to a two-stage liquefaction reaction,
wherein the first catalyst is an iron-based catalyst, and the active component of the second catalyst is selected from one or more of cobalt, molybdenum, nickel, tungsten and iron.
2. The method of claim 1, wherein the iron-based catalyst is a supported iron-based catalyst and/or a non-supported iron-based catalyst;
preferably, the carrier of the supported iron-based catalyst is coal powder, the active component is ferric salt, and the ferric salt is one or more selected from ferrous sulfate, ferrous nitrate, ferrous chloride, ferric sulfate, ferric nitrate and ferric chloride;
preferably, the active component of the non-supported iron-based catalyst is one or more of iron ore, iron-containing waste residues, iron oxides, iron salts, pyrite and aluminum-smelting red mud;
preferably, the addition amount of the first catalyst is 0.2-3 wt% of the coal powder in the coal slurry calculated by iron element;
preferably, the first catalyst is added in an amount of 0.5-1.2 wt% of the coal dust in the coal slurry, calculated by iron element.
3. The method of claim 1 or 2, wherein the sulfur adjuvant is one or more of sulfur powder, liquid sulfur, carbon disulfide, and dimethyl disulfide;
preferably, the molar ratio of the sulfur promoter calculated as sulfur element to the first catalyst calculated as iron element is 1.5-2.5: 1.
4. The method according to any one of claims 1 to 3, wherein the hydrogen donor solvent is one or more of coal high-temperature coking decrystallized anthracene oil, coal high-temperature coking decrystallized washing oil, petroleum heavy oil catalytic cracking recycle oil, petroleum heavy oil catalytic cracking clarified oil hydrogenated oil and coal direct liquefaction hydrogenation stabilized oil;
preferably, the coal slurry concentration is 30-65 wt%;
more preferably, the coal slurry concentration is 40-60 wt%.
5. The process of any one of claims 1 to 3, wherein the primary liquefaction reaction is carried out in a primary reactor, the primary reactor being one or more of a bubbling bed, an ebullating bed, a fully backmixed suspended bed, and an internal and external loop reactor.
6. The method of any one of claims 1-3, wherein the conditions of the primary liquefaction reaction include: the temperature is 430-470 ℃, the time is 25-60min, and the hydrogen pressure is 10-25 MPa;
preferably, the conditions of the first stage liquefaction reaction include: the temperature is 440-460 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
7. The process of any of claims 1-3, wherein the second catalyst is selected from the group consisting of ores containing at least one of cobalt, molybdenum, tungsten, and iron, oxides of at least one of cobalt, molybdenum, nickel, tungsten, and iron, and water-soluble salts of at least one of cobalt, molybdenum, nickel, tungsten, and iron;
preferably, the adding amount of the second catalyst is 40-1000ppm of the weight of the coal dust in the coal slurry;
preferably, the second catalyst is added in an amount of 50-500ppm of the weight of the coal dust in the coal slurry based on active ingredients.
8. The process of any one of claims 1 to 3, wherein the two-stage liquefaction reaction is carried out in a two-stage reactor, the two-stage reactor being one or more of a bubbling bed, an ebullating bed, a fully backmixed suspended bed and an internal and external loop reactor.
9. The method of any one of claims 1-3, wherein the conditions of the two-stage liquefaction reaction include: the temperature is 430-470 ℃, the time is 25-65min, and the hydrogen pressure is 10-25 MPa;
preferably, the conditions of the secondary liquefaction reaction include: the temperature is 445-465 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
10. Use of the process of any one of claims 1 to 9 in the direct liquefaction of coal.
Technical Field
The invention relates to the field of direct coal liquefaction, in particular to a method for direct coal liquefaction by two-stage catalysis and application thereof.
Background
The direct coal liquefaction is a novel coal chemical clean coal technology which converts coal into a liquid product by a thermochemical reaction and a catalytic reaction under the dual actions of a hydrogen supply solvent and a catalyst under the condition of high temperature and high pressure hydrogen. The coal direct liquefaction oil product produced by the technology has high density, high heat capacity, high heat stability, high heat value, low condensation point, low sulfur, low nitrogen, low aromatic hydrocarbon and high naphthenic hydrocarbon, has unique physical properties different from the conventional petroleum-based oil product, and can provide a new source for military oil and special fuel in the aerospace field. In addition, the asphalt obtained by coal liquefaction and refining has the characteristics of low sulfur content, high hydrogen-carbon ratio, high softening point, high coking value, good high-temperature melt property and the like, and can be used as a high-quality raw material of high-end carbon. Therefore, the direct coal liquefaction technology has been a hot spot of great attention in the coal clean and efficient conversion and utilization industry.
The direct coal liquefaction process involves complex physical and chemical processes, and has a plurality of influencing factors, mainly including: the type and nature of the coal, the reactor form, the catalyst, the hydrogen donor solvent, the reaction operating conditions, and the like. The direct coal liquefaction catalyst can promote coal pyrolysis and accelerate pyrolysis macromolecule hydrocracking, stabilize coal pyrolysis free radicals, improve liquefied oil yield and improve oil quality, and how to effectively utilize the catalyst hydrogenation liquefaction activity is always a hotspot of direct coal liquefaction research.
The catalyst active component iron can react with hydrogen sulfide to produce Fe under the condition of coal liquefaction1-xS, which has good catalytic activity for coal liquefaction, due to low costThis has been a priority for direct coal liquefaction catalysts. For example, CN1579623A, a coal powder supported iron-based catalyst is added to a first section of a reactor, and the supported iron-based catalyst is mixed with raw material coal powder and a hydrogen donor solvent for pulping and then sent to a liquefaction reactor. Other relatively well-formed prior art coal liquefaction technologies such as the japanese NEDOL coal liquefaction process, the american HTI coal liquefaction process, the japanese NBCL coal liquefaction process, etc., wherein the direct coal liquefaction catalyst is added in the coal liquefaction reaction stage, the feed pulping stage. However, the above method requires further improvement in coal conversion and oil yield.
Disclosure of Invention
The invention aims to solve the problems of low conversion rate of coal, low oil yield and the like in the prior art, and provides a method for two-stage catalytic direct liquefaction of coal.
The inventor of the invention discovers through intensive research that when the coal direct liquefaction catalyst participates in a coal pyrolysis free radical and free radical hydrogenation reaction, catalyst particles can be combined with mineral substances after releasing coal free radicals and polymer coking substances of the coal free radicals which do not obtain hydrogen in time to cause the catalyst to be wrapped, so that the active site of the catalyst is annihilated, the catalytic activity of the catalyst is insufficient in a two-stage harsher liquefaction atmosphere, the activity of the coal direct liquefaction reaction is reduced, and the problems of reduction of the conversion rate of coal and the oil yield and the like are further caused. Therefore, the inventors of the present invention have made further studies to solve the problems of ensuring the activity of a catalyst in the direct coal liquefaction process and improving the coal liquefaction conversion rate and the oil yield, and as a result, have found that a coal slurry containing a specific first catalyst, a sulfur promoter, coal powder, and a hydrogen donor solvent is subjected to a first-stage liquefaction reaction with hydrogen; then, in the presence of a specific second catalyst, the first-stage liquefaction reaction is subjected to a second-stage liquefaction reaction with hydrogen, whereby the coal conversion rate, the oil yield, and the liquefied hydrogen supply performance of the liquefied crude oil can be improved, thereby completing the present invention.
That is, the present invention provides, in one aspect, a method for two-stage catalytic direct liquefaction of coal, wherein the method comprises:
1) carrying out a first-stage liquefaction reaction on coal slurry containing a first catalyst, a sulfur auxiliary agent, coal powder and a hydrogen supply solvent and hydrogen;
2) in the presence of a second catalyst, the product obtained in the step 1) and hydrogen are subjected to a two-stage liquefaction reaction,
wherein the first catalyst is an iron-based catalyst, and the active component of the second catalyst is selected from one or more of cobalt, molybdenum, nickel, tungsten and iron.
Preferably, the iron-based catalyst is a supported iron-based catalyst and/or a non-supported iron-based catalyst.
Preferably, the carrier of the supported iron-based catalyst is coal powder, the active component is iron salt, and the iron salt is one or more selected from ferrous sulfate, ferrous nitrate, ferrous chloride, ferric sulfate, ferric nitrate and ferric chloride.
Preferably, the active component of the unsupported iron-based catalyst is one or more of iron ore, iron-containing waste residues, iron oxides, iron salts, pyrite and aluminum-smelting red mud.
Preferably, the addition amount of the first catalyst is 0.2-3 wt% of the coal powder in the coal slurry calculated by iron element; more preferably, the first catalyst is added in an amount of 0.5-1.2 wt% of the coal dust in the coal slurry, calculated on the basis of iron element.
Preferably, the sulfur adjuvant is one or more of sulfur powder, liquid sulfur, carbon disulfide and dimethyl disulfide.
Preferably, the molar ratio of the sulfur promoter calculated as sulfur element to the first catalyst calculated as iron element is 1.5-2.5: 1.
Preferably, the hydrogen donor solvent is one or more of coal high-temperature coking decrystallized anthracene oil, coal high-temperature coking decrystallized washing oil, petroleum heavy oil catalytic cracking recycle oil, petroleum heavy oil catalytic cracking clarified oil hydrogenated oil and coal direct liquefaction hydrogenation stabilized oil.
Preferably, the coal slurry concentration is 30-65 wt%; more preferably, the coal slurry concentration is 40-60 wt%.
Preferably, the first stage liquefaction reaction is carried out in a first stage reactor, the first stage reactor being one or more of a bubbling bed, a fully backmixed suspended bed and an internal and external loop reactor.
Preferably, the conditions of the first stage liquefaction reaction include: the temperature is 430-470 ℃, the time is 25-60min, and the hydrogen pressure is 10-25 MPa; more preferably, the conditions of the first stage liquefaction reaction include: the temperature is 440-460 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
Preferably, the second catalyst is selected from the group consisting of ores containing at least one of cobalt, molybdenum, tungsten and iron, oxides of at least one of cobalt, molybdenum, nickel, tungsten and iron and water-soluble salts of at least one of cobalt, molybdenum, nickel, tungsten and iron.
Preferably, the adding amount of the second catalyst is 40-1000ppm of the weight of the coal dust in the coal slurry; more preferably, the second catalyst is added in an amount of 50-500ppm of the weight of the coal dust in the coal slurry based on the active ingredients.
Preferably, the two-stage liquefaction reaction is carried out in a two-stage reactor, the two-stage reactor being one or more of a bubbling bed, a fully back-mixed suspended bed and an internal and external loop reactor.
Preferably, the conditions of the secondary liquefaction reaction include: the temperature is 430-470 ℃, the time is 25-65min, and the hydrogen pressure is 10-25 MPa; more preferably, the conditions of the secondary liquefaction reaction include: the temperature is 445-465 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
In a second aspect the invention provides the use of the above process in the direct liquefaction of coal.
Through the technical scheme, the product does not need to be separated in the first-stage and second-stage liquefaction reaction processes, and the specific second catalyst can be directly added before the second-stage liquefaction reaction, so that the coal liquefaction conversion rate, the oil yield and the liquefied hydrogen supply performance of the liquefied crude oil are improved, and the processing conditions for preparing the hydrogen supply solvent from the liquefied crude oil are further alleviated.
Drawings
FIG. 1 is a schematic process flow diagram of a two-stage catalytic direct coal liquefaction process of the present invention.
Description of the reference numerals
1: coal slurry preparation tank
2: coal slurry preheater
3: first stage reactor
4: catalyst slurry oil homogenizing tank
5: static mixer
6: two-stage reactor
A1: coal powder, sulfur auxiliary agent and hydrogen donor solvent
A2: hydrogen donor solvent
B1: steam generating device
B2: condensed water
C1: first catalyst
C2: second catalyst
H1: circulating hydrogen
H2: hydrogen gas
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a two-stage catalytic direct coal liquefaction method, which comprises the following steps:
1) carrying out a first-stage liquefaction reaction on coal slurry containing a first catalyst, a sulfur auxiliary agent, coal powder and a hydrogen supply solvent and hydrogen;
2) in the presence of a second catalyst, the product obtained in the step 1) and hydrogen are subjected to a two-stage liquefaction reaction,
wherein the first catalyst is an iron-based catalyst, and the active component of the second catalyst is selected from one or more of cobalt, molybdenum, nickel, tungsten and iron.
According to the invention, the first catalyst, the coal powder, the sulfur auxiliary agent and the hydrogen supply solvent are fully mixed to prepare the coal slurry, and the coal slurry and the hydrogen gas are subjected to a primary liquefaction reaction.
According to the invention, the coal powder can be prepared from raw material coal through a crushing and drying process. Preferably, the particle size of the coal powder is less than 100 μm, and the moisture content is 1-6 wt%; more preferably, the pulverized coal has a particle size of less than 74 μm and a moisture content of 4-5 wt%. When the particle size of the pulverized coal is larger than the above range, the direct coal liquefaction reaction is insufficient, and when the moisture content of the pulverized coal exceeds the above range, the effective hydrogen partial pressure is reduced, and unnecessary energy consumption is generated.
According to the invention, the coal slurry concentration refers to the proportion of the addition amount of the coal powder in the total weight of the coal powder and the hydrogen donor solvent.
In the present invention, the concentration of the coal slurry may be 30 to 65 wt%, preferably, the concentration of the coal slurry is 40 to 60 wt%, and more preferably, the concentration of the coal slurry is 40 to 50 wt%. When the coal slurry concentration is in the range, the viscosity of the coal slurry is proper, so that pumping pipe conveying is facilitated, and if the coal slurry concentration is higher than the range, the viscosity of the coal slurry is increased, so that pumping pipe conveying is not facilitated; if the coal slurry concentration is lower than the above range, the coal liquefaction processing amount becomes small, the economy is poor, and the prepared coal slurry is deposited, which is also not favorable for pumping pipe transportation.
In the invention, the iron-based catalyst can be a supported iron-based catalyst and/or a non-supported iron-based catalyst, the carrier of the supported iron-based catalyst can be pulverized coal, the active component of the supported iron-based catalyst is ferric salt, the ferric salt can be ferrous salt and/or ferric salt, specifically, the ferrous salt can be one or more of ferrous sulfate, ferrous nitrate and ferrous chloride, and the ferric salt can be one or more of ferric sulfate, ferric nitrate and ferric chloride; the active component of the non-supported iron catalyst can be one or more of iron ore, iron-containing waste residues, iron oxides, iron salts, pyrite and aluminum-smelting red mud. In the present invention, preferably, the iron-based catalyst is a supported iron-based catalyst using pulverized coal as a carrier.
According to the invention, the first catalyst can be added in an amount of 0.2-3 wt% of the pulverized coal, calculated as iron element; preferably, the first catalyst is added in an amount of 0.5-1.2 wt% of the pulverized coal, calculated on the basis of iron element.
In the present invention, in order to change the catalyst into an active state, the coal slurry may further contain a sulfur aid, which is not particularly limited, and may be any of various sulfur aids commonly used in the direct coal liquefaction reaction in the art, as long as the sulfur aids can be decomposed into H under sulfidation conditions2S, for example, the sulfur adjuvant may be one or more of sulfur powder, liquid sulfur, carbon disulfide, and dimethyl disulfide. In the present invention, preferably, the sulfur auxiliary agent is sulfur powder.
In the present invention, the amount of the sulfur adjuvant may be determined according to the amount of the first catalyst, and preferably, the molar ratio of the sulfur adjuvant calculated as sulfur element to the first catalyst calculated as iron element is 0.8-5: 1; more preferably, the molar ratio of the sulfur promoter, calculated as elemental sulfur, to the first catalyst, calculated as elemental iron, is from 1.5 to 2.5: 1.
According to the present invention, the hydrogen donor solvent may be selected from hydrogen donor solvents used in coal direct liquefaction in the art, and is not particularly limited, and may be, for example, one or more of coal high-temperature coking decrystallized anthracene oil, coal high-temperature coking decrystallized wash oil, petroleum-based heavy oil catalytic cracking recycle oil, petroleum-based heavy oil catalytic cracking clarified oil hydrogenated oil, and coal direct liquefaction hydrogenation stabilized oil. Preferably, the hydrogen donor solvent is coal direct liquefaction hydrogenation stabilized oil.
In the invention, the high-temperature coking and decrystallization anthracene oil of coal refers to decrystallization anthracene oil generated in the high-temperature coking process of coal.
In the invention, the high-temperature coking decrystallization washing oil of coal refers to decrystallization washing oil generated in the high-temperature coking process of coal.
In the invention, the petroleum heavy oil catalytic cracking cycle oil refers to cycle oil produced in the aromatic hydrocarbon extraction and generation process of the petroleum heavy oil catalytic cracking cycle oil.
In the invention, the hydrogenated oil of the petroleum heavy oil catalytic cracking clarified oil is solvent oil obtained by carrying out one or more times of hydrogenation treatment on the coal high-temperature coking and decrystallizing anthracene oil, the coal high-temperature coking and decrystallizing washing oil and the catalytic cracking clarified oil.
In the invention, the coal direct liquefaction hydrogenation stable oil is solvent oil obtained by hydrotreating liquefied crude oil obtained by a coal direct liquefaction process.
In a preferred embodiment of the invention, when the direct coal liquefaction reaction is carried out for the first time, the hydrogen supply solvent adopts three-pass hydrogenated oil of coal high-temperature coking and decrystallizing anthracene oil and coal high-temperature coking and decrystallizing washing oil (the weight ratio of the anthracene oil to the washing oil is 1: 1).
In a preferred embodiment of the present invention, when the direct coal liquefaction reaction is continuously performed, the hydrogen donor solvent uses a direct coal liquefaction hydrogenation-stabilized oil.
According to the present invention, preferably, after the coal slurry is prepared, the coal slurry is preheated, and then the preheated coal slurry is introduced into a first-stage reactor to perform a first-stage liquefaction reaction. The preheating temperature may be, for example, 350-400 deg.C, preferably 385-399 deg.C.
In the present invention, the first-stage reactor may be any of various reactors for performing a direct coal liquefaction reaction in the art, and is not particularly limited, for example, the first-stage reactor may be one or more of a bubbling bed, a full back-mixed suspension bed, and an internal and external loop reactor.
In the present invention, preferably, the conditions of the one-stage liquefaction reaction include: the temperature is 430-470 ℃, the time is 25-60min, and the hydrogen pressure is 10-25 MPa; more preferably, the conditions of the first stage liquefaction reaction include: the temperature is 440-460 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
The inventor of the present invention has found through intensive research that if the catalyst is not supplemented after the first-stage liquefaction reaction, the second-stage liquefaction reaction is directly performed after the first-stage liquefaction reaction, and finally the conversion rate and the oil yield of the coal after the second-stage liquefaction reaction are not ideal, and the reason for this is probably because fresh coal powder, fresh catalyst and fresh hydrogen supply solvent are subjected to a relatively severe liquefaction reaction in the presence of hydrogen in the first-stage reactor, but in the process of gradual liquefaction of the coal, part of free radicals of the coal are not stabilized by hydrogen and are polymerized, and the generated polymer, minerals in the coal and the catalyst attached to the minerals are wrapped with each other, so that the active sites of the catalyst are annihilated, and the catalyst activity of the catalyst is reduced when the coal is continuously liquefied, and further liquefaction of the coal is not facilitated.
Therefore, the inventors of the present invention have found, based on the finding, that in order to compensate for the loss of the catalyst activity in the first-stage liquefaction reaction and cope with the more severe coal liquefaction reaction atmosphere in the second-stage liquefaction reaction, a specific second catalyst is additionally added to the feed of the second-stage liquefaction reaction, thereby improving the coal liquefaction conversion rate and the oil yield and the liquefaction hydrogen supply performance of the liquefied crude oil, and further relaxing the processing conditions for preparing the hydrogen supply solvent from the liquefied crude oil.
According to the invention, after the first-stage liquefaction reaction is finished, the product is not required to be separated and otherwise treated, the first-stage liquefaction reaction product is directly contacted with the second catalyst and enters the second-stage reactor to carry out the second-stage liquefaction reaction, the operation process is very simple and convenient, and the process is greatly optimized.
In the present invention, the second catalyst is selected from the group consisting of ores containing at least one of cobalt, molybdenum, tungsten, and iron, oxides of at least one of cobalt, molybdenum, nickel, tungsten, and iron, and water-soluble salts of at least one of cobalt, molybdenum, nickel, tungsten, and iron; preferably, the active ingredient of the second catalyst is a water-soluble salt of molybdenum.
According to the invention, the addition amount of the second catalyst is 40-1000ppm of the weight of the coal dust in the first stage of liquefaction reaction based on active components. Preferably, the second catalyst is added in an amount of 50-500ppm of the weight of the primary coal powder based on the active ingredients.
According to the invention, the second catalyst can be used in the form of an oil-soluble and/or water-soluble emulsion.
In the present invention, when the second catalyst is used in an oil-soluble form, the metal precursor containing the active ingredient is reacted with an organic acid, an amine substance or an alcohol substance to prepare the second catalyst in an oil-soluble form.
In the present invention, when the second catalyst is used in a water-soluble emulsified state, a second catalyst aqueous solution containing an active ingredient (the content of the active ingredient in the aqueous solution may be 5 to 25% by weight) is mixed with a hydrogen donor solvent and then homogenized and emulsified (the weight ratio of the aqueous solution to the hydrogen donor solvent may be 1:0.2 to 2), thereby preparing the second catalyst in a water-soluble emulsified state.
According to the present invention, the two-stage liquefaction reaction is performed in a two-stage reactor, which may be various reactors commonly used in the art for performing a direct coal liquefaction reaction, without particular limitation, and for example, the two-stage reactor may be a bubbling bed, an ebullating bed, a full back-mixed suspension bed, an internal and external loop reactor, and the like.
According to the invention, the conditions of the two-stage liquefaction reaction comprise: the temperature is 430-470 ℃, the time is 25-65min, and the hydrogen pressure is 10-25 MPa; preferably, the conditions of the secondary liquefaction reaction include: the temperature is 445-465 ℃, the time is 30-45min, and the hydrogen pressure is 19-20 MPa.
After the second-stage liquefaction reaction is finished, the second-stage reaction product enters a separation system for subsequent separation. The subsequent separation process can be performed according to various methods commonly used for separation of products of the refining reaction, for example, a product after the second-stage liquefaction reaction can be firstly separated into a first gas phase and a liquid-solid mixed phase, the obtained first gas phase is cooled step by step and then separated into gas and light oil, and the remaining part of the obtained gas is recycled to the direct coal liquefaction reaction after a part of tail gas is discharged; and (3) carrying out step-by-step pressure reduction and normal pressure reduction distillation on the obtained liquid-solid mixed phase to obtain a second gas phase, an oil product and residues, and mixing the oil product with the light oil to obtain liquefied crude oil. The separation of the products after direct coal liquefaction is a well-known technique in the art and will not be described in detail herein.
In a preferred embodiment of the invention, the process is carried out using an apparatus as shown in FIG. 1, comprising: a coal slurry preparation tank 1, a
The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. In the following examples, all reagents used are commercially available unless otherwise specified.
The various yields were calculated on a dry ashless coal (daf coal) (as measured according to national standard GB/T212-2008) basis and are defined as follows:
coal conversion: 1- (tetrahydrofuran insolubles in residue-unoxidized ash in residue)/daf coal, wherein unoxidized ash in residue refers to the actual weight of iron, sulfur and other inorganics entering the coal slurry plus the weight of ash in the coal);
oil yield: liquefying n-hexane soluble material/daf coal in the crude oil;
gas yield: tail gas does not contain H2Non-condensable gas/daf coal;
water yield: generating water/daf coal in the light oil;
asphaltenes: (n-hexane insoluble-tetrahydrofuran insoluble in residue)/daf coal;
hydrogen consumption: (fresh H)2H in the offgas2) (ii) daf coal;
PDQI value of the liquefied crude oil was determined by NMR spectrometer (Bruker 500M, USA)Line of1H-NMR measurement and calculation.
PDQI values: the hydrogen donating index, which represents the hydrogen donating ability of a solvent, refers to the ratio of the mass of hydrogen atom beta to the mass of the solvent on the cycloalkyl group of the cycloalkylaromatic hydrocarbon, i.e., the number of milligrams of hydrogen atom beta to the cycloalkyl group of the cycloalkylaromatic hydrocarbon per gram of hydrogen donating solvent.
In the following examples and comparative examples, the raw coal used was Shendong coal, the basic properties of which are shown in Table 1:
TABLE 1
Note: mad is air drying base moisture; ad is ash; vdaf is volatile.
In the following examples and comparative examples, the hydrogen donor solvent used was coal direct liquefaction hydrogenation stabilized oil, and the basic properties are shown in table 2:
TABLE 2
Note: IBP is the initial boiling point;
50% refers to the temperature at which 50% by weight of the oil is distilled off;
90% refers to the temperature at which 90% by weight of the oil is distilled off.
In the following examples and comparative examples, the pulverized coal used was pulverized and dried as a raw material coal to obtain 85% or more pulverized coal having a particle size of less than 74 μm and a moisture content of 4.5 wt%.
The following examples and comparative examples were carried out in the apparatus shown in FIG. 1.
In the following examples and comparative examples, the preparation of the first catalyst was carried out according to the method described in CN 1579623A:
1) 5.7kg of industrial FeSO is taken4·7H2Dissolving O in 46.88kg of water, adding the O into 15.78kg of coal powder, and uniformly stirring to obtain FeSO4Coal slurry;
2) another 1.27kg of ammonia water was added to 17.38kg of water and the mixture was stirredAdding the obtained ammonia water into the FeSO obtained in the step 1)4Coal slurry is stirred for 10 seconds;
3) the product obtained in the step 2) is heated at 40 ℃ for 3m3Oxidizing for 100 minutes under the air flow;
4) and (4) carrying out centrifugal filtration on the oxidation product to obtain a filter cake, namely the first catalyst.
In the following examples, the second catalyst was used in oil-soluble form and was prepared as follows:
1) carrying out precipitation reaction on a 15 wt% sodium hydroxide aqueous solution and a 15 wt% molybdenum nitrate (or 30 wt% cobalt nitrate, 30 wt% iron nitrate, 30 wt% nickel nitrate and 30 wt% tungsten metatungstate) aqueous solution in a cocurrent manner (wherein the molar ratio of alkali in the sodium hydroxide aqueous solution to molybdenum, cobalt, iron, nickel and tungsten salts is 2:1), the pH value of a reaction system is 7.5, the temperature is 75 ℃, the reaction residence time is 6 hours, and after the reaction is finished, filtering, washing and drying are carried out to obtain a molybdenum (or cobalt, iron, nickel and tungsten) metal precursor;
2) mixing the metal precursor obtained in the step 1) and hexadecanoic acid in a molar ratio of 1: 3, reacting in oxygen-free atmosphere at 230 deg.c for 4 hr to obtain the oil soluble Mo (or Co, Fe, Ni and W) catalyst, i.e. the second catalyst.
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