阅读说明：本技术 褐煤加氢催化裂解制汽油和航空煤油组分的方法 (Method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking ) 是由 王杰 毛峰 于 2020-12-14 设计创作，主要内容包括：本发明公开了褐煤加氢催化裂解制汽油和航空煤油组分的方法,采用两段反应器同步反应,褐煤在第一段反应器中进行加氢热解,产生挥发分,挥发分未经过度冷却通过第二段反应器进行催化加氢提质,产生油品和气体产物。氢气从第一段反应器入口处进入,压力与后续反应器保持相同；第二段反应器中先预升温至500℃并保温1h,然后降至300-400℃不变；而后以2-20℃/min升温速率将第一段反应器中褐煤升温至650-750℃,保温10min。本发明催化裂解得到气态烃产率明显增大；制备的焦油产品呈透明无色状,含有较多的碳数从6至12的正构烷烃,并富含环戊烷和环已烷及其同系物,还有明显的十氢萘和四氢萘存在,这些是汽油、航空煤油的主要组分。(The invention discloses a method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking, which adopts two-stage reactor synchronous reaction, lignite is subjected to hydrogenation pyrolysis in a first-stage reactor to generate volatile components, and the volatile components are subjected to catalytic hydrogenation upgrading through a second-stage reactor without being cooled excessively to generate oil products and gas products. Hydrogen enters from the inlet of the first-stage reactor, and the pressure is kept the same as that of the subsequent reactor; pre-heating to 500 ℃ in the second-stage reactor, preserving heat for 1h, and then reducing to 300-400 ℃ without changing; then heating the lignite in the first-stage reactor to 650-750 ℃ at the heating rate of 2-20 ℃/min, and preserving the heat for 10 min. The yield of the gaseous hydrocarbon obtained by catalytic cracking is obviously increased; the prepared tar product is transparent and colorless, contains more normal alkanes with the carbon number of 6-12, is rich in cyclopentane, cyclohexane and homologues thereof, and has obvious decahydronaphthalene and tetrahydronaphthalene which are main components of gasoline and aviation kerosene.)

1. A method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking is characterized by comprising the following steps:

two-stage reactors are adopted for synchronous reaction, lignite is subjected to hydro-pyrolysis in the first-stage reactor to generate volatile, and the volatile is subjected to catalytic hydrogenation upgrading through the second-stage reactor without being cooled excessively to generate oil products and gas products.

Wherein, the first stage reactor is filled with lignite, the second stage reactor is filled with catalyst, hydrogen enters the reactor from the inlet of the first stage reactor, the pressure of the hydrogen is kept the same as that of the second stage reactor, and the pressure is controlled to be 3-6 MPa; preheating to 500 ℃ in a second-stage reactor, and preserving heat for 1h to ensure that the catalyst is fully dehydrated and the active metal in the oxidation state is reduced to be in a metal state, then reducing the temperature of a catalyst bed layer to 400 ℃ of 300-; then heating the lignite to 650-750 ℃ at the heating rate of 2-20 ℃/min, preserving the heat for 10min,

in the reaction process, volatile matters are carried to a catalyst layer in the second-stage reactor through a low-temperature coal layer area to carry out catalytic hydrogenation and quality improvement.

2. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 1, characterized in that:

wherein the second-stage reactor and the first-stage reactor are arranged up and down, the first-stage reactor adopts a fixed bed or a moving bed, a coal sample can be fed intermittently or continuously, and the particle size is determined according to the size of the reactors; the second stage reactor adopts a fixed bed reactor.

3. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 1, characterized in that:

wherein, lignite or high-volatile low-rank coal is used as a raw material in the first-stage reactor, and the ash content is not limited;the space velocity of the volatile in the second-stage reactor passing through the catalyst layer is 1-10h^-1。

4. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 1, characterized in that:

hydrogen enters the reactor from the inlet of the first-stage reactor, the pressure of the hydrogen is kept the same as that of the second-stage reactor, and the pressure is controlled to be 5 MPa; preheating to 500 ℃ in a second-stage reactor, and preserving heat for 1h to ensure that the catalyst is fully dehydrated and the active metal in the oxidation state is reduced to be in a metal state, then reducing the temperature of a catalyst bed layer to 350 ℃, and keeping the temperature of the catalyst layer unchanged; and then heating the lignite to 700 ℃ at the heating rate of 15 ℃/min, and preserving the heat for 10 min.

5. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 1, characterized in that:

wherein the catalyst takes a formed molecular sieve as a carrier and is loaded with one or more transition metal combinations of Ni, Mo and Co;

during preparation, nickel nitrate, cobalt nitrate and ammonium molybdate solution are taken as precursors, and the formed molecular sieve is immersed in the precursor solution for at least 12 hours; then evaporating water in a vacuum oven at 60 ℃, heating to 110 ℃ for full drying, putting the dried catalyst into a muffle furnace, heating to 550 ℃ for roasting for 4 hours.

6. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 4, characterized in that:

wherein the carrier is HZSM-5, the particle size is 3-5mm, the silica-alumina ratio is 20, and the specific surface area is 300m²(ii)/g; the nickel or cobalt loading is 0.5-2% of the HZSM-5 carrier, and the molybdenum loading is 2-5% of the HZSM-5 carrier.

7. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 5, characterized in that:

wherein the catalyst is Ni-HZSM-5 or NiMo-HZSM-5, the Ni loading is 1.0 wt.%, and the Mo loading is 3 wt.%.

8. The method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking according to claim 3, characterized in that:

wherein the space velocity of the volatile components passing through the catalyst layer is 3.7h^-1。

Technical Field

The invention belongs to the technical field of lignite hydrogenation catalytic cracking, and provides a method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking.

Background

Lignite resources in China are rich, but due to the characteristics of low metamorphic degree, high water content, low heat value and the like, the direct combustion and utilization have the problems of low efficiency and large pollution, and the development space is limited. The method has the advantages of efficiently and cleanly utilizing inferior lignite resources, improving the utilization value of lignite, and being in line with the development trend of the later coal chemical industry for transformation updating.

The lignite is high in hydrogen content and volatile component yield, and the preparation of high-quality oil gas through lignite pyrolysis is a new way for green and efficient utilization of lignite. However, the tar obtained by the conventional pyrolysis has a plurality of heavy components, high content of heteroatoms such as nitrogen, sulfur and oxygen, poor quality, can not be directly used as transportation fuel, and has low commercial value. The hydrofining of coal pyrolysis tar is a conventional method for preparing crude coal tar into transportation fuels such as gasoline, diesel oil, kerosene and the like: for example, Korea et al have filed an invention patent of "method for hydrorefining cracked tar" (CN 110540865A); the invention patent of 'a process method for preparing oil by hydrocracking and lightening coal tar pitch' is applied to Zhu Shi Rong and the like (CN 102212391A). However, the method is characterized in that the crude tar is used as a raw material, the pyrolysis process is not optimized on the whole to prepare the transportation fuel with high yield, and the original 'potential available structural composition' in the lignite can undergo irreversible over-decomposition in the pyrolysis process, so that the overall conversion efficiency is low. In addition, the coal tar composition is unstable, and the tar re-agglomeration and agglomeration possibly caused in the storage and transportation process are relatively troublesome problems in the coal tar conversion operation.

Coal hydropyrolysis is one of the methods for improving the yield and quality of oil and gas (Canel M, Misirlioglu Z, Canel E, et al distribution and compliance of hydrocarbon products during slow pyrolysis and hydropyrolysis of Turkish lignites [ J ] Fuel,2016,186:504-517), but the directionality of the conventional hydropyrolysis reaction is not high, and the tar still contains more heavy, unsaturated compounds and heteroatom compositions, and has no substantial difference from the conventional pyrolysis tar compositions, and can not be directly fractionated to prepare transportation fuels. Catalytic coal hydropyrolysis is a method for greatly improving the yield and quality of tar. The utilization of two fixed reactors is a feasible industrialized technology for realizing the on-line hydrogenation catalytic refining of the volatile components of the lignite. In the technology, lignite is subjected to non-catalytic hydropyrolysis in a fixed bed or a moving bed in a first section, and volatile components are subjected to catalytic hydropyrolysis through a catalyst layer in a second section. Compared with the catalytic hydrogenation method of directly mixing coal and catalyst by using a fluidized bed reactor, the technology can avoid the difficulty of separating coke and catalyst generated after the hydropyrolysis and the loss of effective catalyst components. Compared with the conventional method for refining the coal tar by combining pyrolysis with pyrolysis, the method has the advantages that the pyrolysis process is promoted by hydrogenation conditions, the yield of effective volatile components can be improved, and the fixed bed catalyst layer has independent temperature control conditions, so that the optimization of catalytic activity is realized, and the production of target products is facilitated. Moreover, the online catalytic hydrogenation of the volatile matter can avoid the deterioration of tar composition and reduce the heat loss in the tar condensation process. There are several related research reports on the coal hydrocatalytic cracking using two-stage fixed bed reactor, but the aim is mainly to produce light aromatic hydrocarbon, for example, Chareonpanich et al report on the preparation of monocyclic aromatic hydrocarbon using molecular sieve catalyst (meta Chareonpanich, Zhang Z G, Nishijima a, et al. effect of catalysts on unsaturated hydrocarbons in hydrocracked of volatile hydrocarbon matrix [ J. Fuel,1995.), and there is no research report on the direct conversion of lignite into gasoline and aviation kerosene using two-stage fixed bed reactor.

The technology of utilizing two-stage fixed bed reactor to prepare gasoline and aviation kerosene directly from lignite relates to the use of proper catalyst, and the hydrocracking catalyst commonly used in industry mostly uses molecular sieve or porous alumina as catalyst carrier, and transition metal, such as Ni, Mo, Co, W, etc. as active component. For example, Liu Quanjie et al filed an invention patent (CN102838439A) of "a method for producing decalin by naphthalene hydrogenation", using a molecular sieve ZSM-5 carrier, nickel and molybdenum as active metals, and an alkali metal as a promoter; exxon Mobil chemical patent application for "Multi-stage upgraded Hydrocarbon pyrolysis Tar" (CN111032834A) in which a hydrogenation zone comprises Ni-Co-Mo-Al₂O₃Catalyst, the second hydrogenation zone comprising Co-Mo-Al₂O₃A catalyst. However, the above patents are directed to the hydro-conversion upgrading of coal tar or specific components in coal tar, and do not relate to in-situ catalytic hydrocracking of pyrolysis volatiles.

Takarada et Al reported the use of Co-Mo-Al₂O₃The catalyst was studied for the catalytic hydropyrolysis of coal in a fluidized bed, and the target product was light aromatic hydrocarbons such as benzene, toluene and xylene (Takarada T, Onoyama Y, Takayama K, et al]Catalysis Today,1997,39(1): 127-. Although nickel molybdenum cobalt supported molecular sieve catalysts are widely usedThe coal tar is hydrorefined, but the technical report that lignite is directly and highly directionally prepared into gasoline and aviation kerosene through online catalytic hydrogenation of volatile components is not seen.

Disclosure of Invention

The invention aims to solve the technical problems, and provides a method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking aiming at the technical problems existing in the current deep utilization of lignite.

According to the first aspect of the invention, a method for preparing gasoline and aviation kerosene components through lignite hydrocatalytic cracking is provided, two-stage reactors are adopted for synchronous reaction, lignite is subjected to hydropyrolysis in the first-stage reactor to generate volatile matters, and the volatile matters are subjected to catalytic hydrogenation upgrading through the second-stage reactor without being excessively cooled to generate oil products and gas products.

Wherein, the first stage reactor is filled with lignite, and the second stage reactor is filled with catalyst.

Hydrogen enters the reactor from the inlet of the first-stage reactor, the pressure of the hydrogen is kept the same as that of the second-stage reactor, and the pressure is controlled to be 3-6 MPa; preheating to 500 ℃ in a second-stage reactor, and preserving heat for 1h to ensure that the catalyst is fully dehydrated and the active metal in the oxidation state is reduced to be in a metal state, then reducing the temperature of a catalyst bed layer to 400 ℃ of 300-; then heating the lignite to 650-750 ℃ at the heating rate of 2-20 ℃/min, and preserving the heat for 10 min.

In the reaction process, volatile matters are carried to a catalyst layer in a second-stage reactor through a low-temperature coal layer region to carry out catalytic hydrogenation quality improvement, liquid products generated by the reaction are collected through a cold trap, the moisture yield and the oil product yield are measured, gas products are collected through an outlet air bag, and the main gas yield is measured.

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking provided by the invention, the second-stage reactor and the first-stage reactor are arranged up and down, the first-stage reactor adopts a fixed bed or a moving bed, a coal sample can be fed intermittently or continuously, and the particle size is determined according to the size of the reactors; the second stage reactor is a fixed bed reactor, but is not limited to this form, and may alternatively be a fluidized catalytic cracking reactor (FCC).

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking, provided by the invention, lignite or low-rank coal with high volatile content is used as a raw material in the first-stage reactor, the ash content is not limited, and the method is suitable for low-maturity low-rank lignite; the space velocity of the volatile in the second-stage reactor passing through the catalyst layer is 1-10h^-1。

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking provided by the invention, hydrogen enters the reactor from the inlet of the first-stage reactor, the pressure of the hydrogen is kept the same as that of the second-stage reactor, and the pressure is controlled to be 5 MPa; preheating to 500 ℃ in a second-stage reactor, and preserving heat for 1h to ensure that the catalyst is fully dehydrated and the active metal in the oxidation state is reduced to be in a metal state, then reducing the temperature of a catalyst bed layer to 350 ℃, and keeping the temperature of the catalyst layer unchanged; and then heating the lignite to 700 ℃ at the heating rate of 15 ℃/min, and preserving the heat for 10 min.

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking, provided by the invention, the catalyst takes a formed molecular sieve as a carrier and is loaded with one or more transition metal combinations of Ni, Mo and Co; during preparation, nickel nitrate, cobalt nitrate and ammonium molybdate solution are taken as precursors, and the formed molecular sieve is immersed in the precursor solution for at least 12 hours; then evaporating water in a vacuum oven at 60 ℃, heating to 110 ℃ for full drying, putting the dried catalyst into a muffle furnace, heating to 550 ℃ for roasting for 4 hours.

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking, provided by the invention, the carrier is HZSM-5, the particle size is 3-5mm, the silicon-aluminum ratio is 20, and the specific surface area is 300m²(ii)/g; the nickel or cobalt loading is 0.5-2% of the HZSM-5 carrier, and the molybdenum loading is 2-5% of the HZSM-5 carrier.

Preferably, in the method for preparing gasoline and aviation kerosene components by lignite hydrocatalytic cracking, provided by the invention, the catalyst is Ni-HZSM-5 or NiMo-HZSM-5, the Ni loading is 1.0 wt.%, and the Mo loading is 3 wt.%.

Preferably, in the present inventionIn the method for preparing the gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking, the airspeed of volatile components passing through the catalyst layer is 3.7h^-1。

In view of the above description, the technical requirements for the two reaction stages are summarized as follows:

1. the first stage reaction requires:

firstly, the reactor adopts a fixed bed or a moving bed, the coal sample can be fed intermittently or continuously, the particle size is determined according to the size of the reactor, and the smooth air flow of the bed layer is ensured.

Secondly, hydrogen atmosphere is adopted, the pressure is suitable for keeping the pressure of a subsequent reactor balanced, and the hydrogen atmosphere can effectively prevent radicals in volatile components from reuniting and depositing, so that the hydrogen atmosphere is an important process factor for improving the yield of the volatile components.

And thirdly, controlling the coal material to slowly heat up, wherein the heating rate range is about 2-20 ℃/min (preferably 15 ℃/min), and avoiding the problem that the effective components of oil products which can be potentially generated, such as long-chain aliphatic hydrocarbon compounds, other easily-decomposed compounds (such as oxygen-containing compounds) and the like in the lignite, are influenced by the rapid heating, and are excessively decomposed to become stable micromolecular gas products, so that the subsequent catalytic hydrocracking process can not react to generate fuel oil. Lignite differs from higher-rank coals in that it contains abundant plant-tagged constituents, such as fatty acids and terpene compounds, which are major sources of oil formation.

Fourthly, the final temperature is preferably 650-750 ℃, and the temperature is too low, so that the effective volatile components in the lignite can not be released, and the yield of oil products is influenced; the high temperature is not favorable for improving the thermal efficiency of the pyrolysis process, and the high temperature gas may also influence the subsequent catalyst layer.

And the volatile component is carried to the catalyst layer through the low-temperature coal layer region, so that the influence of the overhigh airflow temperature on the temperature of the subsequent catalyst layer is avoided.

Sixthly, the volatile components pass through the pipeline and are insulated, so that the volatile components are not condensed due to too low temperature and block the pipeline.

2. The second stage reaction requires:

the reactor is a fixed bed reactor, but is not limited to a fixed bed reactor, and a fluidized catalytic cracking reactor (FCC) can be selected.

Secondly, volatile components generated by the first stage are complex, condensable components comprise a large amount of heavy asphalt, unsaturated hydrocarbon, oxygen-containing compounds, sulfur-containing compounds and nitrogen-containing compounds, which are main reasons for poor quality of the crude tar, and the substances are contacted with a catalyst through a second stage reactor to generate a series of gas-solid phase catalytic hydrocracking reactions, so that the quality of oil products is improved.

The temperature of the catalyst layer is required to be 300-400 ℃, the catalyst activity is insufficient when the temperature is too low, and the yield of aliphatic hydrocarbon is reduced and the yield of light aromatic hydrocarbon is increased when the temperature is too high.

Pressurizing hydrogen is an important condition for promoting catalytic cracking, the pressure of the hydrogen is controlled to be 3-6MPa, the pressure is too low, the hydrogenation degree is not high, the pressure is improved, the catalytic hydrocracking oil preparation is facilitated, and the situation that the too high pressure is only a selection made by comprehensively considering the aspects of equipment investment, safety and operation difficulty is avoided.

The space velocity is determined by the pressure, when the pressure is lower, the space velocity can be properly increased, in the pressure range of the claim, the corresponding space velocity range is 1-10h^-1Preferably 3.7h^-1。

3. The catalyst requires:

the performance requirement of the catalyst is adapted to the process conditions, and the catalyst is specific to the lignite raw material but not specific to other raw materials.

The catalyst has catalytic activity for cracking heavy tar, selectively removing heteroatom, hydrogenating unsaturated aliphatic hydrocarbon and converting aromatic hydrocarbon into aliphatic hydrocarbon.

③ using formed molecular sieve (such as HZSM-5) as carrier, nickel nitrate, cobalt nitrate and ammonium molybdate solution as precursor, loading transition metal on the molecular sieve by impregnation method, the high dispersivity of metal composition is the precondition for improving the catalyst activity, such as Ni-HZSM-5, Mo-HZSM-5, NiMo-HZSM-5 and CoMo-HZSM-5 molecular sieves, but the catalyst is not limited to loading one or two transition metals, the carrier can be common porous Al₂O₃And other molecular sieves.

Controlling the content of the loaded metal, and reducing the cost of the catalyst under the condition of ensuring the activity of the catalyst, wherein the loading capacity of nickel or cobalt is 0.5-2%, and the loading capacity of molybdenum is 2-5% (based on HZSM-5).

Drying the impregnated catalyst, roasting at 550 ℃ to convert the active metal into an oxidation state, and reducing the catalyst at 500 ℃ in a hydrogen atmosphere before a hydrocracking experiment to convert the oxidation state metal into a reduction state metal.

Sixthly, although the transition metal generally has hydrogenation capacity, different metal carrier catalysts have different activities, the multi-metal supported HZSM-5 catalyst has better deoxidation, denitrification and unsaturated bond hydrogenation capacity, and the catalyst activity is stable.

Seventhly, aiming at the process characteristics, the relative catalytic activity of the prepared catalyst for generating aliphatic hydrocarbon is as follows:

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					Catalytic activity	☆☆☆☆	☆☆	☆☆☆	☆☆☆☆☆

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The invention has the beneficial technical effects that:

by taking the Yinxi lignite as a raw material and comparing the method with a non-catalytic hydrotreating method which does not have a catalyst layer and has completely the same other operating conditions and does not have a catalyst layer in a second-stage reactor, the difference of the results is obvious:

(1) although the refined oil yield obtained by catalytic hydrogenation of the invention is only slightly reduced compared with the tar yield obtained by non-catalytic hydrogenation, the yield of gaseous hydrocarbons, especially methane, obtained by catalytic cracking is obviously increased;

(2) in the aspect of color of the prepared tar product, the hydrocracked tar which is not catalytically cracked is brown, while the catalytic hydrocracked oil is transparent and colorless;

(3) in the composition of tar, the uncatalyzed hydrocracked tar contains a large amount of monocyclic and polycyclic aromatic hydrocarbons, but mainly consists of paraffin with the carbon number of more than 16, and more oxygen-containing compounds (mainly phenolic compounds) exist, and nitrogen-containing compounds are also detected. Compared with the prior art, the hydrocatalytic cracking oil contains more normal alkanes with the carbon number of 6-12, is rich in cyclopentane, cyclohexane and homologues thereof, and also has obvious existence of decalin and tetralin, the compounds are main components of gasoline (C5-C12) and aviation kerosene (C8-C16), the content of fused ring aromatic hydrocarbons such as fluorene, phenanthrene and pyrene is low, and the heteroatom compounds such as ketones, phenols, benzofuran and quinoline almost completely disappear.

(4) Compared with tar which is not subjected to hydrocatalytic cracking, hydrocatalytic cracking oil contains a large proportion of open-chain saturated aliphatic hydrocarbon and saturated naphthenic hydrocarbon, accounts for 68.3 percent, and has a carbon number range of C6-C15; secondly, aromatic hydrocarbon accounts for about 30.3 percent, and the carbon number range is C6-C16; the unsaturated aliphatic hydrocarbon proportion is very low, 0.9%; hydrocatalytic cracking tar is virtually free of oxygenates, sulfur-containing compounds, and nitrogen-containing compounds.

(5) Compared with two cracking methods by using the Hami lignite as a raw material, the results are similar, the yield of the catalytic hydrofined oil is 12.0 percent, and the yield of methane is 17.2 percent; ethane yield 5.0%; the yield of propane is 1.2%; the refined oil contains a large proportion of open-chain saturated aliphatic hydrocarbon and saturated aliphatic hydrocarbon, and the relative area accounts for 70 percent; secondly, 29.5 percent of aromatic hydrocarbon; 0.5% of oxygen-containing compounds; the content of nitrogen-containing compounds and sulfur-containing compounds is extremely low.

In addition, the system equipment is similar to the existing equipment, the investment is low, the operation is simple and easy to control, the environmental problem is solved, meanwhile, a high-added-value product is provided, and a technical scheme is provided for realizing deep clean utilization of lignite in the industrial field.

Drawings

FIG. 1 is a schematic diagram of a two-stage reactor apparatus for lignite hydrocatalytic cracking;

FIG. 2 is a comparison of the appearance of the catalytic hydrocracked oil and non-catalytic cracked tar of the lignitous coal of example 1;

FIG. 3 is a GC-MS analysis chart of the catalytic hydrocracked oil and catalytically uncracked tar of the lignite of example 1, wherein (A) is a GC-MS analysis chart of the catalytically uncracked tar, and (B) is a GC-MS analysis chart of the catalytic hydrocracked oil;

FIG. 4 is a GC-MS analysis chart of the lignite catalytic hydrocracking oil of example 2.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

Example 1 Overall Process flow

As shown in figure 1, the device for preparing gasoline and aviation kerosene components by lignite hydrogenation catalytic cracking comprises a first-stage reactor 1, a second-stage reactor 2 and a condenser 3.

The first stage reactor 1 is a lower stage reactor for lignite hydro-pyrolysis, and is provided with a raw coal bunker 11 at the upper end of the reactor, a semicoke product outlet 12 at the lower end of the reactor, a pressurized hydrogen inlet 13 at the bottom end of the side wall, and a volatile component outlet 14 at the top end of the side wall at the opposite side, wherein the outlets are communicated with the second stage reactor 2 through pipelines.

The second-stage reactor 2 is an upper-stage reactor and is used for carrying out volatile component catalytic hydrogenation upgrading, and the top end of the second-stage reactor is communicated with the condenser 3 through a pipeline.

In the invention, the first-stage reactor 1 adopts a fixed bed or a moving bed, lignite is filled in the first-stage reactor, a coal sample can be fed intermittently or continuously, and the particle size is determined according to the size of the reactor; the second stage reactor 2 is packed with a catalyst and is a fixed bed reactor, but is not limited to this type, and may alternatively be a fluidized catalytic cracking reactor (FCC).

The catalyst takes a formed molecular sieve (such as HZSM-5) as a carrier, and is loaded with one or more transition metal combinations of Ni, Mo and Co; during preparation, nickel nitrate, cobalt nitrate and ammonium molybdate solution are taken as precursors, and the formed molecular sieve is immersed in the precursor solution for at least 12 hours; then evaporating water in a vacuum oven at 60 ℃, heating to 110 ℃ for full drying, putting the dried catalyst into a muffle furnace, heating to 550 ℃ for roasting for 4 hours.

When the lignite is catalytically cracked, two reactors are adopted for synchronous reaction, the lignite is subjected to hydro-pyrolysis in the first reactor 1 to generate volatile, and the volatile is subjected to catalytic hydrogenation upgrading through the second reactor without being excessively cooled to generate oil products and gas products.

Specifically, hydrogen enters the reactor from a pressurized hydrogen inlet 13 of the first-stage reactor, the hydrogen pressure is kept the same as that of the second-stage reactor, and the hydrogen pressure is controlled to be 3-6 MPa; preheating to 500 ℃ in a second-stage reactor, and preserving heat for 1h to ensure that the catalyst is fully dehydrated and the active metal in the oxidation state is reduced to be in a metal state, then reducing the temperature of a catalyst bed layer to 400 ℃ of 300-; then heating the lignite to 650-750 ℃ at the heating rate of 2-20 ℃/min, and preserving the heat for 10 min.

In the reaction process, volatile matters generated by the first-stage reactor are carried to a catalyst layer in the second-stage reactor through a low-temperature coal layer region to carry out catalytic hydrogenation quality improvement, liquid products generated by the reaction are collected through a cold trap, the moisture yield and the oil product yield are measured, gas products are collected through an outlet air bag, and the main gas yield is measured.

The specific catalytic cracking process is described below with specific use of Yuxi lignite and Hami lignite as raw materials, as detailed in examples 2 and 3.

Example 2 hydrocatalytic cracking of Yuxi lignite

The two-stage reactor which takes the Yuxi lignite as the raw material catalyzes the hydrocracking. Industrial analysis of the yuxi lignite: 24.6% of ash, 41.8% of volatile matter and 33.6% of fixed carbon (dry basis); elemental analysis: 62.8% of carbon, 5.9% of hydrogen, 1.3% of nitrogen, 30.0% of oxygen and 0.0% of sulfur (all of which are dry-based ashless groups). The specific cracking steps are as follows:

1. the preparation steps of the catalyst are as follows:

taking 20g of HZSM-5 molecular sieve spherical catalyst, wherein the particle size of the catalyst is 3-5mm, the silica-alumina ratio is 20, and the specific surface area is 300m²(ii)/g; taking 20g, soaking the catalyst in 1g of nickel nitrate, 1.1g of ammonium molybdate and 25g of deionized water in a beaker for 12 hours, then evaporating water in a vacuum oven at 60 ℃, heating to 110 ℃ for fully drying, putting the dried catalyst in a muffle furnace, heating to 550 ℃ for roasting for 4 hours. The NiMo-HZSM-5 molecular sieve has the Ni content of 1.0 wt.% and the Mo content of 3 wt.% (based on the molecular sieve).

Other metal supported catalysts were prepared in a similar manner as described above.

2. The hydrocracking test step comprises:

in the two-stage vertical fixed bed reactor, the first stage reactor located at the lower section is filled with 2g of dry Yuxi lignite, and the second stage reactor located at the upper section is filled with 6g of dry catalyst. Hydrogen enters the reactor from the inlet of the lower section, is punched to 5MPa, and the flow rate is controlled at 500 ml/min. The temperature of the upper section is raised to 500 ℃ in advance, the temperature is kept for 1h, and in the process, the molecular sieve catalyst is fully dehydrated and the active metal in the oxidation state is reduced to the metal state; the catalyst bed temperature was then reduced to a predetermined 350 c and maintained constant. Heating the lignite to 700 ℃ at the heating rate of 15 ℃/min, and keeping the temperature for 10 min. And collecting liquid products generated by the reaction through a cold trap, determining the moisture yield and the oil product yield, collecting gas products through an outlet air bag, and determining the main gas yield.

3. And (3) comparison test: the pyrolyzation of the lignites is carried out in the same two sections of fixed bed reactors, the second section reactor is only distinguished from being not provided with a catalyst layer, and other operating conditions are completely the same.

4. Analysis of results

4.1 product comparison

Table 1 summarizes the process conditions and tar (anhydrous) and hydrocarbon gas yields for two different runs. From the results in Table 1, it can be seen that the refined oil yield of 12.7 wt.% obtained by catalytic hydrogenation is only slightly reduced compared with the tar yield obtained without catalytic hydrogenation, but the yield of gaseous hydrocarbons, especially methane, obtained by catalytic cracking is obviously increased.

TABLE 1 comparison of catalytic hydrocracking of Yuxi lignite with non-catalytic cracking yields of tar and gaseous hydrocarbons

4.2 Tar product color contrast

The sample color pairs for tar obtained without catalytic cracking (run I) and with catalytic cracking (run II) are shown in fig. 2. The non-catalytically cracked hydropyrolysis tar is brown, while the catalytically hydrocracked oil is transparent and colorless.

4.3 GC-MS comparison of the analyses

The GC-MS analysis of the corresponding Yuxi lignite catalytic hydrocracking oil and non-catalytic pyrolysis tar of FIG. 2 is shown in FIG. 3: the uncatalyzed hydrocracking tar (fig. 3A) contains a large amount of monocyclic and polycyclic aromatic hydrocarbons, including tetracyclic aromatic hydrocarbons, and the aliphatic hydrocarbons are mainly normal paraffins but mainly paraffin with more than 16 carbon atoms, and more oxygen-containing compounds (mainly phenolic compounds) exist, and nitrogen-containing compounds are also detected. In contrast, hydrocatalytic pyrolysis oil (fig. 3B) contains a large amount of n-alkanes having 6 to 12 carbon atoms, is rich in cyclopentane, cyclohexane and homologues thereof, and also contains significant decalin and tetralin, which are main components of gasoline (C5-C12) and aviation kerosene (C8-C16), and has a low content of fused ring aromatic hydrocarbons such as fluorene, phenanthrene and pyrene, and almost all heteroatom compounds such as ketones, phenols, benzofurans and quinolines disappear.

4.4 GC-MS identification gives a comparison of the relative proportions and carbon number ranges of different classes of compounds

Table 2 lists the relative proportions and carbon number ranges of the different classes of compounds identified by GC-MS. The results show that compared with the tar which is not hydrocatalytically cracked, hydrocatalytically cracked oil contains a larger proportion of open-chain saturated aliphatic hydrocarbons and saturated naphthenic hydrocarbons, accounting for 68.3%, with the carbon number range of C6-C15; secondly, aromatic hydrocarbon accounts for about 30.3 percent, and the carbon number range is C6-C16; the unsaturated aliphatic hydrocarbon proportion is very low, 0.9%; hydrocatalytic cracking tar is virtually free of oxygenates, sulfur-containing compounds, and nitrogen-containing compounds.

TABLE 2 summary of the relative proportions of the different classes of compounds in the Yuxi lignite catalytic hydrocracking and non-catalytic cracking tars

Example 3 Harmi lignite hydrocatalytic cracking

The catalytic hydrocracking test is carried out by taking the Hami lignite as a raw material, and the industrial analysis of the Hami lignite is as follows: 5.3% of ash, 48.3% of volatile matter and 46.4% of fixed carbon (dry basis); elemental analysis: 71.8% of carbon, 6.2% of hydrogen, 1.0% of nitrogen, 21% of oxygen and 0.0% of sulfur (all dry ashless groups).

The catalyst preparation was identical to 2.

The hydrocracking test step comprises: in the two-section vertical fixed bed reactor, the lower section is filled with 2g of dry-base Harm lignite, and other steps are completely the same as the above steps.

In the aspect of product yield, the yield of the catalytic hydrofined oil of the hami lignite under the test condition is 12.0 percent, and the yield of methane is 17.2 percent; ethane yield 5.0%; the propane yield was 1.2%, all on a dry basis.

FIG. 4 shows a GC-MS analysis chart of the Harmi lignite catalytic hydrocracking oil. The refined product contains a large proportion of open-chain saturated aliphatic hydrocarbon and saturated aliphatic hydrocarbon through catalytic hydrocracking, and the relative area accounts for 70 percent; secondly, 29.5 percent of aromatic hydrocarbon; 0.5% of oxygen-containing compounds; the content of nitrogen-containing compounds and sulfur-containing compounds is extremely low.