Refining method and application of inferior diesel oil raw material

Abstract

The invention relates to the field of hydrotreatment of aromatic-rich distillate oil, in particular to a refining method and application of an inferior diesel oil raw material. The method comprises the following steps: sequentially carrying out at least two times of hydrofining on an inferior diesel oil raw material, wherein the temperature of the previous hydrofining is lower than the temperature of the next hydrofining in two adjacent times of hydrofining. According to the present invention, the inferior diesel oil raw material is refined by using the method, such that the hydrofining denitrification rate can be well controlled, the high aromatic hydrocarbon retention rate can be obtained, and the added value of the hydrofining product can be improved.

Description

Technical Field

[0001] The invention relates to the field of aromatic-rich fraction oil hydroprocessing, and in particular to a method for refining inferior diesel raw materials and application thereof. Background Art

[0002] The annual processing capacity of catalytic cracking units in my country has exceeded 100 million tons, second only to the United States. Aromatic heavy distillate oils, such as catalytic cracking diesel (LCO), account for a relatively high proportion in my country's diesel pool, accounting for about 30%, and are the main secondary processed diesel components. Their total aromatic content is as high as 80%, naphthalene bicyclic aromatics account for about 70%, and monocyclic aromatics and tricyclic aromatics account for about 15% each. Ethylene tar is also a heavy distillate oil (>205°C) rich in aromatic oil products (aromatic content greater than 90%). It is the product of high-temperature condensation of raw materials and products during steam cracking of ethylene cracking raw materials. The main components are monocyclic and polycyclic aromatic compounds, and also contain heterocyclic compounds of elements such as N, S, and O. Due to different cracking raw materials, the yield of ethylene tar is also different, generally accounting for about 1 / 5 of ethylene production. As the ethylene raw materials become heavier, its yield is on the rise.

[0003] In the field of aromatic fraction hydroprocessing, catalytic cracking feedstock hydroprocessing technology has been industrialized since the 1970s and has been applied in many refineries processing sulfur-containing or high-sulfur crude oil. At present, mature catalytic cracking feedstock pretreatment technology is available. In order to further improve product quality and conversion rate, the catalytic feedstock hydroprocessing process has gradually changed from traditional hydrodesulfurization refining (HDS) to mild hydrocracking (MHC) to improve the denitrification, residual carbon and polycyclic aromatic hydrocarbon saturation capabilities.

[0004] LCO has a high sulfur content (0.2-1.5wt%) and a nitrogen content generally greater than 400ppm. In order to meet the ever-expanding new uses of LCO and the development of new processes that are compatible with it (such as the new process of using catalytic LCO hydrogenation conversion-selective alkylation to produce benzene (B), toluene (T) and xylene (X)), the removal of impurities such as sulfur and nitrogen in LCO has become the key to the further development and application of LCO. Because a large amount of sulfur, nitrogen and other impurities in LCO have a poisoning effect on subsequent hydrogenation, selective ring opening and other catalysts, they must first be removed through a hydrorefining process. LCO belongs to the diesel fraction, and its deep desulfurization and denitrification are difficult. The main reasons are: (1) LCO contains sulfur compounds such as 4,6-dimethylbenzothiophene (4,6-DMDBT), polysubstituted condensed ring nitrogen compounds, etc. Due to the steric hindrance effect of the substituents, the reaction activity is low, and deep desulfurization and denitrification are difficult; (2) Polycyclic aromatic hydrocarbons and nitrogen-containing substances in the raw materials and H2S in the products have an inhibitory effect on deep desulfurization; (3) Transitional hydrogenation is not allowed during the desulfurization and denitrification process, because this will lead to a large number of hydrogenation ring-opening reactions, which will destroy the purpose of subsequent selective hydrogenation ring-opening to increase the production of aromatics. (4) In the hydrodesulfurization (HDS) process, methyl groups must be retained to the maximum extent to maximize the production of xylene. Therefore, in order to remove these sulfur and nitrogen, a multifunctional, highly active, and highly selective hydrorefining catalyst must be selected.

[0005] US4206036A uses titanium oxide as a carrier, and after loading active components, it is used as a hydrorefining catalyst (desulfurization, denitrification). However, the carrier has low mechanical strength, small specific surface area, and is expensive, and cannot be used industrially.

[0006] US2006 / 0052235A1 introduces a hydrodesulfurization catalyst with a mesoporous molecular sieve as a carrier, Co and Mo as active components, and a silicone resin as a binder. The hydrorefining catalyst has a high hydrodesulfurization (HDS) / olefin saturation activity, but the patent does not give the absolute activity of HDS, and the mesoporous molecular sieve has poor stability and is difficult to operate for a long time in a harsh hydrodesulfurization environment.

[0007] The aromatic-rich heavy distillate oil has a high carbon-hydrogen ratio, the gasoline octane number and diesel cetane number obtained by hydrogenation are low, the hydrogen consumption is high, and the economy is poor. CN102234539A completely saturates the aromatics in the aromatic-rich oil and then hydrocracking it to produce gasoline and diesel, which has high production costs and is not economical.

[0008] The existing technology generally adopts hydrogenation saturation and hydrocracking for aromatic-rich heavy distillate oil. For aromatic-rich heavy distillate oil with an aromatic content greater than 80%, not only is the hydrogen consumption high, but also the precious aromatic resources therein are wasted.

[0009] The selective hydrogenation refining process can be used to selectively hydrogenate the aromatic-rich heavy distillate oil, and the polycyclic aromatic hydrocarbons therein can be selectively hydrogenated into benzene-based aromatics to prepare solvent oil or as a raw material for producing benzene, toluene and xylene aromatics, which can reduce hydrogen consumption and increase its added value. Summary of the invention

[0010] The purpose of the present invention is to overcome the problems of high hydrogen consumption and poor economy in the existing aromatic fraction oil hydrogenation technology, and to provide a method and application for refining inferior diesel raw materials, which has low hydrogen consumption and can improve the added value of products.

[0011] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for refining inferior diesel raw materials, which comprises: subjecting the inferior diesel raw materials to at least two hydrorefining treatments in sequence, wherein the temperature of the first hydrorefining treatment of two adjacent hydrorefining treatments is lower than the temperature of the second hydrorefining treatment.

[0012] The second aspect of the present invention provides a two-stage hydrorefining method for low-quality diesel raw materials, the method comprising:

[0013] (a) under catalyst conditions, the low-quality diesel component is mixed with hydrogen to complete the first stage of hydrofining reaction to obtain a first stage of hydrogenation reaction product;

[0014] (b) The first stage hydrogenation reaction product is not separated, but is mixed with hydrogen gas after cooling under catalyst conditions to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product.

[0015] The third aspect of the present invention provides a three-stage hydrorefining method for low-quality diesel raw materials, the method comprising:

[0016] (a) under the first catalyst condition, the low-quality diesel component is mixed with hydrogen to complete a first stage hydrofining reaction to obtain a first stage hydrogenation reaction product;

[0017] (b) the first stage hydrogenation reaction product is not separated, but is mixed with hydrogen under the first catalyst condition after cooling to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product;

[0018] (c) The product of the second stage hydrogenation reaction is not separated, but is mixed with hydrogen under the second catalyst condition after cooling to complete the second stage hydrogenation refining reaction, thereby obtaining the product of the third stage hydrogenation reaction.

[0019] A fourth aspect of the present invention provides application of the method in processing low-quality diesel raw materials.

[0020] Through the above technical solution, the present invention has the following advantages:

[0021] By refining inferior diesel raw materials through the method of the present invention, the denitrification rate of hydrofining can be better controlled, and a higher aromatics retention rate can be obtained, thereby increasing the added value of the hydrofining product. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] The invention provides a method for refining inferior diesel raw materials, which comprises: subjecting the inferior diesel raw materials to at least two hydrorefining treatments in sequence, wherein the temperature of the first hydrorefining treatment of two adjacent hydrorefining treatments is lower than the temperature of the second hydrorefining treatment.

[0024] By refining inferior diesel raw materials through the method of the present invention, the denitrification rate of hydrofining can be better controlled and a higher aromatics retention rate can be obtained.

[0025] In the present invention, there is no particular restriction on the amount by which the temperature of the first hydrofining of two adjacent hydrofinings is lower than the temperature of the latter hydrofining. According to a preferred embodiment of the present invention, the temperature of the first hydrofining of two adjacent hydrofinings is lower than the temperature of the latter hydrofining by 20-250°C, preferably 20-100°C, more preferably 20-80°C, for example, it can be 20°C, 30°C, 50°C, 80°C, 100°C, 150°C, 200°C, 250°C. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0026] In the present invention, as long as the purpose of the present invention can be achieved, there is no special requirement for the temperature of the first hydrofining. According to a preferred embodiment of the present invention, the temperature of the first hydrofining is 200-450° C., preferably 210-400° C. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0027] In the present invention, as long as the purpose of the present invention can be achieved, there is no special requirement for the temperature of the last hydrofining. According to a preferred embodiment of the present invention, the temperature of the last hydrofining is 240-520° C., preferably 240-460° C. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0028] In the present invention, the conditions for hydrofining can be conventionally selected in the art. According to a preferred embodiment of the present invention, the conditions for hydrofining include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa.

[0029] According to a preferred embodiment of the present invention, the conditions for the hydrofining include: the weight hourly space velocity of the hydrocarbon feedstock is 0.5-3h -1 , preferably 0.5-2h -1 .

[0030] According to a preferred embodiment of the present invention, the conditions for the hydrotreating include: a hydrogen-to-oil volume ratio of 600-5000:1, preferably 800-4000:1.

[0031] By adopting the above-mentioned preferred hydrotreating conditions, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0032] In the present invention, as long as the purpose of the present invention can be achieved, there is no particular requirement for how many times the inferior diesel raw material is subjected to hydrofining in sequence. According to a preferred embodiment of the present invention, the method comprises subjecting the inferior diesel raw material to hydrofining 2-5 times, preferably 2-3 times. By adopting the aforementioned preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0033] In the present invention, all low-quality diesel can be applied to the present invention. In order to further improve the treatment effect, according to a preferred embodiment of the present invention, the initial distillation point of the low-quality diesel raw material is 150-250°C, and the final distillation point is 300-380°C.

[0034] According to a preferred embodiment of the present invention, the sulfur content of the inferior diesel feedstock is 500-7000ug / mL, preferably 800-5000ug / mL; the nitrogen content is 100-1000ug / mL, preferably 200-800ug / mL; the aromatic content is >60wt%, preferably >70wt%. By adopting the above preferred scheme, the denitrification rate of refining can be further controlled, and the aromatic retention rate can be further improved.

[0035] According to a preferred embodiment of the present invention, the inferior diesel feedstock is selected from at least one of catalytic cracking diesel, coking diesel, hydrotreated diesel, straight-run diesel, coal tar, direct coal liquefaction oil and indirect coal liquefaction oil.

[0036] In the present invention, the hydrotreating catalyst may be a catalyst commonly used in the art. According to a preferred embodiment of the present invention, the active component of the hydrotreating catalyst is selected from oxides of Group VIB and / or Group VIII metal elements, preferably selected from Group VIB and Group VIII metal elements.

[0037] According to a preferred embodiment of the present invention, the hydrorefining catalyst further comprises a lanthanide metal element as a promoter metal. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0038] According to a preferred embodiment of the present invention, in the active components of the hydrorefining catalyst, the weight ratio of the metal elements of Group VIB, Group VIII and Lanthanide series in terms of oxides is 1:0.1-0.9:0-0.1; preferably 1:0.2-0.8:0-0.1; more preferably 1:0.2-0.8:0.01-0.06. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0039] According to a preferred embodiment of the present invention, the VIB Group metal element is molybdenum and / or tungsten.

[0040] According to a preferred embodiment of the present invention, the Group VIII metal element is nickel and / or cobalt.

[0041] According to a preferred embodiment of the present invention, the lanthanide element is praseodymium.

[0042] According to a preferred embodiment of the present invention, when the hydrofining is performed twice, the weight content of the active components of the catalyst of the second hydrofining is not higher than the weight content of the active components of the catalyst of the first hydrofining, calculated as metal oxides, and is preferably 0-5% lower. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0043] According to a preferred embodiment of the present invention, when the hydrofining is performed for no less than three times, the weight content of active components in the catalysts of the third and subsequent hydrofinings is lower than the weight content of active components in the catalysts of the first and second hydrofinings. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0044] According to a preferred embodiment of the present invention, the weight content of active components in the catalysts of the third and subsequent hydrofining processes is 1-9% lower than the weight content of active components in the catalysts of the first and second hydrofining processes. By adopting the above preferred scheme, the denitrogenation rate of the refining can be further controlled, and the aromatics retention rate can be further improved.

[0045] According to a preferred embodiment of the present invention, the carrier of the hydrorefining catalyst is selected from at least one of alumina, silica, titanium dioxide and activated carbon.

[0046] According to a preferred embodiment of the present invention, the weight content of the VIB group metal element in the hydrorefining catalyst as oxide is 0-30%, preferably 6-25%, the weight content of the VIII group metal element as oxide is 0-18%, preferably 1.5-15%; the weight content of the lanthanide metal element as oxide is 0-1%, preferably 0.1-0.8%.

[0047] The present invention provides a two-stage hydrorefining method for low-quality diesel, comprising:

[0048] (a) under the conditions of a first hydrotreating catalyst, the low-quality diesel component is mixed with hydrogen to complete a first stage hydrotreating reaction to obtain a first stage hydrogenation reaction product;

[0049] (b) The first stage hydrogenation reaction product is not separated, but is mixed with hydrogen gas under the second hydrogenation refining catalyst condition after cooling to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product.

[0050] According to a preferred embodiment of the present invention, the conditions of the first stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 200-450°C, preferably 210-400°C.

[0051] According to a preferred embodiment of the present invention, the conditions of the second stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 220-520°C, preferably 220-440°C.

[0052] The present invention provides a three-stage hydrorefining method for low-quality diesel, comprising:

[0053] (a) under the conditions of a first hydrotreating catalyst, the low-quality diesel component is mixed with hydrogen to complete a first stage hydrotreating reaction to obtain a first stage hydrogenation reaction product;

[0054] (b) the first stage hydrogenation reaction product is not separated, but is mixed with hydrogen after cooling under the second hydrogenation refining catalyst condition to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product;

[0055] (c) The second stage hydrogenation reaction product is not separated, but is mixed with hydrogen gas under the condition of the third hydrogenation refining catalyst after cooling to complete the second stage hydrogenation refining reaction, thereby obtaining the third stage hydrogenation reaction product.

[0056] According to a preferred embodiment of the present invention, the conditions of the first stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 200-450°C, preferably 210-400°C.

[0057] According to a preferred embodiment of the present invention, the conditions of the second stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 220-520°C, preferably 220-440°C.

[0058] According to a preferred embodiment of the present invention, the conditions of the third stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 240-520°C, preferably 240-460°C.

[0059] In the present invention, the catalyst needs to be pre-sulfurized before activity evaluation. According to a preferred embodiment of the present invention, the pre-sulfurization conditions are: wet sulfidation in a cyclohexane solution containing 500-5000ppm CS2, starting sulfidation at 130-200°C, programmed temperature increase, a heating rate of 5-30°C / h, and a constant temperature of 280-380°C for 4-30h.

[0060] The invention provides an application of the method described in the invention in processing low-quality diesel raw materials.

[0061] The present invention will be described in detail below through examples. In the following examples, the raw materials are all commercially available;

[0062] Fragrance insurance rate:

[0063] Desulfurization rate:

[0064] Denitrification rate:

[0065] In the formula,

[0066] R A is the fragrance protection rate%;

[0067] X S is the sulfur conversion rate (%);

[0068] X N is the nitrogen conversion rate (%);

[0069] C A in is the mass percentage of total aromatics in the raw material

[0070] C A out is the mass percentage of total aromatics in the product

[0071] C S in is the mass percentage of sulfur in the raw material;

[0072] C S out is the mass percentage of sulfur in the product;

[0073] C N in is the mass percentage of nitrogen in the raw material;

[0074] C N out is the mass percentage of nitrogen in the product.

[0075] Example 1

[0076] The hydrotreating reactor I and the hydrotreating reactor II are respectively filled with 30 ml of hydrotreating catalyst, and the reaction is carried out in a pressurized fixed adiabatic bed reaction device. The inferior diesel feedstock is subjected to two hydrotreating treatments in sequence together with hydrogen.

[0077] The catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are NiO 4.5%, MoO3 12.5%, and Co2O3 5.5% based on the total weight of the catalyst;

[0078] Inferior diesel raw material: distillation range 203℃-340℃, total aromatics 84%, S content 2800ppm, N content 450ppm;

[0079] The catalyst needs to be pre-sulfided before the reaction. The conditions are: wet sulfidation in a cyclohexane solution containing 2000ppm CS2, starting sulfidation at 160°C, program heating, heating rate of 15°C / h, and constant temperature at 330°C for 20h;

[0080] Reaction conditions: Weight hourly space velocity of hydrocarbon raw material 1.0h -1 ; Reaction pressure 5.8MPa; Hydrogen-oil volume ratio 1500:1; Refining reactor I inlet temperature 270℃; Refining reactor II inlet temperature 300℃.

[0081] Catalyst evaluation results:

[0082] The first stage of hydrofining: desulfurization rate 85.71%, denitrification rate 82.22%, aromatics protection rate 97.62%;

[0083] The second stage of hydrofining: desulfurization rate 99.64%, denitrification rate 98.89%, aromatics protection rate 94.05%.

[0084] Example 2

[0085] The hydrotreating reactor I and the hydrotreating reactor II are respectively filled with 30 ml of hydrotreating catalyst, and the reaction is carried out in a pressurized fixed adiabatic bed reaction device. The inferior diesel feedstock is subjected to two hydrotreating treatments in sequence together with hydrogen.

[0086] The catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are NiO 4.5%, MoO3 12.5%, and WO3 5.5% based on the total weight of the catalyst;

[0087] Inferior diesel raw material: distillation range 155℃-305℃, total aromatics 72%, S 1000ppm, N 220ppm;

[0088] The catalyst needs to be pre-sulfurized before the reaction. The conditions are: wet sulfidation in a cyclohexane solution containing 2000ppm CS2, starting sulfidation at 140℃, program heating, heating rate 20℃ / h, and constant temperature at 320℃ for 22h;

[0089] Reaction conditions: Weight hourly space velocity of hydrocarbon raw material 0.6h -1 ; Reaction pressure 4.5MPa; Hydrogen-oil volume ratio 900:1; Refining reactor I inlet temperature 240℃; Refining reactor II inlet temperature 290℃.

[0090] Catalyst evaluation results:

[0091] The first stage of hydrofining: desulfurization rate 85%, denitrification rate 81.82%, aromatics protection rate 97.92%;

[0092] The second stage of hydrofining: desulfurization rate 99%, denitrification rate 97.73%, aromatics protection rate 94.44%.

[0093] Example 3

[0094] The hydrotreating reactor I and the hydrotreating reactor II are respectively filled with 30 ml of hydrotreating catalyst, and the reaction is carried out in a pressurized fixed adiabatic bed reaction device. The inferior diesel feedstock is subjected to two hydrotreating treatments in sequence together with hydrogen.

[0095] The catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are NiO 4.5%, MoO3 12.5%, and Co2O3 5.5% based on the total weight of the catalyst;

[0096] Inferior diesel raw material: distillation range 160℃-310℃, total aromatics 86%, S 4500ppm, N 780ppm;

[0097] The catalyst needs to be pre-sulfurized before the reaction. The conditions are: wet sulfidation in a cyclohexane solution containing 2000ppm CS2, starting sulfidation at 150°C, program heating, heating rate of 15°C / h, and constant temperature at 340°C for 18h;

[0098] Reaction conditions: Weight hourly space velocity of hydrocarbon raw material 1.8h -1 ; Reaction pressure 6.8MPa; Hydrogen-oil volume ratio 3800:1; Refining reactor I inlet temperature: 300℃; Refining reactor II inlet temperature: 320℃.

[0099] Catalyst evaluation results:

[0100] The first stage of hydrofining: desulfurization rate 88.89%, denitrification rate 89.74%, aromatics protection rate 95.35%;

[0101] The second stage of hydrofining: desulfurization rate 99.78%, denitrification rate 98.97%, aromatics protection rate 93.72%.

[0102] Example 4

[0103] Same as Example 1, except that the inlet temperature of the refining reactor I is 270°C; the inlet temperature of the refining reactor II is 280°C.

[0104] Catalyst evaluation results:

[0105] The first stage of hydrofining: desulfurization rate 85.71%, denitrification rate 82.22%, aromatics protection rate 97.62%;

[0106] The second stage of hydrofining: desulfurization rate 90%, denitrification rate 93.33%, aromatics protection rate 95.24%.

[0107] Example 5

[0108] Same as Example 1, except that the inlet temperature of the refining reactor I is 230°C; the inlet temperature of the refining reactor II is 320°C.

[0109] Catalyst evaluation results:

[0110] The first stage of hydrofining: desulfurization rate 83.57%, denitrification rate 81.56%, aromatics protection rate 97.98%;

[0111] The second stage of hydrofining: desulfurization rate 99.61%, denitrification rate 98.22%, aromatics protection rate 93.57%.

[0112] Example 6

[0113] Same as Example 1, except that the S content of the inferior diesel feedstock is 6000 ppm.

[0114] Catalyst evaluation results:

[0115] The first stage of hydrofining: desulfurization rate 83.33%, denitrification rate 80%, aromatics protection rate 96.43%;

[0116] The second stage of hydrotreating: desulfurization rate 91.67%, denitrification rate 93.33%, aromatics protection rate 93.21%.

[0117] Example 7

[0118] The same as Example 1, except that the hydrotreating reactor II is filled with 30 ml of hydrotreating catalyst, and the catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active component is calculated based on the total weight of the catalyst, NiO 18.5%.

[0119] Catalyst evaluation results:

[0120] The first stage of hydrofining: desulfurization rate 78.57%, denitrification rate 73.33%, aromatics protection rate 95.24%;

[0121] The second stage of hydrotreating: desulfurization rate 90.36%, denitrification rate 92.89%, aromatics protection rate 91.67%.

[0122] Example 8

[0123] The same as Example 1, except that a third stage of hydrotreating is added, the hydrotreating reactor III is filled with 30 ml of hydrotreating catalyst, the reaction is carried out in a pressurized fixed adiabatic bed reaction device, and the inferior diesel feedstock is subjected to three hydrotreatings in sequence.

[0124] The third stage hydrofining catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are calculated based on the total weight of the catalyst, NiO 4.5%, MoO3 10.5%, Co2O3 3%;

[0125] Reaction conditions: Weight hourly space velocity of hydrocarbon raw material 1.0h -1 ; Reaction pressure 5.8MPa; Hydrogen to oil volume ratio is 1500:1, the inlet temperature of refining reactor I is 260℃; the inlet temperature of refining reactor II is 290℃; the inlet temperature of refining reactor III is 310℃.

[0126] Catalyst evaluation results:

[0127] The first stage of hydrofining: desulfurization rate 84.64%, denitrification rate 80.44%, aromatics protection rate 97.98%;

[0128] The second stage of hydrofining: desulfurization rate 99.61%, denitrification rate 98.67%, aromatics protection rate 94.64%;

[0129] The third stage of hydrofining: desulfurization rate 99.75%, denitrification rate 99%, aromatics protection rate 90.48%.

[0130] Example 9

[0131] The same as Example 8, except that the catalyst of the refining reactor III is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are calculated based on the total weight of the catalyst, NiO 4.5%, MoO3 12.5%, and Co2O3 5.5%.

[0132] Catalyst evaluation results:

[0133] The first stage of hydrofining: desulfurization rate 84.64%, denitrification rate 80.44%, aromatics protection rate 97.98%;

[0134] The second stage of hydrofining: desulfurization rate 99.61%, denitrification rate 98.67%, aromatics protection rate 94.64%;

[0135] The third stage of hydrofining: desulfurization rate 99.68%, denitrification rate 98.78%, aromatics protection rate 88.1%.

[0136] Example 10

[0137] Same as Example 8, except that the inlet temperature of the refining reactor I is 270°C; the inlet temperature of the refining reactor II is 280°C; and the inlet temperature of the refining reactor III is 290°C.

[0138] Catalyst evaluation results:

[0139] The first stage of hydrofining: desulfurization rate 85.71%, denitrification rate 82.22%, aromatics protection rate 97.62%;

[0140] The second stage of hydrofining: desulfurization rate 90%, denitrification rate 93.33%, aromatics protection rate 95.24%;

[0141] The third stage of hydrofining: desulfurization rate 95.36%, denitrification rate 94.44%, aromatics protection rate 92.86%.

[0142] Embodiment 11

[0143] The same as Example 1, except that the specific composition of the second hydrotreating catalyst is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are calculated based on the total weight of the catalyst, NiO 6.5%, MoO3 14.5%, Co2O3 6.5%;

[0144] Catalyst evaluation results:

[0145] The first stage of hydrofining: desulfurization rate 83.93%, denitrification rate 78.89%, aromatics protection rate 97.02%;

[0146] The second stage of hydrofining: desulfurization rate 99.36%, denitrification rate 97.78%, aromatics protection rate 92.86%.

[0147] Example 12

[0148] The same as Example 1, except that the catalyst for the second hydrotreating is as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are calculated based on the total weight of the catalyst, NiO 10%, MoO3 12.5%;

[0149] Catalyst evaluation results:

[0150] The first stage of hydrofining: desulfurization rate 83.57%, denitrification rate 77.78%, aromatics protection rate 96.43%;

[0151] The second stage of hydrofining: desulfurization rate 99.29%, denitrification rate 97.33%, aromatics protection rate 92.38%.

[0152] Embodiment 13

[0153] The same as Example 1, except that an active agent is added to the two-stage hydrorefining catalyst. The catalyst is specifically as follows: the catalyst is a supported catalyst, the carrier is alumina, and the active components are calculated based on the total weight of the catalyst, NiO 4.5%, MoO3 12.5%, Co2O3 5.5%, and praseodymium oxide 0.5%.

[0154] Catalyst evaluation results:

[0155] The first stage of hydrofining: desulfurization rate 86.36%, denitrification rate 84.44%, aromatics protection rate 97.38%;

[0156] The second stage of hydrofining: desulfurization rate 99.71%, denitrification rate 99.11%, aromatics protection rate 94.4%.

[0157] Comparative Example 1

[0158] Same as Example 1, except that the inlet temperature of the refining reactor I is 300°C; the inlet temperature of the refining reactor II is 270°C.

[0159] Catalyst evaluation results:

[0160] The first stage of hydrofining: desulfurization rate 89.29%, denitrification rate 86.67%, aromatics protection rate 92.86%;

[0161] The second stage of hydrotreating: desulfurization rate 92.86%, denitrification rate 91.11%, aromatics protection rate 90.48%.

[0162] Comparative Example 2

[0163] Same as Example 1, except that the inlet temperature of the refining reactor I is 280°C; the inlet temperature of the refining reactor II is 280°C.

[0164] Catalyst evaluation results:

[0165] The first stage of hydrofining: desulfurization rate 86.43%, denitrification rate 83.33%, aromatics protection rate 96.43%;

[0166] The second stage of hydrofining: desulfurization rate 88.93%, denitrification rate 88.89%, aromatics protection rate 94.76%.

[0167] Comparative Example 3

[0168] The same as Example 1, except that only the hydrotreating reactor I is used, and the reactor inlet temperature is 280°C.

[0169] Catalyst evaluation results:

[0170] The first stage of hydrofining: desulfurization rate 86.43%, denitrification rate 83.33%, aromatics protection rate 96.46%.

[0171] It can be seen from the results of the examples and comparative examples that the use of the technical solution of the present invention for refining inferior diesel feedstock has high desulfurization rate, denitrification rate and aromatization rate.

[0172] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for refining low-quality diesel raw materials, characterized in that: The method comprises: subjecting the inferior diesel raw material to at least two hydrorefining treatments in sequence, wherein the temperature of the first hydrorefining treatment of two adjacent hydrorefining treatments is lower than the temperature of the second hydrorefining treatment.

2. The method according to claim 1, wherein: The temperature of the first hydrofining of two adjacent hydrofinings is 20-250°C lower than the temperature of the second hydrofining, preferably 20-100°C, more preferably 20-80°C; and / or The temperature of the first hydrofining is 200-450°C, preferably 210-400°C; and / or The temperature of the last hydrofining is 240-520°C, preferably 240-460°C.

3. The method according to claim 1 or 2, wherein: The conditions of the hydrofining include: The reaction pressure is 3.5-7.5 MPa, preferably 4-7 MPa; and / or The weight hourly space velocity of hydrocarbon feedstock is 0.5-3h -1 , preferably 0.5-2h -1 ; and / or The volume ratio of hydrogen to oil is 600-5000:1, preferably 800-4000:

1.

4. The method according to any one of claims 1 to 3, wherein: The method comprises subjecting the inferior diesel raw material to 2-5 hydrofining treatments in sequence, preferably 2-3 hydrofining treatments.

5. The method according to any one of claims 1 to 4, wherein: The initial distillation point of the inferior diesel raw material is 150-250°C, and the final distillation point is 300-380°C. Preferably, the sulfur content of the inferior diesel feedstock is 500-7000ug / mL, preferably 800-5000ug / mL; the nitrogen content is 100-1000ug / mL, preferably 200-800ug / mL; the aromatic content is >60wt%, preferably >70wt%; More preferably, the diesel feedstock is selected from at least one of catalytic cracking diesel, coking diesel, hydrotreated diesel, straight-run diesel, coal tar, direct coal liquefaction oil and indirect coal liquefaction oil.

6. The method according to any one of claims 1 to 5, wherein: The active component of the hydrotreating catalyst is selected from metal elements of Group VIB and / or Group VIII, preferably selected from metal elements of Group VIB and Group VIII; preferably, the hydrotreating catalyst further comprises a lanthanide metal element; Preferably, The VIB Group metal element is molybdenum and / or tungsten; and / or The Group VIII metal element is nickel and / or cobalt; and / or The lanthanide metal element is praseodymium; More preferably, When the hydrofining is performed twice, the weight content of the active components of the catalyst of the second hydrofining is not higher than the weight content of the active components of the catalyst of the first hydrofining, calculated as metal oxides, and is preferably 0-5% lower; When the hydrofining is performed for not less than three times, the weight content of active components in the catalysts of the third and subsequent hydrofinings is lower than the weight content of active components in the catalysts of the first and second hydrofinings, calculated as metal oxides, preferably 1-9% lower; More preferably, The weight content of Group VIB metal elements in the hydrorefining catalyst as oxides is 0-30%, preferably 6-25%; the weight content of Group VIII metal elements as oxides is 0-18%, preferably 1.5-15%; the weight content of lanthanide metal elements as oxides is 0-1%, preferably 0.1-0.8%.

7. The method according to claim 6, wherein: In the active components of the hydrotreating catalyst, the weight ratio of the VIB group metal elements, the VIII group metal elements and the lanthanide metal elements in terms of oxides is 1:0.1-0.9:0-0.1; preferably 1:0.2-0.8:0-0.1; more preferably 1:0.2-0.8:0.01-0.

06.

8. A two-stage hydrorefining method for low-quality diesel raw materials, characterized in that: The method includes: (a) under the conditions of a first hydrotreating catalyst, the low-quality diesel component is mixed with hydrogen to complete a first stage hydrotreating reaction to obtain a first stage hydrogenation reaction product; (b) the first stage hydrogenation reaction product is not separated, but is mixed with hydrogen after cooling under the second hydrogenation refining catalyst condition to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product; Preferably, The conditions of the first stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or the hydrogen to oil volume ratio is 600-5000:1, preferably 800-4000:1; the inlet temperature is 200-450°C, preferably 210-400°C; and / or The conditions of the second stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 220-520°C, preferably 220-440°C.

9. A three-stage hydrorefining method for low-quality diesel raw materials, characterized in that: The method includes: (a) under the conditions of a first hydrotreating catalyst, the low-quality diesel component is mixed with hydrogen to complete a first stage hydrotreating reaction to obtain a first stage hydrogenation reaction product; (b) the first stage hydrogenation reaction product is not separated, but is mixed with hydrogen after cooling under the second hydrogenation refining catalyst condition to complete the second stage hydrogenation refining reaction, thereby obtaining the second stage hydrogenation reaction product; (c) the second stage hydrogenation reaction product is not separated, but is mixed with hydrogen gas under the condition of the third hydrogenation refining catalyst after cooling to complete the second stage hydrogenation refining reaction, thereby obtaining the third stage hydrogenation reaction product; Preferably, The conditions of the first stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or the hydrogen to oil volume ratio is 600-5000:1, preferably 800-4000:1; the inlet temperature is 200-450°C, preferably 210-400°C; and / or The conditions of the second stage hydrofining reaction include: a reaction pressure of 3.5-7.5 MPa, preferably 4-7 MPa; and / or a hydrocarbon feedstock weight hourly space velocity of 0.5-3 h -1 , preferably 0.5-2h -1 ; and / or the hydrogen to oil volume ratio is 600-5000:1, preferably 800-4000:1; the inlet temperature is 220-520°C, preferably 220-440°C; and / or The conditions of the third stage hydrofining reaction include: the reaction pressure is 3.5-7.5MPa, preferably 4-7MPa; and / or the weight hourly space velocity of the hydrocarbon feedstock is 0.5-3h -1 , preferably 0.5-2h -1 ; and / or a hydrogen to oil volume ratio of 600-5000:1, preferably 800-4000:1; an inlet temperature of 240-520°C, preferably 240-460°C.

10. Use of the method according to any one of claims 1 to 9 in processing low-quality diesel raw materials.