Method for producing high-value chemical raw material from straight-run diesel oil

Abstract

The invention relates to the technical field of diesel oil processing, and discloses a method for producing a high-value chemical raw material from straight-run diesel oil, which comprises the following steps: (1) contacting the straight-run diesel oil with a hydrocracking catalyst, and carrying out a selective cracking reaction of an alkyl cyclic hydrocarbon side chain to obtain a selective cracking product; wherein the side chain breaking rate of alkyl cyclic hydrocarbon with the side chain carbon number larger than 2 in the straight-run diesel oil is not lower than 60%, and the total mole loss rate of cycloalkane and aromatic hydrocarbon in the selective cracking product is not higher than 15%; (2) separating the selective cracking product to obtain a light fraction rich in chain hydrocarbon and a heavy fraction rich in cyclic hydrocarbon; and (3) contacting the heavy fraction with a hydrogenation ring-opening catalyst, and carrying out a hydrogenation ring-opening reaction. According to the method, the high-quality ethylene cracking raw material and the reforming raw material with high potential aromatic hydrocarbon content can be obtained, and high-value chemical raw materials can be efficiently produced from straight-run diesel oil.

Description

Technical Field

[0001] The invention relates to the technical field of diesel processing, and in particular to a method for producing high-value chemical raw materials from straight-run diesel. Background Art

[0002] In 2019, the domestic refining capacity increased by 25 million tons / year, and the total refining capacity reached 860 million tons / year. The refining capacity was seriously oversupplied, while the terminal consumption of refined oil continued to slow down; among them, the apparent consumption of diesel in 2019 decreased by 6.25% year-on-year. Reducing the diesel-to-gasoline ratio and the outlet of refinery diesel have become one of the problems that need to be solved urgently. In my country's diesel pool, straight-run diesel accounts for 50%. The mass fraction of aromatics in straight-run diesel is generally higher than that in straight-run naphtha, which is not an ideal high-quality ethylene cracking raw material. If straight-run diesel can be further processed to produce high-quality ethylene cracking raw materials with higher added value, on the one hand, it can reduce the diesel-to-gasoline ratio and solve the diesel outlet problem of refineries. On the other hand, it can increase the raw material diversity of domestic ethylene cracking units.

[0003] The mass fraction of chain alkanes in straight-run diesel is about 40%, and the cyclic hydrocarbons contain high-value alkyl side chains, and the proportion of chain carbon in the carbon distribution is more than 70%. If these units with chain alkane structures can be converted into high-quality ethylene cracking raw materials; at the same time, cyclic hydrocarbons with bare rings or few or short side chains can be obtained, and then naphtha with high aromatic potential content can be obtained through directional hydrogenation ring-opening reaction, then the efficient and high-value conversion of straight-run diesel into chemical raw materials can be achieved. However, controlling the reaction process and the molecular structure of the product is the key and difficulty.

[0004] CN104611040A discloses a hydrocracking method, in which heavy distillate oil is mixed with hydrogen and then subjected to hydrorefining and hydrocracking reactions in sequence, wherein a hydrocracking catalyst with reduced hydrogenation activity is loaded in a cracking reactor along the direction of the reaction flow, thereby achieving improvement in the aromatic potential and selectivity of heavy naphtha.

[0005] CN102959054A discloses a combined hydrocracking and dewaxing method for hydrocarbons. In this method, the raw oil is subjected to hydrogenation treatment and a first hydrocracking reaction zone reaction in sequence to obtain a first hydrocracking reaction effluent, which enters a first catalytic dewaxing reaction zone for reaction. The reaction effluent is separated and fractionated to obtain a naphtha fraction, a first diesel fraction and a bottom product fraction, wherein the bottom product fraction is reacted in a second hydrocracking or second catalytic dewaxing reaction zone, and the reaction effluent is separated and fractionated to form a second diesel fraction and a lubricating oil product fraction.

[0006] The focus of existing research is to control the depth of conversion and the selectivity of target fraction products. There is still a lack of research on the selectivity of conversion of raw material molecules with different structures, chain hydrocarbons and cyclic hydrocarbon structural units in the raw material molecules, and the molecular structure of the products. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of single product structure and low utilization rate of the prior art in which straight-run diesel is used to produce fuel oil as the main product, and to provide a method for producing high-value chemical raw materials from straight-run diesel. The method can obtain high-quality ethylene cracking raw materials and reforming raw materials with high aromatic potential content, thereby realizing efficient production of high-value chemical raw materials from straight-run diesel.

[0008] In order to achieve the above object, the present invention provides a method for producing high-value chemical raw materials from straight-run diesel, comprising the following steps:

[0009] (1) contacting straight-run diesel with a hydrocracking catalyst to carry out a selective cracking reaction of the side chains of alkyl cyclic hydrocarbons to obtain a selective cracking product; wherein the side chain breaking rate of the alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 60%, and the total molar loss rate of cycloalkanes and aromatics in the cracking product is not more than 15%;

[0010] (2) separating the selective cracking products to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons;

[0011] (3) contacting the heavy fraction with a hydrogenation ring-opening catalyst to carry out a hydrogenation ring-opening reaction.

[0012] Compared with the prior art, the present invention retains the original structure of the straight-run diesel raw material molecule to the maximum extent by coupling the hydrocracking reaction with the separation, realizes the partitioning and directional conversion of the chain structure and the ring structure of the petroleum hydrocarbons, and then contacts the heavy fraction with the hydrogenation ring-opening catalyst for hydrogenation ring-opening reaction, which is conducive to obtaining naphtha with high aromatic potential content. Preferably, the light fraction separated after the hydrocracking reaction has a higher proportion of normal alkanes and can be used as a high-quality ethylene cracking raw material. The above method can realize the high-value utilization of straight-run diesel. DETAILED DESCRIPTION

[0013] 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.

[0014] The present invention provides a method for producing high-value chemical raw materials from straight-run diesel, comprising the following steps:

[0015] (1) contacting straight-run diesel with a hydrocracking catalyst to carry out a selective cracking reaction of the side chains of alkyl cyclic hydrocarbons to obtain a selective cracking product; wherein the side chain breaking rate of the alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 60%, and the total molar loss rate of cycloalkanes and aromatics in the selective cracking product is not more than 15%;

[0016] (2) separating the selective cracking products to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons;

[0017] (3) contacting the heavy fraction with a hydrogenation ring-opening catalyst to carry out a hydrogenation ring-opening reaction.

[0018] According to the present invention, the hydrocracking reaction in step (1) mainly involves cracking of chain alkanes, breaking of alkyl side chains of cyclic hydrocarbons and dealkylation reactions. After the hydrocracking reaction, the side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 60%. Compared with the straight-run diesel, the total molar loss rate of cycloalkanes and aromatic hydrocarbons in the selective cracking product is not higher than 15%. In this case, the original structure of the straight-run diesel raw material molecule can be retained to the maximum extent, and the partitioned and directional conversion of the chain structure and the cyclic structure of petroleum hydrocarbons can be achieved, which is conducive to obtaining a reforming raw material with a high aromatic potential content.

[0019] The present invention has no particular limitation on the composition and source of the straight-run diesel, and conventional straight-run diesel in the art can be applied to the present invention. Preferably, the straight-run diesel includes chain hydrocarbons, substituted or unsubstituted cycloalkanes and substituted or unsubstituted aromatics. Based on the total mass of the straight-run diesel, the content of the chain hydrocarbons is 20-70wt%, preferably 30-60wt%; the content of the substituted or unsubstituted cycloalkanes is 10-50wt%, preferably 20-40wt%; the content of the substituted or unsubstituted aromatics is 5-40wt%, preferably 10-30wt%. The substituents in the substituted cycloalkanes or aromatics can be, for example, C3-C6 alkanes.

[0020] In the present invention, the "alkyl cyclic hydrocarbon" refers to alkyl-substituted aromatic hydrocarbons and alkyl-substituted cycloalkanes.

[0021] According to some preferred embodiments of the present invention, the side chain breaking rate of the alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 70%, preferably 70-90%. Controlling the side chain breaking rate of the alkyl cyclic hydrocarbons in the raw material within the above preferred range is conducive to retaining the original structure of the straight-run diesel raw material molecule and realizing the partitioning and directional conversion of the chain structure and the ring structure of petroleum hydrocarbons.

[0022] According to some preferred embodiments of the present invention, compared with the straight-run diesel, the total molar loss rate of cycloalkanes and aromatics in the cracking product is not higher than 12%, preferably 4-12%.

[0023] In the present invention, the total molar loss rate of cycloalkanes and aromatics (%) = molar amount of cycloalkanes and aromatics in cracked products / molar amount of cycloalkanes and aromatics in straight-run diesel × 100%. The molar amount of cycloalkanes and aromatics in cracked products and the molar amount of cycloalkanes and aromatics in straight-run diesel are determined and calculated by coal diesel hydrocarbon composition (SH0606) and hydrocarbon carbon number distribution (HCND) methods.

[0024] The present invention has a wide range of choices for the hydrocracking catalyst used in the selective cracking reaction, and can use catalysts known in the art that can catalyze hydrocracking reactions to meet the above-mentioned side chain breaking rate of alkyl cyclic hydrocarbons and the molar loss rate of cyclic hydrocarbons and aromatic hydrocarbons.

[0025] According to some preferred embodiments of the present invention, the hydrocracking catalyst comprises a first molecular sieve and a first active metal component, wherein the first molecular sieve is a molecular sieve having a ten-membered ring channel or a molecular sieve having both a ten-membered ring channel and a twelve-membered ring channel, and is preferably at least one of MFI, EUO and NES molecular sieves. The use of the preferred first molecular sieve is beneficial to the selective cracking of alkyl cyclic hydrocarbons and helps to retain the native structure of the straight-run diesel feedstock molecule to the maximum extent.

[0026] According to the present invention, preferably, the first active metal component is selected from at least one of Group VIII metals and Group VIB metals, and the Group VIII metal is preferably at least one of Fe, Co, Ni, Ru, Rh, Pd, and Pt, more preferably Ni and / or Co. The Group VIB metal is preferably at least one of Mo, Cr, and W, more preferably Mo.

[0027] In the present invention, the first active metal component may contain only Group VIII metals, only Group VIB metals, or both Group VIII metals and Group VIB metals.

[0028] According to some preferred embodiments of the present invention, the first active metal component includes at least one of the metal elements of Group VIII and at least one of the metal elements of Group VIB. Preferably, the first active metal component includes Ni and / or Co, and Mo. In the above preferred case, it is beneficial to further improve the catalytic activity of the hydrocracking catalyst.

[0029] The present invention has a wide selection range for the content of each component in the hydrocracking catalyst. Preferably, based on the total mass of the hydrocracking catalyst, the content of the first molecular sieve is 0.5-50wt%, preferably 3-30wt%; calculated as metal oxide, the content of Group VIII metal is 1-10wt%, preferably 1-6wt%, and the content of Group VIB metal is 1-40wt%, preferably 5-35wt%.

[0030] In the present invention, the hydrocracking catalyst may also contain a first heat-resistant inorganic oxide matrix. The present invention has no special requirements for the content of the first heat-resistant inorganic oxide matrix, which is based on the content of the first molecular sieve and the first active metal component. According to the 100% principle, the rest is the first heat-resistant inorganic oxide.

[0031] The present invention has no particular limitation on the specific type of the first heat-resistant inorganic oxide, and conventional heat-resistant inorganic oxides in the art can be used. Preferably, the first heat-resistant inorganic oxide matrix is ​​aluminum oxide and / or silicon oxide, for example, aluminum oxide, silicon oxide, or aluminum oxide-silicon oxide composite oxide. The first heat-resistant inorganic oxide matrix can be a commercially available product or can be prepared by any known preparation method, and the present invention has no particular limitation on this.

[0032] The present invention has a wide selection range for the aluminum oxide, which can be selected from any one of γ, η, θ, δ and χ transition phase aluminum oxides, preferably γ-alumina. The aluminum oxide may also contain an auxiliary element, which is preferably any one of silicon, titanium, magnesium, boron, zirconium, thorium, niobium, cerium, lanthanum and praseodymium. Preferably, based on the total amount of the aluminum oxide, the content of the auxiliary element is 0.1-5wt%.

[0033] Preferably, the silicon oxide-aluminum oxide composite oxide has a pseudo-boehmite structure and can be a commercially available product or prepared by any existing technology, such as the Siral series of commercial silicon oxide-aluminum oxides produced by Condea of ​​Germany.

[0034] The present invention has no particular limitation on the specific conditions of the hydrocracking reaction, which are also based on satisfying the above-mentioned side chain breaking rate of alkyl cyclic hydrocarbons and the molar loss rate of cyclic hydrocarbons and aromatic hydrocarbons.

[0035] According to some preferred embodiments of the present invention, the conditions of the hydrocracking reaction include: a hydrogen partial pressure of 3-20 MPa, preferably 3-10 MPa, a reaction temperature of 280-400°C, preferably 280-370°C; a liquid hourly volume space velocity of 1-6 h -1 , preferably 1.5-4h -1, the volume ratio of hydrogen to oil is 300-1500, preferably 300-1000. In the present invention, unless otherwise specified, the pressures involved are gauge pressures.

[0036] In the present invention, the selective cracking product is separated into a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons by the separation in step (2). The present invention has no particular limitation on the separation method and conditions, as long as the chain hydrocarbons and the cyclic hydrocarbons can be separated, and those skilled in the art can select according to actual needs.

[0037] According to some preferred embodiments of the present invention, the separation method is fractional distillation, and preferably, the fractional distillation temperature is 175-220°C.

[0038] According to the present invention, the separated heavy fraction rich in cyclic hydrocarbons is contacted with a hydrogenation ring-opening catalyst to carry out a hydrogenation ring-opening reaction, and the obtained light fraction rich in chain hydrocarbons can be used as an ethylene cracking feedstock after optional fractionation.

[0039] According to the present invention, the hydrogenation ring-opening reaction in step (3) makes the ring-opening rate of the polycyclic hydrocarbons in the heavy fraction greater than 60%, preferably 80-95%. The "polycyclic hydrocarbons" include aromatic hydrocarbons and cycloalkanes containing two or more rings. Controlling the ring-opening rate of the polycyclic hydrocarbons in the heavy fraction within the above preferred range is conducive to maximizing the conversion of straight-run diesel into chemical raw materials and improving the aromatic potential of heavy naphtha products.

[0040] The ring opening rate of polycyclic hydrocarbons in the heavy fraction is calculated according to the following formula:

[0041] Opening rate (%) = (N 1 -n 1 ) / N 1 ×100%;

[0042] Among them, N 1 It represents the sum of the amount of polycyclic hydrocarbons such as aromatic hydrocarbons and cycloalkanes with two or more rings in the heavy fraction, n 1 It represents the sum of the amount of aromatic hydrocarbons, cycloalkanes and other polycyclic hydrocarbons containing two or more rings in the hydrogenation ring-opening products, and the unit is mol. The amount of substance is calculated from the test results of hydrocarbon composition and hydrocarbon carbon number distribution.

[0043] The present invention has a wide selection range for the hydrocracking catalyst used in the hydroring-opening reaction, and a catalyst known in the art that can catalyze the hydrocracking reaction can be used to meet the ring-opening rate of aromatic hydrocarbons and cycloalkanes with two or more rings in the above-mentioned heavy fraction.

[0044] According to some preferred embodiments of the present invention, the hydrogenation ring-opening catalyst comprises a second molecular sieve and a second active metal component, wherein the second molecular sieve is a molecular sieve with twelve-membered ring channels, preferably FAU and / or BEA molecular sieve.

[0045] Preferably, the molar ratio of silicon oxide to aluminum oxide of the second molecular sieve is 3-50, preferably 3-30.

[0046] Preferably, the second active metal component is selected from at least one of Group VIII metal elements and Group VIB metal elements; the Group VIII metal is preferably at least one of Fe, Co, Ni, Ru, Rh, Pd, Pt, more preferably Ni and / or Co. The Group VIB metal is preferably at least one of Mo, Cr, W, more preferably Mo.

[0047] In the present invention, the second active metal component may contain only Group VIII metals, only Group VIB metals, or both Group VIII metals and Group VIB metals.

[0048] According to some preferred embodiments of the present invention, the second active metal component includes at least one of the metal elements of Group VIII and at least one of the metal elements of Group VIB. In the above preferred case, it is beneficial to further improve the catalytic activity of the hydrogenation ring-opening catalyst.

[0049] According to some particularly preferred embodiments of the present invention, the second active metal component includes Ni and / or Co, and Mo.

[0050] According to some preferred embodiments of the present invention, based on the total mass of the hydrogenation ring-opening catalyst, the content of the second molecular sieve is 10-80wt%, preferably 30-75wt%; calculated as metal oxide, the content of Group VIII metal is 0.5-6wt%, preferably 0.5-4wt%, and the content of Group VIB metal is 1-30wt%, preferably 2-25wt%.

[0051] Preferably, the hydrogenation ring-opening catalyst further contains a second heat-resistant inorganic oxide matrix, and the selection range of the second heat-resistant inorganic oxide matrix is ​​the same as that of the first heat-resistant inorganic oxide matrix, which will not be repeated here.

[0052] In the present invention, the "first" and "second" in "first molecular sieve", "second molecular sieve", "first active metal component", "second active metal component", "first heat-resistant inorganic oxide matrix" and "second heat-resistant inorganic oxide matrix" are only used to distinguish different components in the hydrocracking catalyst and the hydroring-opening catalyst.

[0053] The present invention has no particular limitation on the sources of the hydrocracking catalyst and the hydrogenation ring-opening catalyst, which can be purchased from commercial sources or prepared by any preparation method known in the art.

[0054] According to some preferred embodiments of the present invention, the temperature of the hydrocracking reaction is not higher than the temperature of the hydrogenation ring-opening reaction, and preferably, the temperature of the hydrocracking reaction is 10-50° C. lower than the temperature of the hydrogenation ring-opening reaction. The above preferred embodiments are adopted to maximize the retention of the native structure of the chain hydrocarbons in the hydrocracking reaction zone, inhibit coking, and enhance the ring-opening activity of the hydrogenation ring-opening reaction.

[0055] According to some preferred embodiments of the present invention, the conditions for the hydrogenation ring-opening reaction include: a hydrogen partial pressure of 3MPa-20MPa, preferably 3-10MPa, a reaction temperature of 320-450°C, preferably 350-430°C; a liquid hourly volume space velocity of 0.5-5h -1 , preferably 0.5-3h -1 , the volume ratio of hydrogen to oil is 300-1500, preferably 600-1500.

[0056] The method for producing high-value chemical raw materials from straight-run diesel provided by the present invention can be carried out in any reaction device that is sufficient to allow the straight-run diesel to contact and react with the catalyst under hydrogenation reaction conditions. For example, the hydrocracking reaction and hydrogenation ring-opening reaction can be carried out in a fixed bed reactor, a moving bed reactor or an ebullating bed reactor.

[0057] In the present invention, the light fraction separated after the hydrocracking reaction has a higher proportion of normal hydrocarbons and can be directly used as a high-quality ethylene cracking feedstock. The light fraction can also be subjected to a second separation with the product obtained from the hydrogenation ring-opening reaction to obtain light naphtha and heavy naphtha.

[0058] According to some preferred embodiments of the present invention, the method further comprises: mixing the product of the hydrogenation ring-opening reaction with a light fraction rich in chain hydrocarbons for a second separation to obtain light naphtha and heavy naphtha.

[0059] The second separation can be performed in a conventional manner and under conventional conditions in the art. Preferably, the second separation is fractionation, and the cutting temperature of the second separation is 160-180°C.

[0060] The present invention will be described in detail below through examples.

[0061] In the following examples, the density of the straight-run diesel used is 0.8177 g / cm 3 , wherein the content of chain alkanes is 59.3wt%, the content of cycloalkanes is 29wt%, and the content of aromatics is 11.7wt%.

[0062] Example 1

[0063] The hydrocracking reaction zone is filled with a hydrocracking catalyst containing EUO molecular sieves, which are from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrocracking catalyst includes 15wt% EUO molecular sieves, 3.2wt% NiO, 20wt% MoO 3 and 61.8wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide in the EUO type molecular sieve is 30.

[0064] The hydrogenation ring-opening reaction zone is filled with a hydrogenation ring-opening catalyst containing a BEA type molecular sieve, the BEA type molecular sieve comes from the Changling Branch of Sinopec Catalyst Co., Ltd., and the hydrogenation ring-opening catalyst includes 50wt% BEA type molecular sieve, 1.6wt% NiO, 15wt% MoO 3 and 33.4 wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the BEA type molecular sieve is 25.

[0065] (1) The straight-run diesel is sent to the hydrocracking reaction zone to contact with the hydrocracking catalyst to carry out the hydrocracking reaction. The reaction conditions include 6.4 MPa, 340°C, 2.0 h -1 , hydrogen-to-oil ratio is 700. Compared with the straight-run diesel, the side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the cracking product is 66.5%, and the total molar loss rate of cycloalkanes and aromatics is 12.7%.

[0066] (2) The cracked product was fractionated at a cutting temperature of 200° C. to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons, wherein the yield of the light fraction was 25.2%.

[0067] (3) The heavy fraction is sent to the hydrogenation ring-opening reaction zone to contact with the hydrogenation ring-opening catalyst for hydrogenation ring-opening reaction. The reaction conditions include: 6.4 MPa, 390°C, 1.0 h -1 , hydrogen to oil ratio of 1100, to obtain a hydrogenation ring-opening product. The ring-opening rate of polycyclic cyclic hydrocarbons in the heavy fraction was calculated according to the following formula, and the results are shown in Table 1:

[0068] Opening rate (%) = (N 1 -n 1 ) / N 1 ×100%;

[0069] Among them, N 1 It represents the sum of the amount of polycyclic hydrocarbons such as aromatic hydrocarbons and cycloalkanes with two or more rings in the heavy fraction, n 1It represents the sum of the amount of aromatic hydrocarbons, cycloalkanes and other polycyclic hydrocarbons containing two or more rings in the hydrogenation ring-opening products, and the unit is mol. The amount of substance is calculated from the test results of hydrocarbon composition and hydrocarbon carbon number distribution.

[0070] (4) The light fraction and the hydrogenation ring-opening products of the heavy fraction are fed into a fractionation tower with a cutting temperature of 165°C to obtain light naphtha rich in chain hydrocarbons and heavy naphtha rich in cyclic hydrocarbons, which are used as ethylene cracking feedstock and aromatics feedstock, respectively. The product compositions are shown in Table 1.

[0071] In Table 1, the ratio of normal alkanes to isoalkanes in light naphtha is calculated by the following formula:

[0072]

[0073] Among them, P 1 、p 1 Respectively represent the sum of the amount of all normal paraffins and all isoparaffins in the light naphtha product, mol. Normal paraffins and isoparaffins are calculated from the mass fractions and corresponding molecular masses determined by chromatography.

[0074] In Table 1, the aromatic potential content (wt%) in heavy naphtha is calculated by the following formula:

[0075] Aromatic potential content in heavy naphtha (wt%) = a×C6N+b×C7N+c×C8N+d×C9N+e×C10N+Σall aromatics;

[0076] Wherein, C6N-C10N and ∑ all aromatics represent the mass fractions of cycloalkanes with carbon numbers of 6, 7, 8, 9, and 10 and all aromatics in the heavy naphtha product, respectively, and a, b, c, d, e, etc. represent the conversion coefficients of cycloalkanes with carbon numbers of 6, 7, 8, 9, and 10 to aromatics with corresponding carbon numbers, i.e., the ratios of the relative molecular weight of aromatics to the relative molecular weight of cycloalkanes with the same carbon number, which are 0.929, 0.939, 0.946, 0.952, and 0.957, respectively.

[0077] Example 2

[0078] The hydrocracking reaction zone is filled with a hydrocracking catalyst containing an MFI molecular sieve, which is from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrocracking catalyst includes 15wt% MFI molecular sieve, 3.2wt% NiO, 20wt% MoO 3 , 61.8wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the MFI type molecular sieve is 36.

[0079] The hydrogenation ring-opening reaction zone is filled with a hydrogenation ring-opening catalyst containing a FAU molecular sieve, which comes from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrogenation ring-opening catalyst includes 50wt% FAU molecular sieve, 1.6wt% NiO, 15wt% MoO 3 , 33.4wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the FAU type molecular sieve is 6.

[0080] (1) The straight-run diesel is sent to the hydrocracking reaction zone to contact with the hydrocracking catalyst to carry out the hydrocracking reaction. The reaction conditions include 6.4 MPa, 340°C, 2.0 h -1 , hydrogen-to-oil ratio is 700. The side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the cracking products is 72.6%, and the total molar loss rate of cycloalkanes and aromatics is 10.4%.

[0081] (2) The obtained cracked product is fractionated at a cutting temperature of 200° C. to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons, wherein the yield of the light fraction is 28.4%.

[0082] (3) The heavy fraction enters the hydrogenation ring-opening reaction zone and contacts with the hydrogenation ring-opening catalyst for hydrogenation ring-opening reaction. The reaction conditions include: 6.4 MPa, 390 °C, 1.0 h -1 The hydrogen-to-oil ratio was 1100, and the hydrogenation ring-opening product was obtained. The ring-opening rates of aromatic hydrocarbons and cycloalkanes containing two or more rings in the heavy fraction are shown in Table 1.

[0083] (4) The light fraction in step (2) and the above-mentioned hydrogenation ring-opening product are fed into a fractionation tower with a cutting temperature of 165° C. to obtain light naphtha rich in chain hydrocarbons and heavy naphtha rich in cyclic hydrocarbons. The product composition is shown in Table 1.

[0084] Example 3

[0085] The hydrocracking reaction zone is filled with a hydrocracking catalyst containing EUO molecular sieves, which are from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrocracking catalyst includes 30wt% EUO molecular sieves, 3.2wt% NiO, 20% MoO 3 , 46.8wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the EUO type molecular sieve is 36.

[0086] The hydrogenation ring-opening reaction zone is filled with a hydrogenation ring-opening catalyst containing a FAU molecular sieve, which comes from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrogenation ring-opening catalyst includes 50wt% FAU molecular sieve, 1.6wt% NiO, 15% MoO 3and 33.4 wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the FAU type molecular sieve is 6.

[0087] (1) The straight-run diesel is sent to the hydrocracking reaction zone to contact with the hydrocracking catalyst to carry out the hydrocracking reaction. The reaction conditions include 6.4 MPa, 340°C, 2.0 h -1 , hydrogen-to-oil ratio is 700. The side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the hydrocracking product is 70.3%, and the total molar loss rate of cycloalkanes and aromatics is 13.8%.

[0088] (2) The obtained cracked product was fractionated at a cutting temperature of 200° C. to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons, wherein the yield of the light fraction was 35.7%.

[0089] (3) The heavy fraction enters the hydrogenation ring-opening reaction zone and contacts with the hydrogenation ring-opening catalyst for hydrogenation ring-opening reaction. The reaction conditions include: 6.4 MPa, 390 °C, 1.0 h -1 The hydrogen-to-oil ratio was 1100, and the hydrogenation ring-opening product was obtained. The ring-opening rates of aromatic hydrocarbons and cycloalkanes containing two or more rings in the heavy fraction are shown in Table 1.

[0090] (4) The light fraction in step (2) and the above-mentioned hydrogenation ring-opening product are fed into a fractionation tower with a cutting temperature of 165° C. to obtain light naphtha rich in chain hydrocarbons and heavy naphtha rich in cyclic hydrocarbons. The product composition is shown in Table 1.

[0091] Example 4

[0092] The hydrocracking reaction zone is filled with a hydrocracking catalyst containing an MFI molecular sieve, which is from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrocracking catalyst includes 15wt% MFI molecular sieve, 3.2wt% NiO, 20wt% MoO 3 and 61.8 wt % of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the MFI type molecular sieve is 30.

[0093] The hydrogenation ring-opening reaction zone is filled with a hydrogenation ring-opening catalyst containing a BEA type molecular sieve, which comes from the Changling Branch of Sinopec Catalyst Co., Ltd. The hydrogenation ring-opening catalyst includes 50wt% BEA type molecular sieve, 1.6wt% NiO, 15% MoO 3 , 33.4wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the BEA type molecular sieve is 25.

[0094] (1) The straight-run diesel is sent to the hydrocracking reaction zone to contact with the hydrocracking catalyst for hydrocracking reaction. The reaction conditions include 6.4 MPa, 350°C, 2.0 h -1, hydrogen-to-oil ratio is 700. The side chain breaking rate of alkyl cyclic hydrocarbons with side chain carbon number greater than 2 in the hydrocracking products is 75.2%, and the total molar loss rate of cycloalkanes and aromatics is 8.8%.

[0095] (2) The obtained cracked product was fractionated at a cutting temperature of 200° C. to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons, wherein the yield of the light fraction was 27.6%.

[0096] (3) The heavy fraction enters the hydrogenation ring-opening reaction zone and contacts with the hydrogenation ring-opening catalyst for hydrogenation ring-opening reaction. The reaction conditions include: 6.4 MPa, 400 °C, 1.0 h -1 The hydrogen-to-oil ratio was 1100, and the hydrogenation ring-opening product was obtained. The ring-opening rates of aromatic hydrocarbons and cycloalkanes containing two or more rings in the heavy fraction are shown in Table 1.

[0097] (4) The light fraction in step (2) and the above-mentioned hydrogenation ring-opening product are fed into a fractionation tower with a cutting temperature of 165° C. to obtain light naphtha rich in chain hydrocarbons and heavy naphtha rich in cyclic hydrocarbons. The product composition is shown in Table 1.

[0098] Comparative Example 1

[0099] A single reactor and a single catalyst are used for the reaction. The straight-run diesel is directly contacted with a hydrogenation ring-opening catalyst for a ring-opening reaction. The catalyst is a hydrogenation ring-opening catalyst containing a FAU molecular sieve. The FAU molecular sieve comes from the Changling Branch of Sinopec Catalyst Co., Ltd. The molar ratio of silicon oxide to aluminum oxide is 6. The hydrogenation ring-opening catalyst includes 50wt% FAU molecular sieve, 1.6wt% NiO, 15wt% MoO 3 , 33.4wt% of γ-alumina. The reaction conditions include 6.4MPa, 370°C, 1.5h -1 , hydrogen-to-oil ratio 1000. The results of the full fraction analysis showed that, relative to the straight-run diesel feedstock, the side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 was 58.7%, and the ring opening rate of polycyclic cyclic hydrocarbons was 25.6%.

[0100] The above reaction product was sent to a fractionating tower with a cutting temperature of 165°C to obtain a light naphtha fraction and a heavy naphtha fraction. The product composition is shown in Table 1.

[0101] Comparative Example 2

[0102] The reactor is sequentially loaded with hydrocracking catalyst 1 and hydrocracking catalyst 2, wherein:

[0103] The hydrocracking catalyst 1 comprises 50 wt% BEA molecular sieve (purchased from Changling Branch of Sinopec Catalyst Co., Ltd.), 1.6 wt% NiO, 15 wt% MoO 3and 33.4 wt% of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the BEA type molecular sieve is 25.

[0104] Hydrocracking catalyst 2 includes 15wt% MFI molecular sieve (purchased from Sinopec Catalyst Co., Ltd. Changling Branch), 3.2wt% NiO, 20wt% MoO 3 and 61.8 wt % of γ-alumina, wherein the molar ratio of silicon oxide to aluminum oxide of the MFI type molecular sieve is 30.

[0105] The straight-run diesel was first contacted with the hydrocracking catalyst 1 to react under the reaction conditions of 6.4 MPa, 370°C, 1.5 h -1 , hydrogen-to-oil ratio is 1100. Compared with the straight-run diesel, the side chain breaking rate of alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the cracking product is 43.2%, and the total molar loss rate of cycloalkanes and aromatics is 38.8%.

[0106] The obtained product is then contacted with a hydrocracking catalyst 2 for reaction under the conditions of 6.4 MPa, 370°C, 1.5 h -1 , hydrogen-to-oil ratio 1100.

[0107] The above reaction products were fed into a fractionation tower with a cut temperature of 165°C to obtain light naphtha fraction and heavy naphtha fraction, and the product composition is shown in Table 1. The results of the full fraction analysis showed that the ring opening rate of polycyclic cyclic hydrocarbons was 60.8% relative to the straight-run diesel feedstock.

[0108] Table 1

[0109]

[0110] By comparing the above embodiments and comparative examples, it can be seen that the method for producing high-value chemical raw materials from straight-run diesel provided by the present invention can retain the original structure of the straight-run diesel raw material molecules to the greatest extent, and the obtained heavy naphtha has a higher aromatic potential content, and the light naphtha has a high ratio of normal / isomeric paraffins, which is beneficial as a high-quality ethylene cracking raw material, thereby realizing the high-value utilization of straight-run diesel.

[0111] 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 producing high-value chemical raw materials from straight-run diesel, characterized in that: The following steps are involved: (1) contacting straight-run diesel with a hydrocracking catalyst to carry out a selective cracking reaction of the side chains of alkyl cyclic hydrocarbons to obtain a selective cracking product; wherein the side chain breaking rate of the alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 60%, and the total molar loss rate of cycloalkanes and aromatics in the selective cracking product is not more than 15%; (2) separating the selective cracking products to obtain a light fraction rich in chain hydrocarbons and a heavy fraction rich in cyclic hydrocarbons; (3) contacting the heavy fraction with a hydrogenation ring-opening catalyst to carry out a hydrogenation ring-opening reaction.

2. The method according to claim 1, wherein: The total molar loss rate of cycloalkanes and aromatics in the selective cracking product is not higher than 12%, preferably 4-12%; Preferably, the side chain breaking rate of the alkyl cyclic hydrocarbons with a side chain carbon number greater than 2 in the straight-run diesel is not less than 70%, preferably 70-90%.

3. The method according to claim 1 or 2, wherein: The hydrogenation ring-opening reaction in step (3) is such that the ring-opening rate of the polycyclic cyclic hydrocarbons in the heavy fraction is not less than 60%, preferably 80-95%.

4. The method according to any one of claims 1 to 3, wherein: The hydrocracking catalyst comprises a first molecular sieve and a first active metal component, wherein the first molecular sieve is a molecular sieve having a ten-membered ring channel or a molecular sieve having both a ten-membered ring channel and a twelve-membered ring channel, and is preferably at least one of MFI, EUO and NES molecular sieves; Preferably, the first active metal component is selected from at least one of Group VIII metals and Group VIB metals, the Group VIII metal is preferably at least one of Fe, Co, Ni, Ru, Rh, Pd, and Pt; the Group VIB metal is preferably at least one of Mo, Cr, and W; Preferably, based on the total mass of the hydrocracking catalyst, the content of the first molecular sieve is 0.5-50wt%, preferably 3-30wt%; calculated as metal oxide, the content of the Group VIII metal is 1-10wt%, preferably 1-6wt%, and the content of the Group VIB metal is 1-40wt%, preferably 5-35wt%; Preferably, the hydrocracking catalyst further contains a first heat-resistant inorganic oxide matrix, and the first heat-resistant inorganic oxide matrix is ​​preferably aluminum oxide and / or silicon oxide.

5. The method according to any one of claims 1 to 4, wherein: The hydrogenation ring-opening catalyst comprises a second molecular sieve and a second active metal component, wherein the second molecular sieve is a molecular sieve with twelve-membered ring channels, preferably a FAU and / or BEA molecular sieve; Preferably, the molar ratio of silicon oxide to aluminum oxide of the second molecular sieve is 3-50; Preferably, the second active metal component is selected from at least one of Group VIII metal elements and Group VIB metal elements; Preferably, based on the total mass of the hydrogenation ring-opening catalyst, the content of the second molecular sieve is 10-80wt%, preferably 30-75wt%; calculated as metal oxide, the content of the Group VIII metal is 0.5-6wt%, preferably 0.5-4wt%, and the content of the Group VIB metal is 1-30wt%, preferably 2-25wt%; Preferably, the hydrocracking catalyst further contains a second heat-resistant inorganic oxide matrix, and the second heat-resistant inorganic oxide matrix is ​​preferably aluminum oxide and / or silicon oxide.

6. The method according to any one of claims 1 to 5, wherein: The temperature of the hydrocracking reaction is not higher than the temperature of the hydrogenation ring-opening reaction; Preferably, the temperature of the hydrocracking reaction is 10-60°C lower than the temperature of the hydrogenation ring-opening reaction.

7. The method according to any one of claims 1 to 6, wherein the conditions of the hydrocracking reaction include: The hydrogen partial pressure is 3-20MPa, preferably 3-10MPa, the reaction temperature is 280-400°C, preferably 280-370°C; the liquid hourly volume space velocity is 1-6h -1 , preferably 1.5-4h -1 , the volume ratio of hydrogen to oil is 300-1500, preferably 300-1000.

8. The method according to any one of claims 1 to 7, wherein: The conditions of the hydrogenation ring-opening reaction include: hydrogen partial pressure of 3-20 MPa, preferably 3-10 MPa, reaction temperature of 320-450° C., preferably 350-430° C.; liquid hourly volume space velocity of 0.5-5 h -1 , preferably 0.5-3h -1 , the volume ratio of hydrogen to oil is 300-1500, preferably 600-1500.

9. The method according to any one of claims 1 to 8, wherein: The separation method is fractional distillation, and preferably, the cutting temperature is 165-220°C.

10. The method according to any one of claims 1 to 9, wherein: The method further comprises: mixing the product of the hydrogenation ring-opening reaction with a light fraction rich in chain hydrocarbons for a second separation to obtain light naphtha and heavy naphtha; Preferably, the cutting temperature of the second separation is 160-180°C.

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