Method and system for chemically converting paraffin

Abstract

The invention relates to a method and a system for chemically converting paraffins. The method for chemically converting the paraffin comprises the following steps: 1) providing the paraffin as shown in the following structural formula (I): # imgabs0 # (I) in the structural formula (I), in which R is C2-C6 straight chain or branched chain alkyl, and 2) carrying out a conversion reaction on the paraffin in the presence of hydrogen so as to convert the paraffin into C2-C6 n-paraffin, thereby obtaining a conversion product. According to the present invention, the low-quality ethylene raw material can be effectively converted into the high-quality ethylene raw material, the n-hydrocarbon content in the hydrogenation product can be substantially improved by the hydro-converted paraffin so as to improve the ethylene and triene yield of the ethylene device, and the process has characteristics of simple process, low operation difficulty and good economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and in particular to a method and system for chemically converting paraffin. Background Art

[0002] Whether it is naphtha obtained by distillation of crude oil or light naphtha obtained by cracking reaction containing molecular sieve catalyst (including hydrocracking and catalytic cracking, etc.), its small molecular isoparaffins are rich in a large amount of 2-methylalkanes (including isopentane, 2-methylpentane, pentane and 2-methylhexane, etc.). Although these 2-methylalkanes can be used as gasoline blending components, they are limited in amount due to the influence of saturated vapor pressure. At the same time, with the continuous development of the chemical industry, the production capacity of ethylene is also increasing year by year, which also makes the supply of ethylene raw materials a problem. 2-methylalkanes can be used as ethylene raw materials, but due to the influence of its molecular structure, in the free radical reaction process of steam cracking, its ethylene and triene yields are low, and it is not an ideal ethylene raw material.

[0003] In the prior art, there are relatively mature processes and supporting catalysts for the conversion of isobutane, which can achieve the normalization reaction of isobutane. However, there has been no public research on 2-methylalkanes with a relatively high carbon number. If these small molecular 2-methylalkanes can be converted into normal alkanes, the yield of ethylene products can be greatly improved when used as ethylene raw materials, which has wide economic benefits. Summary of the invention

[0004] The inventors of the present invention have found that This special structured chain alkane that exists in large quantities in the oil processing process, when R=1, the energy consumed for its conversion is much higher than when R>1, and the reaction conditions are more stringent, making it difficult to convert it together; when R>6, its molecular structure is larger, and it is very easy to convert it in the conventional hydrocracking process, and the processing difficulty is relatively low. When R is 2-6, its molecular structure is smaller, and the reaction difficulty is very large whether it is the dehydrogenation or cracking of the alkane, and it is difficult to convert it using conventional processing methods. In view of the shortcomings of the prior art, the present invention provides a conversion method for this isoalkane with a special molecular structure, which can effectively convert isoalkane into C2-C6 normal alkanes, and then when used as ethylene raw materials, it can greatly increase the yield of the target product of the ethylene device.

[0005] Specifically, the present invention relates to the following aspects.

[0006] 1. A method for chemically converting paraffins, comprising the following steps:

[0007] 1) providing a chain alkane represented by the following structural formula (I),

[0008]

[0009] In the structural formula (I), R is a C2-C6 straight chain or branched chain alkyl group (preferably a C2-C4 straight chain or branched chain alkyl group, more preferably a C2-C3 straight chain alkyl group),

[0010] 2) subjecting the chain alkanes to a conversion reaction in the presence of hydrogen to convert them into C2-C6 normal alkanes to obtain conversion products.

[0011] 2. The method according to any one of the preceding or following aspects, wherein the conversion reaction needs to be carried out in the presence of a catalyst, and the catalyst comprises a molecular sieve, an active metal component and a binder.

[0012] 3. The method according to any one of the preceding or following aspects, wherein the catalyst is a molecular sieve having shape-selective catalytic properties, preferably selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve and EU-1 molecular sieve, more preferably selected from one or more of mordenite and ZSM molecular sieve, particularly preferably selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve and ZSM-38 molecular sieve, in particular selected from one or more of mordenite and ZSM-5 molecular sieve.

[0013] 4. A method according to any of the preceding or following aspects, wherein the catalyst further comprises a binder, the binder is generally alumina or silica (preferably alumina), and the content of the binder is 5-65wt% (preferably 10-35wt%) based on the weight of the catalyst.

[0014] 5. The method according to any of the preceding or following aspects, wherein the active metal component is selected from non-noble metals of Group VI, Group VII, Group VIB or Group VIII, non-noble metal oxides or non-noble metal sulfides with non-noble metals of Group VIB and / or Group VIII as active metal components, and more preferably one or more of molybdenum, tungsten, cobalt, nickel, or sulfides or oxides thereof.

[0015] 6. A method according to any of the preceding or subsequent aspects, wherein the content of the VIB Group metal (calculated as oxide) is 5.0-30.0 wt% (preferably 10-20 wt%), and the content of the VIII Group non-precious metal (calculated as oxide) is 0.5-15.0 wt% (preferably 3-10 wt%), based on the weight of the catalyst.

[0016] 7. The method according to any one of the preceding or following aspects, wherein the content of the molecular sieve is 30-80 wt% (preferably 40-70 wt%) based on the weight of the catalyst.

[0017] 8. A method according to any of the preceding or following aspects, wherein the specific surface area of ​​the catalyst is 200-400 m 2 / g, and the pore volume is 0.25-0.45mL / g.

[0018] 9. The method according to any of the preceding or following aspects, wherein the reaction conditions of the conversion reaction include: a reaction pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG), a reaction temperature of 250-500° C. (preferably 350-450° C.), a liquid hourly volume space velocity of 0.1-15.0 h- 1 (Preferably 0.5-5.0h- 1 ), the volume ratio of hydrogen to oil is 10:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1).

[0019] 10. The method according to any of the preceding or following aspects, wherein the operating conditions of the steam cracking include: reaction temperature 750-900°C, reaction pressure 0.1-0.5MPaG, water-to-oil mass ratio 0.2-0.6.

[0020] 11. The method according to any of the preceding or following aspects, further comprising the following steps:

[0021] Separating the conversion product to obtain a separation stream mainly composed of the C2-C6 normal alkanes (e.g., accounting for more than 80 wt%, more than 90 wt%, or more than 95 wt% of the total amount), and

[0022] The separated stream is steam cracked to obtain a cracking product comprising ethylene.

[0023] 12. The method according to any of the preceding or following aspects further comprises the following steps:

[0024] Separating the conversion products to obtain a normal stream mainly composed of C4-C6 normal alkanes (e.g., accounting for more than 80 wt%, more than 90 wt%, or more than 95 wt% of the total amount) and / or a low-carbon stream mainly composed of C2-C3 hydrocarbons (e.g., accounting for more than 90 wt% or more than 95 wt% of the total amount), and

[0025] The normal stream and / or the low carbon stream are steam cracked to obtain a cracking product comprising ethylene.

[0026] 13. A system for chemically converting paraffins, comprising the following units:

[0027] 1) a chain alkane providing unit, which is configured to provide a chain alkane represented by the following structural formula (I),

[0028]

[0029] In the structural formula (I), R is a C2-6 straight chain or branched chain alkyl (preferably a C2-4 straight chain or branched chain alkyl, more preferably a C2-3 straight chain alkyl),

[0030] 2) A paraffin conversion unit, which is configured to convert the paraffin into C2-C6 normal paraffins by a conversion reaction in the presence of hydrogen to obtain a conversion product.

[0031] Technical Effects

[0032] Compared with the prior art, the method and system provided by the present invention can achieve one of the following technical effects or a combination of all or part of them:

[0033] 1. For small molecular isoalkanes, especially isoalkanes with a methyl branch on the second carbon atom of a straight-chain alkane, they exist in large quantities in both crude oil and products obtained after an oil processing process, and the isoalkanes with this molecular structure are much higher than isoalkanes with other molecular structures. This isoalkanes with a special molecular structure have major problems whether as a product or in subsequent processing, and are not high-quality products or raw materials. The inventors of the present invention have found through research that for this isoalkanes with a special molecular structure, by selecting a molecular sieve with a special pore structure, when a certain amount of hydrogenation metal is loaded, the catalyst has a strong dehydrogenation performance, and the effective conversion of this isoalkanes can be achieved, so that more of them can be converted into normal alkanes. When used as an ethylene raw material, the yield of the target product of the ethylene device can be greatly improved.

[0034] 2. The conversion process of the present invention is simple. Whether it is a simple modification of the existing hydrogenation device (including naphtha hydrogenation, jet fuel, diesel hydrogenation and wax oil hydrogenation) or a new device, the overall investment is low; combined with a hydrogenation conversion catalyst with a low manufacturing cost, isoparaffins can be efficiently converted into normal paraffins, which has the advantages of low investment and high returns. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a process flow diagram of the process method of the present invention.

[0036] exist Figure 1 In the figure, 1-chain alkane, 2-hydrogen, 3-hydrogenation reaction zone, 4-effluent from the hydroconversion reaction zone, 5-high-pressure separator, 6-gas phase stream hydrogen-rich gas, 7-liquid phase stream.

[0037] Figure 2 The figure is a process flow diagram of the process method of the present invention.

[0038] exist Figure 2 In the figure, 1-chain alkane, 2-hydrogen, 3-hydrogenation conversion reaction zone, 4-hydrogenation conversion reaction zone effluent, 5-high-pressure separator, 6-gas phase stream hydrogen-rich gas, 7-liquid phase stream, 8-fractionation tower, 9-gas phase product, 10-liquid phase product. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are described in detail below, but it should be pointed out that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims in the appendix.

[0040] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definitions in this specification shall prevail.

[0041] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0042] In the context of the present invention, all numerical values ​​for parameters (eg amounts or conditions) are to be understood as being modified in all instances by the term "about", regardless of whether "about" actually appears before the numerical value.

[0043] In the context of the present invention, unless otherwise specified, each device used in the present invention may use a structure conventionally selected in the art without any particular limitation.

[0044] In the context of the present invention, the term "C2-C6 normal alkane" refers to a normal alkane having a carbon number of from 2 to 6. It should be particularly clarified that, although there is no distinction between normal alkanes and isoalkanes for alkanes having a carbon number of from 2 to 3, for the sake of convenience of description, alkanes having a carbon number of from 2 to 3 are also regarded as normal alkanes. In addition, unless otherwise specified, the present invention may refer to any one or more of the normal alkanes having a carbon number of from 2 to 6, or may refer to all normal alkanes having a carbon number of from 2 to 6.

[0045] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight and pressure is gauge pressure.

[0046] In the context of the present invention, any two or more embodiments or aspects of the present invention may be arbitrarily combined, and the technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0047] According to one embodiment of the present invention, it relates to a method for chemically converting paraffins.

[0048] Here, the chain alkane is represented by the following structural formula (I).

[0049]

[0050] According to one embodiment of the present invention, in structural formula (I), R is a C2-C6 straight or branched alkyl, preferably a C2-C4 straight or branched alkyl, more preferably a C2-C3 straight alkyl. According to the present invention, when R=1, the energy consumed by its conversion is much higher than when R>1, and the reaction conditions are more stringent, making it difficult to convert it together; when R>6, its molecular structure is larger, and it is very easy to convert it in the conventional hydrocracking process, and the processing difficulty is relatively low. When R has a branched chain, the difficulty of the reaction of two tertiary carbon atoms being simultaneously dehydrogenated to generate tertiary positive carbon ions will be greatly increased, and the isoparaffins of this molecular structure will not undergo normalization reaction, and there is only one reaction path, the cracking reaction, and its hydrogen consumption will be greatly increased; at the same time, due to the complex branched structure, the difficulty of entering the molecular sieve pores also increases, and the cracking difficulty is large, and because it has two methyl branches, at least one isoparaffin is still produced in the conversion product after the cracking reaction, and the conversion effect is not good.

[0051] According to the present invention, the paraffins can be produced by any method known in the art. Here, as the production method of the paraffins, for example, hydrocracking, catalytic cracking or atmospheric and vacuum distillation can be cited, thereby producing a hydrocarbon stream containing the paraffins. According to the present invention, preferably, the hydrocarbon stream is a light naphtha component obtained by hydrocracking a hydrocarbon oil feedstock. In addition, the hydrocarbon stream can be used for the conversion reaction described below in the present invention after separation (such as distillation or adsorption) or without separation, without particular limitation.

[0052] According to one embodiment of the present invention, the alkane is subjected to a conversion reaction in the presence of hydrogen and converted into C2-C6 normal alkanes to obtain a conversion product. According to the present invention, there is no particular limitation on the conversion rate of the alkane in the conversion reaction. Therefore, the alkane can achieve the conversion rate (single-pass conversion rate) after a single conversion reaction, or it can achieve the conversion rate after multiple recycling (for example, the unreacted alkane is separated from the conversion product and then the conversion reaction is carried out). For example, the conversion rate (preferably single-pass conversion rate) can be 30wt% or more, 40wt% or more, 50wt% or more, 60wt% or more, 70wt% or more, 80wt% or more, or 90wt% or more.

[0053] According to one embodiment of the present invention, the conversion reaction can be a hydrogenation normalization reaction to obtain a conversion product with C4-C6 normal alkanes as the main product, or it can be a hydrocracking reaction to obtain a conversion product with C2-C3 hydrocarbons as the main product. The inventors of the present invention have found through research that the chain alkane needs to adopt a molecular sieve with a special pore structure to effectively convert it, and at the same time, the catalyst also has a strong hydrogenation / dehydrogenation activity. The isoalkane of this special structure first undergoes a dehydrogenation reaction at the hydrogenation center to generate olefins, and the acid center where the olefin molecules are transferred undergoes a change in molecular structure. If it moves to a strong acid center, it is easier to undergo a cracking reaction; if it moves to a medium-strong acid center, it is easier to undergo a normalization reaction. By selecting molecular sieves with different reaction characteristics, the strengthening of these two reaction paths can be achieved.

[0054] According to one embodiment of the present invention, the reaction conditions of the conversion reaction include: a reaction pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG), a reaction temperature of 250-500°C (preferably 350-450°C), a liquid hourly volume space velocity of 0.1-15.0 h- 1 (Preferably 0.5-5.0h- 1), the hydrogen to oil volume ratio is 10:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1). The inventors of the present invention have found that compared with the isobutane conversion reaction in the prior art, the reaction conditions of the conversion reaction of the present invention are milder, especially the reaction temperature is lower, such as generally 10-50°C lower. The inventors of the present invention have also found that at this lower reaction temperature, the paraffin still shows a higher conversion rate, such as the paraffin can show a single-pass conversion rate of more than 40wt%, more than 50wt%, more than 60wt%, more than 70wt%, more than 80wt% or more than 90wt% under the reaction conditions of the present invention. The inventors of the present invention have further found that the conversion reaction is specific for the paraffin. Specifically, the smaller the molecular hydrocarbon is, the more difficult it is to dehydrogenate. The dehydrogenation activity of isobutane is much lower than that of other isoalkanes. At the same time, a catalyst with smaller pores is also required during the conversion process to ensure that it has a certain residence time. Therefore, the conversion of isobutane using the method of the present invention requires a higher reaction temperature (for example, 20-30° C. higher) than that of other isoalkanes. In addition, for the conversion of chain alkanes with a higher number of carbon atoms (for example, R=7 or more), as the carbon number increases, the difficulty of normalization and hardening gradually increases, while the difficulty of cracking reaction gradually decreases. For components with R=7 or more, it is difficult for normalization reaction to occur during the reaction, and too much cracking reaction will cause a significant increase in hydrogen consumption, resulting in poor conversion effect.

[0055] According to one embodiment of the present invention, the conversion reaction is carried out in the presence of a catalyst, and the catalyst comprises a molecular sieve and an active metal component.

[0056] According to one embodiment of the present invention, the molecular sieve is a molecular sieve with shape-selective catalytic performance, preferably selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve and EU-1 molecular sieve, more preferably selected from one or more of mordenite and ZSM molecular sieve, particularly preferably selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve and ZSM-38 molecular sieve, especially selected from one or more of mordenite and ZSM-5 molecular sieve. Here, based on the weight of the catalyst, the content of the molecular sieve is 30-80wt% (preferably 40-70wt%). The inventors of the present invention have found that the acid strength of the molecular sieve directly affects the reaction characteristics of isoparaffins, and the molecular sieve has more strong acid centers, which is more prone to cracking reactions, such as ZSM-5 molecular sieves; and the medium-strong acid centers are more, and it is easier to normalize, such as mordenite. Therefore, according to the present invention, different reaction pathways can be achieved by selecting the acid strength of the molecular sieve.

[0057] According to one embodiment of the present invention, the active metal component is an active non-precious metal component, preferably selected from non-precious metals of Group VI, Group VII, Group VIB or Group VIII, non-precious metal oxides or non-precious metal sulfides with non-precious metals of Group VIB and / or Group VIII as active metal components, more preferably one or more of molybdenum, tungsten, cobalt, nickel, or their sulfides or oxides. Here, based on the weight of the catalyst, the content of the Group VIB metal (in terms of oxide) is 5.0-30.0wt% (10.0-20.0wt%), and the content of the Group VIII non-precious metal (in terms of oxide) is 0.5-15.0wt% (preferably 3.0-10.0wt%).

[0058] According to one embodiment of the present invention, the catalyst further comprises a binder. The type of the binder can be a conventional choice in the art, including but not limited to aluminum oxide and silicon oxide, wherein aluminum oxide is preferred. Here, based on the weight of the catalyst, the content of the binder is 5-65wt% (preferably 10-35wt%).

[0059] According to one embodiment of the present invention, the specific surface area of ​​the catalyst is 200-400m 2 / g, and the pore volume is 0.25-0.45mL / g.

[0060] According to one embodiment of the present invention, the preparation method of the catalyst can be prepared according to conventional methods in the art. The preparation method includes the preparation of a carrier and the loading of an active metal component, wherein the preparation process of the carrier is as follows: the molecular sieve and the binder are mechanically mixed, molded, and then dried and calcined to prepare a catalyst carrier. Conventional conditions can be used for drying and calcining the carrier. The drying condition is: drying at 100°C-150°C for 1-12 hours. The calcination condition is: calcining at 450°C-550°C for 2.5-6.0 hours.

[0061] According to one embodiment of the present invention, in the preparation method of the catalyst, the method for loading the active metal component is a conventional method, such as a kneading method, an impregnation method, etc., preferably an impregnation method. The impregnation method can be a saturated impregnation method, an excess impregnation method or a complex impregnation method, that is, the catalyst carrier is impregnated with a solution containing the required active metal component, and then dried and calcined to obtain the first catalyst. The drying conditions are: drying at 100°C-150°C for 1-12 hours. The calcination conditions are: calcining at 450°C-550°C for 2.5-6.0 hours.

[0062] According to one embodiment of the present invention, the content of C7+ hydrocarbons in the conversion product is not higher than 5wt% (preferably not higher than 1wt%), based on the total weight of the conversion product being 100wt%. According to the present invention, the conversion reaction basically does not produce C7+ hydrocarbons, and the methane output is also very low (e.g., less than 5wt%). Since methane is a low value-added product in the petrochemical process, it can only be used as fuel gas; at the same time, since methane has the highest hydrogen content among all molecular structure hydrocarbons, excessive methane is generated after hydrogenation conversion, which will cause a large amount of ineffective loss of hydrogen.

[0063] According to one embodiment of the present invention, depending on the conversion rate, the content of C5-C6 isoparaffins in the conversion product is generally 0-50wt% (preferably 10-40wt%), based on the total weight of the conversion product as 100wt%. The hydroconversion process includes two reaction paths, normalization and cracking, and normalization is a more ideal reaction path because it does not consume hydrogen and does not contain invalid components such as isoparaffins and methane in the conversion product. The normalization reaction is affected by chemical equilibrium, that is, the higher the isoparaffin content, the easier it is to undergo normalization. When the conversion rate is low, although there will be more normalization reactions, the increase in the normal paraffins in the product is effective; and when the conversion rate is high, a large amount of isoparaffins undergo cracking reactions, which reduces the concentration of isoparaffins in the reactants and also inhibits the occurrence of normalization reactions.

[0064] According to one embodiment of the present invention, also depending on the conversion rate, the content of C2-C6 normal alkanes in the conversion product is 40-90wt% (preferably 50-80wt%), based on the total weight of the conversion product being 100wt%.

[0065] According to one embodiment of the present invention, the method further comprises the following steps: separating the conversion product to obtain a separation stream mainly composed of the C2-C6 normal alkanes (e.g., accounting for more than 80wt%, more than 90wt% or more than 95wt% of the total amount). According to the specific situation of the conversion rate, unreacted paraffins may also be obtained through the separation. The unreacted paraffins can be used as a circulating material to continue the conversion reaction together with fresh paraffins, thereby converting a higher proportion of paraffins into C2-C6 normal alkanes.

[0066] According to this embodiment of the present invention, the method further comprises the following steps: separating the conversion products to obtain a normal stream mainly composed of C4-C6 normal alkanes (e.g., accounting for more than 80wt%, more than 90wt% or more than 95wt% of the total amount) and / or a low-carbon stream mainly composed of C2-C3 hydrocarbons (e.g., accounting for more than 90wt% or more than 95wt% of the total amount). According to the specific circumstances of the conversion rate, unreacted paraffins may also be obtained through this separation. The unreacted paraffins may be used as a circulating material to continue the conversion reaction with fresh paraffins, thereby converting a higher proportion of paraffins into C2-C6 normal alkanes.

[0067] According to one embodiment of the present invention, the conversion product, the separation stream, the normal stream or the low-carbon stream shows high chemical activity compared with the paraffins, and can therefore be advantageously used in chemical treatments such as steam cracking, alkane degassing, hydrocracking, etc. to obtain high value-added chemicals, preferably used in steam cracking to produce ethylene.

[0068] According to one embodiment of the present invention, the conversion product, the separation stream, the normal stream or the low-carbon stream are steam cracked to obtain a cracking product containing ethylene. According to the present invention, the conversion product, the separation stream, the normal stream or the low-carbon stream is an ideal ethylene cracking feedstock, and the ethylene yield when using these streams is generally above 30wt%, thereby finding a high-value utilization method for low-value-added paraffins in the prior art.

[0069] According to one embodiment of the present invention, the operating conditions of the steam cracking include: reaction temperature 750-900° C., reaction pressure 0.1-0.5 MPaG, and water-to-oil mass ratio 0.2-0.6.

[0070] According to one embodiment of the present invention, a system for chemically converting paraffin is also provided, which comprises a paraffin providing unit and a paraffin conversion unit. According to the present invention, the system is specifically configured to implement the method described in the foregoing text of this specification, so except for the contents clearly defined in this paragraph, any other contents or matters not clearly defined can be directly referred to the contents or matters correspondingly described in the foregoing text of this specification for the method, and there is no special limitation.

[0071] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0072] according to Figure 1 The paraffin 1 is mixed with hydrogen 2 and enters the hydroconversion reaction zone 3. The effluent 4 of the hydroconversion reaction zone enters the high-pressure separator 5. The separated gaseous phase stream hydrogen-rich gas 6 is recycled, and the liquid phase stream is used as ethylene feedstock.

[0073] according to Figure 2 , the paraffin 1 is mixed with hydrogen 2 and enters the hydroconversion reaction zone 3, the effluent 4 of the hydroconversion reaction zone enters the high-pressure separator 5, the separated gaseous phase stream hydrogen-rich gas 6 is recycled, the liquid phase stream 7 enters the distillation tower for separation to obtain the gaseous phase product 9 as the ethylene raw material, and the liquid phase product 10 is circulated to the inlet of the hydroconversion reaction zone 3.

[0074] Example

[0075] The present invention is further described in detail below using examples and comparative examples, but the present invention is not limited to these examples.

[0076] In the following examples and comparative examples, each hydroconversion catalyst is represented by Cat-A plus a number, such as Cat-A1, Cat-A2, Cat-A3, etc. The hydroconversion catalyst is prepared by a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalyst are shown in Table 1.

[0077] The preparation method of Cat-A1 to Cat-A3 catalysts is:

[0078] (1) Mordenite with a SiO2 / Al2O3 molar ratio of 15 was selected and mechanically mixed with a binder, molded, dried at 120°C for 10 hours, and calcined at 500°C for 4 hours to prepare a catalyst carrier.

[0079] (2) The catalyst carrier obtained in step (1) is impregnated with the active component, dried at 120°C for 10 hours, and calcined at 500°C for 4 hours to prepare a hydrogenation conversion catalyst.

[0080] The preparation method of Cat-A4 to Cat-A7 catalysts is:

[0081] (1) ZSM-5 with a SiO2 / Al2O3 molar ratio of 10 was selected and mechanically mixed with a binder, molded, dried at 120°C for 10 hours, and calcined at 500°C for 4 hours to prepare a catalyst carrier.

[0082] (2) The catalyst carrier obtained in step (1) is impregnated with the active component, dried at 120°C for 10 hours, and calcined at 500°C for 4 hours to prepare a hydrogenation conversion catalyst.

[0083] The properties of raw materials are shown in Table 2.

[0084] Table 1

[0085]

[0086] Table 2

[0087] raw material Raw material 1 Raw material 2 Raw material 3 Raw material 4 Raw material 5 R of alkanes Ethyl n-propyl n-Butyl n-pentyl n-Hexyl raw material Raw material 6 Raw material 7 Raw material 8 Raw Materials 9 R of alkanes Isopropyl Tert-butyl methyl Zheng Gengji

[0088] Example 1

[0089] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0090] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A1;

[0091] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0092] Example 2

[0093] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0094] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A2;

[0095] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0096] Example 3

[0097] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0098] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A3;

[0099] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0100] Example 4

[0101] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0102] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A4;

[0103] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0104] Example 5

[0105] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0106] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A5;

[0107] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0108] Example 6

[0109] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0110] (1) Raw material 1 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A6;

[0111] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0112] Example 7

[0113] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0114] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A1;

[0115] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0116] Example 8

[0117] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0118] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A2;

[0119] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0120] Example 9

[0121] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0122] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A3;

[0123] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0124] Example 10

[0125] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0126] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A4;

[0127] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0128] Embodiment 11

[0129] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0130] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A5;

[0131] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0132] Example 12

[0133] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0134] (1) Raw material 2 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with hydroconversion catalyst Cat-A6;

[0135] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0136] Example 13

[0137] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0138] (1) The raw material 3 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0139] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0140] Embodiment 14

[0141] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0142] (1) The raw material 4 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A4;

[0143] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0144] Embodiment 15

[0145] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0146] (1) The raw material 5 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0147] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0148] Example 16

[0149] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0150] (1) The raw material 6 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0151] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0152] Embodiment 17

[0153] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0154] (1) The raw material 7 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A4;

[0155] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0156] Comparative Example 1

[0157] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0158] (1) The raw material 8 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0159] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0160] Comparative Example 2

[0161] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0162] (1) The raw material 8 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0163] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0164] Comparative Example 3

[0165] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0166] (1) The raw material 9 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A1;

[0167] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0168] Comparative Example 4

[0169] The chemical conversion of paraffins is carried out by Figure 1 Process, including:

[0170] (1) The raw material 9 is mixed with hydrogen and sequentially enters the hydroconversion reaction zone; the hydroconversion reaction zone is loaded with the hydroconversion catalyst Cat-A4;

[0171] (2) Step (1) The gas-liquid separation of the reaction effluent from the hydroconversion reaction zone is into hydrogen-rich gas and liquid phase stream, the hydrogen-rich gas is recycled, and the liquid phase stream is directly used as ethylene feedstock. The process conditions and quality improvement results in this example are shown in Table 3.

[0172] Table 3 Quality improvement results

[0173] serial number Example 1 Example 2 Example 3 Hydrogenation conversion raw material Raw material 1 Raw material 1 Raw material 1 catalyst Cat-A1 Cat-A2 Cat-A3 Reaction temperature / ℃ 400 390 405 Reaction pressure / MPa 4 4 4 Hydrogen to oil volume ratio 800 800 600 <![CDATA[Space velocity per hour -1 > 1.2 1 1 Hydrogen consumption, % 0.9 0.77 1.44 <![CDATA[Content of C2-C6 normal paraffins in the product, wt%]]> 47 45 62 Steam cracking to produce ethylene Reaction temperature / ℃ 880 880 880 Reaction pressure / MPa 0.3 0.3 0.3 Water-oil mass ratio 0.4 0.4 0.4 Ethylene yield, wt% 32.7 32.1 36.5 Propylene yield, wt% 15.7 15.6 15.1 Butadiene yield, wt% 3.9 4 3.4 serial number Example 4 Example 5 Example 6 Hydrogenation conversion raw material Raw material 1 Raw material 1 Raw material 1 catalyst Cat-A4 Cat-A5 Cat-A6 Reaction temperature / ℃ 390 400 405 Reaction pressure / MPa 4 4 4 Hydrogen to oil volume ratio 600 600 600 Volume space velocity / h-1 1 0.8 1 Hydrogen consumption, % 1.1 1.31 1.74 Product C2-C6 normal alkane content, wt% 50 53 65 Steam cracking to produce ethylene Reaction temperature / ℃ 880 880 880 Reaction pressure / MPa 0.3 0.3 0.3 Water-oil mass ratio 0.4 0.4 0.4 Ethylene yield, wt% 33.5 34.4 37.3 Propylene yield, wt% 15.5 15.3 14.9 Butadiene yield, wt% 3.8 3.7 3.3

[0174] Table 3 Quality improvement results

[0175] serial number Example 7 Example 8 Example 9 Hydrogenation conversion raw material Raw material 2 Raw material 2 Raw material 2 catalyst Cat-A1 Cat-A2 Cat-A3 Reaction temperature / ℃ 380 390 395 Reaction pressure / MPa 4 4 4 Hydrogen to oil volume ratio 600 600 600 <![CDATA[Space velocity per hour -1 > 1 0.8 1 Hydrogen consumption, % 0.94 1.25 1.54 <![CDATA[Content of C2-C6 normal paraffins in the product, wt%]]> 44 49 61 Steam cracking to produce ethylene Reaction temperature / ℃ 880 880 880 Reaction pressure / MPa 0.3 0.3 0.3 Water-oil mass ratio 0.4 0.4 0.4 Ethylene yield, wt% 31.8 33.4 36.2 Propylene yield, wt% 15.6 15.6 15.1 Butadiene yield, wt% 4 3.8 3.4 serial number Example 10 Embodiment 11 Example 12 Hydrogenation conversion raw material Raw material 2 Raw material 2 Raw material 2 catalyst Cat-A4 Cat-A5 Cat-A6 Reaction temperature / ℃ 390 395 400 Reaction pressure / MPa 4 4 4 Hydrogen to oil volume ratio 600 600 600 Volume space velocity / h-1 1 1 1 Hydrogen consumption, % 1.1 1.51 2 Product C2-C6 normal alkane content, wt% 45 59 66 Steam cracking to produce ethylene Reaction temperature / ℃ 880 880 880 Reaction pressure / MPa 0.3 0.3 0.3 Water-oil mass ratio 0.4 0.4 0.4 Ethylene yield, wt% 32.1 35.6 37.6 Propylene yield, wt% 15.6 15.2 14.9 Butadiene yield, wt% 4 3.4 3.3

[0176] Table 3 Quality improvement results

[0177]

[0178] Table 3 Quality improvement results

[0179]

[0180] By comparison, it can be seen that the method of the present invention can effectively convert low-quality ethylene raw materials into high-quality ethylene raw materials. The chain alkanes after hydrogenation conversion can greatly increase the content of normal hydrocarbons in the hydrogenation products, thereby increasing the ethylene and triene yields of the ethylene device. In addition, the process is simple, the operation difficulty is low, and it has very good economic benefits.

Claims

1. A method for chemically converting paraffins, comprising the following steps: 1) providing a chain alkane represented by the following structural formula (I), （I） In the structural formula (I), R is a C2-C6 straight chain or branched alkyl group (preferably a C2-C4 straight chain or branched alkyl group, more preferably a C2-C3 straight chain alkyl group), 2) The chain alkane is subjected to a conversion reaction in the presence of hydrogen to be converted into C2-C6 normal alkanes to obtain a conversion product.

2. The method of claim 1, wherein the conversion reaction is carried out in the presence of a catalyst, and the catalyst comprises a molecular sieve and an active metal component.

3. The method according to claim 2, wherein the molecular sieve is a molecular sieve having shape-selective catalytic performance, preferably selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve and EU-1 molecular sieve, more preferably selected from one or more of mordenite and ZSM molecular sieve, particularly preferably selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve and ZSM-38 molecular sieve, in particular selected from one or more of mordenite and ZSM-5 molecular sieve.

4. The method according to claim 2, wherein the catalyst further comprises a binder (preferably alumina), and the content of the binder is 5-65wt% (preferably 10-35wt%) based on the weight of the catalyst.

5. The method of claim 2, wherein the active metal component is selected from non-noble metals of Group VI, Group VII, Group VIB or Group VIII, non-noble metal oxides or non-noble metal sulfides with non-noble metals of Group VIB and / or Group VIII as active metal components, more preferably one or more of molybdenum, tungsten, cobalt, nickel, or their sulfides or oxides.

6. The method of claim 5, wherein the content of the Group VIB metal (calculated as oxide) is 5.0-30.0 wt% (preferably 10-20 wt%), and the content of the Group VIII non-noble metal (calculated as oxide) is 0.5-15.0 wt% (preferably 3-10 wt%), based on the weight of the catalyst.

7. The method according to claim 2, wherein the content of the molecular sieve is 30-80wt% (preferably 40-70wt%) based on the weight of the catalyst.

8. The method of claim 1, wherein the reaction conditions of the conversion reaction include: The reaction pressure is 0.5-10.0MPaG (preferably 2.0-8.0MPaG or 2.0-5.0MPaG), the reaction temperature is 250-500℃ (preferably 350-450℃), and the liquid hourly volume space velocity is 0.1-15.0h -1 (Preferably 0.5-5.0h -1 ), the volume ratio of hydrogen to oil is 10:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1).

9. The method of claim 1, further comprising the steps of: Optionally separating the conversion product to obtain a separated stream mainly composed of the C2-C6 normal alkanes (e.g., accounting for more than 80 wt%, more than 90 wt%, or more than 95 wt% of the total amount), or separating the conversion product to obtain a normal stream mainly composed of C4-C6 normal alkanes (e.g., accounting for more than 80 wt%, more than 90 wt%, or more than 95 wt% of the total amount) and / or a low-carbon stream mainly composed of C2-C3 hydrocarbons (e.g., accounting for more than 90 wt% or more than 95 wt% of the total amount), and The conversion product, the separation stream, the normal stream or the low-carbon stream is steam cracked to obtain a cracking product comprising ethylene.

10. The method of claim 9, wherein the operating conditions of the steam cracking include: The reaction temperature is 750-900°C, the reaction pressure is 0.1-0.5MPaG, and the water-oil mass ratio is 0.2-0.

6.

11. A system for chemically converting paraffins, comprising the following units: 1) a chain alkane providing unit, which is configured to provide a chain alkane represented by the following structural formula (I), （I） In the structural formula (I), R is a C2-C6 straight chain or branched alkyl group (preferably a C2-C4 straight chain or branched alkyl group, more preferably a C2-C3 straight chain alkyl group), 2) A paraffin conversion unit, which is configured to convert the paraffin into C2-C6 normal paraffins by a conversion reaction in the presence of hydrogen to obtain a conversion product.

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