A process for producing mixed isomeric alkanes

Abstract

The application discloses a method for producing mixed isomeric alkanes, which is characterized in that a raw material containing isomeric alkenes, synthesis gas and a Fischer-Tropsch synthesis catalyst are contacted under synthesis gas conversion reaction conditions, wherein the catalyst comprises a carrier and at least one of cobalt, iron and ruthenium which are active components in the synthesis gas conversion reaction. The device for the contacting reaction is a fixed bed reactor, a slurry bed reactor, a moving bed reactor or a boiling bed reactor. Compared with the prior art method for producing isomeric alkanes, the method for directly producing mixed isomeric alkanes from synthesis gas conversion is simpler and has higher selectivity of isomeric alkanes.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing mixed isoparaffins. BACKGROUND

[0002] Fischer-Tropsch synthesis is a core process for optimizing the use of non-petroleum carbon resources such as coal, biomass, shale gas, and biomass through syngas conversion in the field of energy chemicals. Hydrocarbons produced based on Fischer-Tropsch synthesis and other technologies have excellent performance and can be directly used or mixed with fuels produced from low-quality crude oil for use, to meet increasingly stringent environmental protection and oil product performance requirements. However, the current oil price is low and there is no warming trend in a short period of time, and the "coal restriction" policy has led to an increase in coal prices; therefore, the profit of the route of coal indirect liquefaction to oil using Fischer-Tropsch synthesis technology is limited, and the technology is highly homogenized. How to turn these severe challenges into opportunities for syngas chemistry, and achieve differentiation, high-endization, and high added value of syngas conversion products, is a problem that the academic and industrial communities are jointly considering at this stage.

[0003] Fischer-Tropsch synthesis products are subjected to hydroisomerization to obtain high-grade lubricating oil base oil or isoparaffin solvent oil, to realize high-value of Fischer-Tropsch products. CN105521818A discloses a hydroisomerization catalyst and a preparation method and application thereof, and when the hydroisomerization catalyst is used as a catalyst for Fischer-Tropsch synthesis wax hydroisomerization reaction, long straight-chain alkanes in the Fischer-Tropsch synthesis wax can be effectively converted into branched isoparaffins, a higher isomerization product yield is obtained, and the obtained isomerization product has a lower pour point and a higher viscosity index, and is suitable for use as lubricating oil base oil. CN101921621A discloses a production method of isoparaffin solvent oil, which is a combination process of hydroprocessing-hydroisomerization-hydrofinishing for producing isoparaffin solvent oil from distillate oil or light deoiled fraction and the like as raw materials.

[0004] In summary, mixed isoparaffins are important base raw materials for lubricating oil base oil and isoparaffin solvent oil, and there is still a need to develop a method for directly producing mixed isoparaffins from syngas. SUMMARY

[0005] The purpose of the present application is to provide a method for directly producing mixed isoparaffins from syngas conversion. Compared with the prior art method for producing isoparaffins, the method of the present application is simpler and has higher isoparaffin selectivity.

[0006] A method for producing mixed isoparaffins, characterized in that a raw material containing isomeric olefins, syngas, and a Fischer-Tropsch synthesis catalyst are contacted under syngas conversion reaction conditions.

[0007] The Fischer-Tropsch synthesis catalyst comprises a carrier and a synthesis gas conversion active component selected from at least one of Group VIII metals.

[0008] The synthesis gas conversion reaction conditions include a temperature of 50-350°C, a pressure of 0.1-15 MPa, and a H2 and CO molar ratio of 0.4-3.

[0009] The active component loading of the catalyst is 5-70% by weight, preferably 8-50% by weight, and further preferably 10-30% by weight, based on the total weight of the catalyst.

[0010] The method of the present application can directly produce mixed isomeric alkanes under Fischer-Tropsch synthesis reaction conditions. The obtained liquid product contains a high content of isomeric alkanes and becomes various high-quality oil products. For example, the product component with a distillation range of <150°C is high-quality naphtha or high-quality solvent oil, the product component with a distillation range of 200-320°C is high-quality diesel oil, and the product component with a distillation range of >320°C is high-quality lubricating oil base stock. In particular, the product component with a distillation range of >320°C contains a high content of isomeric alkanes, which greatly reduces the process severity of subsequent isomerization and pour point depression to produce lubricating oil base stock, and thus becomes a high-quality lubricating oil base stock. Compared with the prior art, the method of the present application is simpler and has higher isomeric alkane selectivity.

[0011] Other features and advantages of the present application will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0012] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0013] The present application provides a method for producing mixed isomeric alkanes, characterized in that a raw material containing isomeric alkenes, synthesis gas and a Fischer-Tropsch synthesis catalyst are contacted under synthesis gas conversion reaction conditions.

[0014] The isomeric alkenes are selected from C4-C 10 The isomeric alkenes are selected from C4-C

[0015] The synthesis gas conversion reaction conditions include a temperature of 50 to 350°C, preferably 100 to 280°C, more preferably 180 to 250°C, a pressure of 0.1 to 15 MPa, preferably 1 to 5 MPa, and a molar ratio of H2 to CO of the synthesis gas of 0.4 to 3, preferably 1 to 2.5.

[0016] The contact reaction device is one of a batch reactor or a continuous reactor. The batch reactor includes a batch autoclave reactor. The continuous reactor includes one of a fixed bed reactor, a slurry bed reactor, a moving bed reactor, or a boiling bed reactor. The continuous reactor is preferred.

[0017] The space-time yield of the synthesis gas used in the continuous reactor is 200 to 20,000 hours -1 , preferably 500 to 12,000 hours -1 , and the reaction time of the batch reactor is 1 to 200 hours, preferably 2 to 50 hours.

[0018] The space-time yield of the isomerized olefin satisfies a molar ratio of CO to the isomerized olefin of 1 to 2,000, preferably 2 to 1,000, more preferably 3 to 300, and particularly preferably 5 to 100.

[0019] The Fischer-Tropsch synthesis catalyst includes a support and a synthesis gas conversion reaction active component, wherein the active component is selected from at least one of Group VIII metals, preferably at least one of cobalt, iron, and ruthenium. The catalyst support can be one or more of various supports capable of being used as a Fischer-Tropsch synthesis catalyst support, such as alumina, silica, titania, magnesia, zirconia, thoria, beryllia, clay, molecular sieve, and activated carbon, preferably one or more of alumina, silica, titania, and activated carbon. The support can also be one or more of the above supports modified with one or more of phosphorus, silicon, fluorine, boron, and carbon. The above modified supports can be commercially available or can be modified using existing methods.

[0020] The active component of the catalyst (in terms of metal elements) is loaded at 5 to 70% by weight, preferably 8 to 50% by weight, and further preferably 10 to 30% by weight, based on the total weight of the catalyst.

[0021] The catalyst further includes a metal promoter selected from at least one of Pt, Pd, Ru, Rh, Ir, La, Zr, Ce, Y, and Cu. The metal promoter is contained in an amount of 10% by weight or less, preferably 0.05 to 6% by weight, in terms of metal elements, based on the total weight of the catalyst.

[0022] The method for preparing the Fischer-Tropsch synthesis catalyst is not particularly limited and can be any of the methods known to those skilled in the art, for example, an active metal component selected from at least one of the Group VIII metals is loaded on the carrier under conditions sufficient to deposit an effective amount of the active metal component on the carrier, specifically, the loading method is not particularly limited. For example, the carrier can be contacted with a solution containing an effective amount of a compound containing the active metal component, such as by impregnation, co-precipitation, vapor-phase chemical deposition, etc., preferably impregnation, followed by drying and calcination.

[0023] Specifically, the conditions for impregnation include a temperature of 10-90°C, preferably 15-40°C, and a time of 1-24 hours, preferably 2-6 hours. The conditions for drying include a temperature of 60-350°C, preferably 100-200°C, and a time of 1-24 hours, preferably 2-6 hours. When the catalyst needs to be calcined, the temperature for calcination is preferably 200-700°C, and the time for calcination is 1-12 hours, further preferably the temperature is 250-500°C, and the time for calcination is 2-6 hours, in order to convert the compound containing the active metal component into its oxide.

[0024] The method for introducing the metal promoter contained in the catalyst can be carried out by one or more of the following methods:

[0025] 1) the carrier is first impregnated with a solution containing the metal promoter, and then impregnated with a solution containing the active metal component;

[0026] 2) the carrier is first impregnated with a solution containing the active metal component, and then impregnated with a solution containing the metal promoter;

[0027] 3) the carrier is simultaneously impregnated with a solution containing the active metal component and a solution containing the metal promoter;

[0028] 4) a solution containing the active metal component and a solution containing the metal promoter are prepared into one impregnation solution, and then the carrier is impregnated with the impregnation solution.

[0029] The catalyst needs to be reduced with a reducing gas such as hydrogen before use.

[0030] The selectivity of isomeric alkanes can be greatly increased from 3.9% to 42.3% while maintaining the similar conversion rate and methane selectivity of conventional Fischer-Tropsch synthesis by using the method of the present application. DETAILED DESCRIPTION

[0032] The following examples facilitate a better understanding of the present application, but do not limit the present application. In the following examples, the percentage content, unless otherwise specified, is mass percentage. The ratio of converted CO to the CO in the feed gas is defined as CO conversion X CO , the mole percentage of CO converted into methane to the converted CO is defined as methane selectivity S CH4 , the mole percentage of CO converted into isomeric alkanes to the converted CO is defined as isomeric alkane selectivity S iso .

[0033] In order to directly compare the different fraction contents and characteristics of the products, the fraction weight content and isomeric alkane selectivity S iso of the 200-320℃ high-quality diesel distillation range component and the >320℃ high-quality lubricating oil base oil feedstock distillation range component were determined by the petroleum fraction distillation range distribution method (ASTM D6352-12) and GC / MS structure analysis method iso , where S iso is defined as the weight percentage of isomeric alkanes in the fraction to the overall weight of the fraction.

[0034] Example 1

[0035] This example is used to illustrate the method provided by the present application.

[0036] The cobalt-based catalyst used in this example was prepared by the equal volume impregnation method. According to the metal salt content required by the equal volume impregnation method, an impregnation solution containing 36.1 milliliters of cobalt nitrate, dichlorotetraamine platinum with a cobalt content of 208 grams / liter and a platinum content of 1.38 grams / liter was prepared. The impregnation solution was poured into 42.5 grams of γ-Al2O3 carrier (Sasol alumina, average particle size 40-80 microns, the same below), stirred at 20°C for 4 hours, then dried at 120°C, calcined at 400°C for 4 hours, and then reduced to room temperature and stored in a desiccator. The obtained catalyst is denoted as R-Co.

[0037] The R-Co catalyst was diluted with quartz sand of the same particle size and loaded into a fixed bed reactor. First, 160 milliliters / minute of hydrogen was used to reduce the catalyst at 400°C for 4 hours. After reduction, 80 milliliters / minute of feed gas with a composition of H2 / CO / N2=56% / 28% / 16% (volume percentage) was introduced into the reactor at 210°C (the space time velocity of the synthesis gas was 10000 hours -1 ), and at the same time, 4-methyl-1-pentene liquid was mixed with the gas at a liquid feed rate of 0.2 milliliters / hour and introduced into the reactor, and the pressure was controlled at 2.5 MPa. The reaction was started, and after 48 hours of reaction, the gas and liquid samples were analyzed. The reaction results are shown in Table 1.

[0038] Comparative Example 1

[0039] This comparative example is used to illustrate the comparative method.

[0040] The procedure of Example 1 was followed except that no liquid was passed. That is, after reduction, the reaction was started by passing the feed gas into the reactor at 210°C but no 4-methyl-l-pentene liquid was passed. The results of the reaction are shown in Table 1.

[0041] Comparative Example 2

[0042] This comparative example is provided to illustrate a comparative process.

[0043] The procedure of Example 1 was followed except that 1-hexene liquid was passed. That is, after reduction, the reaction was started by passing the feed gas into the reactor at 210°C and simultaneously passing 1-hexene liquid into the reactor mixed with the gas at a liquid feed rate of 0.2 ml / hour. The gas and liquid samples were analyzed after 48 hours of reaction. The results of the reaction are shown in Table 1.

[0044] Example 2

[0045] This example is provided to illustrate the process provided by the present invention.

[0046] The R-Co catalyst was charged into a fixed bed reactor and reduced with 160 ml / min of hydrogen at 400°C for 4 hours. After reduction, the feed gas consisting of H2 / CO / N2= 56% / 28% / 16% (volume percent) was passed into the reactor at 210°C at a rate of 80 ml / min (space velocity of 10000 h"1of syngas) and simultaneously 2-methyl-l-pentene liquid was passed into the reactor mixed with the gas at a liquid feed rate of 0.2 ml / hour. The pressure was controlled at 2.5 MPa and the reaction was started. The gas and liquid samples were analyzed after 48 hours of reaction. The results of the reaction are shown in Table 1. -1

[0047] Example 3

[0048] This example is provided to illustrate the process provided by the present invention.

[0049] The R-Co catalyst was charged into a fixed bed reactor and reduced with 160 ml / min of hydrogen at 400°C for 4 hours. After reduction, the feed gas consisting of H2 / CO / N2 / iso-butene = 55% / 27.5% / 15.7% / 1.8% (volume percent) was passed into the reactor at 210°C at a rate of 90 ml / min (space velocity of 10000 h"1of syngas) and the pressure was controlled at 2.5 MPa and the reaction was started. The gas and liquid samples were analyzed after 48 hours of reaction. The results of the reaction are shown in Table 1. -1

[0050] Example 4

[0051] This example is provided to illustrate the process provided by the present invention.​​

[0052] The R-Co catalyst was ground to 100-200 mesh and reduced with 320 ml / min of hydrogen at 400°C for 4 hours. After reduction, the catalyst was transferred by a glove box into an autoclave (slurry bed reactor) containing 40 g of medium wax and 10 g of 4-methylpentene, checked for air tightness, heated to 210°C, and a feed gas consisting of H2 / CO / N2= 56% / 28% / 16% (volume percent) at 160 ml / min was introduced into the reactor (space velocity of the synthesis gas was 15000 h"1) at a pressure of 2.5 MPa. The reaction was started by introducing the 4-methyl-1-pentene liquid at a liquid feed rate of 0.4 ml / h mixed with the gas and was analyzed after 120 hours. The results are shown in Table 1. -1

[0053] Example 5

[0054] This example is intended to illustrate the process provided by the present invention.

[0055] The R-Co catalyst was ground to 100-200 mesh and reduced with 320 ml / min of hydrogen at 400°C for 4 hours. After reduction, the catalyst was transferred by a glove box into an autoclave (slurry bed reactor) containing 40 g of medium wax and 10 g of 4-methylpentene, checked for air tightness, heated to 210°C, and a feed gas consisting of H2 / CO / N2= 56% / 28% / 16% (volume percent) at 160 ml / min was introduced into the reactor (space velocity of the synthesis gas was 15000 h"1) at a pressure of 2.5 MPa. The reaction was started by introducing the 4-methyl-1-pentene liquid at a liquid feed rate of 0.4 ml / h mixed with the gas and was analyzed after 120 hours. The results are shown in Table 1. -1

[0056] Example 6

[0057] This example is intended to illustrate the process provided by the present invention.

[0058] The ruthenium-based catalyst used in this example was prepared by incipient wetness impregnation. Specifically, an impregnation solution containing 54 g / L of ruthenium and 5.22 g / L of zirconium was prepared by incipient wetness impregnation. The impregnation solution was decanted onto 40 g of γ-Al2O3(Sasol alumina, average particle size 40-80 microns), stirred at 25°C for 4 hours, dried at 120°C, calcined at 350°C for 4 hours, and allowed to cool to room temperature in a desiccator. The resulting catalyst was labeled R-Ru.

[0059] ​​The obtained R-Ru catalyst was diluted with quartz sand of the same particle size and charged into a fixed bed reactor. The reactor was first reduced with 160 ml / min of hydrogen at 350°C for 4 hours. After the reduction was completed, a feed gas having a composition of H2 / CO / N2=56% / 28% / 16% (volume percent) at 80 ml / min was passed into the reactor at 195°C (space velocity of the synthesis gas was 10000 hours -1 ), and at the same time, 4-methyl-1-pentene liquid was passed into the reactor by mixing with the gas at a liquid feed rate of 0.2 ml / hour. The pressure was controlled at 2.5 MPa, and the reaction was started. After 48 hours of the reaction, the gas and liquid samples were analyzed. The results of the reaction are shown in Table 1.

[0060] Example 7

[0061] This example is provided to illustrate the method according to the present application.

[0062] The method according to Example 1 was followed, except that the liquid feed rate of 4-methyl-1-pentene was changed to 0.067 ml / hour. The results of the reaction are shown in Table 1.

[0063] Example 8

[0064] This example is provided to illustrate the method according to the present application.

[0065] The method according to Example 1 was followed, except that the liquid feed rate of 4-methyl-1-pentene was changed to 2 ml / hour. The results of the reaction are shown in Table 1.

[0066] Table 1

[0067]

[0068] As can be seen from the results of Example 1 and Comparative Example 1, the selectivity of isomeric alkanes is greatly increased from 3.9% to 42.3% while maintaining the conversion rate and the selectivity of methane similar to those of the conventional Fischer-Tropsch synthesis. As can be seen from the results of Example 1 and Comparative Example 2, the use of n-olefins such as 1-hexene results in little isomeric alkanes. As can be seen from the results of Example 1, Example 7 and Example 8, the selectivity of isomeric alkanes is higher when the molar ratio of CO / isomeric olefin is within the preferred range.

[0069] These examples show that the method according to the present application can directly convert synthesis gas to isomeric alkanes.

[0070] The above detailed the preferred embodiments of the present application, but the present application is not limited to the specific details of the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0071] It should also be noted that various specific technical features described in the above detailed description can be combined in any suitable manner without necessarily being mutually exclusive. To avoid unnecessary repetition, various possible combinations of features are not described again separately by the present application.

Claims

1. A method for producing mixed isoalkanes, comprising: Under syngas reforming conditions, a feedstock containing C4-C10 isoolefins, syngas, and a Fischer-Tropsch synthesis catalyst are contacted to obtain mixed isoalkanes. The space-time velocities of the isoolefins satisfy a CO to isoolefin molar ratio of 5-113. The syngas reforming conditions include a temperature of 100-280°C, a pressure of 1-5 MPa, and a H2 to CO molar ratio of 1-2.

5. The Fischer-Tropsch synthesis catalyst comprises a support and an active component, wherein the active component is selected from at least one Group VIII metal, and the support is selected from one or more of alumina, silicon dioxide, titanium dioxide, magnesium oxide, zirconium oxide, thorium oxide, beryllium oxide, clay, and activated carbon.

2. The method according to claim 1, wherein, The isomeric olefin is selected from at least one of isobutene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-2-pentene, and 4-methyl-2-pentene.

3. The method according to claim 1, wherein, The contact reaction apparatus is either a batch reactor or a continuous reactor.

4. The method according to claim 3, wherein, The space-time velocity of the syngas used in the continuous reactor is 200-20000 h⁻¹. -1 The reaction time of the batch reactor is 1-200 hours.

5. The method according to claim 3, wherein, The space-time velocity of the syngas used in the continuous reactor is 500-12000 h⁻¹. -1 The reaction time of the batch reactor is 2-50 hours.

6. The method according to claim 1, wherein, The space-time velocity of the isoolefin satisfies a molar ratio of CO to isoolefin of 5-100.

7. The method according to claim 1, wherein, The active component is selected from at least one of cobalt, iron, and ruthenium.

8. The method according to claim 1, wherein, The catalyst support is selected from one or more of the supports modified with one or more of phosphorus, silicon, fluorine, boron, and carbon.

9. The method according to claim 1, wherein, Based on the total weight of the catalyst, the loading of the active component of the catalyst is 5-70% by weight.

10. The method according to claim 1, wherein, Based on the total weight of the catalyst, the loading of the active component of the catalyst is 8-50% by weight.

11. The method according to claim 1, wherein, Based on the total weight of the catalyst, the loading of the active component of the catalyst is 10-30% by weight.

12. The method according to claim 1, wherein, The catalyst further comprises a metal promoter selected from at least one of Pt, Pd, Ru, Rh, Ir, La, Zr, Ce, Y, and Cu.

13. The method according to claim 12, wherein, Based on the total weight of the catalyst, the content of the metal additive, calculated as metal element, is 0.05-6% by weight.

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