Catalyst for dehydration of 2-alcohol, preparation method thereof, and method for preparing alpha-olefins by dehydration of 2-alcohol

Abstract

The present invention relates to the technical field of 2-alcohol dehydration to generate alpha-olefins, and in particular to a catalyst for 2-alcohol dehydration and its preparation method and application, as well as a method for 2-alcohol dehydration to prepare alpha-olefins, the catalyst comprising: a main component, an alkaline earth metal oxide and a rare earth metal oxide, wherein the main component is selected from at least one of zirconium oxide, silicon oxide, titanium oxide and aluminum oxide; relative to 100 parts by weight of the main component, the content of the alkaline earth metal oxide is 0.05-10 parts by weight; the content of the rare earth metal oxide is 0.01-12 parts by weight. Acid and base groups are simultaneously present on the catalyst surface of the present invention, which can play a synergistic catalytic role in the catalytic process for alcohol dehydration, with better activity, selectivity and longer service life relative to a single acid site or base site.

Description

Technical Field

[0001] The present invention relates to the technical field of 2-alcohol dehydration to generate alpha-olefins, and in particular to a catalyst for 2-alcohol dehydration and a preparation method thereof, as well as a method for preparing alpha-olefins by dehydrating 2-alcohols. Background Art

[0002] Alpha-olefins are olefins with terminal carbon-carbon double bonds, with the general molecular formula CH2=CH-R (R is an alkyl group). They are very important petrochemical raw materials and are widely used in various fields, such as comonomers, intermediates, plasticizers, biocides, emulsifiers, oil additives, and in the production of surfactants, plastics, and various fine organic chemicals. The main methods for producing alpha-olefins are paraffin cracking, solvent extraction, ethylene oligomerization, Fischer-Tropsch synthesis, and alcohol dehydration. Paraffin cracking and solvent extraction are gradually being phased out due to their stringent operating conditions, complex reaction processes, low product purity, and numerous byproducts. Ethylene oligomerization offers a simple and mature process, producing high-purity, high-quality products with minimal waste, and is a monopoly of global oil majors. Fischer-Tropsch synthesis uses coal as a raw material, offering low industrial costs, but high product separation costs and challenges. Alcohol dehydration offers a simple process, high product purity, and centralized distribution, resulting in a relatively clean production process and low energy consumption during distillation.

[0003] US20180009725A1 discloses a method for producing ethylene by vapor-phase dehydration of ethanol using a heteropolyacid catalyst supported on a composite oxide. The support is composed of zirconium oxide and various transition metal oxides, with zirconium oxide comprising at least 50 wt% of the total weight of the support. The transition metal oxide is selected from oxides of Groups IIIB-VIB metals, including oxides of Sc, Y, La, Ti, Zr, Hf, Nb, Ta, or W, preferably TiO2, ZrO2, Nb2O5, Y2O3, La2O3, and WO3. The heteropolyacid is phosphotungstic acid or silicotungstic acid, preferably silicotungstic acid. Compared to conventional supported heteropolyacid catalysts, the supported catalyst of the present invention exhibits a longer service life in alcohol dehydration reactions, with the supported catalyst retaining 25% of its maximum activity after 200 hours. However, heteropolyacid catalysts primarily catalyze organic reactions in a homogeneous manner, making separation of the catalyst and product difficult, making catalyst recovery difficult. Furthermore, the low specific surface area of these catalysts limits their catalytic activity.

[0004] "Dehydration crystal of 2-octanol over zirconia catalysts: Influence of structure, sulfate addition and pretreatment" (Journal of Molecular Catalysis A: Chemical 118 (1997) 89-99) discloses that zirconia catalysts pretreated with sulfate or oxygen exhibit high activity for alcohol dehydration reactions. However, in actual applications, it was found that they had poor thermal stability, short service life, and were easily deactivated by carbon deposition. In addition, SO4, the main source of acid centers in the catalyst, 2- It is easy to be lost in liquid phase reactions, resulting in a decrease in catalytic activity, which limits its application in industrial production.

[0005] In summary, the existing catalysts for catalytic dehydration of 2-alcohols to produce α-olefins have many disadvantages in industrial application, such as easy corrosion, environmental pollution, difficult separation, many side reactions, low product selectivity, low catalytic activity, and severe carbonization. Summary of the Invention

[0006] The present invention aims to overcome the numerous drawbacks of existing catalysts for the dehydration of 2-alcohols to produce α-olefins, such as numerous side reactions, low product selectivity, low catalytic activity, and severe carbonization, in industrial applications, and to provide a catalyst for the dehydration of 2-alcohols, a method for preparing the catalyst, and a method for producing α-olefins by dehydrating 2-alcohols.

[0007] The inventors of the present invention have found that by using a catalyst with a specific composition and having suitable acid-base properties, the catalyst can not only exhibit good catalytic activity in the 2-alcohol dehydration reaction, but also be less likely to coke and deactivate, which is beneficial to extending the service life of the catalyst.

[0008] To achieve the above objectives, the present invention provides, in a first aspect, a catalyst for dehydration of 2-alcohols, wherein the catalyst comprises: a main component, an alkaline earth metal oxide, and a rare earth metal oxide, wherein the main component is selected from at least one of zirconium oxide, silicon oxide, titanium oxide, and aluminum oxide;

[0009] Relative to 100 parts by weight of the main component, the alkaline earth metal oxide is 0.05-10 parts by weight; and the rare earth metal oxide is 0.01-12 parts by weight.

[0010] A second aspect of the present invention provides a method for preparing a catalyst for the dehydration of 2-alcohols, wherein the method comprises: mixing a main component source, an alkaline earth metal source, and a rare earth metal source in a solvent in a weight ratio of 100:0.04-15:0.01-20 to obtain a mixed solution; then adding a precipitant to the mixed solution, and then aging the solution; and then calcining the product obtained by aging; wherein the main component source is selected from at least one of a zirconium source, a silicon source, a titanium source, and an aluminum source.

[0011] The third aspect of the present invention provides a catalyst prepared according to the method described in the second aspect.

[0012] A fourth aspect of the present invention provides a method for preparing α-olefins by dehydrating 2-alcohols, comprising: contacting 2-alcohol with the catalyst of the first or third aspect in the presence or absence of a carrier gas to carry out a dehydration reaction.

[0013] Through the above technical solution, the catalyst of the specific composition used in the present invention has acid and base groups on its surface. On the one hand, it can play a synergistic catalytic role in the catalytic process of alcohol dehydration, and has better activity and selectivity than a single acid site or a single base site. On the other hand, it can promote the diffusion of the reaction system, accelerate the reaction rate, reduce carbon deposition, slow down pore blockage, and extend the service life of the catalyst. DETAILED DESCRIPTION

[0014] The endpoints of the ranges and any values disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0015] As mentioned above, the first aspect of the present invention provides a catalyst for dehydration of 2-alcohols, wherein the catalyst comprises: a main component, an alkaline earth metal oxide, and a rare earth metal oxide, wherein the main component is selected from at least one of zirconium oxide, silicon oxide, titanium oxide, and aluminum oxide;

[0016] Relative to 100 parts by weight of the main component, the alkaline earth metal oxide is 0.05-10 parts by weight; and the rare earth metal oxide is 0.01-12 parts by weight.

[0017] The present invention uses a catalyst with specific components, so that acidic sites and basic sites are simultaneously present on the catalyst surface. In the catalytic alcohol dehydration reaction, the acidic sites and basic sites can play a synergistic role. On the one hand, the simultaneous introduction of alkaline earth metal oxides and rare earth metal oxides can improve the basicity of the catalyst while better maintaining the number of acidic sites on the surface of the main component, so that more acid-base synergistic active centers are generated on the catalyst surface, which is conducive to the formation of α-olefins and inhibits the formation of β-olefins, thereby improving the selectivity of α-olefins. On the other hand, the acidic groups and basic groups on the catalyst surface are controlled within a certain range, which can improve the adsorption-desorption performance of the catalyst, thereby promoting the diffusion of the reaction system, accelerating the reaction rate, reducing carbon deposition, and alleviating pore blockage.

[0018] In some preferred embodiments of the present invention, in order to further optimize the selectivity and service life of the catalyst for α-olefins, under preferred conditions, the ammonia adsorption capacity of the catalyst is 0.15-0.44 mmol g -1 The carbon dioxide adsorption capacity of the catalyst is 0.18-0.4 mmol g -1 Preferably, the ammonia adsorption capacity of the catalyst is 0.15-0.25mmolg -1 The carbon dioxide adsorption capacity of the catalyst is 0.32-0.4 mmol g -1 .

[0019] According to the present invention, under preferred conditions, the specific surface area of the catalyst is 40-150m 2 g -1 ; Under the above preferred conditions, the catalytic performance of the catalyst can be further improved.

[0020] According to the present invention, under preferred conditions, the pore volume of the catalyst is 0.05-0.2 mL g -1 ; Under the above preferred conditions, the catalytic performance of the catalyst can be further improved.

[0021] The present invention does not particularly limit the method for combining the main component and the alkaline earth metal oxide and rare earth metal oxide. The alkaline earth metal oxide and rare earth metal oxide may be supported on the main component or dispersed within the main component. In the present invention, dispersion within the main component is preferred; that is, the catalyst is a composite metal oxide catalyst. In the present invention, the dispersion or support of the alkaline earth metal oxide and rare earth metal oxide has little effect on the microstructure of the catalyst. Therefore, the resulting catalyst has a pore structure similar to that of the main component.

[0022] According to the present invention, in order to further optimize the catalytic performance of the catalyst and control the number of acidic sites and basic sites on the catalyst surface, under preferred conditions, relative to 100 parts by weight of the main component, the alkaline earth metal oxide is 0.1-6 parts by weight, more preferably 0.6-1.5 parts by weight, for example, it can be 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, or any value in the range consisting of any two of the above values.

[0023] According to the present invention, under preferred conditions, the rare earth metal oxide is 0.02-4 parts by weight relative to 100 parts by weight of the main component, more preferably 0.3-1.2 parts by weight, for example, it can be 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, or any value in the range formed by any two of the above values.

[0024] Further preferably, the weight ratio of the alkaline earth metal oxide to the rare earth metal oxide is 0.1-55:1, preferably 0.5-18:1.

[0025] According to the present invention, under preferred conditions, the alkaline earth metal oxide is selected from at least one of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide and barium oxide; more preferably, magnesium oxide and / or calcium oxide.

[0026] According to the present invention, under preferred conditions, the rare earth metal oxide is selected from at least one of lanthanide metal oxides; preferably at least one of lanthanum oxide, cerium oxide, ytterbium oxide, neodymium oxide and praseodymium oxide; more preferably at least one of lanthanum oxide, cerium oxide and ytterbium oxide.

[0027] In the present invention, the catalyst can be prepared by an existing method capable of obtaining ammonia adsorption and carbon dioxide adsorption amounts that meet the above ranges, and obtaining a catalyst having ammonia adsorption and carbon dioxide adsorption amounts that meet the above ranges is practicable for those skilled in the art.

[0028] The second aspect of the present invention provides a method for preparing the catalyst, comprising: mixing a main component source, an alkaline earth metal source and a rare earth metal source in a solvent in a weight ratio of 100:0.04-15:0.01-20 to obtain a mixed solution; then adding a precipitant to the mixed solution, and then aging it; and then calcining the product obtained by aging; wherein the main component source is selected from at least one of a zirconium source, a silicon source, a titanium source and an aluminum source.

[0029] In the above catalyst preparation method, those skilled in the art will understand that: if the raw material providing the main component source already contains the required amount of alkaline earth metal elements and rare earth metal elements, then only such raw material needs to be used for molding; if the raw material providing the main component source does not contain alkaline earth metal elements and rare earth metal elements or the content of the elements is low (insufficient), then additional alkaline earth metal elements and rare earth metal elements can be introduced.

[0030] According to the present invention, under preferred conditions, the zirconium source is selected from at least one of zirconium oxychloride, zirconium nitrate, zirconyl nitrate and zirconyl sulfate.

[0031] According to the present invention, under preferred conditions, the silicon source is selected from tetraethyl orthosilicate and / or silica sol.

[0032] According to the present invention, under preferred conditions, the titanium source is selected from titanium oxide.

[0033] According to the present invention, under preferred conditions, the aluminum source is selected from aluminum hydroxide and / or pseudo-boehmite.

[0034] Further preferably, the alkaline earth metal source is present in the form of a solution of an alkaline earth metal salt (referred to as solution A), and the alkaline earth metal salt is selected from at least one of alkaline earth metal nitrates, alkaline earth metal formates, alkaline earth metal oxalates and alkaline earth metal lactates; preferably alkaline earth metal nitrates; further preferably, the alkaline earth metal nitrate is selected from at least one of magnesium nitrate, calcium nitrate, strontium nitrate and barium nitrate, preferably magnesium nitrate and / or calcium nitrate; the solvent in the solution is selected from water and / or ethanol, preferably water.

[0035] According to the present invention, under preferred conditions, the rare earth metal source exists in the form of a solution of a rare earth metal salt (referred to as solution B), and the rare earth metal salt is selected from at least one of rare earth metal nitrates, rare earth metal formates, rare earth metal oxalates and rare earth metal lactates; preferably rare earth metal nitrates; further preferably, the rare earth metal nitrate is selected from at least one of lanthanum nitrate, cerium nitrate, ytterbium nitrate, neodymium nitrate and praseodymium nitrate, preferably at least one of lanthanum nitrate, cerium nitrate and ytterbium nitrate; the solvent in the solution is selected from water and / or ethanol, preferably water.

[0036] According to the present invention, under preferred conditions, the precipitant is selected from at least one of ammonia water, urea, sodium carbonate and sodium hydroxide.

[0037] The present invention has no particular limitation on the order of adding the solution A and the solution B. The solution A and the solution B can be mixed and then added to the system containing the main component source, or they can be added separately to the system containing the main component source.

[0038] The present invention can provide an embodiment in which the aging operation can be to keep the product of the coprecipitation reaction at a constant temperature. Under preferred conditions, the aging temperature is 50-100°C, preferably 60-100°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any value in the range of any two of the above values; more preferably, the aging time is 0.5-10h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, or any value in the range of any two of the above values.

[0039] According to the present invention, under preferred conditions, the method further comprises: centrifuging, washing and drying the product obtained by aging; wherein the drying time can be reasonably selected according to the drying temperature, the amount of material and the type of drying equipment. Under preferred conditions, the drying temperature is 70-150°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or any value in the range of any two of the above values, preferably 80-120°C; the drying time is 6-20h; for example, it can be 6h, 6.5, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 16h, 16.5h, 17h, 14.5h, 18h, 18.5h, 19h, 19.5h, 20h, or any value in the range of any two of the above values.

[0040] According to the present invention, roasting can remove the crystal water in the salt and decompose the salt to generate oxides. Under preferred conditions, the roasting conditions include: 1-5 ° C min -1The temperature is raised to 400-900°C at a heating rate of 100-200°C, and calcined at 400-900°C for 1-20h; for example, the calcination temperature can be 400°C, 450°C, 500°C, 525°C, 550°C, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 800°C, 825°C, 850°C, 900°C or any value in the range of any two of the above values, preferably 500-600°C; the calcination time can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 16h, 16.5h, 17h, 17.5h, 18h, 18.5h, 19h, 19.5h, 20h or any value in the range consisting of any two of the above values, preferably 1-6h.

[0041] The preparation method of the catalyst provided by the invention is simple, and the obtained catalyst has high catalytic activity.

[0042] The third aspect of the present invention provides a catalyst prepared according to the method described in the second aspect above; the catalyst comprises: a main component, an alkaline earth metal oxide and a rare earth metal oxide, wherein the main component is selected from at least one of zirconium oxide, silicon oxide, titanium oxide and aluminum oxide; relative to 100 parts by weight of the main component, the content of the alkaline earth metal oxide is 0.05-10 parts by weight; the content of the rare earth metal oxide is 0.01-12 parts by weight.

[0043] Preferably, the ammonia adsorption capacity of the catalyst is 0.15-0.44 mmol g -1 , preferably 0.15-0.25 mmol g -1 The carbon dioxide adsorption capacity of the catalyst is 0.18-0.4mmol g -1 , preferably 0.32-0.4 mmol g -1 The specific surface area of the catalyst is 40-150m 2 g -1 The pore volume of the catalyst is 0.05-0.2mL g -1 .

[0044] A fifth aspect of the present invention provides a method for preparing α-olefins by dehydrating 2-alcohols, comprising: contacting 2-alcohol with the catalyst of the first or third aspect in the presence or absence of a carrier gas to carry out a dehydration reaction.

[0045] The method of the present invention may further comprise the step of preparing the catalyst, that is, preparing a catalyst having components meeting the aforementioned requirements for use in the dehydration reaction.

[0046] According to the present invention, under preferred conditions, the dehydration reaction conditions include: temperature of 220-360°C, preferably 250-330°C; pressure of 0.08-0.3 MPa; liquid phase volume space velocity of 0.05-0.9h -1 , preferably 0.1-0.6h -1 Preferably, when the carrier gas is present, the flow rate of the carrier gas is 10-50mL min -1 , preferably 15-45 mL min -1 .

[0047] In the present invention, the type of the carrier gas may be known to those skilled in the art, for example, it may be nitrogen.

[0048] In the present invention, the 2-alcohol (i.e., the hydroxyl group is connected to the β carbon atom) is selected from C2-C 18 Preferably, the 2-alcohol is C2-C8; further preferably, the 2-alcohol is selected from at least one of 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol and 2-octanol.

[0049] In the present invention, "C2-C 18 The term "alcohol" refers to alcohols having 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms, respectively.

[0050] In the present invention, room temperature refers to a temperature of 25±5°C.

[0051] The present invention will be described in detail below through examples.

[0052] In the following examples, the specific surface area and pore volume of the catalyst were measured by the nitrogen adsorption-desorption method (BET). The test conditions were: experimental gas: N2 (purity 99.999%); degassing conditions: 10°C min -1 The temperature was raised to 350° C. and vacuumed for 4 h. Instrument name: Automatic Micropore & Chemisorption Analyzer; Instrument model: ASAP2420, MICROMERITICS (USA);

[0053] The acidic site (ammonia adsorption capacity) of the catalyst was obtained by NH3-TPD test. The test method is as follows: Accurately weigh about 0.1g of sample into a sample tube and stir at 10℃min under He gas purge. -1 Raise to 600℃, stay for 1h, then reduce to 120℃, change the gas to 10% NH3-He mixed gas, adsorb for 60min, then change to He gas purge for 1h, start counting after the baseline is stable, and use 10℃ min -1 The temperature was raised to 600°C and maintained for 30 minutes. The recording was stopped to complete the experiment. The peak area was integrated to calculate the NH3 desorption amount (acidic sites of the catalyst). The testing instrument was an Automated Catalyst Characterization System (Autochem 2920, manufactured by MICROMERITICS, USA).

[0054] The basicity of the catalyst (CO2 adsorption capacity) was tested by CO2-TPD. The test conditions were as follows: accurately weigh about 0.1g of sample into a sample tube, and then measure the sample at 10℃min under He gas purge. -1 Raise to 600℃, stay for 1h, then reduce to 120℃, change the gas to 10% CO2-He mixture, adsorb for 60min, then change to He gas purge for 1h, start counting after the baseline is stable, and use 10℃ min -1 The temperature was raised to 600°C and maintained for 30 minutes. The recording was stopped, and the experiment was complete. The peak area was integrated to calculate the CO2 desorption amount (catalyst basicity). The instrument used was an Automated Catalyst Characterization System (Autochem 2920, manufactured by MICROMERITICS, USA).

[0055] The elemental compositions of the main components and catalysts were analyzed by plasma emission spectrometry.

[0056] The carbon deposits on the catalyst were measured using O2-TPO. The test conditions were as follows: 0.2g of sample was accurately weighed, and argon was used as the carrier gas at a flow rate of 40mL / min. The sample was pretreated at 150°C for 60 minutes, then cooled to 100°C. A mixture of oxygen and argon (20% oxygen by volume) was used as the analytical gas at a flow rate of 40mL / min. The sample was subjected to a temperature-programmed oxidation process at a rate of 10°C / min to 900°C. The CO2 and CO gas signals were detected during the temperature-programmed oxidation process. The testing instrument was a fully automatic temperature-programmed chemical adsorption instrument (AutoChem II 2920, manufactured by Micromeritics, USA).

[0057] Comparative Example 1

[0058] Weigh 370.3 g of zirconium oxynitrate and dissolve it in 3 L of deionized water to prepare a zirconium concentration of 0.53 mol L -1 Then, in an 80°C water bath with vigorous stirring, an aqueous ammonia solution (25 wt%) was added dropwise to the solution to adjust the pH of the solution to 10 to obtain a mixed system, and then the mixed system was allowed to stand in a beaker for 2.5 hours; then, the mixture was centrifuged and the obtained precipitate was washed with deionized water to a pH of 6.5, and then dried at 80°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The desired sample was obtained by heating at a rate of 25°C to 550°C and calcining at this temperature for 2 hours, which was recorded as catalyst B-1. The test results are shown in Table 1.

[0059] Comparative Example 2

[0060] Weigh 368g of zirconium oxynitrate and 9.5g of calcium nitrate tetrahydrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.53mol L -1 , Ca 2+ The concentration is 0.013 mol L -1 a mixed solution; in a 70°C water bath with vigorous stirring, an aqueous ammonia solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 9.8 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.6 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 70°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The desired sample was obtained by heating the catalyst at a rate of 25°C to 540°C and calcining the catalyst at this temperature for 2 h. The catalyst was designated as catalyst B-2. The test results are shown in Table 1.

[0061] Example 1

[0062] Weigh 375g zirconium oxynitrate, 9.5g calcium nitrate tetrahydrate, and 1.7g lanthanum nitrate and dissolve them in 3L deionized water to prepare a zirconium concentration of 0.54mol L -1 , Ca 2+ The concentration is 0.013 mol L -1 、La 3+ The concentration is 0.0013 mol L -1a mixed solution; in a 70°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 10.2 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.6 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 85°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was precipitated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 hours to obtain catalyst A-1. The test results are shown in Table 1.

[0063] Example 2

[0064] Weigh 370g zirconium oxynitrate, 10.9g calcium nitrate tetrahydrate, and 2.54g cerium nitrate and dissolve them in 3L deionized water to prepare a zirconium concentration of 0.53mol L -1 , Ca 2+ The concentration is 0.015 mol L -1 、Ce 3+ The concentration is 0.003 mol L -1 a mixed solution; in a 75°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 9.9 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.4 h; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 75°C for 2 h and then at 120°C for 2 h; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 545°C and calcined at this temperature for 2 hours to obtain catalyst A-2. The test results are shown in Table 1.

[0065] Example 3

[0066] Weigh 372g of zirconium oxynitrate, 12.5g of calcium nitrate tetrahydrate, and 1.34g of ytterbium nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54mol L -1 , Ca 2+ The concentration is 0.018 mol L -1 、Yb 3+ The concentration is 0.001 mol L -1a mixed solution; in a 78°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 9.9 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.7 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 70°C for 2 hours and then at 125°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 hours to obtain catalyst A-3. The test results are shown in Table 1.

[0067] Example 4

[0068] Weigh 375g zirconium oxynitrate, 50.5g calcium nitrate tetrahydrate, and 0.08g neodymium nitrate and dissolve them in 3L deionized water to prepare a zirconium concentration of 0.54mol L -1 , Ca 2+ The concentration is 0.071 mol L -1 、Nd 3+ The concentration is 0.00008 mol L -1 a mixed solution; in an 80°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 10.0 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.4 h; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 70°C for 2 h and then at 130°C for 2 h; finally, the dried product was precipitated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 hours to obtain catalyst A-4. The test results are shown in Table 1.

[0069] Example 5

[0070] Weigh 372g of zirconium oxynitrate, 0.83g of calcium nitrate tetrahydrate, and 15.72g of praseodymium nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54mol L -1 , Ca 2+ The concentration is 0.001 mol L -1 、 Pr 3+ The concentration is 0.016 mol L -1a mixed solution; in a 77°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 9.9 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.7 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 85°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 hours to obtain catalyst A-5. The test results are shown in Table 1.

[0071] Example 6

[0072] Weigh 372g of zirconium oxynitrate, 7.57g of magnesium nitrate hexahydrate, and 6.32g of lanthanum nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54 mol L -1 Mg 2+ The concentration is 0.01 mol L -1 、La 3+ The concentration is 0.005 mol L -1 a mixed solution; in an 80°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 10 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.5 h; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 75°C for 2 h and then at 125°C for 2 h; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 h to obtain catalyst A-6. The test results are shown in Table 1.

[0073] Example 7

[0074] Weigh 372g of zirconium oxynitrate, 0.17g of barium nitrate, and 63.2g of lanthanum nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54mol L -1 、Ba 2+ The concentration is 0.0002 mol L -1 、La 3+ The concentration is 0.049 mol L -1a mixed solution; in an 82°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 9.9 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.6 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 85°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 h to obtain catalyst A-7. The test results are shown in Table 1.

[0075] Example 8

[0076] Weigh 372g of zirconium oxynitrate, 40.5g of strontium nitrate, and 0.05g of lanthanum nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54mol L -1 、Sr 2+ The concentration is 0.064 mol L -1 、La 3+ The concentration is 0.00004 mol L -1 a mixed solution; in a water bath at 82°C with vigorous stirring, an aqueous ammonia solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 10.1 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.4 h; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 65°C for 2 h and then at 124°C for 2 h; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1 The temperature was raised from 25°C to 550°C and calcined at this temperature for 2 h to obtain catalyst A-8. The test results are shown in Table 1.

[0077] Comparative Example 3

[0078] Weigh 375g of zirconium oxynitrate and 1.7g of lanthanum nitrate and dissolve them in 3L of deionized water to prepare a zirconium concentration of 0.54mol L -1 、La 3+ The concentration is 0.0013 mol L -1 a mixed solution; in a 70°C water bath with vigorous stirring, an ammonia aqueous solution (25 wt%) was added dropwise to the mixed solution to adjust the pH to 10.2 to obtain a precipitate system; the precipitate system was allowed to stand in a beaker for 2.6 hours; then centrifuged, and the obtained precipitate was washed with deionized water to a pH of 6.5, followed by drying at 85°C for 2 hours and then at 120°C for 2 hours; finally, the dried product was refrigerated in a muffle furnace at 3°C min -1The desired sample was obtained by heating the catalyst at a rate of 25°C to 550°C and calcining the catalyst at this temperature for 2 h. The catalyst was designated as catalyst B-3. The test results are shown in Table 1.

[0079] Comparative Example 4

[0080] A catalyst was prepared according to the method of Example 1, except that 125 g of calcium nitrate tetrahydrate was weighed and dissolved in 3 L of deionized water, as shown in Table 1, and recorded as catalyst B-4.

[0081] Comparative Example 5

[0082] A catalyst was prepared according to the method of Example 1, except that 0.17 g of calcium nitrate tetrahydrate was weighed and dissolved in 3 L of deionized water, as shown in Table 1, and recorded as catalyst B-5.

[0083] Comparative Example 6

[0084] A catalyst was prepared according to the method of Example 1, except that 106 g of lanthanum nitrate was weighed and dissolved in 3 L of deionized water, as shown in Table 1, and recorded as catalyst B-6.

[0085] Comparative Example 7

[0086] A catalyst was prepared according to the method of Example 1, except that 0.027 g of lanthanum nitrate was weighed and dissolved in 3 L of deionized water, as shown in Table 1, and recorded as catalyst B-7.

[0087] Table 1

[0088]

[0089]

[0090] Note: * Alkaline earth refers to the weight of alkaline earth metal oxide relative to 100g of the main component;

[0091] ** Rare earth refers to the weight of rare earth metal oxide relative to 100 g of the main component.

[0092] Test Example 1

[0093] This test example is used to illustrate the method for preparing 4-methyl-1-pentene by dehydrating methyl isobutyl carbinol (MIBC).

[0094] 50 mL of the catalyst prepared in the example was respectively loaded into a fixed-bed reactor and preheated at 310°C for 1 h using nitrogen. Then, methyl isobutyl carbinol (MIBC) was metered and fed into the reaction system using a metering pump. After being preheated to 100°C, it entered the upper end of the reactor. The liquid phase volumetric space velocity of methyl isobutyl carbinol (MIBC) was 0.3 h -1The dehydration reaction was carried out in the reactor at a reaction temperature of 310°C and a reaction pressure of normal pressure. After the reaction stabilized (i.e., after 360 hours of reaction), the reaction liquid was sampled and analyzed. The analysis results are listed in Table 2.

[0095] The sampling and analysis method is gas chromatography, which is calibrated by preparing correction factors of standard samples;

[0096] The conversion rate and selectivity were calculated based on the molar content of each component in the reaction solution (methyl isobutyl carbinol is abbreviated as MIBC, 4-methyl-1-pentene is abbreviated as 4MP1, 4-methyl-2-pentene is abbreviated as 4MP2, and methyl isobutyl ketone is abbreviated as MIBK).

[0097] MIBC conversion rate = 100% - n1 / [(n1+n2+n3+n4)+2×n5]×100%

[0098] 4MP1 selectivity = n2 / [(n2+n3+n4)+2×n5]×100%

[0099] 4MP2 selectivity = n3 / [(n2+n3+n4)+2×n5]×100%

[0100] Wherein, n1 is the molar content of MIBC in the reaction solution; n2 is the molar content of 4MP1 in the reaction solution; n3 is the molar content of 4MP2 in the reaction solution; n4 is the molar content of MIBK in the reaction solution; and n5 is the molar content of oligomers in the reaction solution.

[0101] 4MP1 ratio = 4MP1 / (4MP2+4MP1)×100%

[0102] The 4MP1 ratio is the ratio of 4MP1 selectivity to the sum of 4MP1 and 4MP2 selectivities, that is, the ratio of α-olefin to the sum of α-olefin and β-olefin, indicating that the product generated by the reaction contains more α-olefin, that is, the selectivity of α-olefin is high.

[0103] Table 2

[0104]

[0105] As can be seen from Table 2, in the reaction of catalyzing the dehydration of methyl isobutyl carbinol (MIBC) to prepare 4-methyl-1-pentene, the conversion rate of methyl isobutyl carbinol is as high as 94%, and the proportion of 4MP1 is as high as 90%, indicating that the catalyst of the present invention has higher catalytic activity.

[0106] After 1000 hours of continuous reaction, the carbon deposition amounts of catalysts A-1 to A-8 prepared in the examples were all less than 2 wt%; the carbon deposition amounts of catalysts B-1 to B-7 prepared in the comparative examples reached 3.5-8 wt%; and the conversion rates and 4MP1 proportions of catalysts A-1 to A-8 did not change significantly compared with those at 360 h, with the reduction in conversion rate being no more than 2%, and the reduction in 4MP1 proportion being no more than 1%; the conversion rates and 4MP1 proportions of catalysts B-1 to B-7 were significantly reduced compared with those at 360 h, with the reduction in conversion rate being 16-25%, and the reduction in 4MP1 proportion being 22%-35%; indicating that the catalysts prepared in the examples of the present invention have a longer service life.

[0107] Test Example 2

[0108] This test example is used to illustrate the method for preparing 1-octene by dehydrating 2-octanol in the present invention.

[0109] 50 mL of the catalyst A-1 prepared in Example 1 was loaded into a fixed-bed reactor and preheated at 310° C. for 1 h using nitrogen. 2-octanol was then metered into the reaction system using a metering pump and preheated to 100° C. before entering the upper end of the reactor. The liquid phase volume space velocity of 2-octanol was 0.3 h -1 The dehydration reaction was carried out in the reactor at a reaction temperature of 310°C and a reaction pressure of normal pressure. After the reaction stabilized, the reaction liquid was sampled and analyzed (the analysis conditions and the calculation method of conversion rate and selectivity were the same as those in Test Example 1). The analysis results are shown in Table 3:

[0110] The sampling and analysis method is gas chromatography, which is calibrated by preparing correction factors of standard samples;

[0111] The conversion rate and selectivity were calculated based on the molar content of each component in the reaction solution.

[0112] 2-octanol conversion = 100% - m1 / [(m1+m2+m3)+2×m4]×100%

[0113] 1-octene selectivity = m2 / [(m2+m3)+2×m4]×100%

[0114] 2-octene selectivity = m3 / [(m2+m3)+2×m4]×100%

[0115] Wherein, m1 is the molar content of 2-octanol in the reaction solution; m2 is the molar content of 1-octene in the reaction solution; m3 is the molar content of 2-octene in the reaction solution; and m4 is the molar content of oligomers in the reaction solution.

[0116] 1-octene ratio = 1-octene / (2-octene + 1-octene) × 100%

[0117] The 1-octene ratio is the ratio of 1-octene selectivity to the sum of 1-octene and 2-octene selectivities, that is, the ratio of α-olefins to the sum of α-olefins and β-olefins, indicating that the product generated by the reaction contains more α-olefins, that is, the selectivity for α-olefins is high.

[0118] Table 3

[0119] Reaction time 2-octanol conversion, % 1-octene proportion, % 360h 82.76 87.5 1000h 82.71 87.4

[0120] As can be seen from Table 3, after 1000 hours of catalytic reaction, the conversion rate of 2-octanol and the proportion of 1-octene of Catalyst A-1 did not change significantly compared to those after 360 hours. The decrease in conversion rate was no more than 0.1%, and the decrease in 1-octene proportion was no more than 0.1%, indicating that the catalyst obtained in this embodiment of the present invention has a long service life.

[0121] Test Example 3

[0122] This test example is used to illustrate the method for preparing 1-butene by dehydrating 2-butanol in the present invention.

[0123] 50 mL of the catalyst A-1 prepared in Example 1 was placed in a fixed-bed reactor and preheated at 310°C for 1 h using nitrogen. 2-Butanol was then metered into the reaction system using a metering pump and preheated to 100°C before entering the upper end of the reactor. The liquid phase volume space velocity of 2-butanol was 0.3 h -1 The dehydration reaction was carried out in the reactor at a reaction temperature of 310°C and a reaction pressure of normal pressure. After the reaction stabilized, the reaction liquid was sampled and analyzed (the analysis conditions and the calculation method of conversion rate and selectivity were the same as those in Test Example 1). The analysis results are shown in Table 4:

[0124] The conversion rate and selectivity were calculated based on the molar content of each component in the reaction solution.

[0125] 2-Butanol conversion rate = 100% - w1 / [(w1+w2+w3)+2×w4]×100%

[0126] 1-Butene selectivity = w2 / [(w2+w3)+2×w4]×100%

[0127] 2-Butene selectivity = w3 / [(w2+w3)+2×w4]×100%

[0128] Wherein, w1 is the molar content of 2-butanol in the reaction solution; w2 is the molar content of 1-butene in the reaction solution; w3 is the molar content of 2-butene in the reaction solution; and w4 is the molar content of oligomers in the reaction solution.

[0129] 1-Butene ratio = 1-Butene / (2-Butene+1-Butene)×100%

[0130] The 1-butene ratio is the ratio of the 1-butene selectivity to the sum of the 1-butene and 2-butene selectivities, that is, the ratio of α-olefins to the sum of α-olefins and β-olefins, indicating that the product generated by the reaction contains more α-olefins, that is, the selectivity of α-olefins is high.

[0131] Table 4

[0132] Reaction time 2-Butanol conversion, % 1-Butene proportion, % 360h 93.10 89.4 1000h 93.04 89.3

[0133] As can be seen from Table 4, after 1000 hours of catalytic reaction, the conversion rate of 2-butanol and the selectivity of 1-butene of Catalyst A-1 did not change significantly compared with 360 hours, the decrease in conversion rate was no more than 0.1%, and the decrease in the proportion of 1-butene was no more than 0.1%, indicating that the catalyst obtained in this embodiment of the present invention has a long service life.

[0134] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing α-olefins by dehydrating 2-alcohols, the method comprising: contacting the 2-alcohol with a catalyst for dehydration of the 2-alcohol in the presence or absence of a carrier gas to carry out a dehydration reaction, wherein the catalyst for dehydration of the 2-alcohol comprises: a main component, an alkaline earth metal oxide, and a rare earth metal oxide, wherein the main component is selected from at least one of zirconium oxide, silicon oxide, titanium oxide, and aluminum oxide; the rare earth metal oxide is selected from at least one of lanthanum oxide, cerium oxide, ytterbium oxide, neodymium oxide, and praseodymium oxide; and the alkaline earth metal oxide is selected from at least one of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide; Relative to 100 parts by weight of the main component, the alkaline earth metal oxide is 0.1-6 parts by weight; the rare earth metal oxide is 0.02-4 parts by weight; The carbon dioxide adsorption capacity of the catalyst is 0.18-0.4 mmol‧g -1 ; The ammonia adsorption capacity of the catalyst is 0.15-0.44 mmol‧g -1 ; The specific surface area of the catalyst is 65.8-150m 2 ‧g -1 ; The pore volume of the catalyst is 0.1-0.2 mL‧g -1 .

2. The method according to claim 1, wherein The weight ratio of the alkaline earth metal oxide to the rare earth metal oxide is 0.1-55:

1.

3. The method according to claim 2, wherein: The weight ratio of the alkaline earth metal oxide to the rare earth metal oxide is 0.5-18:

1.

4. The method according to claim 1, wherein The rare earth metal oxide is at least one of lanthanum oxide, cerium oxide and ytterbium oxide.

5. The method according to claim 1, wherein The preparation method of the catalyst for 2-alcohol dehydration comprises: mixing a main component source, an alkaline earth metal source, and a rare earth metal source in a solvent at a weight ratio of 100:2.03-15:0.02-20 to obtain a mixed solution; then adding a precipitant to the mixed solution, and then aging the solution; and then calcining the product obtained by aging. Wherein, the main component source is selected from at least one of a zirconium source, a silicon source, a titanium source and an aluminum source.

6. The method according to claim 5, wherein: The zirconium source is selected from at least one of zirconium oxychloride, zirconium nitrate, zirconyl nitrate and zirconyl sulfate.

7. The method according to claim 5, wherein: The silicon source is selected from tetraethyl orthosilicate and / or silica sol.

8. The method according to claim 5, wherein The titanium source is selected from titanium oxide.

9. The method according to claim 5, wherein: The aluminum source is selected from aluminum hydroxide and / or pseudo-boehmite.

10. The method according to claim 5, wherein The precipitant is selected from at least one of ammonia water, urea, sodium carbonate and sodium hydroxide.

11. The method according to claim 5, wherein: The alkaline earth metal source exists in the form of an alkaline earth metal salt solution, and the alkaline earth metal salt is selected from at least one of alkaline earth metal nitrates, alkaline earth metal formates, alkaline earth metal oxalates and alkaline earth metal lactates.

12. The method according to claim 5, wherein: The alkaline earth metal salt is selected from at least one of magnesium nitrate, calcium nitrate, strontium nitrate and barium nitrate.

13. The method according to claim 5, wherein: The aging conditions include: temperature of 50-100° C. and time of 0.5-10 h.

14. The method according to claim 5, wherein The calcination conditions include: 1-5℃‧min -1 The heating rate is from room temperature to 400-900°C, and calcined at 400-900°C for 1-20h.

15. The method according to claim 1, wherein The dehydration reaction conditions include: temperature of 220-360°C; pressure of 0.08-0.3 MPa; liquid phase volume space velocity of 0.05-0.9 h -1 ; When carrier gas is present, the flow rate of the carrier gas is 10-50 mL‧min -1 .

16. The method according to claim 15, wherein The dehydration reaction conditions include: temperature of 250-330°C; liquid phase volume space velocity of 0.1-0.6 h -1 ; and / or, when a carrier gas is present, the flow rate of the carrier gas is 15-45 mL‧min -1 .

17. The method according to claim 1, wherein The 2-alcohol is selected from C2-C 18 2-ol.

18. The method according to claim 17, wherein The 2-alcohol is selected from C2-C8 2-alcohols.

19. The method according to claim 18, wherein The 2-alcohol is selected from at least one of 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol.

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