Process for the preparation of dienes based on cyclic ethers

Abstract

The application provides a method for preparing a diene based on an epoxy ether. The method comprises the following steps: taking an epoxy ether as a raw material, and making the epoxy ether generate a diene through a gas phase ring-opening dehydration reaction under the action of a solid catalyst. The solid catalyst comprises one or more of hydroxyapatite, a silicon aluminum phosphate molecular sieve, an ion exchange resin assembled by SiO2, a rare metal oxide, and a rare metal phosphate. The method for preparing the diene based on the epoxy ether has research value and application prospect.

Description

Technical Field

[0001] This application relates to the field of biomass resource catalytic conversion and utilization technology, and in particular to a method for preparing dienes based on cyclic ethers. Background Technology

[0002] C4-C6 conjugated dienes are important industrial synthetic raw materials. C4 conjugated dienes, such as 1,3-butadiene, self-polymerize to obtain cis-1,4-polybutadiene, which copolymerizes with acrylonitrile to form nitrile rubber. They can also copolymerize with a third component, such as acrylonitrile-butadiene-styrene rubber, used in the manufacture of automotive tires and sealing materials, flexible rubbers such as hoses and gloves, and rigid thermoplastics. The basic building block of "natural rubber" is the branched C5 conjugated diene isoprene, from which synthetic "natural rubber" can be produced. Similarly, 1,3-pentadiene, 1,3-hexadiene, and 2,4-hexadiene, which also contain conjugated double bonds, are monomers for synthesizing adhesives, plastics, and resins, and are also important organic synthesis reagents. Industrially, diene production is mainly based on non-renewable fossil resources. Utilizing biomass-derived cyclic ether compounds for diene production is one of the sustainable development technological approaches. However, compared with the traditional route of preparing dienes from fossil resources, the route of preparing dienes from biomass-derived cyclic ether compounds is not currently economically feasible due to its high cost. Therefore, there is an urgent need for an economically feasible method for preparing dienes. Summary of the Invention

[0003] Therefore, it is necessary to provide a new method for preparing dienes based on cyclic ethers to address the problem of high production costs of dienes from biomass-derived cyclic ether compounds.

[0004] One aspect of this application provides a method for preparing a diene based on a cyclic ether, comprising:

[0005] Using cyclic ethers as raw materials, under the action of a solid catalyst, the cyclic ethers undergo a gas-phase ring-opening dehydration reaction to generate dienes;

[0006] The solid catalyst includes one or more of hydroxyapatite, silica-alumina molecular sieve, SiO2-assembled ion exchange resin, rare metal oxides, and rare metal phosphates.

[0007] In some embodiments, the gas-phase ring-opening dehydration reaction satisfies one or more of the following conditions:

[0008] (1) The total space velocity of the gas-phase ring-opening dehydration reaction is 500–1,000,000 mL g-cat. -1 h -1 ;

[0009] (2) the temperature of the gas phase ring-opening dehydration reaction is 200-500℃.

[0010] In some embodiments, the solid catalyst is hydroxyapatite, which has a general formula of M 10 (XO4)6Y2, wherein M is a divalent cation, X is P or V, and Y is a monovalent anion;

[0011] Optionally, the divalent cation is at least one of Ca 2+ , Sr 2+ , or Pb 2+ .

[0012] Optionally, the monovalent anion is at least one of OH - or F - .

[0013] In some embodiments, the hydroxyapatite is calcium hydroxyapatite.

[0014] In some embodiments, the calcium hydroxyapatite has a molar ratio of Ca to P, denoted as Ca / P, and 0 < Ca / P ≤ 1.70, optionally 1.50 < Ca / P ≤ 1.67, and further optionally 1.50 < Ca / P ≤ 1.60.

[0015] In some embodiments, the calcium hydroxyapatite has a calcination temperature of 300-800℃, optionally 400-700℃, and further optionally 400-600℃.

[0016] In some embodiments, the temperature of the gas phase ring-opening dehydration reaction is 200-450℃, optionally 250-400℃, and further optionally 300-370℃.

[0017] In some embodiments, the solid catalyst is a silicoaluminophosphate molecular sieve, optionally SAPO-34.

[0018] In some embodiments, the solid catalyst is SAPO-34, and the SAPO-34 has a mass fraction of SiO2 less than or equal to 10 wt%, optionally less than or equal to 9 wt%, and further optionally less than or equal to 7 wt%, based on the total mass of the solid catalyst.

[0019] In some embodiments, the temperature of the gas phase ring-opening dehydration reaction is 200-500℃, optionally 250-400℃, and further optionally 250-300℃.

[0020] In some embodiments, the solid catalyst is a SiO2 assembled ion exchange resin.

[0021] Optionally, the ion exchange resin comprises Nafion, and the SiO2 assembled ion exchange resin comprises Nafion / SiO2.

[0022] In some embodiments, the mass fraction of Nafion in the solid catalyst is less than or equal to 13 wt% based on the total mass of the solid catalyst.

[0023] In some embodiments, the solid catalyst is a rare metal oxide.

[0024] Optionally, the rare metal is tantalum or tungsten.

[0025] In some embodiments, the solid catalyst is Ta2O5.

[0026] Optionally, the Ta2O5 is obtained by precipitation, aging and calcination using a precursor solution containing a tantalum source, and the calcination temperature in the preparation process of the Ta2O5 is 200-700°C.

[0027] In some embodiments, the solid catalyst is a supported WO3 catalyst.

[0028] Optionally, the support in the supported WO3 catalyst is SiO2 or Al2O3.

[0029] Optionally, the mass fraction of WO3 in the supported WO3 catalyst is less than or equal to 30 wt% based on the total mass of the solid catalyst.

[0030] Further optionally, the calcination temperature in the preparation process of the supported WO3 catalyst is 650-900°C.

[0031] In some embodiments, the temperature of the gas phase ring-opening dehydration reaction is 250-400°C, and optionally 250-300°C.

[0032] In some embodiments, the solid catalyst is a rare metal phosphate, and optionally one or more of tantalum phosphate and lanthanum phosphate.

[0033] In some embodiments, the cyclic ether comprises one or more of substituted or unsubstituted tetrahydrofuran and substituted or unsubstituted tetrahydropyran.

[0034] Optionally, the cyclic ether comprises one or more of tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran and 2,5-dimethyltetrahydrofuran.

[0035] In the above-mentioned method for preparing a diene based on an ether, the ether is converted into a diene by the action of a specific solid catalyst, and the catalyst is inexpensive and readily available. Therefore, the method for preparing a diene based on an ether provided by the present application has research value and application prospects, and makes it possible to industrialize and mass-produce a sustainable diene at low cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed to be used in the description of the specific embodiments or prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0037] Figure 1 HAP 1.51 -400 catalyzed tetrahydrofuran to 1,3-butadiene performance over time graph (●: tetrahydrofuran conversion, △: 1,3-butadiene selectivity, □: 1,3-butadiene yield);

[0038] Figure 2 HAP 1.51 -400 catalyzed 2-methyltetrahydrofuran to pentadiene performance over time graph (●: 2-methyltetrahydrofuran conversion, △: pentadiene selectivity, □: pentadiene yield). DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0041] Except in the Examples, or where otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used herein are to be understood as modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations. At the very least, they should be construed in light of the

[0042] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0043] If not specifically stated, the "comprise" and "include" mentioned in the present application represent open type, and can also be closed type. For example, the "comprise" and "include" can represent that other components not listed can also be included or contained, or can only include or contain the listed components.

[0044] If not specifically stated, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, either of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or A and B are both true (or exist).

[0045] The embodiments of the present application provide a preparation method of a diene based on an ether, comprising:

[0046] Taking an ether as a raw material, a diene is generated by a gas phase ring-opening dehydration reaction of the ether under the action of a solid catalyst;

[0047] The solid catalyst comprises one or more of hydroxyapatite, silicoaluminophosphate molecular sieve, ion exchange resin assembled by SiO2, rare metal oxide, and rare metal phosphate.

[0048] The cyclic ether can include one or more of substituted or unsubstituted tetrahydrofuran, substituted or unsubstituted tetrahydropyran. Alternatively, the cyclic ether includes one or more of tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran and 2,5-dimethyltetrahydrofuran. It is to be noted that if the cyclic ether includes tetrahydrofuran, the diene includes 1,3-butadiene; if the cyclic ether includes 2-methyltetrahydrofuran, 3-methyltetrahydrofuran or tetrahydropyran, the diene includes a mixture of pentadiene isomers; if the cyclic ether includes 2,5-dimethyltetrahydrofuran, the diene includes a mixture of hexadiene isomers. Understandably, the cyclic ether described herein preferably adopts a biomass-derived cyclic ether compound, which is preferably derived from lignocellulose-derived 5-hydroxymethylfurfural, furfural or itaconic acid, etc. as a source, and is converted into by catalytic hydrogenation (deoxidation).

[0049] Understandably, the cyclic ether is usually liquid at room temperature (25°C), which can be pure cyclic ether, aqueous solution of cyclic ether or mixture of cyclic ether and inert organic solvent.

[0050] The gas phase ring-opening dehydration reaction preferably includes the following steps:

[0051] The cyclic ether is input into a vaporization device by a feed pump and mixed with an inert carrier gas for preheating, and then enters a reactor packed with the solid catalyst; and the raw material gas containing the cyclic ether is contacted with the solid catalyst to occur ring-opening dehydration reaction to obtain diene.

[0052] The reactor can be a fixed bed reactor, a fluidized bed reactor, a moving bed reactor, etc. The inert carrier gas can be argon, helium or nitrogen. The reaction feed process preferably heats the cyclic ether so that it is at least a gas when it reaches the catalyst bed.

[0053] The cyclic ether is mixed with an inert carrier gas to vaporize the cyclic ether raw material and adjust the partial pressure of the cyclic ether in the raw material gas.

[0054] In the gas phase ring-opening dehydration reaction, the flow rate of the raw material gas is expressed by the total volume (i.e. GHSV) of the raw material gas (raw material and carrier gas) passing through the catalyst per unit mass per unit time. The total space velocity (GHSV) can be selected from 500 to 1,000,000 mL g-cat -1 h -1 .

[0055] The temperature of the gas phase ring-opening dehydration reaction refers to the actual temperature of the reactor, which is changed by adjusting the set temperature of the heat carrier, etc.

[0056] The gas phase ring-opening dehydration reaction produces a diene, and further preferably also includes recovering the diene in the form of a diene solution by condensation or solvent capture, etc. It can also include a capture separation process that captures the diene-containing gas using a liquid medium, or a condensation separation process that condenses and captures the diene-containing gas. By refining the diene solution using conventional methods such as distillation, rectification, or crystallization, etc., a diene of high purity can be obtained. Further, for dienes containing isomers, rectification can be used to purify them according to their different boiling points.

[0057] When the catalyst is hydroxyapatite, the hydroxyapatite has a general formula of M 10 (XO4)6Y2, where M is a divalent cation, X is P or V, and Y is a monovalent anion. Optionally, the divalent cation is at least one of Ca 2+ , Sr 2+ , or Pb 2+ . Optionally, the monovalent anion is at least one of OH - or F - . The hydroxyapatite described herein can be a commercial product or a product available on the market, or can be prepared by conventional methods or known methods. Preferably, it is prepared by a precipitation method.

[0058] The method for preparing the catalyst hydroxyapatite (M 10 (XO4)6Y2) includes the following steps:

[0059] S10, adding an alkali solution such as ammonia, NaOH, or KOH to a solution containing a source of M 2+ and X;

[0060] S11, continuously stirring and adjusting the pH of the solution to 7-12;

[0061] S12, aging the precipitate obtained by the reaction, filtering, and washing, etc. to obtain the hydroxyapatite.

[0062] For good catalytic performance, the method preferably further includes the step of:

[0063] S13, calcining the hydroxyapatite catalyst.

[0064] Preferably, the calcination temperature is 300-800°C, further preferably, the calcination temperature of the hydroxyapatite catalyst is 400-700°C, and more preferably, the calcination temperature of the hydroxyapatite catalyst is 400-600°C.

[0065] Preferably, the hydroxyapatite catalyst is calcium hydroxyapatite.

[0066] For example, in the preparation of hydroxyapatite, optional calcium sources such as calcium nitrate, calcium chloride, calcium hydroxide, etc., optional phosphorus sources such as phosphoric acid or soluble hydrogen phosphate, preferably, ammonium dihydrogen phosphate and diammonium hydrogen phosphate.

[0067] The hydroxyapatite has strong ion substitution, and the molar ratio of Ca and P (i.e. Ca / P ratio) can be changed by changing the preparation conditions.

[0068] The hydroxyapatite with different Ca / P ratios can be obtained by adjusting the ratio of the added calcium source and phosphorus source and the pH of the solution during preparation. The heating temperature during synthesis ranges from 0 to 100°C, and the stirring time ranges from 1 to 12h. The prepared hydroxyapatite can be subjected to drying or calcination treatment as needed. The calcination treatment can be performed in air, heating the sample to 300-800°C for 1-12h.

[0069] The hydroxyapatite of the present application has no particular limitation on the molar ratio of Ca and P contained therein. The molar ratio of Ca and P in the hydroxyapatite is denoted as Ca / P, which is optionally 0 < Ca / P ≤ 1.70, further optionally 1.50 < Ca / P ≤ 1.67, further optionally 1.50 < Ca / P ≤ 1.60, and particularly preferably 1.51.

[0070] In the above "0 < Ca / P ≤ 1.70", the Ca / P ratio includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values, and specific examples include but are not limited to the point values in the examples and the following point values: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69; or a range composed of any two numerical values. Understandably, in "1.50 < Ca / P ≤ 1.67" and "1.50 < Ca / P ≤ 1.60", the Ca / P ratio also includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values, or a range composed of any two numerical values.

[0071] In some embodiments, the catalyst is the hydroxyapatite of any of the above embodiments, and the temperature of the gas-phase ring-opening dehydration reaction is 200-450°C, optionally 250-400°C, further optionally 300-370°C.

[0072] In some embodiments, the silicoaluminophosphate molecular sieve is SAPO-34.

[0073] Further, the SiO2 mass fraction in the SAPO-34 is less than or equal to 10 wt%, optionally less than or equal to 9 wt%, and further optionally less than or equal to 7 wt%, based on the total mass of the solid catalyst.

[0074] The phosphosilicate molecular sieve described in the present application can be a commercial product or a product available on the market, or can be prepared by a conventional method or a known method. In some embodiments, the SAPO-34 is further calcined to remove impurities.

[0075] In some embodiments, the solid catalyst is the phosphosilicate molecular sieve of any of the above embodiments, and the temperature of the gas phase ring-opening dehydration reaction is 200-500°C, optionally 250-400°C, and further optionally 250-300°C.

[0076] The ion exchange resin in the SiO2-assembled ion exchange resin includes Nafion, i.e., a perfluorosulfonic acid resin. The Nafion / SiO2 (SiO2-assembled Nafion) can be a product available on the market or synthesized by a known method, for example, by using a dissolved Nafion perfluorosulfonic acid resin solution and tetraethyl orthosilicate as raw materials, and by an in-situ sol-gel technique.

[0077] Optionally, the mass fraction of Nafion in the Nafion / SiO2 is less than or equal to 13 wt%, based on the total mass of the solid catalyst.

[0078] In some embodiments, the rare metal in the rare metal oxide is tantalum or tungsten, and the solid catalyst is Ta2O5 and / or WO3.

[0079] In some embodiments, the solid catalyst is Ta2O5.

[0080] The rare metal oxide can be a commercial product or a product available on the market, or can be prepared by a conventional method or a known method.

[0081] In some embodiments, the Ta2O5 is obtained by precipitation, aging, and calcination of a precursor solution containing a tantalum source, and the calcination temperature in the preparation process of the Ta2O5 is 200-700°C.

[0082] In some embodiments, the solid catalyst is a supported WO3 catalyst. Optionally, the support in the supported WO3 catalyst is SiO2 or Al2O3. Optionally, the weight fraction of WO3 in the supported WO3 catalyst is less than or equal to 30 wt%, based on the total mass of the solid catalyst.

[0083] The supported WO3 catalyst can be a commercial product or a product available on the market, or synthesized by a conventional or known method. In some embodiments, the supported WO3 catalyst is obtained by impregnation and calcination using ammonium metatungstate ((NH4)6H2W 12 O 40 The calcination temperature during the preparation of the supported WO3 catalyst is 650-900°C.

[0084] In some embodiments, the solid catalyst is a rare metal oxide, and the temperature of the gas phase ring-opening dehydration reaction is 250-400°C, which can be optionally 250-300°C.

[0085] The rare metal phosphate can comprise one or more of tantalum phosphate and lanthanum phosphate.

[0086] The rare metal phosphate can be a commercial product or a product available on the market, or prepared by a conventional or known method. For example, lanthanum phosphate can be prepared by precipitation using an aqueous solution containing La 3+ and an aqueous solution containing a phosphorus source as raw materials, and drying and / or calcination treatment can be performed as needed, and the calcination temperature can be 300-800°C; and tantalum phosphate is prepared by a hydrothermal method using tantalum tartrate as a tantalum source, diammonium hydrogen phosphate as a phosphorus source, and cetyltrimethylammonium bromide as a template, and the calcination temperature can be 300-800°C.

[0087] The following are specific examples. The purpose is to make further detailed description of the present application, to help the skilled and researchers further understand the present application, and the technical conditions do not constitute any limitation on the present application. Any form of modification made within the scope of the claims of the present application is within the protection scope of the claims of the present application. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available products, or can be prepared by known methods. The experimental methods not specified in the examples are carried out according to conventional conditions, such as the conditions described in the literature, books or the methods recommended by the manufacturer.

[0088] Examples 1-16

[0089]

Catalyst Preparation

[0090] SAPO-34 (7.0 wt% SiO2, Dalian Institute of Chemical Physics, Chinese Academy of Sciences) and SAPO-34 (9.3 wt% SiO2, Dalian Institute of Chemical Physics, Chinese Academy of Sciences) samples were calcined in air at 400°C for 1 hour and at 550°C for 5 hours, and then granulated to 40-60 mesh for use.

[0091] 【1,3-Butadiene Preparation】

[0092] The vapor phase ring-opening dehydration of tetrahydrofuran neat liquid (99.5%, GC) was carried out in a continuous flow quartz fixed-bed reactor (6 or 9 mm i.d.) at atmospheric pressure. The procedure was as follows: The catalyst (40-60 mesh, acid-washed quartz sand diluted) of the mass and type shown in Table 1 was packed in the middle of the reactor tube, sandwiched between two quartz wool layers. The catalyst was pretreated by purging with dry N2at 30 mL / min for 1 h at the calcination temperature and then reduced to the corresponding reaction temperature (shown in Table 1) before the reaction. Tetrahydrofuran liquid was injected into the preheating device at a rate of 0.4 mL / h using a microsyringe pump and then introduced into the catalyst bed after being preheated and mixed with the carrier gas N2(69 mL / min). The composition of the feed gas in each example was 2.9 kPa tetrahydrofuran / 98.1 kPa N2. The catalyst, catalyst loading, reaction temperature, total space velocity, reaction time, and reaction results are shown in Table 1. In the following examples, the reactants and products were analyzed online by gas chromatography. The reaction results of Examples 5-16 are the results of continuously increasing the reaction temperature in one reaction. In which (this formula applies to all examples):

[0093] Ether conversion (%) = moles of consumed cyclic ether / moles of cyclic ether in the feed * 100;

[0094] Diene selectivity (C%) = moles of carbon of generated diene / moles of carbon of consumed cyclic ether * 100;

[0095] Diene yield (%) = moles of generated diene / moles of cyclic ether in the feed * 100.

[0096] Examples 17-28

[0097]

Catalyst Preparation

[0098] Ta2O5was prepared by a method known in the art as follows:

[0099] A 100 mL solution of 7 M ammonia was prepared in a round bottom flask and TaCl5powder was added to the uniformly stirred ammonia solution. After the sample was completely added, the mixture was heated to 80°C and refluxed for 3 h. After the stirring was stopped and the sample was aged for 12 h, it was washed with 80°C deionized water. The filter cake was dried at 110°C for 12 h and then calcined in a tube furnace in flowing air, increasing to 500°C and holding for 5 h. After calcination, the sample was tabletted, crushed, and sieved to 40-60 mesh for use, and was recorded as Ta2O5-500.

[0100] Supported WO3catalyst: According to the desired WO3loading of the catalyst to be prepared, an ammonium metatungstate ((NH4)6H2WO7) solution of the corresponding concentration and amount was prepared. 12 O 40, AMT) aqueous solution (3 mL water per 1 g Al2O3), the Al2O3 was impregnated in the solution at room temperature with stirring for 4 h, then the excess water was removed by a rotary evaporator, the obtained solid was dried at 110 °C overnight, and then was calcined at 800 °C for 4 h in flowing air, and then was taken out, tableted, crushed, and sieved to 40-60 mesh for use.

[0101] [Preparation of 1,3-butadiene]

[0102] The preparation method was substantially the same as that of Example 1, except that the pretreatment temperature was 400 °C in Examples 27 and 28, and the catalyst, catalyst amount, reaction temperature, total space velocity, reaction time, and reaction results are shown in Table 1. The reaction results of Examples 19-26 were the results of continuously increasing the reaction temperature in one reaction.

[0103] Examples 29-30

[0104] [Preparation of catalyst]

[0105] The 13 wt% Nafion / SiO2 was prepared by a sol-gel method known in the art.

[0106] Take 17 mL of tetraethyl orthosilicate, add 1 mL of hydrochloric acid (0.04 mol / L) and 4 mL of deionized water, respectively, stir at room temperature until the tetraethyl orthosilicate is fully hydrolyzed, and obtain a transparent silica sol; slowly add 15 mL of NaOH solution (0.1 mol / L) to 14 mL of Nafion solution (0.05 g / mL), stir well, and obtain a Nafion alkali solution; then quickly pour the silica sol into the Nafion alkali solution, stop stirring after about 30 s, and then form a glassy silica gel. The aged silica gel is placed in a 95 °C oven for drying for 48 h, and then is placed in a vacuum drying oven overnight (95 °C); the obtained sample is crushed, ion exchanged (1 h) with an HCl solution (3.5 mol / L), washed, and repeated 5 times; vacuum dried at 95 °C for 24 h, and granulated to 40-60 mesh for use.

[0107] [Preparation of 1,3-butadiene]

[0108] The preparation method was substantially the same as that of Example 1, except that the pretreatment temperature was 240 °C, and the catalyst, catalyst amount, reaction temperature, total space velocity, reaction time, and reaction results are shown in Table 1.

[0109] Examples 31-34

[0110] [Preparation of catalyst]

[0111] The TaOPO4 was prepared according to a method known in the art, as follows:

[0112] A certain amount of diammonium hydrogen phosphate was dissolved in 14 mL of water (the molar ratio of Ta and P was recorded as Ta / P, and the theoretical Ta / P was 1). The diammonium hydrogen phosphate solution was slowly added to a tartaric acid tantalum solution (prepared by 4.94 g of ethanol tantalum and tartaric acid by a known method), and stirred at 35°C. 1.4 g of cetyltrimethylammonium bromide was dissolved in 15 mL of water, and stirred at 35°C for half an hour until the cetyltrimethylammonium bromide was completely dissolved. The cetyltrimethylammonium bromide solution was gradually added to the single-phase solution of tartaric acid tantalum, and after the addition was completed, it was continuously stirred at 35°C for 1 hour, and then transferred to a stainless steel reactor, and placed in a 130°C constant temperature oven for hydrothermal treatment for 24 hours. After cooling to room temperature, a white colloid was obtained. The obtained colloid was washed with deionized water three times, and then washed with anhydrous ethanol three times to obtain a white solid. The white solid was placed in a 60°C air-drying oven for drying for 6 hours, calcined at 550°C in air for 6 hours, and granulated to 40-60 mesh for use, and recorded as TaOPO4-550 (the measured Ta / P was 1.7, measured by inductively coupled plasma emission spectroscopy ICP-OES, and 550 represented the calcination temperature).

[0113] LaPO4was prepared according to a method known in the art, as follows:

[0114] A certain amount of lanthanum nitrate hexahydrate was used as the lanthanum source, and phosphoric acid was used as the phosphorus source. A certain amount of 1M La (NO3) 3 aqueous solution and 1M phosphoric acid solution was prepared according to the molar ratio of La / P being equal to 1. The phosphoric acid was slowly added to the La (NO3) 3 solution under stirring at room temperature. After the addition was completed, concentrated ammonia water was added to adjust the pH of the solution to 7, and then stirred for 1 hour. After aging for 3 hours, the solution was washed with deionized water, dried overnight, calcined at 400°C in air for 4 hours, and granulated to 40-60 mesh for use, and recorded as LaPO4-400 (the measured La / P was 1.0, measured by inductively coupled plasma emission spectroscopy ICP-OES, and 400 represented the calcination temperature).

[0115] 【1,3-Butadiene preparation】

[0116] The preparation method was basically the same as that of Example 1. The catalyst, catalyst amount, reaction temperature, total space velocity, reaction time, and reaction results are shown in Table 1.

[0117] Examples 35-48

[0118]

Catalyst preparation

[0119] The preparation method of the catalysts of Examples 35-36 is as follows:

[0120] Under a 40°C water bath and continuous stirring, 150 mL of a 0.250 mol L -1 (NH4)2HPO4aqueous solution was added dropwise to a 250 mL 0.15 mol L-1 Ca(NO3)2 aqueous solution, while adding concentrated ammonia solution to keep the pH of the solution at 7 ± 0.2; after the addition was completed, the stirring was continued for 1 h, and the obtained precipitate suspension was placed in an oven at 40 °C for aging for 12 h. The white solid filter cake was slurried, stirred and washed with deionized water, and this operation was repeated until the conductivity of the filtrate was less than 15 μS cm -1 ; finally, the filter cake was dried at 110 °C overnight and then calcined in a tube furnace at 400 °C for 5 h in flowing air. The prepared catalyst was denoted as HAP 1.51 -400 (the subscript 1.51 represents the actual Ca / P molar ratio, which was measured by inductively coupled plasma optical emission spectrometry, ICP-OES; 400 represents the calcination temperature), and was granulated to 40-60 mesh for use.

[0121] Examples 37-38 The catalyst preparation method was exactly the same as that of Example 35. Examples 39-48 The catalyst preparation method was basically the same as that of Example 35, except that the concentration of the Ca(NO3)2 aqueous solution was adjusted to 0.225 mol L -1 , 0.228 mol L -1 , 0.239 mol L -1 , 0.251 mol L -1 and 0.263 mol L -1 , respectively, and the pH of the solution was 9 ± 0.1, 10 ± 0.1, 10 ± 0.1, 10 ± 0.1 and 10 ± 0.1, respectively, and the obtained catalysts were denoted as:

[0122] HAP 1.57 -400 (the subscript 1.57 represents the actual Ca / P molar ratio, which was measured by inductively coupled plasma optical emission spectrometry, ICP-OES; 400 represents the calcination temperature);

[0123] HAP 1.59 -400 (the subscript 1.59 represents the actual Ca / P molar ratio, which was measured by inductively coupled plasma optical emission spectrometry, ICP-OES; 400 represents the calcination temperature);

[0124] HAP 1.63 -400 (the subscript 1.63 represents the actual Ca / P molar ratio, which was measured by inductively coupled plasma optical emission spectrometry, ICP-OES; 400 represents the calcination temperature);

[0125] HAP 1.66 -400 (the subscript 1.66 represents the actual Ca / P molar ratio, which was measured by inductively coupled plasma optical emission spectrometry, ICP-OES; 400 represents the calcination temperature);

[0126] HAP 1.68- 400 (subscript 1.68 represents actual Ca / P molar ratio, measured by inductively coupled plasma optical emission spectrometry (ICP-OES); 400 represents calcination temperature).

[0127] [Preparation of 1,3-butadiene]

[0128] The preparation method is basically the same as that of Example 1, and the catalyst, catalyst amount, reaction temperature, total space velocity, reaction time and reaction results are shown in Table 1.

[0129] As can be seen from Table 1, when the Ca / P molar ratio of the calcium hydroxyphosphate is less than 1.68, the selectivity of 1,3-butadiene gradually increases with the decrease of the Ca / P molar ratio.

[0130] Examples 49-54

[0131] [Preparation of catalyst]

[0132] The preparation method of the catalysts of Examples 49-54 is basically the same as that of Example 35, except that the calcination temperature of the catalyst is changed to 500°C, 600°C or 700°C, and the catalysts are respectively denoted as:

[0133] HAP 1.51 - 500 (subscript 1.51 represents actual Ca / P molar ratio, measured by inductively coupled plasma optical emission spectrometry (ICP-OES); 500 represents calcination temperature);

[0134] HAP 1.51 - 600 (subscript 1.51 represents actual Ca / P molar ratio, measured by inductively coupled plasma optical emission spectrometry (ICP-OES); 600 represents calcination temperature);

[0135] HAP 1.51 - 700 (subscript 1.51 represents actual Ca / P molar ratio, measured by inductively coupled plasma optical emission spectrometry (ICP-OES); 700 represents calcination temperature).

[0136] [Preparation of 1,3-butadiene]

[0137] The preparation method is basically the same as that of Example 1, except that the pretreatment temperature is 400°C, and the catalyst, catalyst amount, reaction temperature, total space velocity, reaction time and reaction results are shown in Table 1.

[0138] As can be seen from Table 1, when the calcination temperature of the calcium hydroxyphosphate is less than 700°C, the selectivity of 1,3-butadiene increases with the decrease of the calcination temperature, and the selectivity of 1,3-butadiene on the samples calcined at 400-600°C is similar.

[0139] Examples 55-58

[0140] Catalyst preparation

[0141] The same as Example 35.

[0142] 1,3-Butadiene preparation

[0143] The same as the preparation method of Example 1, except that the catalyst, catalyst amount, reaction temperature, total space velocity, reaction time and reaction results are shown in Table 1.

[0144] As shown in Table 1, when the catalyst is calcium hydroxyphosphate, the selectivity of 1,3-butadiene increases with the decrease of reaction temperature at 350-400°C.

[0145] Examples 59-60

[0146] Catalyst preparation

[0147] The same as Example 35.

[0148] Pentadiene preparation

[0149] Examples 59-60: The gas phase ring-opening dehydration reaction of pure liquid 2-methyltetrahydrofuran (99.5%, GC) was carried out in a continuous flow quartz fixed bed reactor (inner diameter 9 mm) at normal pressure. The specific steps are as follows: 500 mg of HAP 1.51 -400 catalyst (40-60 mesh, acid-washed quartz sand dilution) was packed in the middle of the reaction tube, sandwiched between two layers of quartz wool. Before the reaction, the catalyst was purged in 30 mL / min of dry N2at the calcination temperature for 1 h, and then reduced to the reaction temperature of 350°C. The 2-methyltetrahydrofuran liquid material was injected into the preheating device at a speed of 0.5 mL / h using a micro-injection pump, and then mixed with the carrier gas N2(69 mL / min) to enter the catalyst bed layer. At this time, the total space velocity was 8500 mL g-cat -1 h -1 At this time, the composition of the raw material gas was 2.9 kPa 2-methyltetrahydrofuran / 98.1 kPa N2. The reaction results are shown in Table 2.

[0150] Examples 61-62

[0151] Catalyst preparation

[0152] The same as Example 35.

[0153] Isoprene preparation

[0154] The gas phase ring-opening dehydration reaction of pure liquid 3-methyltetrahydrofuran (99.5%, GC) was carried out in a continuous flow quartz fixed bed reactor (inner diameter 9 mm) at normal pressure. The specific steps are as follows: 300 mg of HAP 1.51-400 catalyst (40-60 mesh, diluted with acid-washed quartz sand) was packed in the middle of the reaction tube, sandwiched between two layers of quartz wool. Before the reaction, the catalyst was purged in dry N2 at 30 mL / min for 1 h at the calcination temperature, and then cooled to the reaction temperature of 400 °C. Liquid 3-methyltetrahydrofuran was injected into the preheating device at a rate of 0.4 mL / h using a micro-injection pump for preheating and mixing with carrier gas N2 (58 mL / min) before being introduced into the catalyst bed. At this point, the total space velocity was 11900 mL g-cat. -1 h -1 At this point, the composition of the feed gas was 2.9 kPa 3-methyltetrahydrofuran / 98.1 kPa N2. The reaction results are shown in Table 3.

[0155] Example 63

[0156] Catalyst Preparation

[0157] Same as Example 35.

[0158] [Preparation of 1,3-butadiene]

[0159] The preparation method is basically the same as that in Example 37, except that the feed gas flow rate is adjusted to a total space velocity of 1100 mL g-cat. -1 h -1 HAP testing 1.51 -Stability of the 400 catalyst over a long period of reaction at an initial conversion of 80%.

[0160] The results are attached. Figure 1 .Depend on Figure 1 It can be seen that after 10 hours of reaction, the tetrahydrofuran conversion slowly decreased from 80% to 74%, while the 1,3-butadiene selectivity remained relatively stable at 87%–91% and the 1,3-butadiene yield at 65%–73%. Therefore, the HAP used in this application... 1.51 The -400 catalyst exhibits high selectivity and high stability in the ring-opening dehydration of tetrahydrofuran to produce 1,3-butadiene.

[0161] Example 64

[0162] Catalyst Preparation

[0163] Same as Example 35.

[0164] Preparation of pentadiene

[0165] The preparation method is basically the same as that in Example 59, except that the feed gas flow rate is adjusted to a total space velocity of 2100 mL g-cat. -1 h -1 HAP testing 1.51 -400 catalyst stability over long-term reaction at near 100% initial conversion.

[0166] The results are attached. Figure 2 .Depend on Figure 2 It can be seen that after 10 hours of reaction, the conversion of 2-methyltetrahydrofuran remained at 96-97%, the selectivity of pentadiene remained at 97-98%, and the yield of pentadiene remained relatively stable at around 95%. Therefore, the HAP used in this application... 1.51 The -400 catalyst exhibits high selectivity and high stability in catalytic ring-opening dehydration of 2-methyltetrahydrofuran to produce pentadiene.

[0167] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0168] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

[0169] Table 1

[0170]

[0171]

[0172] Table 2

[0173]

[0174] Table 3

[0175]

Claims

1. A method for preparing dienes based on cyclic ethers, characterized in that, include: Using cyclic ethers as raw materials, a gas-phase ring-opening dehydration reaction is carried out in the presence of a solid catalyst to generate a diene; the cyclic ethers include one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, and 2,5-dimethyltetrahydrofuran. The solid catalyst is of the general formula M 10 Hydroxyapatite of (XO4)6Y2; Where M is a divalent cation, X is P, and Y is a monovalent anion; the divalent cation is Ca. 2+ and Sr 2+ At least one of the following, wherein the monovalent anion is OH - ; The total space velocity of the gas-phase ring-opening dehydration reaction is 500~1,000,000 mL g-cat. -1 h -1 The temperature of the gas-phase ring-opening dehydration reaction is 200~500 ℃.

2. The method for preparing dienes based on cyclic ethers according to claim 1, characterized in that, The solid catalyst includes calcium hydroxyphosphate.

3. The method for preparing dienes based on cyclic ethers according to claim 2, characterized in that, The molar ratio of Ca to P in the hydroxyapatite is denoted as Ca / P, and its range is 0. <Ca / P≤1.70。 4. The method for preparing dienes based on cyclic ethers according to claim 3, characterized in that, 1.50 <Ca / P≤1.67。 5. The method for preparing dienes based on cyclic ethers according to claim 4, characterized in that, 1.50 <Ca / P≤1.60。 6. The method for preparing dienes based on cyclic ethers according to claim 2, characterized in that, The calcination temperature during the preparation of the hydroxyapatite is 300~800 ℃.

7. The method for preparing dienes based on cyclic ethers according to claim 6, characterized in that, The calcination temperature during the preparation of the hydroxyapatite is 400~700 ℃.

8. The method for preparing dienes based on cyclic ethers according to claim 7, characterized in that, The calcination temperature during the preparation of the hydroxyphosphate is 400~600 ℃.

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