Catalyst for preparing styrene by side-chain alkylation of toluene with methanol, preparation method and application thereof

Abstract

The present invention discloses a catalyst for the side-chain alkylation of toluene with methanol to styrene, a preparation method and an application thereof. The catalyst is prepared by using non-stoichiometric hydroxyapatite as a matrix and modifying it with metal oxides and inorganic acids. The non-stoichiometric hydroxyapatite is Ca 10‑x (HPO4) x (PO4) 6‑x (OH) 2‑x , wherein 0.16 ≤ x ≤ 0.52, that is, 1.64 ≥ Ca / P ≥ 1.58. The mass loading of the metal oxide is 0.1-5 wt%, and the mass loading of the inorganic acid is 0.1-7 wt%. The catalyst has high activity and can efficiently catalyze the side-chain alkylation reaction of toluene with methanol to produce styrene.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technologies, and particularly to a catalyst for preparing styrene by side-chain alkylation of toluene with methanol, a preparation method thereof, and an application thereof. Background Art

[0002] Styrene (SM), as the most basic aromatic chemical, is the largest consumption chemical product among benzene derivatives and can be used to manufacture various chemical products such as polystyrene (PS), expanded polystyrene (EPS), acrylonitrile-butadiene-styrene resin (ABS), styrene-acrylonitrile resin (SAN), styrene-butadiene rubber (SBR), unsaturated polyester resin (UPR), and ion exchange resin (IER).

[0003] The preparation of styrene by side-chain alkylation of toluene with methanol is a styrene production route with potential industrial value. Compared with the traditional two-step ethylbenzene dehydrogenation process for preparing styrene, this production route can directly produce styrene from toluene and methanol in one step, with advantages of small equipment investment, low energy consumption, and low raw material cost. However, the lack of highly active catalysts for side-chain alkylation of toluene with methanol limits the commercial application of this process.

[0004] The side-chain alkylation reaction of toluene with methanol is a catalytic process synergistically catalyzed by acid and base. Currently, the commonly used catalysts with catalytic activity for side-chain alkylation of toluene with methanol mainly include alkali metal ion-type molecular sieves, supported catalysts with activated carbon as the carrier, alkaline earth metal oxide catalysts, hydrotalcite, and organic solid acid-base catalysts, etc. Among them, the alkali metal ion-type molecular sieves have the highest activity. The lower the silicon-aluminum ratio of the alkali metal ion-type molecular sieve, the stronger the metallicity of its equilibrium cations, the stronger its basicity, and the stronger its catalytic activity for the side-chain alkylation reaction of toluene. According to this rule, cesium ion-exchanged X molecular sieve (CsX) has the best catalytic activity for side-chain alkylation of toluene with methanol, and numerous experimental results have also demonstrated this. Although CsX and its modified catalysts have the best activity among the currently studied catalysts, they still cannot meet the requirements of the process for preparing styrene by side-chain alkylation of toluene with methanol. At the same time, the above research results also show that it is difficult to find a suitable catalyst for side-chain alkylation of toluene within the range of alkali metal ion-type molecular sieves. Summary of the Invention

[0005] In view of the above problems, the inventors of the present application believe that to prepare a highly active catalyst required for the side-chain alkylation reaction of toluene with methanol, it is necessary to find an efficient non-molecular sieve catalytic material. Based on this, the present invention is proposed to provide a catalyst for preparing styrene by side-chain alkylation of toluene with methanol, a preparation method thereof, and an application thereof, which can overcome the above problems or at least partially solve the above problems.

[0006] An embodiment of the present invention provides a catalyst for the side-chain alkylation of toluene with methanol to produce styrene. The catalyst uses non-stoichiometric hydroxyapatite as a matrix and is prepared by impregnation method after modification with metal oxides and inorganic acids;

[0007] The chemical composition of the non-stoichiometric hydroxyapatite is Ca 10-x (HPO 4 ) x (PO 4 ) 6-x (OH) 2-x , where 0.16 ≤ x ≤ 0.52, that is: 1.64 ≥ Ca / P ≥ 1.58; the mass loading of the metal oxide is 0.1 - 5 wt%, and the mass loading of the inorganic acid is 0.1 - 7 wt%.

[0008] In some alternative embodiments, the metal oxide includes at least one of oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce, and Al.

[0009] In some alternative embodiments, the inorganic acid includes at least one of boric acid and phosphoric acid.

[0010] An embodiment of the present invention provides a method for preparing a catalyst for the side-chain alkylation of toluene with methanol to produce styrene, including:

[0011] Modifying the non-stoichiometric hydroxyapatite with a metal oxide; the chemical composition of the non-stoichiometric hydroxyapatite is Ca 10-x (HPO 4 ) x (PO 4 ) 6-x (OH) 2-x , where 0.16 ≤ x ≤ 0.52, that is: 1.64 ≥ Ca / P ≥ 1.58; the mass loading of the metal oxide is 0.1 - 5 wt%;

[0012] Modifying the hydroxyapatite modified with the metal oxide with an inorganic acid to obtain a catalyst for preparing styrene. Calculated by the mass ratio of the inorganic acid to the mass of the hydroxyapatite, the mass loading of the inorganic acid is 0.1 - 7 wt%.

[0013] In some alternative embodiments, the modifying the non-stoichiometric hydroxyapatite with a metal oxide includes:

[0014] Using a soluble salt containing a selected metal as an impregnation precursor, after impregnating the non-stoichiometric hydroxyapatite for a set first impregnation duration, drying it at a set first drying temperature, and calcining it at a set first calcination temperature for a set first calcination duration, hydroxyapatite modified with metal oxide is obtained; the mass ratio of the soluble salt to the hydroxyapatite is 1.5 - 2:50.

[0015] In some alternative embodiments, the soluble salt includes at least one of potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, copper nitrate, zinc nitrate, and cerium nitrate.

[0016] In some alternative embodiments, the metal oxide includes at least one of the oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce, and Al.

[0017] In some alternative embodiments, the inorganic acid modification of the hydroxyapatite modified with metal oxide includes:

[0018] Using an inorganic acid as an impregnation precursor, after impregnating the hydroxyapatite modified with metal oxide for a set second impregnation duration, drying it at a set second drying temperature, and calcining it at a set second calcination temperature for a set second calcination duration, hydroxyapatite modified with inorganic acid is obtained.

[0019] In some alternative embodiments, the inorganic acid includes at least one of boric acid and phosphoric acid.

[0020] In some alternative embodiments, the first calcination temperature is 200 - 600 °C, and / or the second calcination temperature is 200 - 600 °C.

[0021] In some alternative embodiments, the first drying temperature is 120 °C, the first calcination temperature is 550 °C, and the first calcination duration is 4 h; and / or the second drying temperature is 120 °C, the second calcination temperature is 550 °C, and the second calcination duration is 4 h.

[0022] In some alternative embodiments, the above method further includes: using calcium nitrate and diammonium hydrogen phosphate as preparation raw materials to prepare the non-stoichiometric hydroxyapatite.

[0023] In some alternative embodiments, the use of calcium nitrate and diammonium hydrogen phosphate as preparation raw materials to prepare the non-stoichiometric hydroxyapatite includes:

[0024] Dripping 0.5 mol / L calcium nitrate and 0.3 mol / L diammonium hydrogen phosphate into deionized water at 60 °C according to a mass ratio of 1:1;

[0025] Ammonia water was added dropwise to deionized water to adjust the pH value, and the pH value was controlled to be between 9 and 11;

[0026] It was stirred at 60 °C for 24 hours and dried at 120 °C to obtain the non-stoichiometric hydroxyapatite.

[0027] An embodiment of the present invention provides a method for preparing styrene by side-chain alkylation of toluene with methanol, and the preparation of styrene is realized by using the above-mentioned catalyst for side-chain alkylation of toluene with methanol to prepare styrene.

[0028] In some alternative embodiments, the above method includes:

[0029] Toluene and methanol with a molar ratio of 0.5 to 10:1 were used as reaction raw materials, and fed into the reactor at a feed mass space velocity of 0.2 to 8 h -1 to prepare styrene at a reaction pressure of 0.1 to 5 Mpa and a reaction temperature of 350 to 500 °C.

[0030] In some alternative embodiments, the reactor includes at least one of a fixed bed, a moving bed or a fluidized bed.

[0031] An embodiment of the present invention provides a styrene prepared by using the above method for preparing styrene by side-chain alkylation of toluene with methanol.

[0032] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0033] Using non-stoichiometric hydroxyapatite as the matrix, a catalyst for side-chain alkylation of toluene with methanol to prepare styrene is prepared by modification with metal oxides and modification with inorganic acids. Modifying non-stoichiometric hydroxyapatite with metal oxides can improve the ability of the catalyst to dehydrogenate formaldehyde to generate intermediate species, and modifying non-stoichiometric hydroxyapatite with inorganic acids can adjust the acidity of hydroxyapatite and improve the stability of the methanol dehydrogenation intermediate species of the catalyst, so that non-stoichiometric hydroxyapatite has better catalyst activity and reaction stability. The catalyst provided by the embodiments of the present invention is an efficient catalyst for preparing styrene. Using this catalyst for side-chain alkylation of toluene with methanol to prepare styrene can improve the conversion rate of styrene and realize the effective preparation of styrene.

[0034] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the written specification, claims, and drawings.

[0035] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0036] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0037] Figure 1 It is a flowchart of the preparation method of the catalyst for the side-chain alkylation of toluene with methanol to styrene in the embodiment of the present invention. Detailed Embodiments

[0038] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0039] In order to solve the problems existing in the prior art, the inventors of the present application have dedicated themselves to researching and preparing an efficient non-zeolite catalytic material as the catalyst for the side-chain alkylation of toluene with methanol to styrene.

[0040] Hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 is a strong basic material. By controlling the synthesis conditions, non-stoichiometric hydroxyapatite Ca 10-x (HPO 4 ) x (PO 4 ) 6-x (OH) 2-x can be obtained, which has both acidity and basicity at the same time, where 0 < x ≤ 1, that is, 1.67 > Ca / P ≥ 1.5. The inventors of the present application have found that by using non-stoichiometric hydroxyapatite with a certain Ca / P ratio range as the matrix and modifying it with metal oxides and inorganic acids, an efficient catalyst for the side-chain alkylation of toluene with methanol to styrene can be prepared, and the effective preparation of styrene can be achieved with this catalyst.

[0041] The embodiment of the present invention provides a catalyst for the side-chain alkylation of toluene with methanol to styrene. This catalyst is prepared by using non-stoichiometric hydroxyapatite as the matrix and modifying it with metal oxides and inorganic acids; the chemical composition of the above non-stoichiometric hydroxyapatite is Ca 10-x (HPO 4 ) x (PO 4 ) 6-x (OH)2-x , wherein, 0.16 ≤ x ≤ 0.52, that is: 1.64 ≥ Ca / P ≥ 1.58; the mass loading of the metal oxide is 0.1-5 wt%, and the mass loading of the inorganic acid is 0.1-7 wt%. The above 0.16 ≤ x ≤ 0.52 corresponds to 1.64 ≥ Ca / P ≥ 1.58. The composition of the non-stoichiometric hydroxyapatite can be represented by the parameter 0.16 ≤ x ≤ 0.52, or can be represented by the parameter 1.64 ≥ Ca / P ≥ 1.58.

[0042] Optionally, the metal oxide includes at least one of oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce, and Al. The inorganic acid includes at least one of boric acid and phosphoric acid.

[0043] The embodiment of the present invention also provides a preparation method of a catalyst for the side-chain alkylation of toluene with methanol to produce styrene, including:

[0044] Step S101: Modify the non-stoichiometric hydroxyapatite with a metal oxide. The non-stoichiometric hydroxyapatite is Ca 10-x (HPO 4 ) x (PO 4 ) 6-x (OH) 2-x , wherein, 0.16 ≤ x ≤ 0.52 and / or 1.64 ≥ Ca / P ≥ 1.58.

[0045] In order to improve the ability of the catalyst to dehydrogenate methanol to generate intermediate species, the non-stoichiometric hydroxyapatite is modified with a metal oxide. The metal oxide modification can be carried out by an impregnation method, and the impregnation precursor is a soluble salt of the metal in the metal oxide.

[0046] Using a soluble salt containing the selected metal as the impregnation precursor, after impregnating the non-stoichiometric hydroxyapatite for more than a set first impregnation time, drying at a set first drying temperature, and calcining at a set first calcination temperature for a set first calcination time, the hydroxyapatite modified with the metal oxide is obtained. The mass loading of the metal oxide in the hydroxyapatite modified with the metal oxide is 0.1-5 wt%, and the metal oxide is the product after calcining the soluble salt. The mass loading of the metal oxide refers to the mass ratio of the metal oxide to the hydroxyapatite.

[0047] Optionally, the above soluble salts include at least one of potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, copper nitrate, zinc nitrate, and cerium nitrate.

[0048] The metal oxide includes at least one of oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce, and Al.

[0049] Optionally, the first calcination temperature is 200 - 600 °C. Preferably, the first drying temperature is 120 °C, the first calcination temperature is 550 °C, and the first calcination duration is 4 h.

[0050] Step S102: Inorganic acid modification is performed on the non-stoichiometric hydroxyapatite modified by metal oxide to obtain a catalyst for preparing styrene.

[0051] In order to adjust the acidity of the catalyst and improve its stability ability for methanol dehydrogenation intermediate species, inorganic acid modification treatment is performed on the non-stoichiometric hydroxyapatite modified by the above metal oxide. The inorganic acid modification can be carried out by the impregnation method, and the impregnation precursor is a solution of inorganic acid.

[0052] After using inorganic acid as the impregnation precursor to impregnate the hydroxyapatite modified by metal oxide for more than the set second impregnation duration, it is dried at the set second drying temperature and calcined at the set second calcination temperature for the set second calcination duration to obtain the hydroxyapatite modified by inorganic acid. Calculated according to the mass ratio of the inorganic acid to the hydroxyapatite, the mass loading of the inorganic acid is 0.1 - 7 wt%.

[0053] Optionally, the inorganic acid includes at least one of boric acid and phosphoric acid.

[0054] Optionally, the second calcination temperature is 200 - 600 °C. Preferably, the second drying temperature is 120 °C, the second calcination temperature is 550 °C, and the second calcination duration is 4 h.

[0055] In some alternative embodiments, the above method further includes: using calcium nitrate and diammonium hydrogen phosphate as raw materials to prepare non-stoichiometric hydroxyapatite. The preparation process of non-stoichiometric hydroxyapatite includes: dropping 0.5 mol / L calcium nitrate and 0.3 mol / L diammonium hydrogen phosphate into deionized water at 60 °C according to a mass ratio of 1:1; dropping ammonia water into the deionized water to adjust the pH value, controlling the pH value between 9 - 11; stirring at 60 °C for 24 hours and drying at 120 °C to obtain non-stoichiometric hydroxyapatite.

[0056] The embodiment of the present invention also provides a method for preparing styrene by side-chain alkylation of toluene with methanol, and the preparation of styrene is realized by using the above catalyst for preparing styrene by side-chain alkylation of toluene with methanol.

[0057] The preparation process of styrene includes: using toluene and methanol with a molar ratio of 0.5 - 10:1 as reaction raw materials, feeding them into the reactor at a feed mass space velocity of 0.2 - 8 h-1, and preparing styrene at a reaction pressure of 0.1 - 5 Mpa and a reaction temperature of 350 - 500 °C.

[0058] Optionally, the reactor includes at least one of a fixed bed, a moving bed, or a fluidized bed.

[0059] An embodiment of the present invention also provides a styrene prepared by using the above method for preparing styrene by side-chain alkylation of toluene with methanol.

[0060] The preparation and application of the above catalyst are illustrated by specific examples below.

[0061] Unless otherwise specified, the raw materials used in the following examples are all commercially purchased, and the instrument equipment uses the parameter settings recommended by the manufacturer. In the following examples, the elemental composition of the catalyst is determined by an Axios 2.4KW type X-ray fluorescence analyzer (XRF) of PANAbalytical.

[0062] Example 1: Preparation of non-stoichiometric hydroxyapatite

[0063] 1) Preparation of non-stoichiometric hydroxyapatite H-1

[0064] 100 parts by weight of a 0.5 mol / L calcium nitrate solution and 100 parts by weight of a 0.3 mol / L diammonium hydrogen phosphate solution were simultaneously added dropwise to 50 parts by weight of deionized water at 60 °C. The pH value of the supernatant was monitored in real time by a pH meter, and the pH value was adjusted in real time by adding ammonia water to control it at 11. After the above precursor solution was added dropwise, it was stirred at 60 °C for 24 h and dried at 120 °C to obtain non-stoichiometric hydroxyapatite, named H-1. It can be known from XRF characterization that its Ca / P ratio is 1.58.

[0065] 2) Preparation of non-stoichiometric hydroxyapatite H-2

[0066] 100 parts by weight of a 0.5 mol / L calcium nitrate solution and 100 parts by weight of a 0.3 mol / L diammonium hydrogen phosphate solution were simultaneously added dropwise to 50 parts by weight of deionized water at 60 °C. The pH value of the supernatant was monitored in real time by a pH meter, and the pH value was adjusted in real time by adding ammonia water to control it at 10.5. After the above precursor solution was added dropwise, it was stirred at 60 °C for 24 h and dried at 120 °C to obtain non-stoichiometric hydroxyapatite, named H-2. It can be known from XRF characterization that its Ca / P ratio is 1.60.

[0067] 3) Preparation of non-stoichiometric hydroxyapatite H-3

[0068] 100 parts by weight of a 0.5 mol / L calcium nitrate solution and 100 parts by weight of a 0.3 mol / L diammonium hydrogen phosphate solution were simultaneously dropped into 50 parts by weight of deionized water at 60 °C. The pH value of the supernatant was monitored in real time by a pH meter, and the pH value was adjusted in real time by dropping ammonia water and controlled at 10. After the above precursor solution was dropped, it was stirred at 60 °C for 24 h and dried at 120 °C to obtain non-stoichiometric hydroxyapatite, named H-3. It can be known from XRF characterization that its Ca / P ratio is 1.62.

[0069] 4) Preparation of non-stoichiometric hydroxyapatite H-4

[0070] 100 parts by weight of a 0.5 mol / L calcium nitrate solution and 100 parts by weight of a 0.3 mol / L diammonium hydrogen phosphate solution were simultaneously dropped into 50 parts by weight of deionized water at 60 °C. The pH value of the supernatant was monitored in real time by a pH meter, and the pH value was adjusted in real time by dropping ammonia water and controlled at 9.0. After the above precursor solution was dropped, it was stirred at 60 °C for 24 h and dried at 120 °C to obtain non-stoichiometric hydroxyapatite, named H-4. It can be known from XRF characterization that its Ca / P ratio is 1.64.

[0071] Example 2: Preparation of a catalyst for the side-chain alkylation of toluene with methanol to styrene

[0072] 1) Preparation of catalyst C-1 for the production of styrene by side-chain alkylation of toluene with methanol

[0073] The saturated water absorption of non-stoichiometric hydroxyapatite H-1 was measured. 0.3 parts by weight of potassium nitrate, 0.2 parts by weight of calcium nitrate and 1 part by weight of copper nitrate were added to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-1 to prepare an impregnation precursor solution. Then, the H-1 sample was impregnated isovolumetrically, left standing overnight, dried at 120 °C and calcined at 550 °C for 4 h. Then, 1.2 parts by weight of boric acid was added to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-1 to prepare an impregnation precursor solution. Then, the above sample modified with metal oxides was impregnated isovolumetrically, left standing overnight, dried at 120 °C and calcined at 550 °C for 4 h to obtain a catalyst for the side-chain alkylation of toluene with methanol Production of styrene , named C-1.

[0074] 2) Preparation of catalyst C-2 for the production of styrene by side-chain alkylation of toluene with methanol

[0075] Determine the saturated water absorption of non-stoichiometric hydroxyapatite H-2. Add 0.3 parts by weight of cesium nitrate, 0.2 parts by weight of magnesium nitrate, 0.5 parts by weight of copper nitrate, and 0.5 parts by weight of zinc nitrate to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the H-2 sample with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h. Then, add 1 part by weight of phosphoric acid (85 wt%) and 0.7 parts by weight of boric acid to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the sample modified with the above metal oxides with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h to obtain the side-chain alkylation of toluene and methanol Production of styrene catalyst, named C-2.

[0076] 3) Preparation of catalyst C-3 for the production of styrene by side-chain alkylation of toluene with methanol

[0077] Determine the saturated water absorption of non-stoichiometric hydroxyapatite H-3. Add 0.3 parts by weight of rubidium nitrate, 0.2 parts by weight of calcium nitrate, and 1 part by weight of copper nitrate to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-3 to prepare an impregnation precursor solution. Then, impregnate the H-3 sample with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h. Then, add 1.2 parts by weight of boric acid to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-3 to prepare an impregnation precursor solution. Then, impregnate the sample modified with the above metal oxides with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h to obtain the side-chain alkylation of toluene and methanol Production of styrene catalyst, named C-3.

[0078] 4) Preparation of catalyst C-4 for the production of styrene by side-chain alkylation of toluene with methanol

[0079] Determine the saturated water absorption of non-stoichiometric hydroxyapatite H-4. Add 0.2 parts by weight of cesium nitrate, 0.3 parts by weight of magnesium nitrate, 1 part by weight of copper nitrate, and 0.5 parts by weight of cerium nitrate to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-4 to prepare an impregnation precursor solution. Then, impregnate the H-2 sample with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h. Then, add 1.5 parts by weight of boric acid to deionized water with a mass required for equal-volume impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-4 to prepare an impregnation precursor solution. Then, impregnate the sample modified with the above metal oxides with equal volume, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h to obtain the side-chain alkylation of toluene and methanol Production of styreneThe catalyst is named C-4.

[0080] 5) Preparation of catalyst C-5 for the production of styrene by side-chain alkylation of toluene with methanol

[0081] Determine the saturated water absorption of non-stoichiometric hydroxyapatite H-2. Add 0.2 parts by weight of potassium nitrate, 0.3 parts by weight of magnesium nitrate, 1 part by weight of copper nitrate, and 0.5 parts by weight of cerium nitrate to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the H-2 sample isovolumetrically, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h. Then, add 1.5 parts by weight of boric acid to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the sample modified with the above metal oxides isovolumetrically, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h to obtain the toluene methanol side-chain alkylation Production of styrene The catalyst is named C-5.

[0082] 6) Preparation of catalyst C-6 for the production of styrene by side-chain alkylation of toluene with methanol

[0083] Determine the saturated water absorption of non-stoichiometric hydroxyapatite H-2. Add 0.2 parts by weight of cesium nitrate, 0.3 parts by weight of chromium nitrate, and 1 part by weight of aluminum nitrate to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the H-2 sample isovolumetrically, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h. Then, add 1.5 parts by weight of boric acid to deionized water with a mass required for isovolumetric impregnation of 50 parts by weight of non-stoichiometric hydroxyapatite H-2 to prepare an impregnation precursor solution. Then, impregnate the sample modified with the above metal oxides isovolumetrically, let it stand overnight, dry at 120 °C, and calcine at 550 °C for 4 h to obtain the toluene methanol side-chain alkylation Production of styrene The catalyst is named C-6.

[0084] Comparative Example 1

[0085] Using 50 parts by weight of commercially purchased 13X powder (Si / Al = 1.23) as the parent, it was exchanged 4 times with 500 parts by weight of 0.3 mol / L CsCl solution at 80 °C, washed with deionized water, centrifuged, and dried at 120 °C for 4 h to prepare the CsX sample. The saturated water absorption of CsX was measured. 0.3 parts by weight of potassium nitrate, 0.2 parts by weight of calcium nitrate, and 1 part by weight of copper nitrate were added to the deionized water with the mass required for isovolumetric impregnation of 50 parts by weight of CsX to prepare an impregnation precursor solution. The CsX was impregnated isovolumetrically, left standing overnight, dried at 120 °C, and calcined at 550 °C for 4 h. Then, 1.2 parts by weight of boric acid was added to the deionized water with the mass required for isovolumetric impregnation of 50 parts by weight of CsX to prepare an impregnation precursor solution. Then, the CsX sample modified with the above metal oxides was impregnated isovolumetrically, left standing overnight, dried at 120 °C, and calcined at 550 °C for 4 h to obtain the catalyst of Comparative Example 1.

[0086] Comparative Example 2

[0087] 100 parts by weight of 0.5 mol / L calcium nitrate solution and 100 parts by weight of 0.3 mol / L diammonium hydrogen phosphate solution were simultaneously dropped into 50 parts by weight of deionized water at 60 °C. The pH value of the supernatant was monitored in real time by a pH meter, and the pH value was adjusted in real time by dropping ammonia water and controlled at 8.5. After the above precursor solution was dropped, it was stirred at 60 °C for 24 h and dried at 120 °C to obtain a non-stoichiometric hydroxyapatite Comparative Example 2 sample. It can be known from XRF characterization that its Ca / P ratio is 1.66.

[0088] The saturated water absorption of the above materials was measured. 0.3 parts by weight of potassium nitrate, 0.2 parts by weight of calcium nitrate, and 1 part by weight of copper nitrate were added to the deionized water with the mass required for isovolumetric impregnation of 50 parts by weight of the above materials to prepare an impregnation precursor solution. Then, the sample was impregnated isovolumetrically, left standing overnight, dried at 120 °C, and calcined at 550 °C for 4 h. Then, 1.2 parts by weight of boric acid was added to the deionized water with the mass required for isovolumetric impregnation of 50 parts by weight of the above non-stoichiometric hydroxyapatite to prepare an impregnation precursor solution. Then, the sample modified with the above metal oxides was impregnated isovolumetrically, left standing overnight, dried at 120 °C, and calcined at 550 °C for 4 h to obtain the catalyst of Comparative Example 2.

[0089] Performance Evaluation of the Catalyst for the Side-Chain Alkylation of Toluene with Methanol to Produce Styrene in Example 3

[0090] The fixed-bed reactor was used to evaluate the catalytic activities of the catalysts in Example 2, Comparative Example 1, and Comparative Example 2. The inner diameter of the reactor was 8 mm, and the catalyst loading was 2 g. The raw materials, toluene and methanol, were pumped in by a piston pump, and the products were analyzed by an Agilent 7890A chromatograph. The hydrocarbon components were separated by an Agilent CP-WAX 25 m×32 μm×1.2 μm capillary column and detected by an FID detector. CO, CO 2 and H 2 were separated by a Porapark Q 4 m×1 / 8″ packed column and detected by a TCD detector.

[0091] In the reaction evaluation, the conversion of toluene X 甲苯 , the conversion of methanol X 甲醇 , the selectivity of styrene S 苯乙烯 , and the selectivity of ethylbenzene S 乙苯 were calculated by the following methods:

[0092]

[0093]

[0094]

[0095]

[0096] The catalysts of the above Example 2, Comparative Example 1, and Comparative Example 2 were used for the side-chain alkylation of toluene and methanol to prepare styrene, and the reaction evaluation results are shown in Table 1.

[0097] Table 1

[0098]

[0099] In the process of preparing styrene, samples were analyzed once every 1 hour during the reaction. The reaction results in Table 1 above are the average values within 8 hours. It can be seen from Table 1 above that when using the catalyst provided in the examples of the present application, under the same or similar experimental conditions, the conversion of toluene and the selectivity of styrene are significantly improved, that is, the conversion of styrene is significantly improved when preparing styrene from toluene and methanol, and the preparation of styrene can be realized more efficiently.

[0100] It should be understood that the specific order or hierarchy of the steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of the steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy recited. Among them, the experimental conditions include various relevant experimental conditions such as the raw material ratio and preparation conditions of the catalyst, and the raw material ratio and preparation of styrene.

[0101] In the foregoing detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than the full scope of the features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0102] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but one of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Further, with respect to the term "comprising" as used in the specification or claims, that term is inclusive in a manner similar to the term "including," as that term is interpreted when used as a transitional word in a claim. Also, any use of the term "or" in the claims or specification is to be meant "non-exclusive or."

Claims

1. A catalyst for the side-chain alkylation of toluene with methanol to produce styrene, characterized in that, the catalyst is prepared by using hydroxyapatite with a non-stoichiometric ratio as a matrix and performing metal oxide modification and inorganic acid modification by an impregnation method; The chemical composition of the non-stoichiometric hydroxyapatite is , where 0.16 ≤ x ≤ 0.52, that is, 1.64 ≥ Ca / P ≥ 1.58; the mass loading of the metal oxide is 0.1 to 5 wt%, and the mass loading of the inorganic acid is 0.1 to 7 wt%; the metal oxide includes at least one of oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce, and Al; the inorganic acid includes at least one of boric acid and phosphoric acid.

2. A method for preparing a catalyst for the side-chain alkylation of toluene with methanol to produce styrene, characterized in that, it includes: Modifying non-stoichiometric hydroxyapatite with metal oxides; the chemical composition of the non-stoichiometric hydroxyapatite is , where 0.16 ≤ x ≤ 0.52, that is, 1.64 ≥ Ca / P ≥ 1.58; the mass loading of the metal oxide is 0.1-5 wt%; the metal oxide includes at least one of oxides of K, Ru, Cs, Mg, Ca, Cu, Zn, Cr, Ce and Al; Performing inorganic acid modification on the hydroxyapatite modified with a metal oxide to obtain a catalyst for preparing styrene. Calculated according to the mass ratio of the inorganic acid to the mass of the hydroxyapatite, the mass loading of the inorganic acid is 0.1-7 wt%; the inorganic acid includes at least one of boric acid and phosphoric acid.

3. The method according to claim 2, characterized in that, the modification of the non-stoichiometric hydroxyapatite with a metal oxide includes: Using a soluble salt containing a selected metal as an impregnation precursor, impregnating the non-stoichiometric hydroxyapatite for more than a set first impregnation time, drying at a set first drying temperature, and calcining at a set first calcination temperature for a set first calcination time to obtain hydroxyapatite modified with a metal oxide.

4. The method according to claim 3, characterized in that, the soluble salt includes at least one of potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, copper nitrate, zinc nitrate, and cerium nitrate.

5. The method according to claim 3, characterized in that, the modification of the hydroxyapatite modified with a metal oxide with an inorganic acid includes: Using an inorganic acid as an impregnation precursor, impregnating the hydroxyapatite modified with a metal oxide for more than a set second impregnation time, drying at a set second drying temperature, and calcining at a set second calcination temperature for a set second calcination time to obtain hydroxyapatite modified with an inorganic acid.

6. The method according to claim 5, characterized in that, the first calcination temperature is 200-600 °C, and / or the second calcination temperature is 200-600 °C.

7. The method according to claim 5, characterized in that, the first drying temperature is 120 °C, the first calcination temperature is 550 °C, the first calcination time is 4 h; and / or the second drying temperature is 120 °C, the second calcination temperature is 550 °C, and the second calcination time is 4 h.

8. The method according to any one of claims 2-7, characterized in that, it further includes: Using calcium nitrate and diammonium hydrogen phosphate as raw materials to prepare the non-stoichiometric hydroxyapatite.

9. The method according to claim 8, characterized in that, the use of calcium nitrate and diammonium hydrogen phosphate as raw materials to prepare the non-stoichiometric hydroxyapatite includes: Dropping 0.5 mol / L calcium nitrate and 0.3 mol / L diammonium hydrogen phosphate into deionized water at 60 °C according to a mass ratio of 1:1; Ammonia water is added dropwise to deionized water to adjust the hydrogen ion concentration index pH value, and the pH value is controlled to be between 9 and 11; Stir for 24 hours at 60 °C and dry at 120 °C to obtain the non-stoichiometric hydroxyapatite.

10. A method for preparing styrene by side-chain alkylation of toluene with methanol, which is characterized in that, the preparation of styrene is achieved by using the catalyst for side-chain alkylation of toluene with methanol as described in claim 1.

11. The method as described in claim 10, which is characterized in that, it includes: Using toluene and methanol with a molar ratio of 0.5 to 10:1 as reaction raw materials, feeding them into a reactor at a feed mass space velocity of 0.2 to 8 h -1 , and preparing styrene at a reaction pressure of 0.1 to 5 Mpa and a reaction temperature of 350 to 500 °C.

12. The method as described in claim 11, which is characterized in that, the reactor includes at least one of a fixed bed, a moving bed or a fluidized bed.

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