Preparation method and application of HZSM-5 molecular sieve loaded W, Fe and Ga ternary metal catalyst

Abstract

The invention belongs to the field of catalysts, and provides a preparation method and application of a W, Fe and Ga ternary metal catalyst loaded on an HZSM-5 molecular sieve. Ferric nitrate, gallium nitrate and ammonium metatungstate are loaded on HZSM-5 through an impregnation method, the WO3 / Fe2O3 / Ga2O3 / HZSM-5 catalyst is formed after high-temperature calcination, and the catalyst can efficiently catalyze the reaction of 2-methyl furan and isopropanol to prepare p-xylene by optimizing the metal loading proportion, temperature, reaction time and the like. According to the catalyst, 2-methyl furan and isopropanol are catalyzed to react and jointly convert into p-xylene for the first time, and a new route is provided for green production of p-xylene.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and particularly to a preparation method and application of a ternary metal catalyst of W, Fe, and Ga supported on HZSM-5 molecular sieve. Background Art

[0002] p-Xylene (pX) is an important industrial compound, mainly used for the production of purified ethylene terephthalate (PTA), which is a precursor of polyethylene terephthalate (PET). And pX, as a component of xylene, has important applications in fields such as solvents, pesticides, and the pharmaceutical industry. Currently, the main source of pX is the alkylation of toluene with methanol or the extraction from BTX (benzene, toluene, xylene isomers) obtained by catalytic reforming of petroleum products. However, due to the serious global warming and environmental pollution problems caused by petroleum, and the goal of achieving carbon neutrality, the use of renewable carbon resources to replace petroleum has received sufficient attention in recent decades.

[0003] Biomass is currently the only renewable carbon source, and there is great potential for synthesizing p-xylene through biomass-derived platform molecules. In recent years, the reaction path for preparing pX from biomass platform molecules is basically based on the Diels-Alder cycloaddition reaction. Most of the raw materials are 2,5-dimethylfuran (DMF) from cellulose, and most of the ene donors (dienophiles) are ethylene, which benefits from the high selectivity of the cycloaddition reaction between the double-methyl symmetric structure of DMF and ethylene.

[0004] There have been a large number of literatures reporting on this route [Wu C, Wu T, Li J, et al. Highly efficient catalytic conversion of biomass-derived 2,5-dimethylfuran into renewable p-xylene over zirconium phosphate catalysts [J]. Applied Catalysis A: General, 2023, 663: 119323.; Feng X, Cui Z, Ji K, et al. Ultra-selective p-xylene production through cycloaddition and dehydration of 2,5-dimethylfuran and ethylene over tin phosphate [J]. Applied Catalysis B: Environmental, 2019, 259: 118108.; ZHAO R, ZHAO Z, LI S, et al. Excellent Performances of Dealuminated H-Beta Zeolites from Organotemplate-Free Synthesis in Conversion of Biomass-derived 2,5-Dimethylfuran to Renewable p-Xylene [J]. ChemSusChem, 2018, 11(21): 3803-3811.; Zhao Y, Wang KZ, Sun ZH, et al. Niobium grafted mesoporous silica for the production of biorenewable p-xylene from concentrated 2,5-dimethylfuran [J]. Green Chemistry, 2022, 24(10): 4095-4107. A method for co-producing bio-based p-xylene and toluene: CN118459305A; A kneading method for preparing bio-based toluene and p-xylene from low-cost lignocellulosic biomass: CN118184480A]. The yield of pX synthesized by the reaction of DMF and ethylene can reach over 90%.

[0005] Other cellulose-based routes have also been extensively studied [A method for preparing bio-based p-xylene from low-cost lignocellulosic biomass: CN118637972A; A method for catalytic synthesis of p-xylene using metal-modified MCM-22 zeolite: CN117205960A; A method for catalytic synthesis of p-xylene using H-MWW zeolite: CN117069558A]. However, the route for synthesizing p-xylene from hemicellulose, another important component of biomass, still needs to be improved. By analogy with the reaction of DMF and ethylene, it can be speculated that 2-methylfuran (MF) derived from hemicellulose reacts with propylene through cycloaddition and dehydration to form m-xylene, which then continues to isomerize to pX. However, this reaction may be more difficult than the conventional DMF reaction, mainly because MF has one less electron-donating group compared to DMF, while propylene has an additional electron-donating group compared to ethylene, which increases the difficulty of the Diels-Alder cycloaddition reaction.

[0006] Currently, there is little research on the synthesis of p-xylene from hemicellulose-derived compounds [Zhu L, Fan M, Wang Y, et al. Selective conversion of furans to p-xylene with surface-modified zeolites [J]. Journal of Chemical Technology & Biotechnology, 2019, 94(9): 2876-87.; A method for preparing bio-based terephthalic acid from furfuryl alcohol: CN118420453A]. The liquefaction characteristics of propylene under high pressure make it necessary to find a suitable propylene donor, and the coking caused by high reaction temperatures and the need for product isomerization also pose obstacles to the implementation of this route [Wu Yuke, Luo Lin, Li Zheng, Lin Lu, Zeng Xianhai. Research progress on the preparation of p-xylene from biomass platform molecules [J]. Chemistry and Industry of Forest Products, 2024, 44(5): 125-133.]. Summary of the Invention

[0007] To solve the problems existing in the above-mentioned prior art, the present invention prepared a ternary metal catalyst of W, Fe, and Ga supported on HZSM-5 zeolite and applied it to catalyze the reaction of 2-methylfuran and isopropanol to prepare p-xylene. Ferric nitrate, gallium nitrate, and ammonium metatungstate were used as the sources of Fe, Ga, and W respectively and loaded on HZSM-5 by the impregnation method. After high-temperature calcination, WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst, in the present invention, by optimizing the types of supported metals, temperature, reaction time, etc., the prepared catalyst can efficiently catalyze the reaction of 2-methylfuran with isopropanol to prepare p-xylene. The present invention realizes for the first time the co-conversion of 2-methylfuran and isopropanol into p-xylene, providing a new route for the green production of p-xylene.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A preparation method of a ternary metal catalyst of W, Fe, and Ga supported on HZSM-5 molecular sieve, comprising the following steps:

[0010] (1) Ferric nitrate nonahydrate, gallium nitrate hexahydrate, and deionized water are formulated into a uniform aqueous solution, and then HZSM-5 is added, stirred, rotary evaporated, ground and refined, and calcined to obtain a catalyst precursor Fe 2 O 3 / Ga 2 O 3 / HZSM-5;

[0011] (2) The Fe 2 O 3 / Ga 2 O 3 / HZSM-5 obtained in step (1) is added with ammonium metatungstate, stirred, rotary evaporated, ground and refined, and calcined to obtain a WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst.

[0012] The HZSM-5 molecular sieve is of the MFI type, with channel diameters of 0.53*0.56 nm and 0.51*0.56 nm, which is in line with the kinetic diameter of p-xylene, and is conducive to improving the selectivity of p-xylene by using the shape-selective effect. It is found by experimental methods that an appropriate silicon-aluminum ratio will provide suitable acidic sites, meeting the requirements of this reaction. Therefore, in step (1), the silicon-aluminum ratio of HZSM-5 is preferably 18-140.

[0013] The metal ratio and loading amount will change the acidity of the catalyst. Adding too much or having an improper ratio will make the acidity unsuitable for the reaction and may also block the pores of the molecular sieve. Therefore, in step (1), the addition ratio of ferric nitrate nonahydrate, gallium nitrate hexahydrate, HZSM-5, and deionized water is preferably 0-8 g: 0-5 g: 5-15 g: 5-40 ml; the further preferred addition ratio is 0-6 g: 0-4 g: 8-12 g: 10-30 ml.

[0014] Preferably, in step (2), the ammonium metatungstate, Fe 2 O3 / Ga 2 O 3 The addition ratio of / HZSM-5 and deionized water is 0.5 - 5 g : 5 - 20 g : 5 - 40 ml; preferably, the addition ratio is 0.5 - 2 g : 8 - 15 g : 10 - 30 ml.

[0015] Preferably, the stirring in step (1) is continuously carried out at room temperature for 12 - 24 hours.

[0016] Preferably, the stirring in step (2) is continuously carried out at room temperature for 6 - 24 hours.

[0017] Preferably, the rotary evaporation in steps (1) and (2) is carried out at 60 - 90 °C for 3 - 12 hours; further, it is held at 80 °C for 6 hours.

[0018] Experiments have found that different baking process parameters will change the metal acidity on the catalyst, and too low a temperature will also lead to incomplete decomposition of the metal precursor. Therefore, preferably, the calcination in steps (1) and (2) is carried out in a muffle furnace at a temperature of 500 - 600 °C and held at this temperature for 4 - 12 hours; further, it is heated to 550 °C at a rate of 5 °C / min and held for 6 h.

[0019] Preferably, after the grinding and refinement in steps (1) and (2), the particle size is screened through a 40 - 60 mesh sieve.

[0020] The present invention also provides the application of the above WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst in the reaction of 2-methylfuran and isopropanol to prepare p-xylene, including the following steps:

[0021] Put the catalyst WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5, 2-methylfuran, and isopropanol into a high-pressure resistant reaction kettle, and carry out the catalytic reaction under a nitrogen atmosphere to obtain p-xylene.

[0022] Experiments have found that the ratio of the catalyst, raw materials and solvent has the best effect within a suitable range, otherwise it will lead to a decrease in the yield. Preferably, WO 3 / Fe 2 O 3 / Ga 2 O 3The addition amounts of / HZSM-5, 2-methylfuran, and isopropanol are 0.1 - 0.3: 0.05 - 0.2: 8 - 12 ml; further, the preferred addition amounts of the three are 0.2 g: 0.1 g: 10 ml.

[0023] Preferably, after sealing the reaction kettle, nitrogen is filled in at 0.1 MPa.

[0024] Preferably, the conditions for the catalytic reaction are: reacting for 6 - 12 h under magnetic stirring at 300 - 800 rpm and 350 - 400 °C; further, reacting for 8 h under magnetic stirring at 600 rpm and 385 °C.

[0025] Compared with the prior art, the present invention has the following advantages and effects:

[0026] The present invention uses W, Fe 、 Ga ternary metal-modified HZSM-5 molecular sieve to regulate acidic sites and pore openings and regulate the selectivity of p-xylene; compared with common cellulose synthesis routes, a route for synthesizing p-xylene from hemicellulose-derived platform compound 2-methylfuran is realized; the present invention first proposes using isopropanol as a propylene donor to achieve a higher p-xylene yield (up to 35.8%) compared with the same type of 2-methylfuran route using other olefin donors. Description of the Drawings

[0027] Figure 1 It is the XRD pattern of the multi-metal oxide-modified HZSM-5 in Example 1.

[0028] Figure 2 It is WO in Example 1 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst's N 2 adsorption-desorption curve.

[0029] Figure 3 It is ZrO prepared in Example 1 2 / Ga 2 O 3 / HZSM-5 catalyst's X-ray photoelectron spectroscopy (XPS pattern) Ga3d, Zr3d spectra, and WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst's Fe2p, Ga3d, W4f spectra.

[0030] Figure 4Ammonia temperature-programmed desorption test (NH 3 -TPD) spectrum of the multi-metal oxide modified HZSM-5 prepared in Example 1.

[0031] Figure 5 Catalytic reaction mechanism of the reaction of MF with isopropanol in Examples 2-13. Detailed implementation manners

[0032] To more clearly elaborate the purpose, technical solution and advantages of the present application, the following will be described in detail with reference to the accompanying drawings and specific embodiments. The exemplary embodiments shown in the accompanying drawings are only for the present, and are not limitations on the implementation manners. The present application can be implemented in multiple forms, and its design concept and core technology are not limited by the embodiments shown in the drawings. The purpose of providing these embodiments is to more conveniently enable those skilled in the art to understand the principle, structure and function of the present application, so as to better master and apply its technical solution. The terms used in this specification are only for describing specific embodiments and do not constitute a limitation on the present application.

[0033] Example 1:

[0034] A multi-metal modified HZSM-5 molecular sieve catalyst is prepared by the following method:

[0035] (1) Weigh 5.4 g of ferric nitrate nonahydrate and 3.6 g of gallium nitrate hexahydrate in 18.8 ml of deionized water to prepare a uniform aqueous solution; then add 9.4 g of HZSM-5 with a silica-alumina ratio of 85 to this solution, and continuously stir at room temperature for 12 hours; rotate and evaporate the stirred mixture at 80 °C for 6 hours. The sample is further ground and refined, and the particle size is screened through a 40-60 mesh sieve; the screened sample is calcined in a muffle furnace, and the furnace temperature is gradually raised to 550 °C at a rate of 5 °C / min, and kept at this temperature for 6 hours to obtain the catalyst precursor Fe 2 O 3 / Ga 2 O 3 / HZSM-5;

[0036] (2) Grind the Fe 2 O 3 / Ga 2 O 3 / HZSM-5 obtained in step (1) and dissolve it in 18.8 ml of deionized water, add 1.1 g of ammonium metatungstate, continuously stir at room temperature for 12 hours, and then rotate and evaporate at 80 °C for 6 hours. The sample is further ground and refined, and the particle size is screened through a 40-60 mesh sieve, and the screened sample is calcined in a muffle furnace, and the furnace temperature is gradually raised to 550 °C at a rate of 5 °C / min, and kept at this temperature for 6 hours to obtain WO 3 / Fe 2O 3 / Ga 2 O 3 / HZSM-5 catalyst.

[0037] ZrO 2 / Ga 2 O 3 / HZSM-5, Fe 2 O 3 / Ga 2 O 3 / HZSM-5, WO 3 / HZSM-5 catalysts were prepared using the same method and process parameters, only replacing the metal raw materials therein, as follows:

[0038] ZrO 2 / Ga 2 O 3 In the preparation of the ZrO 2 / Ga 2 O 3 / HZSM-5, 3.5 g of zirconium nitrate pentahydrate, 3.6 g of gallium nitrate hexahydrate and 9.4 g of HZSM-5 were added in step (1), and then the sample was stirred, rotary evaporated, ground and refined, sieved, and calcined to obtain ZrO

[0039] Fe 2 O 3 / Ga 2 O 3 In the preparation of the / HZSM-5 catalyst, 5.4 g of iron nitrate nonahydrate, 3.6 g of gallium nitrate hexahydrate and 9.4 g of HZSM-5 were added in step (1), and then the sample was stirred, rotary evaporated, ground and refined, sieved, and calcined to obtain Fe 2 O 3 / Ga 2 O 3 / HZSM-5.

[0040] WO 3 In the preparation of the / HZSM-5 catalyst, 1.1 g of ammonium metatungstate and 9.4 g of HZSM-5 were added in step (1), and then the sample was stirred, rotary evaporated, ground and refined, sieved, and calcined to obtain WO 3 / HZSM-5.

[0041] The catalysts prepared in Example 1 were analyzed by X-ray diffraction (XRD), as Figure 1 shown. All the obtained HZSM-5 samples retained their inherent peak shape characteristics, specifically manifested as the characteristic diffraction angles corresponding to MFI: 23.1°, 23.8°, and 24.3°.

[0042] ZrO 2 / Ga2 O 3 / HZSM-5 and Fe 2 O 3 / Ga 2 O 3 No unique diffraction features attributed to the supported metals (Zr, Ga, Fe) and their oxides were detected for O / HZSM-5. The supported metal oxides are likely to be uniformly distributed on the HZSM-5 surface in a highly dispersed state rather than forming large-sized aggregates.

[0043] WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 and WO 3 Diffraction peaks belonging to WO can be observed for / HZSM-5 at 2θ values of 33.330°, 33.639°, 34.021° and 35.524°. The degree of dispersion may be less than that of Fe 3 O 2 O 3 and Ga 2 O 3 .

[0044] The catalysts prepared in Example 1 were subjected to physical adsorption analysis. As Figure 2 shown, compared to the carrier HZSM-5, the specific surface area and pore volume of the catalysts after metal loading decreased.

[0045] The catalysts prepared in Example 1 were tested by X-ray photoelectron spectroscopy (XPS). As Figure 3 shown, Figure 3 for (a) and (b), the XPS spectra of Ga3d and Zr3d of the catalyst ZrO 2 / Ga 2 O 3 / HZSM-5. Excluding the satellite peaks of the impurity peaks, Figure 3 the main signals of (a) and (b) are attributed to Ga 2 O 3 and ZrO 2 . Figure 3 For (c), (d) and (e), the XPS spectra of Fe2p, Ga3d and W4f of the catalyst WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5. Excluding the satellite peaks of the impurity peaks, Figure 3 the main signals of (d) and (e) are attributed to Ga 2 O 3 and WO 3。Combined with WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 XRD diffraction pattern, that is, WO 3 Appearing corresponding characteristic peaks in the XRD pattern can prove that tungsten metal exists in the state of tungsten trioxide at this time. From Figure 3 As shown in (c) of Fe2p, it is found that in addition to Fe 3+ There is also a signal of Fe 2+ , indicating that there is a small amount of ferrous oxide in iron oxide.

[0046] The catalyst prepared in Example 1 was subjected to ammonia temperature-programmed desorption test (NH 3 -TPD), as Figure 4 shown. After loading iron oxide gallium, both the amount of weak acid and the amount of strong acid of the molecular sieve increased significantly, and the positions of the weak acid peak and the strong acid peak remained the same as before loading. In particular, compared with WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 and the rest of the samples, after loading tungsten oxide on the bimetallic oxide-supported catalyst, the relative intensities of the strong acid peak and the weak acid peak increased significantly.

[0047] Examples 2-6

[0048] Examples 2-5 directly used the catalyst prepared in Example 1 for the reaction of 2-methylfuran and isopropanol to prepare p-xylene, and the steps were as follows:

[0049] 0.2 g of catalyst, 0.1 g of 2-methylfuran, and 10 ml of isopropanol were added to a high-pressure resistant reactor. After sealing the reactor, 0.1 MPa of nitrogen was charged, and the reaction was carried out at 600 rpm under magnetic stirring and 385 °C for 8 h. After cooling to room temperature, the reaction solution was filtered through a 0.45 μm organic filter head and analyzed by gas chromatography (GC) and the products were identified by gas chromatography-mass spectrometry (GC-MS).

[0050] Example 6 directly used HZSM-5 as the catalyst, and the rest were the same as the above steps.

[0051] The catalytic effects of different catalysts are shown in Table 1. Examples 2-6 show that WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM-5 catalyst has the highest pX yield.

[0052] Table 1. Catalytic effects of different catalysts

[0053]

[0054]

[0055] Examples 7 - 13

[0056] Use the catalyst WO 3 / Fe 2 O 3 / Ga 2 O 3 / HZSM - 5 in Example 1 as the catalyst for subsequent research. Reaction conditions: 0.1 g of MF, 0.2 g of catalyst, and 8 g of isopropanol. The catalytic effects under different catalytic conditions are shown in Table 2.

[0057] Table 2. Catalytic effects under different catalytic conditions

[0058]

[0059] It can be seen that the reaction temperature and reaction time have obvious effects on the conversion rate of MF, the selectivity and yield of pX. The highest conversion rate of MF is reached at 370°C. With the increase in temperature, the selectivity of pX increases significantly, and the yield also increases rapidly, reaching the maximum value at 385°C. With the extension of time, the selectivity and yield of pX increase and reach the maximum at 10 hours. Continuing to extend the time, the selectivity and yield decrease instead.

[0060] Finally, we need to emphasize that the examples provided here are only a part of the examples of this application, not all of them. Based on this application, all other examples obtained by those skilled in the art without creative efforts shall fall within the scope of protection of this application.

Claims

1. A method for preparing a HZSM-5 molecular sieve loaded with W, Fe, and Ga ternary metal catalyst, characterized in that: The steps include: (1) preparing a uniform solution of ferric nitrate nonahydrate, gallium nitrate hexahydrate and deionized water, then adding HZSM-5, stirring, rotary evaporating, grinding and calcining to obtain a catalyst precursor Fe2O3 / Ga2O3 / HZSM-5; (2) Add ammonium metatungstate to the catalyst precursor Fe2O3 / Ga2O3 / HZSM-5 obtained in step (1), stir, rotary evaporate, grind and calcine to obtain WO3 / Fe2O3 / Ga2O3 / HZSM-5 catalyst.

2. The method according to claim 1, characterized in that: In step (1), the silicon-to-aluminum ratio of the HZSM-5 is 18-140.

3. The method according to claim 1, characterized in that: In step (1), the ferric nitrate nonahydrate, gallium nitrate hexahydrate, HZSM-5, and deionized water are added in a ratio of 0-8 g: 0-5 g: 5-15 g: 5-40 ml; preferably, the addition ratio is 0-6 g: 0-4 g: 8-12 g: 10-30 ml.

4. The method according to claim 1, characterized in that In step (2), the ammonium metatungstate, Fe2O3 / Ga2O3 / HZSM-5 and deionized water are added in a ratio of 0.5-5g:5-20g:5-40ml; preferably, the addition ratio is 0.5-2g:8-15g:10-30ml.

5. The method according to claim 1, characterized in that: The stirring in step (1) is continued at room temperature for 12-24 hours; the stirring in step (2) is continued at room temperature for 6-24 hours.

6. The method according to claim 1, characterized in that The rotary evaporation in steps (1) and (2) is performed at 60-90° C. for 3-12 hours; preferably at 80° C. for 6 hours.

7. The method according to claim 1, characterized in that The calcination in steps (1) and (2) is carried out in a muffle furnace at a temperature of 500-600°C and maintained at this temperature for 4-12 hours; preferably, the temperature is increased to 550°C at a rate of 5°C / min and maintained for 6 hours.

8. Use of the WO3 / Fe2O3 / Ga2O3 / HZSM-5 catalyst prepared by the method according to any one of claims 1 to 7, characterized in that: The catalyst is applied to the reaction of 2-methylfuran and isopropanol to prepare p-xylene.

9. The use according to claim 8, characterized in that Catalyst WO3 / Fe2O3 / Ga2O3 / HZSM-5, 2-methylfuran and isopropanol are added into a high-pressure reactor, and catalytic reaction is carried out under nitrogen atmosphere to obtain p-xylene.

10. The use according to claim 9, characterized in that The addition amount of WO3 / Fe2O3 / Ga2O3 / HZSM-5, 2-methylfuran and isopropanol is 0.1-0.3g: 0.05-0.2g: 8-12ml; preferably, the addition amount of the three is 0.2g: 0.1g: 10ml; the conditions of the catalytic reaction are: reaction at 300-800rpm and 350-400℃ for 6-12h under magnetic stirring; preferably, reaction at 600rpm and 385℃ for 8h under magnetic stirring.

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