Preparation and application of a room temperature catalytic catalyst for the conversion of furanol to methylfuran

Abstract

The present invention discloses the preparation and application of a catalyst for catalyzing the conversion of furanol to methylfuran at room temperature, belonging to the field of fine organic chemicals. Using solid aluminum phosphate as an acidic support, the invention introduces palladium nanoparticles or single-atom palladium atoms via impregnation-reduction to produce a palladium cluster- or single-atom palladium-supported hydrogenation-acid catalytic bifunctional catalyst. This catalyst can catalyze the conversion of furanol to methylfuran in a single step at room temperature with excellent catalytic activity and high selectivity, providing new ideas and methods for the efficient catalytic conversion of biomass.

Description

Technical Field

[0001] The invention belongs to the field of fine organic chemicals, and particularly relates to the preparation and application of a catalyst for catalyzing the conversion of furanol into methylfuran at room temperature. Background Art

[0002] Upgrading lignocellulose into biofuels and fine chemicals is a promising avenue for a sustainable future economy. 2,5-Dimethylfuran (DMF) is considered an important biomass-based compound. Its high calorific value (30 kJ / mL), high boiling point (94°C), and high octane number (RON = 119) make it suitable for direct use as a biofuel. Furthermore, DMF can be used as a feedstock for the production of various high-value-added fine chemicals, such as 2,5-dimethyltetrahydrofuran (DMTHF), linear ketones / alcohols, cyclic ketones, pyrroles, and phthalic anhydride. Among these, DMTHF is a valuable organic solvent. Due to its boiling point close to that of water (90°C), it exhibits excellent combustion properties (RON = 82), and its energy density (31 kJ / mL) is comparable to that of gasoline (34.2 kJ / mL) and far exceeds that of ethanol (23 kJ / mL). Therefore, these methylfurans are excellent gasoline substitutes.

[0003] However, current processes for producing methylfuran from biomass still suffer from drawbacks such as high reaction temperatures, the introduction of homogeneous acids, and low conversion rates. For example, during the hydrolysis and hydrogenation of sugars, the addition of liquid acid catalysts can cause severe corrosion to the equipment (Tan Tianwei, Shen Chun, et al. Acidic solid catalyst for catalytic conversion of fructose to 2,5-dimethylfuran in one step [P], China, invention patent, CN 109985664B, 2019). Using homogeneous inorganic acids as acidic catalysts can severely damage the reaction equipment and result in a maximum DMF yield of only 66.3% (Wei Zuojun, Lou Jiongtao. A one-step method for producing 2,5-dimethylfuran from fructose [P], China, invention patent, CN 105175366A, 2015). Using the ionic liquid BmimCl+Ru / C as a catalyst to catalyze the conversion of fructose to DMF, the yield of 2,5-dimethylfuran (DMF) at 220°C, 5 MPa, and H₂ was only 40.8%, and separation was difficult (Zhang Tao, Li Changzhi. A method for preparing 2,5-dimethylfuran from fructose-based biomass [P], China, invention patent, CN 103864732A, 2014). Using carbon-based solid acid-coated non-precious metals as catalysts generally results in lower DMF yields, with the highest yield being only 71.1% (Li Jifan, Dong Wensheng et al. A bifunctional catalyst for catalyzing the direct conversion of fructose to 2,5-dimethylfuran in one step [P], China, invention patent, CN 108722495B, 2018). Professor Katalin Barta's research group used Cu2O as a catalyst to convert 5-hydroxymethylfurfural to DMF, achieving a DMF yield of 65% at 220°C, 5 MPa, and H2 (AJ Kumalaputri, G. Bottari, et al. ChemSusChem, 2014, 78, 2266-2275). Professor Zhu Yulei's research group used Ni / Al2O3 as a catalyst for the hydrodeoxygenation of 5-hydroxymethylfurfural to produce DMTHF, achieving a DMTHF yield exceeding 90% at 180°C, 1.2 MPa, and H2 (X. Kong, Y.-W. Li, Green Chem. 2015, 174, 2504-2514). Both methods require relatively high reaction temperatures, which increases production costs.

[0004] In view of this, it is of great research significance to design a new solid catalyst that enables multi-step catalytic reactions to be completed under mild conditions, thereby improving economic benefits and selectively and efficiently producing methylfuran. Summary of the Invention

[0005] The purpose of the present invention is to provide a room temperature (30 ° C) catalytic furan alcohol to methyl furan catalyst preparation and application thereof, the catalyst optimizes The spatial distance of the acidic sites and the synergistic effect of regulating acid and metal catalysis improve the activity and selectivity of furanol to methylfuran, improve the conversion efficiency of furanol to methylfuran, and achieve high activity and selectivity of the furanol conversion reaction; the catalyst has a large specific surface area, many exposed active sites, low mass transfer resistance, close coexistence of acid sites and precious metal sites, and efficient utilization of biomass resources is in line with the development concept of green chemistry.

[0006] The present invention specifically adopts the following technical solutions:

[0007] The present invention provides a method for preparing a solid bifunctional catalyst, comprising the following steps:

[0008] 1) mixing aluminum isopropoxide and phytic acid thoroughly, grinding the ground mixture, heating and calcining the mixture to obtain an aluminum phosphate acidic support;

[0009] 2) adding the noble metal precursor and the aluminum phosphate acidic support obtained in step 1) to a solvent, mixing and impregnating the mixture, and removing the liquid after the impregnation reaches equilibrium to obtain a solid powder;

[0010] 3) reducing the solid powder obtained in step 2) at high temperature to obtain a solid bifunctional catalyst.

[0011] Preferably, the calcination temperature in step 1) is 600° C. and the calcination time is 4 hours.

[0012] Preferably, in step 2), the noble metal precursor is palladium chloride and the solvent is ethanol.

[0013] Preferably, the high-temperature reduction in step 3) refers to calcination in a 10% H2 / Ar environment at 400°C for 4 hours.

[0014] Preferably, the solid bifunctional catalyst is a palladium cluster or a single-atom palladium supported hydrogenation-acid catalysis bifunctional catalyst (Pd NP / AlPO4 or SACsPd / AlPO4).

[0015] The present invention also provides the use of the solid bifunctional catalyst obtained by the preparation method in catalyzing the conversion of furanol into methylfuran in one step at room temperature.

[0016] Preferably, the one-step catalytic furanol conversion reaction is as follows: using the biomass derivative furanol as a reactant and tetrahydrofuran as a reaction medium, mixed with the solid bifunctional catalyst, and hydrogenolyzed and converted in a hydrogen atmosphere at 30°C to produce various methylfurans.

[0017] Preferably, the biomass derivative furanol includes: 2,5-dihydroxymethylfuran, 5-methylfurfuryl alcohol, furfuryl alcohol, and furan-3-methanol.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention provides a palladium cluster or single-atom palladium-supported hydrogenation-acid catalytic bifunctional catalyst that can catalyze the conversion of furanol into methylfuran at room temperature. The active sites of the catalyst are evenly distributed and can be recycled multiple times. The preparation method is simple and easy to industrialize.

[0020] 2. The catalyst of the present invention can efficiently catalyze the conversion of biomass furanol into the fine chemical product methylfuran. It is synthesized based on biomass platform compounds, reducing the problem of excessive dependence on petroleum. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A is Pd NP X-ray diffraction patterns of Pd / AlPO4 and SACsPd / AlPO4 catalysts; B is Pd NP X-ray photoelectron spectrum of Pd element in / AlPO4 catalyst. DETAILED DESCRIPTION

[0022] To make the objects, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be described clearly and completely below in conjunction with the examples. Where specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] Example 1Pd NP Preparation of / AlPO4 catalyst

[0025] 1. 2.0 g of commercial aluminum isopropoxide and 1.6 g of commercial phytic acid were thoroughly mixed and ground for 20 min. The ground mixture was then placed in a muffle furnace and calcined at 600° C. for 4 h (heating rate of 5° C. / min) to obtain an aluminum phosphate acidic support.

[0026] 2. 0.0264 g PdCl2 and 0.3 g aluminum phosphate acidic support were added to 10 mL ethanol and mixed. The mixture was heated at 100 ° C to completely evaporate the ethanol. The obtained solid powder was calcined in a tube furnace at 10% H2 / Ar flow rate and 400 ° C for 4 h (heating rate of 5 ° C / min) to obtain the catalyst Pd NP / AlPO4 (the amount of precious metal is 5wt%).

[0027] Example 2 Preparation of SACsPd / AlPO4 Catalyst

[0028] 1. 2.0 g of commercial aluminum isopropoxide and 1.6 g of commercial phytic acid were thoroughly mixed and ground for 20 min. The ground mixture was then placed in a muffle furnace and calcined at 600° C. for 4 h (heating rate of 5° C. / min) to obtain an aluminum phosphate acidic support.

[0029] 2. Take 0.0264g PdCl2 and 0.3g aluminum phosphate acidic support and add them to 10mL ethanol. The mixture is placed in a sealed container, heated to 40°C and stirred continuously. After 12 hours, the solution is drained and dried in a vacuum oven at 150°C overnight. The resulting solid powder is calcined in a tube furnace at a flow rate of 10% H2 / Ar and 400°C for 4 hours (heating rate of 5°C / min) to obtain the catalyst SACsPd / AlPO4 (noble metal content of 0.7wt%).

[0030] Example 3: Pd NP Preparation of 2,5-dimethyltetrahydrofuran (DMTHF) from 2,5-dihydroxymethylfuran over AlPO4 catalyst

[0031] Weigh 0.1mmol 2,5-dihydroxymethylfuran and 10mL tetrahydrofuran (THF) into a 25mL reactor and mix them. Then add 0.05g Pd NP / AlPO4, replace the air in the kettle with hydrogen five to six times to reduce the air content in the kettle; continue heating to 30℃ and maintain for 6h, and collect samples after the reaction is completed.

[0032] Example 4 Preparation of 2,5-dimethylfuran (DMF) by 2,5-dihydroxymethylfuran using SACsPd / AlPO4 catalyst

[0033] Weigh 0.1 mmol of 2,5-dihydroxymethylfuran and 10 mL of THF into a 25 mL reactor and mix. Then add 0.36 g of SACsPd / AlPO4 and replace the air in the reactor with hydrogen five to six times to reduce the air content in the reactor. Continue heating to 30°C and maintain for 6 hours. After the reaction is completed, collect the sample.

[0034] Example 5 Using Pd NP Preparation of DMTHF from 5-Methylfurfuryl Alcohol over 1,2-Dimethyl-1,2-Dimethyl-1,2-Dimethyl-2-[4-(2-methyl-1,2-dihydro-2-pyridine)]-4 ...

[0035] Weigh 0.1mmol 5-methylfurfuryl alcohol and 10mL THF into a 25mL reactor and mix, then add 0.05g Pd NP / AlPO4, replace the air in the kettle with hydrogen five to six times to reduce the air content in the kettle; continue heating to 30℃ and maintain for 6h, and collect samples after the reaction is completed.

[0036] Example 6 Preparation of DMF by 5-methylfurfuryl alcohol using SACsPd / AlPO4 catalyst

[0037] Weigh 0.1 mmol of 5-methylfurfuryl alcohol and 10 mL of THF into a 25 mL reactor and mix. Then add 0.36 g of SACsPd / AlPO4 and replace the air in the reactor with hydrogen five to six times to reduce the air content in the reactor. Continue heating to 30°C and maintain for 6 hours. After the reaction is completed, collect the sample.

[0038] Example 7 Using Pd NP Preparation of 2-methyltetrahydrofuran (2-THMF) by furfuryl alcohol catalyzed by / AlPO4 catalyst 0.1mmol furfuryl alcohol and 10mL THF were weighed and added into a 25mL reactor, and then 0.05g Pd NP / AlPO4, replace the air in the kettle with hydrogen five to six times to reduce the air content in the kettle; continue heating to 30℃ and maintain for 6h, and collect samples after the reaction is completed.

[0039] Example 8 Preparation of 2-methylfuran (2-MF) from furfuryl alcohol using SACsPd / AlPO4 catalyst: 0.1 mmol of furfuryl alcohol and 10 mL of THF were weighed and added to a 25 mL reactor, followed by mixing. 0.36 g of SACsPd / AlPO4 was then added, and the air in the reactor was replaced with hydrogen five to six times to reduce the air content in the reactor. Heating was continued to 30°C for 6 h, and samples were collected after the reaction was completed.

[0040] Example 9 uses Pd NP Preparation of 3-Methyltetrahydrofuran (3-THMF) over Furan-3-Methanol Catalyzed by AlPO4

[0041] Weigh 0.1mmol furan-3-methanol and 10mL THF into a 25mL reactor and mix them. Then add 0.05g Pd NP / AlPO4, replace the air in the kettle with hydrogen five to six times to reduce the air content in the kettle; continue heating to 30℃ and maintain for 6h, and collect samples after the reaction is completed.

[0042] Example 10 Preparation of 3-methylfuran (3-MF) by using SACsPd / AlPO4 catalyst to catalyze furan-3-methanol

[0043] Weigh 0.1 mmol of furan-3-methanol and 10 mL of THF into a 25 mL reactor and mix. Then add 0.36 g of SACsPd / AlPO4 and replace the air in the reactor with hydrogen five to six times to reduce the air content in the reactor. Continue heating to 30°C and maintain for 6 hours. After the reaction is completed, collect the sample.

[0044] The reaction conditions and sample properties of Examples 3-10 are shown in Table 1.

[0045] Table 1

[0046]

[0047]

[0048] As shown in Table 1, the catalyst of the present invention can achieve efficient one-step catalytic conversion of biomass furan alcohol to methylfuran. In Example 3, the yield of 2,5-dimethylfuran from the hydrogenolysis of 2,5-dihydroxymethylfuran was 68.9%. The catalyst is also versatile for reactions with other furan alcohols (5-methylfurfuryl alcohol, furfuryl alcohol, and furan-3-methanol).

[0049] The embodiments described above merely represent several preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they are not intended to limit the present invention. It should be noted that those skilled in the art will readily appreciate that the present invention is susceptible to various variations and modifications. Any modifications, equivalent substitutions, or improvements within the scope of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. Application of a solid bifunctional catalyst in the one-step catalytic conversion of furanol to methylfuran at room temperature; The one-step catalytic furanol conversion reaction comprises: using a biomass derivative furanol as a reactant and tetrahydrofuran as a reaction medium, mixing the biomass derivative furanol with the solid bifunctional catalyst, and hydrogenolyzing and converting the biomass derivative furanol at 30° C. in a hydrogen atmosphere to produce various methylfurans; the biomass derivative furanol includes: 2,5-dihydroxymethylfuran, 5-methylfurfuryl alcohol, furfuryl alcohol, furan-3-methanol; The preparation method of the solid bifunctional catalyst comprises the following steps: 1) Aluminum isopropoxide and phytic acid were thoroughly mixed and ground, and the ground mixture was calcined at 600°C for 4 h to obtain an aluminum phosphate acidic support; 2) taking palladium chloride as a noble metal precursor and the aluminum phosphate acidic support obtained in step 1) and adding them to ethanol for mixing and impregnation, and removing the liquid after the impregnation equilibrium is reached to obtain a solid powder; 3) The solid powder obtained in step 2) is calcined in a 10% H2 / Ar environment at 400°C for 4 h to obtain a palladium cluster or single-atom palladium supported hydrogenation-acid catalytic bifunctional catalyst.

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