阅读说明：本技术 一种锰磷复合氧化物载体的制备方法及其负载铂的催化剂与应用 (Preparation method of manganese-phosphorus composite oxide carrier, platinum-loaded catalyst and application thereof ) 是由 方文浩 高天宇 曹秋娥 于 2019-10-23 设计创作，主要内容包括：本发明公开了一种锰磷复合氧化物载体的制备方法及其负载铂的催化剂与应用,属于催化剂技术领域。本发明将Mn(NO<Sub>3</Sub>)<Sub>2</Sub>·4H<Sub>2</Sub>O和KH<Sub>2</Sub>PO<Sub>4</Sub>溶解于去离子水中得到金属前驱体溶液A；在搅拌条件下,将氢氧化钠溶液逐滴滴入金属前驱体溶液A中调节pH值为8～11得到溶液B；将溶液B置于温度为60～100℃、搅拌条件下回流反应12～48h；固液分离,洗涤固体至洗涤液为中性,干燥、研磨得到前驱体粉末；将前驱体粉末匀速升温至温度为400～800℃并恒温煅烧4～8h,随炉冷却至室温即得锰磷复合氧化物载体。本发明锰磷复合氧化物载体负载铂的催化剂在无碱条件下作为催化剂可催化5-羟甲基糠醛(HMF)选择氧化制备2,5-呋喃二甲酸(FDCA)。(The invention discloses a preparation method of a manganese-phosphorus composite oxide carrier, a platinum-loaded catalyst and application thereof, and belongs to the technical field of catalysts. Mn (NO) is added to the catalyst 3 ) 2 ·4H 2 O and KH 2 PO 4 Dissolving in deionized water to obtain a metal precursor solution A; dropwise adding a sodium hydroxide solution into the metal precursor solution A while stirring to adjust the pH value to 8-11 to obtain a solution B; placing the solution B at the temperature of 60-100 ℃ and performing reflux reaction for 12-48 h under the stirring condition; performing solid-liquid separation, washing the solid until the washing liquid is neutral, drying and grinding to obtain precursor powder; and uniformly heating the precursor powder to 400-800 ℃, calcining at constant temperature for 4-8 h, and cooling to room temperature along with the furnace to obtain the manganese-phosphorus composite oxide carrier. The catalyst with platinum loaded on the manganese-phosphorus composite oxide carrier can be used as a catalyst to catalyze 5-Hydroxymethylfurfural (HMF) to select oxygen under the alkali-free conditionAnd (3) preparing 2, 5-furandicarboxylic acid (FDCA).)

1. The preparation method of the manganese-phosphorus composite oxide carrier is characterized by comprising the following specific steps of:

(1) adding Mn (NO)₃)₂·4H₂O and KH₂PO₄Dissolving in deionized water to obtain a metal precursor solution A;

(2) dropwise adding a sodium hydroxide solution into the metal precursor solution A obtained in the step (1) under the stirring condition, and adjusting the pH value to 8-11 to obtain a solution B;

(3) placing the solution B in the step (2) at the temperature of 60-100 ℃ and performing reflux reaction for 12-48 h under the stirring condition; performing solid-liquid separation, washing the solid until the washing liquid is neutral, drying and grinding to obtain precursor powder;

(4) and (4) uniformly heating the precursor powder obtained in the step (3) to 400-800 ℃, calcining at a constant temperature for 4-8 hours, and cooling to room temperature along with the furnace to obtain the manganese-phosphorus composite oxide carrier.

2. The method for producing a manganese-phosphorus composite oxide support according to claim 1, characterized in that: KH in the step (1)₂PO₄Middle P and Mn (NO)₃)₂·4H₂The molar ratio of Mn in O is (0.42-2.00): 1.

3. The method for producing a manganese-phosphorus composite oxide support according to claim 1 or 2, characterized in that: mn (NO) in metal precursor solution A in step (1)₃)₂·4H₂The molar concentration of O is 0.1-1.0 mol/L.

4. The catalyst with platinum loaded on the manganese-phosphorus composite oxide carrier is characterized in that: the carrier is the manganese-phosphorus composite oxide carrier prepared by the preparation method of the manganese-phosphorus composite oxide carrier according to claim 1, and the loading amount of platinum is 1-4 wt%.

5. The method for preparing the catalyst with platinum supported on the manganese-phosphorus composite oxide carrier as claimed in claim 4, is characterized by comprising the following steps:

1) h is to be₂PtCl₆·6H₂Dissolving O in the polyvinylpyrrolidone aqueous solution to obtain a solution C;

2) under the condition of stirring, NaBH is added₄Dropwise adding the solution into the solution C obtained in the step 1) to react for 10-20 min, adding the manganese-phosphorus composite oxide carrier of claim 4, and continuously stirring to react for 2-4 h; and (3) performing suction filtration and washing by using water at the temperature of 80-100 ℃, washing by using normal-temperature deionized water, and performing vacuum drying at the temperature of 60-120 ℃ for 12-24 hours to obtain the catalyst with the manganese-phosphorus composite oxide carrier loaded with platinum.

6. The method for producing a catalyst in which platinum is supported on a manganese-phosphorus composite oxide carrier according to claim 5, characterized in that: the concentration of the polyvinylpyrrolidone in the polyvinylpyrrolidone water solution in the step 1) is 0.01-0.1 mg/mL.

7. The method for producing a catalyst in which platinum is supported on a manganese-phosphorus composite oxide carrier according to claim 5, characterized in that: step 1) polyvinylpyrrolidone and H in polyvinylpyrrolidone aqueous solution₂PtCl₆·6H₂The mass ratio of Pt in O is (1.0-2.0): 1.

8. The method for producing a catalyst in which platinum is supported on a manganese-phosphorus composite oxide carrier according to claim 5, characterized in that: step 2) NaBH₄NaBH in solution₄And H₂PtCl₆·6H₂The molar ratio of Pt in O is (5-10): 1.

9. The use of the catalyst comprising platinum supported on a manganese-phosphorus composite oxide carrier according to claim 4 as a catalyst for the selective oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid under alkali-free conditions.

Technical Field

The invention relates to a preparation method of a manganese-phosphorus composite oxide carrier, a platinum-loaded catalyst and application thereof, belonging to the technical field of catalysts.

Background

Biomass resources are one of the most abundant renewable resources on earth. Among them, lignocellulose resources are the most common biomass resources, which can be converted into high value-added fuels and chemicals, and alleviate the dependence of human beings on non-renewable fossil fuels to a certain extent, and have become an extremely important development consensus and basic research direction of chemical discipline. The biomass platform compound 5-Hydroxymethylfurfural (HMF) is an important lignocellulose derivative, the structural formula of the biomass platform compound contains furan rings, aldehyde groups and hydroxyl groups, the chemical property is active, and a series of high value-added chemicals can be prepared through the biomass platform compound.

HMF can produce 2, 5-furandicarboxylic acid (FDCA) via the oxidation route. FDCA molecular structure is similar to petroleum refining derivative terephthalic acid (PTA), can replace the latter to generate polyesterification reaction with glycol to produce polyethylene furan acid ester, namely renewable PEF engineering plastics, and is widely used for films and pipelines, in particular to plastic bottles for producing soft drinks, drinking water and fruit juice.

When HMF is oxidized to produce FDCA, the aldehyde and hydroxyl groups are simultaneously oxidized, thus having two different oxidation reaction pathways and more intermediate oxidation products (shown in fig. 1).

Therefore, how to improve and maintain the selectivity and yield of the FDCA is a key and difficult point, and how to develop a new catalyst which has excellent catalytic performance and stable recycling performance under mild reaction conditions.

The published Pt-loaded nanoparticle catalyst for selective oxidative synthesis of FDCA aiming at HMF usually needs to add soluble alkali NaOH or Na₂CO₃Under conditions effective to selectively oxidize the hydroxyl and carbonyl groups of the reactants to carboxyl groups of the product. The addition of the soluble alkali easily causes corrosion of reaction equipment, the maintenance cost of the equipment is increased, the emission of the soluble alkali causes environmental pollution, and the treatment cost is high. On the other hand, in the catalytic system containing the alkali additive, the product is FDCA sodium salt or potassium salt, FDCA can be obtained only by further acidification and purification, and the process cost is high. The reaction temperature in the catalytic system is higher (more than or equal to 120 ℃), the energy consumption is higher, the oxidant pressure is higher (more than or equal to 10bar), and certain potential safety hazards exist. In addition, the catalyst is used in a large amount (HMF/Pt molar ratio is less than or equal to 50) in the catalytic system, so that the cost of the catalytic reaction is increased. Therefore, from the viewpoint of more demanding economic, environmental and safe green chemistry, the precondition for maintaining the advantages of the catalytic system isNext, the use of a green oxidizing agent (O) is established₂) And a solvent (H)₂O), no alkali is added, and the reaction condition is mild.

Disclosure of Invention

Aiming at the technical problem of preparing FDCA (fully drawn yarn) by oxidizing HMF (high molecular weight polyethylene) and providing a manganese-phosphorus composite oxide carrier MnP_nPreparation method of (1) and platinum-loaded catalyst Pt/MnP thereof_nThe invention relates to a manganese-based composite oxide carrier and a Pt nano particle loaded catalyst thereof, and application thereof₂O is a solvent, O₂The oxidizing agent is an oxidizing agent, and can efficiently oxidize HMF to synthesize FDCA under the condition of no alkali additive.

A preparation method of a manganese-phosphorus composite oxide carrier comprises the following specific steps:

(1) adding Mn (NO)₃)₂·4H₂O and KH₂PO₄Dissolving in deionized water to obtain a metal precursor solution A;

(2) dropwise adding a sodium hydroxide solution into the metal precursor solution A obtained in the step (1) under the stirring condition, and adjusting the pH value to 8-11 to obtain a solution B;

(3) placing the solution B in the step (2) at the temperature of 60-100 ℃ and performing reflux reaction for 12-48 h under the stirring condition; performing solid-liquid separation, washing the solid until the washing liquid is neutral, drying and grinding to obtain precursor powder;

(4) and (4) uniformly heating the precursor powder obtained in the step (3) to 400-800 ℃, calcining at a constant temperature for 4-8 hours, and cooling to room temperature along with the furnace to obtain the manganese-phosphorus composite oxide carrier.

KH in the step (1)₂PO₄Middle P and Mn (NO)₃)₂·4H₂The molar ratio of Mn in O is (0.42-2.00): 1.

Mn (NO) in the metal precursor solution A in the step (1)₃)₂·4H₂The molar concentration of O is 0.1-1.0 mol/L.

The catalyst with platinum loaded on the manganese-phosphorus composite oxide carrier is the manganese-phosphorus composite oxide carrier prepared by the preparation method of the manganese-phosphorus composite oxide carrier according to claim 1, and the loading amount of the platinum is 1-4 wt%.

The preparation method of the catalyst with platinum loaded on the manganese-phosphorus composite oxide carrier comprises the following specific steps:

1) h is to be₂PtCl₆·6H₂Dissolving O in the polyvinylpyrrolidone aqueous solution to obtain a solution C;

2) under the condition of stirring, NaBH is added₄Dropwise adding the solution into the solution C obtained in the step 1) to react for 10-20 min, adding the manganese-phosphorus composite oxide carrier of claim 4, and continuously stirring to react for 2-4 h; and (3) performing suction filtration and washing by using water at the temperature of 80-100 ℃, washing by using normal-temperature deionized water, and performing vacuum drying at the temperature of 60-120 ℃ for 12-24 hours to obtain the catalyst with the manganese-phosphorus composite oxide carrier loaded with platinum.

The concentration of the polyvinylpyrrolidone in the polyvinylpyrrolidone aqueous solution in the step 1) is 0.01-0.1 mg/mL.

Polyvinylpyrrolidone and H in polyvinylpyrrolidone aqueous solution in the step 1)₂PtCl₆·6H₂The mass ratio of Pt in O is (1.0-2.0): 1.

The step 2) of NaBH₄NaBH in solution₄And H₂PtCl₆·6H₂The molar ratio of Pt in O is (5-10): 1.

The catalyst with platinum loaded on the manganese-phosphorus composite oxide carrier can be used as a catalyst under the alkali-free condition to catalyze 5-hydroxymethylfurfural to prepare 2, 5-furandicarboxylic acid through selective oxidation.

The invention has the beneficial effects that:

(1) the nonmetal element P is doped into the preparation process of manganese oxide for the first time to synthesize the manganese-phosphorus composite oxide, and Pt/MnP can be prepared by further loading nano Pt particles_nThe catalyst has excellent application prospect in the field of catalytic oxidation;

(2) the manganese-phosphorus composite oxide loaded Pt nano particle catalyst can be prepared by using H₂O is a solvent, O₂Oxidizing HMF to synthesize FDCA by using an oxidizing agent without adding alkali, wherein the yield of the FDCA is as high as more than 99%;

(3) Pt/MnP of the invention_nExcellent catalyst performance, andcompared with the reported Pt catalyst, the invention needs the least catalyst mass, the Pt effective component accounts for only 1mol percent of the reactant HMF at most, and the required oxygen pressure is very low, thereby effectively reducing the cost of the catalyst and ensuring that the reaction is safer and more environment-friendly.

Drawings

FIG. 1 is a schematic diagram of the selective oxidative synthesis of FDCA from HMF; wherein HMF is 5-hydroxymethylfurfural; DFF is 2, 5-diformylfuran; HMFCA is 5-hydroxymethyl-2-furancarboxylic acid; FFCA is 5-formaldehyde-2-furancarboxylic acid; FDCA is 2, 5-furandicarboxylic acid;

FIG. 2 shows Pt/MnP of example 1_nX-ray powder diffraction (XRD) pattern of the catalyst.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.

Comparative example: a preparation method of a manganese-phosphorus composite oxide carrier comprises the following specific steps:

(1) adding Mn (NO)₃)₂·4H₂Dissolving O in deionized water to obtain a metal precursor solution A; wherein Mn (NO) in the metal precursor solution A₃)₂·4H₂The molar concentration of O is 0.5 mol/L;

(2) dropwise adding a sodium hydroxide solution into the metal precursor solution A obtained in the step (1) to adjust the pH value to 9 under the stirring condition to obtain a solution B;

(3) placing the solution B in the step (2) at the temperature of 90 ℃ and carrying out reflux reaction for 24 hours under the stirring condition; performing solid-liquid separation, washing the solid until the washing liquid is neutral, drying and grinding to obtain precursor powder;

(4) and (4) uniformly heating the precursor powder in the step (3) to 500 ℃, calcining at constant temperature for 4 hours, and cooling to room temperature along with the furnace to obtain the manganese oxide carrier.