CN111298818A

CN111298818A - Palladium and platinum catalyst, preparation thereof and application thereof in reaction for preparing furan from furfural

Info

Publication number: CN111298818A
Application number: CN201911115253.2A
Authority: CN
Inventors: 纪娜; 原强; 郑明远; 赵宇
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2020-06-19
Anticipated expiration: 2039-11-14
Also published as: CN111298818B

Abstract

The invention provides a palladium and platinum catalyst and application thereof in furan preparation reaction by furfural decarbonylation, wherein the catalyst is represented by A-C/B; wherein A-C are active components; a is one of metal palladium and platinum, C is carbonate of Li, Na, K, Mg, Ca and La; b is a hierarchical pore carrier with a nano-sheet structure. Palladium and platinum are used as main active components, carbonate containing Li, Na, K, Mg, Ca and La is used for modification, and the modified palladium and platinum are loaded on nano-sheet type molecular sieves, nano-sheet type aluminum oxide and other nano-sheet structured hierarchical pore materials and used for preparing furan by decarbonylation of furfural. The catalyst can realize the catalytic conversion of the furfural into furan with high efficiency, high selectivity and high yield under the conditions of 200-400 ℃ and normal pressure of hydrogen, and keeps high stability. Compared with the catalyst taking the conventional mesoporous material as the carrier, the catalyst has the remarkable advantages of high yield, high stability, green and environment-friendly reaction process and the like.

Description

Palladium and platinum catalyst, preparation thereof and application thereof in reaction for preparing furan from furfural

Technical Field

The invention relates to preparation of furan, in particular to a palladium and platinum catalyst, preparation thereof and application thereof in reaction for preparing furan by decarbonylation of furfural.

Background

The furfural is a chemical raw material with simple production process and low product price. The raw material for producing the furfural is simple in obtaining route and can be prepared from waste materials of agricultural products, and the yield of furan prepared from the furfural is high. Researchers in countries around the world have not stopped studying this aspect since the beginning of the century. In view of the demand of furan in the market, the demand is increasing, and the current production cannot meet the demand of the market. Therefore, the research on furan is more important in all countries. Furan is a very important organic raw material, and is widely applied to numerous organic syntheses and synthesis and research in the aspect of medicines. The raw materials for preparing the furfural are mostly from plant or crop leftovers. Furfural is used as an organic raw material which is very cheap and easy to produce, and is widely produced and applied. At present, the annual yield of furfural in China reaches about tens of thousands of tons, the yield is rich, but most furfural is exported to abroad at low cost, and deep processing production is not fully applied. The method for preparing furan from furfural not only solves the problem of the development of furfural deep-processing products in China, but also meets the requirement on furan in China, and has practical and feasible significance in terms of decarbonylation conversion rate, selectivity and yield.

In the last 30 th century, Hurds et al reported furfural decarbonylation, and in the fifth and sixth 20 th century, many patents were issued successively, and in the middle of the last century, researchers in all countries have done a lot of work on furfural reaction, so far, the research on furfural decarbonylation by the institute of organic synthesis of Ladeswia's republic of sciences was still being conducted, and in addition, many researchers in European countries have also conducted a lot of research on furfural decarbonylation [ Eschchinazi H.catalytic decarbonylation of aldehydes and hydrogenation of aldehydes by paladium [ J ]. Bull Soc Chim France, 1952 ].

The present industrially used two methods of decarbonylation of furfural to prepare furan are mainly liquid phase decarbonylation and gas phase decarbonylation, but the liquid phase decarbonylation method adopts gas phase decarbonylation method because the product is not easy to separate, and the catalyst mainly used in gas phase decarbonylation is Pd/Al₂O₃. However, the existing catalyst Pd has high loading capacity, the preparation method is complex, and the conversion rate, selectivity and stability are all to be improved [ Singh H, Prasad M, Srivatava R Dtions inthe palladium-catalysed decompositionof furfural to furan[J].J Chem TechBiotechnal，1980，30：45-47】。

Disclosure of Invention

The invention aims to provide a palladium and platinum catalyst, a preparation method thereof and application thereof in furan preparation reaction by furfural decarbonylation; the method can realize the catalytic conversion of furfural into furan with high yield and high selectivity under the reaction conditions of low loading and normal-pressure heating and hydrogen introduction.

In order to achieve the purpose, the invention adopts the technical scheme that:

a catalyst for preparing furan by catalyzing furfural is represented by A-C/B; wherein A-C are active components; a is one of metal palladium and platinum, C is carbonate of Li, Na, K, Mg, Ca and La; the total loading capacity of the active components A-C in the catalyst is 1.05-60%, the loading capacity of the active components A is 0.05-10 wt%, and the loading capacity of the active components C is 1-50 wt%. B is a nano-sheet structured multi-stage pore carrier, and is one of nano-sheet type aluminum oxide and nano-sheet type molecular sieve.

The loading amount is the mass fraction of A or C in B.

The catalyst adopts a method of dipping active component salt solution to load the active component on the carrier, and the preferable load of C is 5-20 wt%. The preferred loading of metal A is 0.1-5 wt%.

The preparation method of the palladium and platinum catalyst comprises the steps of dipping soluble salt solution of an active component A on a carrier, adding C for modification, drying at the temperature of 100-160 ℃, and roasting in the air; the roasting temperature is 300-600 ℃, and the roasting time is more than or equal to 2 hours; after the baking, at H₂The reduction is carried out under the condition that the space velocity is 10-100. The calcination temperature of the catalyst is preferably 400-500 ℃.

The soluble salt of the active component A comprises nitrate, chloride and acetate. The preferred salt solution is nitrate solution, and the catalyst of the invention is used for realizing the reaction process of preparing furan from furfural as follows: the decarbonylation reaction of the furfural is carried out in a fixed bed, quartz sand is filled up and down in a reaction tube, and a catalyst is placed in the middle of the reaction tube and close to a thermocouple. Purification of reaction raw material furfuralThe degree is 50-99%, the air speed of the furfural is 0.5-10, and H₂The space velocity is 10-100, the reaction temperature is raised to 200-400 ℃, furan is collected in a condensing device, and the yield is higher than 73% under the appropriate reaction conditions.

The invention has the following advantages:

1. the furfural with high yield in the market of China at present is used as a raw material, the source of the furfural is wide, most chemical plants can produce the furfural, and the production cost is low. Compared with the existing industrial synthetic method of furan, the catalyst provided by the invention has the advantages of high selectivity, high yield, good stability, reproducibility and capability of meeting the requirements of sustainable development.

2. Less palladium and platinum are used as main active components, the running time is long, and after regeneration, the catalyst can still maintain high performance, and the catalyst cost is reduced.

3. The catalytic process has high product yield and selectivity, and the yield of furan can reach over 73% under optimized reaction conditions. Therefore, the method has good application prospect.

The following is a detailed description of the present invention with reference to specific examples.

Detailed Description

Example 1

Preparation of mfi (ns) vector: MFI (NS) refers to a hierarchical pore molecular sieve with a nanosheet structure and cross pores, 22.05g of tetrabutyl phosphorus hydroxide, 22.50g of ethyl orthosilicate and 9.6g of ultrapure water are weighed, stirred at 25 ℃ for 12 hours, the stirred solution is added into a 180ml hydrothermal reaction kettle, the reaction kettle is placed into a 115 ℃ oven for 120 hours, after being taken out, the formed solid is placed into a centrifuge cup, the ultrapure water is added, the mixture is centrifuged at 8000r/min for 3 times, then the separated solid is placed into a 100 ℃ oven for 12 hours, and finally the solid is roasted in a muffle furnace at 550 ℃ for 4 hours. [ Chan Wang, Mingyua Zheng, catalysis conversion of ethanol in butane over high performance LiZnHf-MFI Zeoliranosylethets [ J ]. Green chem.,2019,21,1006 one 1010 ]

Example 2

Al₂O₃Preparation of (NS) vector: al (Al)₂O₃(NS) refers to the hierarchical porous alumina with the nanosheet structure, 9.28g of urea and 6.44g of aluminum nitrate are weighed, 125ml of ultrapure water is added, the mixture is stirred for 30min at 25 ℃, the stirred solution is added into a 180ml of hydrothermal reaction kettle, the reaction kettle is placed into an 80 ℃ oven for 48h, after the reaction kettle is taken out, the gel-like solid is subjected to suction filtration for 3 times by using the ultrapure water and ethanol respectively, then the separated solid is placed into the 80 ℃ oven for 12h, and finally the gel-like solid is roasted in a muffle furnace for 2h at 600 ℃. [ LeiShi, Gao-Ming Deng, Wen-Cui Li₂O₃Nanosheets Rich in Pentacoordinate Al³⁺IonsStabilize Pt-SnClusters for Propane Dehydrogenation[J].Angew.Chem.Int.Ed.2015,54：13994–13998】

Example 3

Pt-Na₂CO₃Preparation of the/MFI (NS) catalyst: palladium nitrate is prepared into a solution, and the Pt concentration of the solution is 1%. Then, the catalyst is prepared by an isovolumetric impregnation method, 0.6g of prepared palladium nitrate solution and 0.3g of ultrapure water are added, 1g of MFI (NS) carrier is taken to be impregnated for 5 hours, and 0.1g of Na is added₂CO₃Thereafter, the mixture was left at room temperature for 12 hours. Drying the catalyst precursor in a 120 ℃ oven for 12 hours, and then roasting the catalyst precursor in air atmosphere, wherein the specific reaction process is as follows: 1.0g of precursor was calcined in a muffle furnace at room temperature for 4h at 400 ℃ over 120 min. The Pt loading amount was 0.6 wt% and Na was obtained₂CO₃Pt-Na with a loading of 10 wt%₂CO₃catalyst/MFI (NS), expressed as Pt-Na₂CO₃/MFI(NS)(0.6wt％Pt-10wt％Na₂CO₃)。

Example 4

Furfural catalytic conversion experiment: 1.0g of catalyst was charged into a reaction tube, the temperature was raised from room temperature, 1H to 300 ℃ and H was introduced₂The flow rate is 60ml/min, and H is adjusted after 1H of reduction₂The flow rate is 30ml/min, and the raw material furfural is started to be input through a constant flow pump, and the flow rate is 3 ml/h. The product was collected and analyzed by gas chromatography. The furfural conversion rate is 1- (molar amount of furfural in the product/molar amount of furfural in the feedstock) x 100%. The yield of furan was calculated as (number of moles of furan in the product/number of moles of furfural in the raw material) x 100%. Yield to the target only in the yieldThe product furan was calculated and other liquid products including furfuryl alcohol, 2-methylfuran were not calculated for their yields. Run time refers to the time required for the yield to drop to 70% of the optimum yield.

Example 5

The performances of catalysts with different metals and different loading amounts in the decarbonylation reaction of furfural are compared with those of the traditional catalyst:

the catalyst preparation conditions were the same as in example 3, except for the selection of the active metal and the mass of the active metal, and the reaction conditions were the same as in example 4. The reaction results are shown in Table 1.

Table 1 comparison of the performance of different metals and different loadings of catalyst in the decarbonylation of furfural with conventional catalysts

Catalyst and process for preparing same	The highest conversion rate of furfural	The highest selectivity of furan%	Run time h
				0.6％Pd-10％Na₂CO₃/MFI(NS)	99	78	204
0.05％Pt-10％Na₂CO₃/MFI(NS)	72	95	27
				0.6％Pt-10％Na₂CO₃/MFI(NS)	99	74	296
10％Pt-10％Na₂CO₃/MFI(NS)	99	95	926
				0.6％Pd-10％Na₂CO₃/γ-Al₂O₃	99	86	12

As can be seen from the table, when the loading is the same, the selectivity is higher when Pd is used as the main active metal, and Pt has better stability as the main active component; when the active metals are the same, the higher the loading capacity is, the better the conversion rate, selectivity and stability are. Compared with the conventional mesoporous material gamma-Al used at present₂O₃Compared with the supported catalyst, the supported catalyst has slightly lower yield but greatly enhanced stability under the condition of the same loading, and the operation time is 25 times that of the current catalyst. Even when compared to 0.05% loading of the catalyst, the run time exceeded that of the currently used catalyst.

Example 6

The performances of different types and supported carbonate Pt catalysts in the decarbonylation reaction of furfural are compared with those of the traditional catalyst:

the catalyst preparation conditions were the same as in example 3, except for the type and loading of carbonate, and the reaction conditions were the same as in example 4. The reaction results are shown in Table 2.

Table 2 comparison of the performance of different kinds and loadings of carbonate Pt catalysts in the decarbonylation of furfural with conventional catalysts

Catalyst and process for preparing same	The highest conversion rate of furfural	The highest selectivity of furan%	Run time h
				0.6％Pt-10％Li₂CO₃/MFI(NS)	86	76	186
0.6％Pt-1％Na₂CO₃/MFI(NS)	73	73	26
				0.6％Pt-10％Na₂CO₃/MFI(NS)	99	74	296
0.6％Pt-50％Na₂CO₃/MFI(NS)	78	69	29
				0.6％Pt-10％K₂CO₃/MFI(NS)	99	64	164
0.6％Pt-10％CaCO₃/MFI(NS)	78	67	25
				0.6％Pt-10％MgCO₃/MFI(NS)	86	62	22
0.6％Pt-10％La₂CO₃/MFI(NS)	91	76	97
				0.6％Pt/MFI(NS)	71	64	13
0.6％Pt-10％Na₂CO₃/γ-Al₂O₃	99	86	12
				0.6％Pt/γ-Al₂O₃	72	66	4

It can be seen from the table that the catalyst without carbonate modification is lower in yield and operation time than the catalyst with carbonate modification. And the loading of carbonate is not as small as possible or as large as possible, but at a suitable value for optimum conversion, selectivity and run time. Compared with different carbonates, the carbonate modified catalyst of monovalent metal has better performance, and the stronger the alkalinity is, the higher the conversion rate is, but the lower the selectivity is, and the Na is comprehensively viewed₂CO₃The modified catalyst performed best. Compared with the conventional mesoporous material gamma-Al used at present₂O₃Compared with the catalyst used as the carrier, the stability of the catalyst is obviously improved no matter which carbonate is used for modification.

Example 7

The performances of Pt catalysts with different carriers in the decarbonylation reaction of furfural are compared:

the catalyst preparation conditions were the same as in example 3, except for the choice of the support and the reaction conditions were the same as in example 4. The reaction results are shown in Table 3

Table 3 comparison of the performances of catalysts with different supports in the decarbonylation of furfural

Catalyst and process for preparing same	The highest conversion rate of furfural	The highest selectivity of furan%	Run time h
				0.6％Pt-10％Na₂CO₃/MFI(NS)	99	74	296
0.6％Pt-10％Na₂CO₃/Al₂O₃(NS)	92	75	144
				0.6％Pt-10％Na₂CO₃/γ-Al₂O₃	99	86	12

As can be seen from the table, compared with the conventional mesoporous material as a carrier, the hierarchical porous material with the nanosheet structure has the advantages that the selectivity is slightly reduced, the running time is greatly improved, the regeneration effect is good, and the industrial application value is better.

Example 8

0.6% Pt-10% Na prepared by different preparation methods₂CO₃Performance comparison of mfi (ns) catalyst in furfural decarbonylation reaction:

the reaction conditions were the same as in example 4 except that the respective conditions of the catalyst preparation method were different. The reaction results are shown in Table 4.

TABLE 4 0.6% Pt-10% Na from different preparations₂CO₃Comparison of Performance of/MFI (NS) catalyst in Furfural decarbonylation reaction

The optimal conditions are that the drying temperature is 120 ℃, the roasting temperature is 400 ℃, the roasting time is 4H, and H₂Space velocity 30. Under this optimum condition, 0.6% Pt-10% Na₂CO₃The run time of the/MFI (NS) catalyst was 296h, while0.6％Pt-10％Na₂CO₃/γ-Al₂O₃The run time for the catalyst was 12h (data in the last column of Table 1), 0.6% Pt-10% Na in the above table₂CO₃The catalyst has better operation time than 0.6 percent Pt-10 percent Na in the range given by the specification₂CO₃/γ-Al₂O₃Run time of catalyst (data in the last column of table 1).

Example 9

The different reaction conditions have an influence on the performance of the catalyst in the decarbonylation reaction of furfural:

0.6% Pt-10% Na prepared in example 3 was used₂CO₃The results of the reaction are shown in Table 5.

TABLE 5 Effect of different reaction conditions on the catalyst Performance in the decarbonylation of Furfural

As can be seen from the table, when the purity of furfural is low, the performance of the catalyst is obviously reduced because other substances such as furoic acid are mixed and the catalyst is sensitive to acid-base property; when the loading capacity is fixed, the active sites are fixed, and the airspeed of the furfural is increased, the furfural cannot react in time, and carbon deposition is directly formed to cover the active metal, so that the performance of the catalyst is influenced; the reaction temperature is not as high as possible, nor as low as possible, but a suitable temperature is required; h₂The catalyst mainly takes away CO, and the CO has a toxic effect on the catalyst, so that the catalyst has a function of protecting the catalyst, and the catalyst has poor performance at a low space velocity and has higher economic cost at a high space velocity. Therefore, the catalyst can achieve better performance when the reaction conditions are within the range given in the summary of the invention.

The optimal experimental reaction conditions are as follows: the purity of the furfural is 99 percent, the airspeed of the furfural is 0.5, the reaction temperature is 300 ℃, and H₂Space velocity 30. Under the condition, 0.6% of Pt-10% of Na₂CO₃The run time of the/MFI (NS) catalyst was 492 h.

While the methods and techniques of the present invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and/or modifications of the methods and techniques described herein may be made without departing from the spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.

Claims

1. A palladium, platinum catalyst characterized by: the catalyst is represented by a formula A-C/B, wherein A-C is an active component, and A is one of metal palladium and metal platinum; c is a carbonate of Li, Na, K, Mg, Ca, La; b is a carrier which is alumina with a nano-sheet structure or a molecular sieve with a nano-sheet structure; the total loading capacity of the active components A-C in the catalyst is 1.05-60%, the loading capacity of the metal A in the catalyst is 0.05-10 wt%, and the loading capacity of the metal C in the catalyst is 1-50 wt%.

2. The catalyst of claim 1, wherein: b in the formula A-C/B is a nano-sheet type multi-stage pore carrier which is one of nano-sheet structured alumina and a molecular sieve.

3. The catalyst of claim 1, wherein: b in the formula A-C/B is a nano-sheet type multi-stage pore carrier which is one of nano-sheet structured alumina and a molecular sieve; it is characterized in that the specific surface area is 150-600m²The pore structure comprises micropores, mesopores and macropores.

4. The catalyst of claim 1, wherein: the preferable loading of C in the catalyst is 5-20 wt%; the preferred loading of A in the catalyst is 0.1-5 wt%.

5. A process as claimed in claim 1The preparation method of the catalyst is characterized by comprising the following steps: impregnating soluble salt solutions of active components A and C on a carrier, drying at the temperature of 100-160 ℃, and roasting in the air; the roasting temperature is 300-600 ℃, and the roasting time is more than or equal to 2 hours; after the baking, at H₂The reduction is carried out under the condition that the space velocity is 10-100.

6. The application of the palladium and platinum catalyst in the decarbonylation of furfural to prepare furan is characterized in that: the reaction for preparing furan by decarbonylation of furfural is carried out on a fixed bed, the purity of the reaction raw material furfural is 50-99%, the airspeed of furfural is 0.5-10, and H is₂The space velocity is 10-100, and the temperature is raised to the reaction temperature of 200 ℃ and 400 ℃.

7. Use according to claim 6, characterized in that: the reaction temperature is 200 ℃ and 400 ℃, H₂The space velocity is 10-100.