CN109985622A

CN109985622A - One kettle way prepares γ-Al2O3The Au-Pd catalyst of load

Info

Publication number: CN109985622A
Application number: CN201910388250.XA
Authority: CN
Inventors: 吴萍萍; 王悦; 白鹏
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2019-05-10
Filing date: 2019-05-10
Publication date: 2019-07-09

Abstract

γ-Al is prepared there is provided herein a kind of₂O₃The short-cut method of the Au-Pd catalyst of load.The present invention is with inorganic salts AlCl₃·6H₂O and NaAlO₂For silicon source, with HAuCl₄For Jin Yuan, PdCl₂For palladium source, one kettle way is prepared for γ-Al under the conditions of coupling agent (3- mercaptopropyi) trimethoxy silane (MPTMS) is existing₂O₃The Au-Pd catalyst of load, and probed into influence of the MPTMS content to catalyst benzyl alcohol oxidation reactivity worth.The presence of coupling agent makes Au, Pd active component effectively load to γ-Al₂O₃In load.Prepared catalyst benzaldehyde yield is up to 74.9%.This method preparation flow is simple, is not necessarily to high temperature crystallization, reduces costs；Gained catalyst gold-palladium dispersion degree is higher, and Au-Pd nano-scale is smaller.

Description

One kettle way prepares γ-Al2O3The Au-Pd catalyst of load

Technical field

The present invention, which designs, a kind of prepares γ-Al₂O₃The short-cut method of the Au-Pd catalyst of load.This method preparation flow letter Single, gained catalyst performance is more excellent.With inorganic salts AlCl₃·6H₂O and NaAlO₂For silicon source, led by structure of PluronicP123 To agent, MPTMS is coupling agent, with HAuCl₄For Jin Yuan, PdCl₂Mesoporous γ-Al is prepared for palladium source₂O₃The Au-Pd of load receives Rice catalyst.

Background technique

Currently, benzaldehyde " green " production technology mainly has toluene oxidation method, reduction method and benzyl alcohol direct oxidation method etc.. Wherein toluene oxidation method is low since there are product yields, the defect more than by-product, limits its industrial applications, and reduction method by It is excessively high without the market competitiveness in hydrogenation reduction process production cost.Benzyl alcohol direct oxidation method, due to being passed through with atom Ji property is high, simple process, environmental-friendly feature and show good application prospect.In recent years, with air, pure oxygen, double Oxygen water and its derivative are oxidant, with the research of metal or the nonmetallic alcohol compound catalytic oxidation for catalyst At once it gives birth to, " green, efficient " is its maximum feature.But how to prepare green, efficient catalyst is still the field One of problem.

Research shows that noble metal nano catalyst shows higher work in the reaction of benzyl alcohol liquid phase oxidation producing benzaldehyde Property, especially load type bimetal catalyst such as Au-Pd, Au-Cu and Au-Ir etc..Hutchings etc. is double golden by the gold-palladium of preparation Metal catalyst is used for benzyl alcohol oxidation research, the results showed that gold-palladium bimetallic catalyst has higher benzene compared with single-metal reforming catalyst Methanol oxidative activity and benzaldehyde selectivity.Research shows that there is synergistic effect, so that the work of bimetallic catalyst between Au-Pd Property be better than corresponding single-metal reforming catalyst.Later someone on this basis, stablizes Au-Pd bimetallic catalyst with PVP.Together When have studied under PVP protection, bimetallic and each single metallic catalyst catalytic phenylmethanol oxidation prepare the performance of benzoic acid, as a result Show that PVP-Au-Pd catalyst compared to other two kinds of single metallic catalysts, either makees oxidant with air or oxygen, It all shows more excellent result.It is former to pass through atomic layer deposition (ALD) for a kind of new short-cut method of the research reports such as Lu The Au@Pd core-shell structure copolymer bimetallic catalyst of sub accurate synthesis load, wherein the synergistic effect promoted due to passing through whole and electronics, The Au@Pd core-shell catalyst that Pd thickness of the shell is 0.6-0.8nm shows that maximum TOF is 27600h^-1。

The catalytic performance of carried noble metal nanocatalyst depends primarily on the size of noble metal nano particles, dispersion degree With the property of carrier.Common carrier has metal oxide (TiO₂, CeO₂, Fe₃O₄And Al₂O₃), metal-organic framework (MOFs), mesoporous silicon oxide, cellulose nano-fibrous and carbon material etc..Aluminium oxide is cheap and easy to get since its crystal form is abundant, tool Have good physicochemical properties (thermal stability, chemical stability, mechanical stability) etc., be widely used in catalyst, The fields such as catalyst carrier, adsorbent.Meso-porous alumina also has and is situated between in addition to the excellent properties with common alumina material Pore property, catalysis, absorption property are more superior.The alumina support specific surface area industrially prepared at present is less than 250m²/ g, Kong Rong is less than 0.5m³/ g, and pore-size distribution is wider.Compared with commercial alumina, the mesoporous γ-of zwitterion double hydrolyzation preparation Al₂O₃With higher specific surface area (> 400m²/ g), more flourishing cellular structure can have by the modified support of modifying agent Different acidic sites, preferable hydrothermal stability are highly suitable as Industrial Catalysis agent carrier.The preparation method of catalyst is then determined Determine the size and dispersion degree of noble metal nano particles, and influences its reactivity worth.The preparation of usual carrier nanometer catalyst Method mainly has infusion process, deposition-precipitation, coprecipitation, ion-exchange etc., but traditional synthetic method mostly has work The problems such as property component dispersion degree is poor, and metal nanoparticle easy-sintering or synthesis process are cumbersome, and condition is difficult to control.

In view of the studies above background, this research attempts to find a kind of simple effective method and receives to synthesize high dispersive noble metal Rice catalyst, improves the stability of noble metal dispersion degree and noble metal nano catalyst, reduces production cost and catalyst cost. γ-Al is prepared the invention discloses a kind of₂O₃The short-cut method of the Au-Pd catalyst of load.With (MPTMS) for one pot of coupling agent Method is prepared for Au-Pd catalyst.MPTMS can be connected in the form of chemical bond with carrier and metal component, in coupling agent MPTMS Under the action of Au, Pd atomic energy and carrier have stronger interaction.The catalyst of this method preparation has preferably benzyl alcohol Oxidation susceptibility.

Summary of the invention

γ-Al is prepared the present invention provides a kind of₂O₃The short-cut method of the Au-Pd catalyst of load, with inorganic salts AlCl₃·6H₂O and NaAlO₂For silicon source, using PluronicP123 as structure directing agent, MPTMS is coupling agent, with HAuCl₄For Jin Yuan, PdCl₂Mesoporous γ-Al is prepared for palladium source₂O₃The Au-Pd nanocatalyst of load.In Al³⁺And AlO^2-It itself carries out double Hydrolysis prepares mesoporous γ-Al₂O₃During introduce MPTMS and metal component one-step synthesis meso-porous alumina load Au- Pd nanocatalyst (0.5%Au-0.5%Pd/ γ-Al₂O₃).This method has the catalyst tool that preparation flow is simple, prepared There is preferably benzyl alcohol selective oxidation susceptibility.

Typical synthesis process is (with 0.5%Au-0.5%Pd/ γ-Al₂O₃) for

(1) electronic balance weighs 2.414g AlCl₃·6H₂O, 2.28g NaAlO₂；It is separately added into 25ml deionized water, AlCl₃0.41g MPTMS, magnetic agitation 30min are added dropwise in solution；

(2) by AlCl₃·6H₂O and NaAlO₂Solution cocurrent pours into beaker, continues to stir 1.5h；

(3) 4.1ml 0.02mol/L PdCl is successively added dropwise₂The HAuCl of solution and 2.1ml 0.02mol/L₄, stir 4h；

(4) it weighs 2.5g P123 and adds 25ml deionized water dissolving, stir to clarify；

(5) colloidal sol for obtaining (3) carries out filtering and washing；

(6) filter cake that (5) obtain is mixed with P123 solution, stirs 4h；

(7) (6) are poured into glass dish to (4~5mm is thick), put oven drying 12h into；

(8) (7) after drying are put into tube furnace roasting, heating rate is 2 DEG C/min, is warming up to 500 DEG C, constant temperature 3h； It is cooled to room temperature to catalyst, in a hydrogen atmosphere, 400 DEG C of reductase 12 h is warming up to 5 DEG C/min, obtain catalyst 0.5% Au-0.5%Pd/ γ-Al₂O₃.Wherein 0.5% is respectively golden, palladium mass content in catalyst.

Compared with pervious preparation method, the present invention has the advantage that

(1) step of the invention directly obtains Au-Pd/ γ-Al₂O₃Catalyst, synthesis process are simple and easy.

(2) use of coupling agent MPTMS can make Au, Pd metal active constituent effectively load to γ-Al₂O₃On

(3) present invention uses cheap, nontoxic inorganic aluminate AlCl₃·6H₂O and NaAlO₂, it is higher and have to avoid price The use of the alkyl aluminum of poison, does not produce pollution.

Detailed description of the invention

Fig. 1 is 4 gained Au-Pd/ γ-Al of embodiment 1- example₂O₃The N of catalyst₂Adsorption and desorption isotherms；

Fig. 2 is 4 gained Au-Pd/ γ-Al of embodiment 1- example₂O₃The graph of pore diameter distribution of catalyst；

Fig. 3 is 4 gained Au-Pd/ γ-Al of embodiment 1- example₂O₃The XRD wide-angle diffraction figure of catalyst；

Table 1 is 4 gained Au-Pd/ γ-Al of embodiment 1- example₂O₃Catalyst benzyl alcohol oxidation result

Specific embodiment

Embodiment 1: at room temperature, respectively by 2.414g AlCl₃·6H₂O and 2.28g NaAlO₂It is dissolved in 25ml distilled water. In AlCl₃0.41g MPTMS is added dropwise in solution, according to Al₂O₃/ MPTMS mole for equal to 10:1；By AlCl₃With NaAlO₂It is molten Liquid cocurrent pours into beaker, generates white precipitate, and gained mixture stirs 1.5h at room temperature, 2.1ml 0.024mol/L is slowly added dropwise PdCl₂The HAuCl of solution and 4.25ml 0.024mol/L₄Then it filtered, washed, obtained containing Au, Pd presoma Alumine hydroxide colloid filter cake.2.5gP123 is added in 25ml deionized water, is stirred to clarify, then by P123 solution with The mixing of alumine hydroxide colloid filter cake, mashing stirring 4h.Product after mashing is placed under 100 DEG C of baking ovens dry 12h, then in horse 500 DEG C not are warming up to the heating rate of 2 DEG C/min in furnace, 500 DEG C of constant temperature calcining 3h.In a hydrogen atmosphere, with 5 DEG C/min liter Temperature obtains catalyst sample 1 to 400 DEG C of reductase 12 h.The specific surface area of gained catalyst is 397.9m²/ g, Kong Rong 1.2cm³/ g, Average pore size 12.4nm.The benzaldehyde yield of the catalyst is 58.7%.

Embodiment 2: at room temperature, respectively by 2.414g AlCl₃·6H₂O and 2.28g NaAlO₂It is dissolved in 25ml distillation respectively In water.In AlCl₃0.26g MPTMS is added dropwise in solution, according to Al₂O₃The molar ratio of/MPTMS is equal to 15；By AlCl₃With NaAlO₂ Solution cocurrent pours into beaker, generates white precipitate, and gained mixture stirs 1.5h at room temperature, 2.1ml is slowly added dropwise The PdCl of 0.024mol/L₂Solution and 4.25ml, the HAuCl of 0.024mol/L₄Then filtered, washed, obtain containing Au, The alumine hydroxide colloid filter cake of Pd presoma.2.5gP123 is added in 25ml deionized water, is stirred to clarify, then will P123 solution is mixed with alumine hydroxide colloid filter cake, mashing stirring 4h.Product after mashing is placed under 100 DEG C of baking ovens dry Then 12h is warming up to 500 DEG C in Muffle furnace with the heating rate of 2 DEG C/min, 500 DEG C of constant temperature calcining 3h.In hydrogen atmosphere Under, 400 DEG C of reductase 12 h are warming up to 5 DEG C/min, obtain catalyst sample 2.The specific surface area of gained catalyst is 449.0m²/ G, Kong Rong 1.0cm³/ g, average pore size 9.3nm.The benzaldehyde yield of the catalyst is 74.9%.

Embodiment 3: at room temperature, respectively by 2.414g AlCl₃·6H₂O and 2.28g NaAlO₂It is dissolved in 25ml distillation respectively In water.In AlCl₃0.26g MPTMS is added dropwise in solution, according to Al₂O₃The molar ratio of/MPTMS is equal to 20；By AlCl₃With NaAlO₂ Solution cocurrent pours into beaker, generates white precipitate, and gained mixture stirs 1.5h at room temperature, 2.1ml is slowly added dropwise The PdCl of 0.024mol/L₂Solution and 4.25ml, the HAuCl of 0.024mol/L₄Then filtered, washed, obtain containing Au, The alumine hydroxide colloid filter cake of Pd presoma.2.5g P123 is added in 25ml deionized water, is stirred to clarify, then will P123 solution is mixed with alumine hydroxide colloid filter cake, mashing stirring 4h.Product after mashing is placed under 100 DEG C of baking ovens dry Then 12h is warming up to 500 DEG C in Muffle furnace with the heating rate of 2 DEG C/min, 500 DEG C of constant temperature calcining 3h.In hydrogen atmosphere Under, 400 DEG C of reductase 12 h are warming up to 5 DEG C/min, obtain catalyst sample 3.The specific surface area of gained catalyst is 453.7m²/ G, Kong Rong 1.3cm³/ g, average pore size 11.4nm.The benzaldehyde yield of the catalyst is 61.52%.

Embodiment 4: at room temperature, respectively by 2.414g AlCl₃·6H₂O and 2.28g NaAlO₂It is dissolved in 25ml distillation respectively In water.In AlCl₃0.1g MPTMS is added dropwise in solution, according to Al₂O₃The molar ratio of/MPTMS is equal to 40；By AlCl₃With NaAlO₂ Solution cocurrent pours into beaker, generates white precipitate, and gained mixture stirs 1.5h at room temperature, 2.1ml is slowly added dropwise The PdCl of 0.024mol/L₂Solution and 4.25ml, the HAuCl of 0.024mol/L₄Then filtered, washed, obtain containing Au, The alumine hydroxide colloid filter cake of Pd presoma.2.5g P123 is added in 25ml deionized water, is stirred to clarify, then will P123 solution is mixed with alumine hydroxide colloid filter cake, mashing stirring 4h.Product after mashing is placed under 100 DEG C of baking ovens dry Then 12h is warming up to 500 DEG C in Muffle furnace with the heating rate of 2 DEG C/min, 500 DEG C of constant temperature calcining 3h.In hydrogen atmosphere Under, 400 DEG C of reductase 12 h are warming up to 5 DEG C/min, obtain catalyst sample 4.The specific surface area of gained catalyst is 466.7m²/ G, Kong Rong 1.4cm³/ g, average pore size 12.1nm.The benzaldehyde yield of the catalyst is 54.9%.

Claims

1. a kind of one kettle way prepares γ-Al₂O₃The synthetic method of the Au-Pd catalyst of load, with 0.5%Au-0.5%Pd/ γ- Al₂O₃For, synthesis step is as follows

(1) respectively by a certain amount of AlCl₃·6H₂O and NaAlO₂It is dissolved in appropriate amount of deionized water and prepares AlCl₃And NaAlO₂It is molten Liquid, and in AlCl₃A certain amount of MPTMS, magnetic agitation 30min to clarification are added dropwise in solution；

(2) cocurrent mixes AlCl obtained by (1) at room temperature₃And NaAlO₂Solution stirs 1.5h after mixing；Then it is added dropwise certain Measure the HAuCl of 0.02mol/L₄The PdCl of solution and 0.02mol/L₂Solution continues to stir 4-8h；

(3) a certain amount of P123 is added in appropriate amount of deionized water and stirs 1h, form clear P123 solution；

(4) product that step (2) obtains is filtered, is washed, and obtains the aluminum hydroxide filter cake containing Au, Pd presoma, by P123 Solution is added in this filter cake and 3-4h is sufficiently stirred；

(5) (4) are poured into glass dish to (4~5mm is thick), put oven drying 12-48h into；

(6) product after drying is warming up to set temperature, and one section of constant temperature calcining in Muffle furnace with the heating rate of 2 DEG C/min Then time is restored in a hydrogen atmosphere, obtain purpose product 0.5%Au-0.5%Pd/ γ-Al₂O₃Catalyst.

2. 0.5%Au-0.5%Pd/ γ-Al according to claim 1₂O₃Synthetic method, it is characterised in that: step (1) The AlCl₃The concentration of aqueous solution is best for 0.4-0.6mol/L, and NaAlO₂The concentration of aqueous solution be 1.0-2.0mol/L most It is good, Al₂O₃The molar ratio of/MPTMS is best when being 10-40.

3. 0.5%Au-0.5%Pd/ γ-Al according to claim 1₂O₃Synthetic method, it is characterised in that: step (2) It is described that PdCl is first added dropwise₂HAuCl is added dropwise after solution₄It solution and to be added dropwise dropwise, stirring to fully reacting, reaction time 4-8h.

4. 0.5%Au-0.5%Pd/ γ-Al according to claim 1₂O₃Synthetic method, it is characterised in that: step (3) The AlCl₃·6H₂The molar ratio of O and P123 is best 22.7~38.7.

5. 0.5%Au-0.5%Pd/ γ-Al according to claim 1₂O₃Synthetic method it is characterized by: step (5) Described in the liquefied mixture thickness that covers on surface plate in 3mm~5mm range be it is best, drying temperature is at 80-120 DEG C for most It is suitable for.

6. 0.5%Au-0.5%Pd/ γ-Al according to claim 1₂O₃Synthetic method it is characterized by: step (5) It is described, the maturing temperature of dried product exhibited at 450-550 DEG C be it is best, calcining time is that 3-8h is best, hydrogen reducing temperature 300-400 DEG C be it is best, recovery time 2-3h is best.