CN109999801A - M-B@Pd-B@Al2O3Catalyst and preparation method thereof, application - Google Patents

Abstract

The invention belongs to the technical field of hydrogenation catalysts, and in particular relates to a M-B@Pd-B@Al ₂ O ₃ catalyst and a preparation method and application thereof. The M-B@Pd-B@Al ₂ O ₃ catalyst of the present invention comprises an active component inner core, an active component intermediate layer wrapped around the active component inner core, and an auxiliary agent outer layer wrapped around the active component intermediate layer; The active component inner core is M-B amorphous alloy, and M is selected from one of Zn, Cu, Fe, Co, and Ni; the active component intermediate layer is Pd-B amorphous alloy; the The outer layer of the additive is alumina. The invention provides a novel catalyst, which has high activity and selectivity when it is used for the selective hydrogenation of levulinic acid in water to prepare γ-valerolactone.

Description

M-B@Pd-B@Al2O3 catalyst and its preparation method and application

technical field

The invention belongs to the technical field of hydrogenation catalysts, and in particular relates to a MB@Pd-B@Al ₂ O ₃ catalyst and a preparation method and application thereof.

Background technique

As a source of energy and fuel, fossil fuels not only have decreasing reserves, but also the sulfur oxides and nitrogen oxides produced during the consumption process can easily cause environmental pollution. As an alternative to fossil fuels, lignocellulosic biomass and its derivatives are not only sustainable, but also produce fine chemicals and fuels that are environmentally friendly.

The hydrogenation of levulinic acid to prepare γ-valerolactone is a very important reaction in the process of biomass chemical industry, and an important intermediate reaction for preparing liquid fuel from cellulose or hemicellulose. At the same time, formic acid, as a common product of cellulose to prepare levulinic acid, can be used as a hydrogen source in the hydrogenation process, which improves the utilization rate of carbon atoms. In addition, it is of great significance to use the water-phase reaction process to efficiently convert the small molecules after hydrolysis of lignocellulose: the process of separating small organic molecules from the water phase is avoided, and the production cost is reduced; For the decomposition reaction and gasification reaction, the temperature is lowered and the energy loss is reduced. Therefore, it is of great economic and social significance to develop a catalyst with high activity and high selectivity that can catalyze the reaction of levulinic acid and formic acid to prepare γ-valerolactone in an aqueous reaction system.

The article "Research on Co/γ-Al ₂ O ₃ Catalytic Hydrogenation of Levulinic Acid to Synthesize γ-Valerolactone" discloses a catalytic hydrogenation process, which combines Co/γ-Al prepared by equal volume impregnation method ₂ O Catalyst, _1.67g of levulinic acid and 40mL of methanol were added to the autoclave, the air in the autoclave was replaced by hydrogen, then the hydrogen was passed to the reaction pressure, and the temperature was slowly raised to the reaction temperature to start the reaction (Zhang Lin et al., Industrial Catalysis, No. 21). Vol. 7, 68-71). When the catalyst is used to catalyze the hydrogenation of levulinic acid to produce γ-valerolactone, the selectivity of valerolactone can only reach 81.4% at the highest, and the selectivity is poor. In addition, in the prior art, the hydrogenation of levulinic acid to produce γ-valerolactone is mostly carried out in the organic phase, because the raw material levulinic acid is generally produced by utilizing biomass hydrolysis, and the levulinic acid produced by the hydrolysis needs to be produced when using the organic phase. separation, and the polarity of the product γ-valerolactone is small, and the use of an organic phase also increases the difficulty of separating the product from the system.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a MB@Pd-B@Al ₂ O ₃ catalyst, which can improve the selectivity to γ-valerolactone when used in the hydrogenation of levulinic acid to produce γ-valerolactone.

The second object of the present invention is to provide a simple process for preparing the MB@Pd-B@Al ₂ O ₃ catalyst.

The third object of the present invention is to provide an application of MB@Pd-B@Al ₂ O ₃ catalyst in hydrogenation reduction reaction, the catalyst has better hydrogenation activity.

To achieve the above object, the technical scheme adopted in the present invention is:

The MB@Pd-B@Al ₂ O ₃ catalyst includes an active component inner core, an active component intermediate layer wrapped around the active component inner core, and an auxiliary outer layer wrapped around the active component intermediate layer; the active component The inner core is MB amorphous alloy, and M is selected from one of Zn, Cu, Fe, Co, and Ni; the active component intermediate layer is Pd-B amorphous alloy; the auxiliary outer layer is oxidized aluminum.

The catalyst of the invention uses M-B amorphous alloy and Pd-B amorphous alloy as active components, and is wrapped with alumina in the outer layer, which avoids the direct contact between active components and water molecules during the water-phase reaction. phase is relatively stable. The active components of the catalyst of the present invention are composed of precious metals and non-precious metals, which not only ensures the hydrogenation activity of the catalyst but also reduces the cost to a certain extent. The catalyst of the invention has higher selectivity and activity when it is used for the selective hydrogenation of levulinic acid in water to produce γ-valerolactone.

The material ratio of M atoms in the MB amorphous alloy, Pd atoms in the Pd-B amorphous alloy, and Al atoms in alumina is 1:(0.05-1.5):(0.05-1.5). The MB@Pd-B@Al ₂ O ₃ catalysts exhibited better activity and selectivity at the above ratios.

In order to ensure sufficient contact between the catalyst and the reactants, the average particle size of the MB@Pd-B@Al ₂ O ₃ catalyst is 3-8 nm.

The preparation method of the above-mentioned MB@Pd-B@Al ₂ O ₃ catalyst comprises the following steps:

1) Mix the M-B amorphous alloy with the Pd sol, and gel under a protective atmosphere, so that the Pd sol becomes a Pd gel and coats the surface of the M-B amorphous alloy, and then adds borohydride to react, The Pd gel is changed into a Pd-B amorphous alloy, and the obtained precipitate is washed after the reaction is completed to obtain a Pd-B wrapped M-B amorphous alloy;

2) Mix the prepared Pd-B-wrapped M-B amorphous alloy with Al sol and gel under a protective atmosphere, so that the Al sol becomes Al gel and is coated on the Pd-B-wrapped M-B non-crystalline alloy. The surface of the crystalline alloy is then separated from solid and liquid, and the solid is washed to obtain it.

The invention provides a preparation method of a novel catalyst, which is simple and can be used for preparing a catalyst with a core-shell structure.

In order to achieve uniform coating of the gel, the gelation in steps 1) and 2) is maintained for 1 to 5 hours at a temperature of 50 to 150° C. and a pressure of a protective gas of 1 to 5 MPa.

In order to facilitate the subsequent process, the preparation method of the M-B amorphous alloy includes: adding borohydride to the soluble salt solution of metal M for reaction, and washing the resulting precipitate to neutrality after the reaction is complete.

In order to completely reduce the M atom, the ratio of the amount of the M atom in the soluble salt solution of the metal M to the B atom in the borohydride is 1:(5-50).

In order to completely reduce the Pd atom, the ratio of the amount of the Pd atom in the Pd sol to the B atom in the borohydride in step 1) is 1:(5-50).

Application of MB@Pd-B@Al ₂ O ₃ catalyst in hydrogenation reduction reaction. The catalyst of the invention has good hydrogenation activity and can be used in common hydrogenation reduction reactions such as furfural hydrogenation, benzene hydrogenation and the like.

The above hydrogenation reduction reaction is the hydrogenation of levulinic acid to generate γ-valerolactone. When the MB@Pd-B@Al ₂ O ₃ catalyst of the invention is used for the hydrogenation of levulinic acid to produce γ-valerolactone, when hydrogen is used as the hydrogen source, the conversion rate of levulinic acid is 100% in the reaction time of 5h , The selectivity of γ-valerolactone has reached more than 99%, which has important industrial application value.

Description of drawings

Figure 1 is a TEM image of the Zn-B@Pd-B@Al ₂ O ₃ catalyst in Example 1 of the MB@Pd-B@Al ₂ O ₃ catalyst;

Figure 2 is a TEM image of the Cu-B@Pd-B@Al ₂ O ₃ catalyst in Example 2 of the MB@Pd-B@Al ₂ O ₃ catalyst;

Figure 3 is a TEM image of the Co-B@Pd-B@Al ₂ O ₃ catalyst in Example 3 of the MB@Pd-B@Al ₂ O ₃ catalyst;

Figure 4 is a TEM image of the Ni-B@Pd-B@Al ₂ O ₃ catalyst in Example 4 of the MB@Pd-B@Al ₂ O ₃ catalyst;

5 is a TEM image of the Fe-B@Pd-B@Al ₂ O ₃ catalyst in Example 5 of the MB@Pd-B@Al ₂ O ₃ catalyst.

Detailed ways

The MB@Pd-B@Al ₂ O ₃ catalyst of the present invention comprises an active component inner core, an active component intermediate layer wrapped outside the active component inner core, and an auxiliary outer layer wrapped outside the active component intermediate layer; the The inner core of the active component is MB amorphous alloy, and M is selected from one of Zn, Cu, Fe, Co, and Ni; the middle layer of the active component is a Pd-B amorphous alloy; the outer layer of the auxiliary agent for alumina. The mass content of B is 0.02-0.04%.

Preferably, the material ratio of M atoms in the MB amorphous alloy, Pd atoms in the Pd-B amorphous alloy, and Al atoms in the alumina is 1:0.4:0.2. The performance of MB@Pd-B@Al ₂ O ₃ catalyst is the best at the above ratio.

The preparation method of the MB@Pd-B@Al ₂ O ₃ catalyst of the present invention comprises the following steps:

1) Mix the M-B amorphous alloy with the Pd sol, and gel under a protective atmosphere, so that the Pd sol becomes a Pd gel and coats the surface of the M-B amorphous alloy, and then adds borohydride to react, The Pd gel is changed into a Pd-B amorphous alloy, and the obtained precipitate is washed after the reaction is completed to obtain a Pd-B wrapped M-B amorphous alloy;

2) Mix the prepared Pd-B-wrapped M-B amorphous alloy with Al sol and gel under a protective atmosphere, so that the Al sol becomes Al gel and is coated on the Pd-B-wrapped M-B non-crystalline alloy. The surface of the crystalline alloy is then separated from solid and liquid, and the solid is washed to obtain it.

Preferably, the protective atmosphere is at least one of hydrogen, nitrogen, argon and helium. Further preferably, the protective gas is hydrogen.

The preparation method of the M-B amorphous alloy includes the following steps: adding borohydride to the soluble salt solution of metal M to carry out the reaction, and washing the resulting precipitate to neutrality after the reaction is completed. The temperature of the reaction is 0-50°C. The borohydride is an aqueous solution of alkali metal borohydride.

Step 1) The preparation method of the Pd sol includes the following steps: adding an alkaline solution to the soluble salt solution of Pd until no more precipitation occurs, and then adding a citric acid solution until the precipitation is completely dissolved.

The concentration of OH ^- in the alkali solution is 0.1-10 mol/L; the concentration of citric acid in the citric acid solution is 0.01-5 mol/L. The soluble salt of Pd is a soluble salt of +2-valent Pd. The alkaline solution is a solution of at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate.

In step 2), the preparation method of the Al sol includes: strengthening the alkali solution in the solution containing Al ³⁺ to generate precipitation, and continuing to strengthen the alkali solution until the precipitation is completely dissolved. The final generated Al sol was confirmed by the Tyndall effect. The strong base is at least one of sodium hydroxide and potassium hydroxide.

The present invention will be further described below with reference to specific embodiments and accompanying drawings.

Example 1 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Zn-B@Pd-B@Al ₂ O ₃ catalyst, including an active component core Zn-B amorphous alloy, which is wrapped around the active component core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Zn, Pd, and Al elements is 1: 0.4:0.2. The mass content of B in the catalyst of this example was measured by ICP to be 0.03%. The morphology of the Zn-B@Pd-B@Al ₂ O ₃ catalyst in this embodiment is shown in FIG. 1 , and it can be seen from FIG. 1 that the average particle size of the catalyst particles is about 5 nm.

Example ₂ of MB@Pd-B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Cu-B@Pd-B@Al ₂ O ₃ catalyst, including an active component inner core Cu-B amorphous alloy, which is wrapped around the active component inner core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Cu, Pd and Al elements is 1: 0.4:0.2. The mass content of B in the catalyst of this example was measured by ICP to be 0.04%. The morphology of the Cu-B@Pd-B@Al ₂ O ₃ catalyst of this embodiment is shown in FIG. 2 , and it can be seen from FIG. 2 that the average particle size of the catalyst particles is about 5 nm.

Example 3 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Co-B@Pd-B@Al ₂ O ₃ catalyst, which includes an active component inner core Co-B amorphous alloy, which is wrapped around the active component inner core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Co, Pd and Al elements is 1: 0.4:0.2. The mass content of B in the catalyst of this example was measured by ICP to be 0.03%. The morphology of the Co-B@Pd-B@Al ₂ O ₃ catalyst of this embodiment is shown in FIG. 3 , and it can be seen from FIG. 3 that the average particle size of the catalyst particles is about 5 nm.

Example 4 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Ni-B@Pd-B@Al ₂ O ₃ catalyst, which includes an active component inner core Ni-B amorphous alloy, and is wrapped around the active component inner core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Ni, Pd, and Al elements is 1: 0.4:0.2. The morphology of the Ni-B@Pd-B@Al ₂ O ₃ catalyst of this embodiment is shown in FIG. 4 , and it can be seen from FIG. 4 that the average particle size of the catalyst particles is about 5 nm.

Example 5 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Fe-B@Pd-B@Al ₂ O ₃ catalyst, which includes an active component core Fe-B amorphous alloy, which is wrapped around the active component core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of Fe, Pd and Al elements is 1: 0.4:0.2. The morphology of the Fe-B@Pd-B@Al ₂ O ₃ catalyst in this embodiment is shown in FIG. 5 , and it can be seen from FIG. 5 that the average particle size of the catalyst particles is about 5 nm.

Example 6 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Zn-B@Pd-B@Al ₂ O ₃ catalyst, including an active component core Zn-B amorphous alloy, which is wrapped around the active component core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Zn, Pd, and Al elements is 1: 0.07:1.3.

Example 7 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Zn-B@Pd-B@Al ₂ O ₃ catalyst, including an active component core Zn-B amorphous alloy, which is wrapped around the active component core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Zn, Pd, and Al elements is 1: 1.5:1.

Example 8 of MB@Pd _- B@ _Al2O3 catalyst

The MB@Pd-B@Al ₂ O ₃ catalyst in this embodiment is a Zn-B@Pd-B@Al ₂ O ₃ catalyst, including an active component core Zn-B amorphous alloy, which is wrapped around the active component core The active component intermediate layer Pd-B amorphous alloy and the auxiliary outer layer Al ₂ O ₃ wrapped outside the active component intermediate layer; in the catalyst, the ratio of the amount of Zn, Pd, and Al elements is 1: 1:0.08.

Example 1 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

The catalyst of this embodiment is Zn-B@Pd-B@Al ₂ O ₃ , and the preparation method thereof specifically adopts the following steps:

₁ ) Dissolve 2.1g ZnCl in 50mL distilled water to make a _ZnCl solution, take _5.8g NaBH and dissolve it in 50mL distilled water to make a NaBH solution, the substance ratio of NaBH and _ZnCl is ₁₀ : ₁ , and the _The NaBH solution was added dropwise to the _ZnCl solution at 30°C under stirring conditions, and the reaction was stirred until no black solid was formed, filtered, and the black solid was washed with distilled water until the filtrate was neutral to obtain Zn-B amorphous alloy.

₂ ) Dissolve 1.1g of PdCl in 50mL of distilled water to form a PdCl solution, add 4mol/L _NaOH solution dropwise to the _PdCl solution, until no more precipitation is formed, then add 1mol/L citric acid solution, Until the precipitation is completely dissolved, the Pd sol is obtained; the Zn-B amorphous alloy is added to the Pd sol, and the temperature is 150 ° C, the hydrogen pressure is 1 MPa, and the stirring speed is 800 r/min for 3 hours, so that the Pd sol becomes It is Pd gel and is wrapped on the surface of MB amorphous alloy to obtain a mixed solution; in the mixed solution, the ratio of Zn to Pd substances is 1:0.4;

Dissolve 3.5g of _NaBH in 50mL of distilled water to form a NaBH solution, and add the _NaBH solution dropwise to the mixture at 30°C under stirring conditions ₍ the ratio of the amount of B to Pd in the system is 15:1) , continue to stir for 30min to complete the reduction reaction, at this time no black solid is formed in the system, filter, and wash the black solid with distilled water until the filtrate is neutral, to obtain a Pd-B wrapped Zn-B amorphous alloy.

3) get 0.41g AlCl ₃ dissolve in 50mL distilled water to be made into AlCl ₃ solution, the NaOH solution of 4mol/L is added dropwise in the AlCl ₃ solution, until no more precipitation is formed, then add the NaOH solution of 4mol/L, Until the precipitation is completely dissolved, the Al sol is obtained; the Zn-B amorphous alloy wrapped by Pd-B is added to the Al sol (in the system, the ratio of the amount of Zn to Al is 1:0.2), and the temperature is 150 ℃, the hydrogen pressure was 1MPa, and the stirring speed was 800r/min for 3h, so that the Al sol became Al gel and was coated on the surface of the Pd-B-wrapped MB amorphous alloy, filtered, and the obtained black solid was used Wash with distilled water until the filtrate is neutral.

The mass content of B in the catalyst prepared in this example was measured by ICP to be 0.02%, and it was confirmed by XRD that Al existed in the form of Al ₂ O ₃ in the catalyst prepared in this example.

Example ₂ of the preparation method of MB@Pd-B@ _Al2O3 catalyst

This embodiment is the preparation method of the catalyst Cu-B@Pd-B@Al ₂ O ₃ in the embodiment 2 of the MB@Pd-B@Al ₂ O ₃ catalyst, and it is the same as the operation steps of the embodiment 1 of the preparation method of the catalyst Basically the same, the only difference is that, in step 1), 2.1 g of ZnCl ₂ is replaced with 2.1 g of CuCl ₂ , and finally a catalyst whose active component core is a Cu-B amorphous alloy is prepared.

Example 3 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of catalyst Co-B@Pd-B@Al ₂ O ₃ in Example 3 of MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of Example 1 of the preparation method of catalyst The same, the only difference is that, in step 1), 2.1 g of ZnCl ₂ is replaced with 2.0 g of CoCl ₂ , and finally a catalyst whose active component core is a Co-B amorphous alloy is prepared.

Example 4 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of catalyst Ni-B@Pd-B@Al ₂ O ₃ in Example 4 of MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of Example 1 of the preparation method of catalyst The same, the only difference is that, in step 1), 2.1 g of ZnCl ₂ is replaced by 2.0 g of NiCl ₂ , and finally a catalyst whose active component core is a Ni-B amorphous alloy is prepared. The mass content of B in the catalyst prepared in this example was measured by ICP to be 0.03%.

Example 5 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of catalyst Fe-B@Pd-B@Al ₂ O ₃ in Example 5 of MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of Example 1 of the preparation method of catalyst The same, the only difference is that, in step 1), 2.1 g of ZnCl ₂ is replaced with 2.0 g of FeCl ₂ , and finally a catalyst with an Fe-B amorphous alloy as the core of the active component is prepared. The mass content of B in the catalyst prepared in this example was measured by ICP to be 0.03%.

Example 6 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of catalyst Zn-B@Pd-B@Al ₂ O ₃ in Example 6 of MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of Example 1 of the catalyst preparation method The same, the difference is that in step 1), when preparing MB amorphous alloy, the ratio of the amount of Zn in ZnCl ₂ to the amount of B in NaBH ₄ is 1:7, and the reaction temperature is room temperature; in step 2), the The Zn-B amorphous alloy was added to the Pd sol and kept for 5 h under the conditions of a temperature of 100 °C, a hydrogen pressure of 3 MPa, and a stirring speed of 800 r/min; the reaction temperature after adding NaBH ₄ solution was room temperature; The ratio of the amount of B in Pd to NaBH ₄ is 1:25; in step 3), the Zn-B amorphous alloy wrapped by Pd-B is added to the Al sol, and the temperature is 100 ° C, the hydrogen pressure is 3 MPa, The stirring speed was kept at 800r/min for 5h.

Example 7 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of the catalyst Zn-B@Pd-B@Al ₂ O ₃ in Example 7 of the MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of the catalyst preparation method Example 1 The same, the difference is that in step 1), when preparing MB amorphous alloy, the ratio of the amount of Zn in ZnCl ₂ to the amount of B in NaBH ₄ is 1:20, and the reaction temperature is 15 ° C; in step 2), The Zn-B amorphous alloy was added to the Pd sol, and the temperature was 80 °C, the hydrogen pressure was 5 MPa, and the stirring speed was 800 r/min for 2 h; the reaction temperature after adding the NaBH ₄ solution was 15 °C; Pd and The ratio of the amount of B in NaBH ₄ is 1:8; in step 3), the Pd-B wrapped Zn-B amorphous alloy is added to the Al sol, and the temperature is 80 °C, the hydrogen pressure is 5 MPa, and the stirring speed is 2h under the condition of 800r/min.

Example 8 of the preparation method of MB@Pd _- B@ _Al2O3 catalyst

This example is the preparation method of the catalyst Zn-B@Pd-B@Al ₂ O ₃ in Example 8 of the MB@Pd-B@Al ₂ O ₃ catalyst, which is basically the same as the operation steps of the catalyst preparation method Example 1 The same, the difference is that in step 1), when preparing MB amorphous alloy, the ratio of Zn in ZnCl ₂ to the amount of B in NaBH ₄ is 1:15, and the reaction temperature is 35 ° C; in step 2), The Zn-B amorphous alloy was added to the Pd sol, and the temperature was 150 °C, the hydrogen pressure was 2 MPa, and the stirring speed was 800 r/min for 4 h; the reaction temperature after adding the NaBH ₄ solution was 35 °C; the Pd sol In step 3), the Pd _- B-wrapped Zn-B amorphous alloy was added to the Al sol at a temperature of 150 °C and a hydrogen pressure of 2MPa and stirring speed of 800r/min for 4h.

In other embodiments of the preparation method of the MB@Pd-B@Al ₂ O ₃ catalyst of the present invention, other soluble M salts, such as ZnSO ₄ , can be used when preparing the MB amorphous alloy; when preparing the Pt sol, the Using other soluble Pd salts, such as Pd(NO ₃ ) ₂ , etc., the concentration of each reaction raw material can be adaptively adjusted within the scope of the present invention according to the reaction conditions, the capacity of the reaction apparatus and other factors, and can be obtained equivalent to the embodiment. test effect.

Example of application of MB@Pd _- B@ _Al2O3 catalyst

In this example, hydrogen and formic acid are used as hydrogen sources, and the catalytic effects of the catalysts of Examples 1 to 8 of MB@Pd-B@Al ₂ O ₃ catalyst in the reaction of levulinic acid hydrogenation to prepare γ-valerolactone are respectively investigated.

When using hydrogen as the hydrogen source, the reaction process is as follows: 0.5g of catalyst and 12.5g of levulinic acid are added to the reactor, 250mL of distilled water is added, the air in the reactor is replaced with nitrogen, and then hydrogen is fed into the reactor to a pressure of 1.0MPa, the temperature was raised to 150°C at a heating rate of 1°C/min, and the stirring speed was controlled to be 800r/min.

When formic acid is used as the hydrogen source, the reaction process is as follows: 0.5 g of catalyst, 10.4 g of levulinic acid and 1.4 g of formic acid are added to the reaction kettle, 250 mL of distilled water is added, the temperature is raised to 150 ° C at a heating rate of 1 ° C/min, and the stirring is controlled. The speed is 800r/min.

After the reaction, the gas chromatograph using the FID detector was used to analyze the product composition, the area correction method was used to calculate the product concentration, and then the conversion rate of levulinic acid and the γ-valerolactone selectivity were calculated. The results are shown in Table 1.

Table 1 Evaluation of catalytic performance of catalysts

It can be seen from the results in Table 1 that Zn-B@Pd-B@Al ₂ O ₃ catalyst, Cu-B@Pd-B@Al ₂ O ₃ catalyst, Fe-B@Pd-B@Al ₂ O ₃ catalyst, Co-B@Pd-B@Al ₂ O ₃ catalyst and Ni-B@Pd-B@Al ₂ O ₃ catalyst both achieved 100% conversion of levulinic acid when using hydrogen as hydrogen source, and the reaction time was 5h The selectivity of γ-valerolactone reached more than 99%. This shows that the catalyst prepared by the present invention has important industrial application value. Formic acid was used as the hydrogen source, and the Zn-B@Pd-B@Al ₂ O ₃ catalyst could still achieve 100% conversion of levulinic acid and 99.5% selectivity of γ-valerolactone at the reaction time of 24 h, indicating that The catalyst has good stability.

Claims (10)

1. MB@Pd-B@Al ₂ O ₃ catalyst, characterized in that the catalyst comprises an active component inner core, an active component intermediate layer wrapped outside the active component inner core, and an active component intermediate layer wrapped outside the active component intermediate layer. The outer layer of the auxiliary agent; the inner core of the active component is MB amorphous alloy, and M is selected from one of Zn, Cu, Fe, Co, and Ni; the middle layer of the active component is Pd-B amorphous alloy ; The outer layer of the auxiliary agent is alumina. 2. The MB@Pd-B@Al ₂ O ₃ catalyst according to claim 1, wherein M atoms in the MB amorphous alloy, Pd atoms in the Pd-B amorphous alloy, and alumina The ratio of the amount of Al atoms is 1:(0.05-1.5):(0.05-1.5). 3 . The MB@Pd-B@Al ₂ O ₃ catalyst according to claim 1 , wherein the MB@Pd-B@Al ₂ O ₃ catalyst has an average particle size of 3-8 nm. 4 . 4. the preparation method of MB@Pd-B@Al ₂ O ₃ catalyst as claimed in claim 1, is characterized in that, comprises the following steps: 1) Mix the M-B amorphous alloy with the Pd sol, and gel under a protective atmosphere, so that the Pd sol becomes a Pd gel and coats the surface of the M-B amorphous alloy, and then adds borohydride to react, The Pd gel is changed into a Pd-B amorphous alloy, and the obtained precipitate is washed after the reaction is completed to obtain a Pd-B wrapped M-B amorphous alloy; 2) Mix the prepared Pd-B-wrapped M-B amorphous alloy with Al sol and gel under a protective atmosphere, so that the Al sol becomes Al gel and is coated on the Pd-B-wrapped M-B non-crystalline alloy. The surface of the crystalline alloy is then separated from solid and liquid, and the solid is washed to obtain it. 5. The preparation method of the MB@Pd-B@Al ₂ O ₃ catalyst according to claim 4, wherein the gelation in step 1) and step 2) is at a temperature of 50-150°C, The pressure of the protective gas is maintained for 1 to 5 hours under the condition of 1 to 5 MPa. 6 . The preparation method of the MB@Pd-B@Al ₂ O ₃ catalyst according to claim 4 , wherein the preparation method of the MB amorphous alloy comprises: adding metal M into the soluble salt solution of metal M. 7 . The borohydride is reacted, and after the reaction is complete, the resulting precipitate is washed to neutrality, that is, it is obtained. 7. The preparation method of MB@Pd-B@Al ₂ O ₃ catalyst according to claim 6, characterized in that, the amount of substance of M atom and B atom in borohydride in the soluble salt solution of metal M The ratio is 1:(5～50). 8. The preparation method of the MB@Pd-B@Al ₂ O ₃ catalyst according to claim 4, wherein the amount of the substance of the Pd atom in the Pd sol in the step 1) and the amount of the B atom in the borohydride is equal to The ratio is 1:(5～50). 9. The application of the MB@Pd-B@Al ₂ O ₃ catalyst according to claim 1 in hydrogenation reduction reaction. 10. The application of the MB@Pd-B@Al ₂ O ₃ catalyst in a hydrogenation reduction reaction according to claim 9, wherein the hydrogenation reduction reaction is the hydrogenation of levulinic acid to generate γ-pentane ester.