Organic-inorganic hybrid catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and discloses an organic-inorganic hybrid catalyst as well as a preparation method and application thereof. The catalyst carrier is composed of g-C3N4 and CuZnAl-LDH (layered double hydroxide), the active component is Pd. The active component of the catalyst is the active metal Pd with a nano structure, so that the loading capacity of the metal can be reduced, high catalytic activity is realized, and the cost of raw materials is greatly saved. A carrier of the catalyst is an organic-inorganic composite carrier and has electron vacancies, so that strong electron interaction between the carrier and active metal species is ensured. Under the action of the catalyst, the dimethyl succinate is subjected to high-selectivity hydrogenation, so that the generation of byproducts is reduced. The catalyst is simple and convenient in preparation process and low in cost, and has relatively high atom economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an organic-inorganic hybrid catalyst and a preparation method and application thereof. Background Art

[0002] 1,4-Butanediol is an important organic chemical raw material with a wide range of industrial applications. Due to its unique chemical properties, 1,4-butanediol can be used to produce a variety of chemicals and materials, including polyurethanes, polyesters, plasticizers, solvents, and various fine chemicals. 1,4-Butanediol is an indispensable raw material in many industries such as automobiles, textiles, pharmaceuticals, and consumer goods. The traditional production method of 1,4-butanediol mainly relies on petrochemical raw materials, such as hydrogenation of succinic acid or dimethyl succinate. With the increasing attention to environmental protection and sustainable development, it is particularly important to develop efficient, low-cost and environmentally friendly methods for the synthesis of 1,4-butanediol. The synthesis of 1,4-butanediol by hydrogenation of dimethyl succinate has become a promising synthetic route due to its advantages such as easy availability of raw materials, mild reaction conditions and environmental friendliness.

[0003] The core technology of 1,4-butanediol production is hydrogenation catalyst, mainly Raney-type catalyst and supported catalyst. Supported catalyst currently mainly uses transition metal as active component, including Pt, Pd and Rh, which is a highly efficient catalyst for hydrogenation reaction, with good conversion rate and high selectivity for conversion to 1,4-butanediol; active component Ru and Re catalysts are also commonly used, but the main products are γ-butyrolactone and tetrahydrofuran. Various oxides with porous structures can be used as carriers, the most commonly used are Al 2 O 3 , ZrO 2 , TiO 2 , SiO 2 and activated carbon. The catalytic hydrogenation reaction of dimethyl succinate usually needs to be carried out at a higher pressure and temperature, which places high demands on equipment and increases production costs. Although non-precious metal catalysts can be used for this reaction, patent CN102784651B provides a method of dissolving the corresponding nitrates of copper, zinc and cerium into an aqueous solution, adding an MgO carrier thereto, adding a NaOH precipitant, calcining to obtain a catalyst matrix, and then reducing it with a hydrogen flow to obtain CuO / ZnO / Ce 2 O 3 / MgO catalyst is used for hydrogenation of dimethyl succinate to produce 1,4-butanediol, with a conversion rate of 100% and a selectivity of 99.5%, but the reaction temperature reaches 200°C, and dimethyl succinate and methanol are prepared into a reaction solution at a ratio of 1:4 (volume ratio) and added to a fixed bed, making product separation more difficult. Precious metal catalysts (such as palladium and platinum) usually have higher activity and selectivity, and are also more expensive. Side reactions may also occur during the hydrogenation process, such as excessive hydrogenation to produce tetrahydrofuran or other by-products, which may affect the purity and yield of the final product. Therefore, it is of great significance to develop a catalyst for hydrogenation of dimethyl succinate to produce 1,4-butanediol with relatively mild reaction conditions and high selectivity. Summary of the invention

[0004] The object of the present invention is to provide an organic-inorganic hybrid catalyst and a preparation method and application thereof, so as to solve the above-mentioned problems existing in the catalyst for preparing 1,4-butanediol by hydrogenation of dimethyl succinate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an organic-inorganic hybrid catalyst, which comprises an organic-inorganic composite carrier and an active component; the organic-inorganic composite carrier is composed of gC 3 N 4 and CuZnAl-LDH; the active component is Pd.

[0007] Preferably, in the above-mentioned organic-inorganic hybrid catalyst, the molar ratio of Cu, Zn and Al elements in the CuZnAl-LDH is 1 to 4:1:1.

[0008] Preferably, in the above organic-inorganic hybrid catalyst, the mass of Pd is 0.1 to 0.6% of the total mass of the organic-inorganic hybrid catalyst.

[0009] Preferably, in the above-mentioned organic-inorganic hybrid catalyst, in the organic-inorganic composite carrier, gC 3 N 4 The mass fraction of CuZnAl-LDH is 20~80%.

[0010] The present invention also provides a method for preparing an organic-inorganic hybrid catalyst, comprising the following steps:

[0011] Cu 2+ 、Zn 2+ 、Al 3+ The mixed aqueous solution and CO 3 2- OH- The mixed aqueous solution is mixed to undergo a hydrothermal reaction to obtain CuZnAl-LDH;

[0012] CuZnAl-LDH was calcined to obtain CuZnAlO; gC 3 N 4 and CuZnAlO in water, then remove water and grind to obtain an organic-inorganic composite carrier;

[0013] The organic-inorganic composite carrier is dispersed in water, then mixed with an aqueous solution of an active component precursor, and then a reducing agent is added to carry out a reduction reaction to obtain the organic-inorganic hybrid catalyst.

[0014] Preferably, in the above-mentioned method for preparing an organic-inorganic hybrid catalyst, the Cu 2+ 、Zn 2+ 、Al 3+ The mixed aqueous solution and CO 3 2- OH - Cu in mixed aqueous solution 2+ 、Zn 2+ 、Al 3+ , CO 3 2- OH - The amount of substance satisfies the following relationship:

[0015]

[0016] in, Cu 2+ 、Zn 2+ The total amount of substance; For Al 3+ The amount of substance.

[0017] Preferably, in the above-mentioned method for preparing an organic-inorganic hybrid catalyst, the temperature of the hydrothermal reaction is 100 to 180° C.; the time of the hydrothermal reaction is 12 to 24 hours.

[0018] Preferably, in the above-mentioned method for preparing an organic-inorganic hybrid catalyst, the active component precursor is PdCl 2 ; The reducing agent is one of sodium borohydride, potassium borohydride and hydrogen; the reduction reaction time is 1 to 5 hours.

[0019] The present invention also provides an application of an organic-inorganic hybrid catalyst in catalyzing the hydrogenation of dimethyl succinate to prepare 1,4-butanediol.

[0020] Preferably, in the above application, the reaction conditions for catalytic hydrogenation of dimethyl succinate to prepare 1,4-butanediol are: reaction temperature of 120-220°C; hydrogen pressure of 3-8 MPa; space velocity of 0.2-3 h -1 ; The hydrogen-ester ratio is 100-200.

[0021] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The active component of the catalyst of the present invention is nanostructured active metal Pd, which can reduce the metal loading while achieving higher catalytic activity, thus greatly saving raw material costs.

[0023] (2) CuZnAl-LDH@gC 3 N 4 The organic-inorganic composite carrier has electron vacancies, which ensures strong electronic interaction between the carrier and the active metal species. Under the action of this catalyst, dimethyl succinate is highly selectively hydrogenated, reducing the generation of by-products.

[0024] (3) The preparation process of the catalyst of the present invention is simple and inexpensive, and has high atom economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0026] Figure 1 gC prepared in Example 1 3 N 4 、CuZnAl-LDH、0.3%Pd / CuZnAl-LDH@gC 3 N 4 SEM images of the catalysts; (a) is CuZnAl-LDH, (b) is gC 3 N 4 , (c) 0.3%Pd / CuZnAl-LDH@gC 3 N 4 catalyst;

[0027] Figure 2 gC prepared in Example 1 3 N 4 、CuZnAl-LDH、0.3%Pd / CuZnAl-LDH@gC 3 N 4 FT-IR spectrum of the catalyst. DETAILED DESCRIPTION

[0028] The present invention provides an organic-inorganic hybrid catalyst, which comprises an organic-inorganic composite carrier and an active component; the organic-inorganic composite carrier is composed of gC 3 N 4 and CuZnAl-LDH; the active component is Pd.

[0029] In the present invention, the molar ratio of Cu, Zn and Al elements in the CuZnAl-LDH is preferably 1 to 4:1:1, more preferably 2 to 4:1:1, and more preferably 3:1:1.

[0030] In the present invention, the mass of the Pd is preferably 0.1 to 0.6% of the total mass of the organic-inorganic hybrid catalyst, more preferably 0.2 to 0.5%, and even more preferably 0.3%.

[0031] In the present invention, in the organic-inorganic composite carrier, gC 3 N 4 The mass fraction of is preferably 20 to 80%, more preferably 30 to 60%, more preferably 50%; the mass fraction of CuZnAl-LDH is preferably 20 to 80%, more preferably 40 to 70%, more preferably 50%.

[0032] The present invention also provides a method for preparing an organic-inorganic hybrid catalyst, comprising the following steps:

[0033] Cu 2+ 、Zn 2+ 、Al 3+ The mixed aqueous solution and CO 3 2- OH - The mixed aqueous solution is mixed to undergo a hydrothermal reaction to obtain CuZnAl-LDH;

[0034] CuZnAl-LDH was calcined to obtain CuZnAlO; gC 3 N 4 and CuZnAlO in water, then remove water and grind to obtain an organic-inorganic composite carrier;

[0035] The organic-inorganic composite carrier is dispersed in water, then mixed with an aqueous solution of an active component precursor, and then a reducing agent is added to carry out a reduction reaction to obtain the organic-inorganic hybrid catalyst.

[0036] In the present invention, the Cu 2+ 、Zn 2+ 、Al 3+ Independently derived from nitrate or chloride.

[0037] In the present invention, the CO3 2- Derived from Na 2 CO 3 OH - Derived from NaOH.

[0038] In the present invention, the Cu 2+ 、Zn 2+ 、Al 3+ The mixed aqueous solution and CO 3 2- OH - Cu in mixed aqueous solution 2+ 、Zn 2+ 、Al 3+ , CO 3 2- OH - The amount of substance satisfies the following relationship:

[0039]

[0040] in, Cu 2+ 、Zn 2+ The total amount of substance; For Al 3+ The amount of substance.

[0041] In the present invention, the temperature of the hydrothermal reaction is preferably 100-180°C, more preferably 110-150°C, and more preferably 120°C; the time of the hydrothermal reaction is preferably 12-24h, more preferably 12-16h, and more preferably 12h.

[0042] In the present invention, after the hydrothermal reaction is completed, washing, filtering, drying and grinding are also included; the drying temperature is preferably 80-100°C, more preferably 90-100°C, and more preferably 100°C; the drying time is preferably 12-24h, more preferably 18-24h, and more preferably 24h.

[0043] In the present invention, the calcination temperature of the CuZnAl-LDH is preferably 300-550°C, more preferably 400-550°C, and more preferably 500°C; the calcination time of the CuZnAl-LDH is preferably 1-6h, more preferably 2-5h, and more preferably 2h; the heating rate of the calcination of the CuZnAl-LDH is preferably 5°C / min.

[0044] In the present invention, the gC 3 N 4 The preparation method is as follows: melamine is roasted in a muffle furnace to obtain gC 3 N4 The calcination temperature is preferably 300-600°C, more preferably 400-550°C, and more preferably 550°C; the calcination time is preferably 2-6h, more preferably 3-5h, and more preferably 4h; the calcination heating rate is preferably 5°C / min.

[0045] In the present invention, the active component precursor is preferably PdCl 2 The reducing agent is preferably one of sodium borohydride, potassium borohydride and hydrogen, more preferably sodium borohydride or potassium borohydride, more preferably potassium borohydride; the reduction reaction time is preferably 1 to 5 hours, more preferably 3 to 5 hours, more preferably 4 hours.

[0046] The present invention also provides an application of an organic-inorganic hybrid catalyst in catalyzing the hydrogenation of dimethyl succinate to prepare 1,4-butanediol.

[0047] In the present invention, the reaction conditions for catalytic hydrogenation of dimethyl succinate to prepare 1,4-butanediol are as follows: the reaction temperature is preferably 120-220°C, more preferably 160-200°C, and more preferably 180°C; the hydrogen pressure is preferably 3-8Mpa, more preferably 4-7Mpa, and more preferably 5Mpa; the space velocity is preferably 0.2-3h -1 , more preferably 0.3 to 1 h -1 , more preferably 0.4h -1 ; The hydrogen-ester ratio is preferably 100-200, more preferably 130-180, and more preferably 150.

[0048] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0051] (1) Grind melamine evenly and put it into a covered crucible, then put it into a muffle furnace and heat it to 550°C at a rate of 5°C / min and calcine it for 4 hours to obtain a light yellow solid. After the muffle furnace is cooled, take out the solid and grind it into powder to obtain gC 3 N 4 ;

[0052] (2) Press Cu 2+ 、Zn 2+、Al 3+ Weigh 7.25 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O was dissolved in 50 mL of deionized water to obtain solution A;

[0053] According to Cu 2+ 、Zn 2+ 、Al 3+ , CO 3 2- OH - The amount of substance satisfies the relationship, so 3.2g NaOH and 2.12g Na 2 CO 3 Dissolve in 50 mL of deionized water to obtain solution B;

[0054] Solution A and solution B were mixed and added into a hydrothermal reactor, and reacted at an oven temperature of 120°C for 12 hours. After the hydrothermal reactor was cooled down, the reaction solution was filtered, washed with deionized water until the pH value of the filtrate was 7, and then dried in an oven at 100°C for 24 hours. The solid was ground into powder to obtain CuZnAl-LDH;

[0055] (3) The CuZnAl-LDH was heated to 500°C in a muffle furnace at a rate of 5°C / min and calcined for 2 h to obtain CuZnAlO; 1 g gC 3 N 4 and 1g CuZnAlO were placed in a beaker, 30mL deionized water was added, stirred at room temperature for 24h, centrifuged, dried, and ground to obtain CuZnAl-LDH@gC 3 N 4 , that is, an organic-inorganic composite carrier;

[0056] (4) Weigh 1g CuZnAl-LDH@gC 3 N 4 In a beaker, add 10 mL of deionized water and use a pipette to take 1.5 mL of PdCl with a Pd content of 0.002 g / mL. 2 The aqueous solution was stirred magnetically for 4 h, and then 10 mL of 0.5 mol / L KBH 4 The solution was stirred magnetically for 4 h. After the reduction reaction, it was centrifuged, dried, and ground to obtain 0.3% Pd / CuZnAl-LDH@gC 3 N4 catalyst.

[0057] Catalyst performance evaluation: Catalyst 0.3% Pd / CuZnAl-LDH@gC 3 N 4 The filling amount is 1g, the reaction temperature is 180℃, the reaction pressure is 5MPa, and the hourly space velocity of dimethyl succinate feed liquid is 0.4h -1 , hydrogen-ester ratio was 150, and after 2 hours, the conversion rate of dimethyl succinate was 99.9%, and the selectivity of 1,4-butanediol was 96.2%. After the catalyst was continuously reacted for 100 hours, the conversion rate of dimethyl succinate and the selectivity of 1,4-butanediol were both above 95%.

[0058] The gC prepared in this example 3 N 4 、CuZnAl-LDH、0.3%Pd / CuZnAl-LDH@gC 3 N 4 The SEM and FT-IR images of the catalyst are shown in Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 It can be seen that Pd / CuZnAl-LDH@gC was successfully prepared in this example. 3 N 4 catalyst.

[0059] Example 2

[0060] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0061] (1)gC 3 N 4 The preparation of is as described in step (1) of Example 1, except that the calcination temperature is 600°C;

[0062] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 4:1:1, and 9.67 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2O, 3.84 g NaOH and 2.12 g Na 2 CO 3 ;

[0063] (3)CuZnAl-LDH@gC 3 N 4 See step (3) of Example 1 for the preparation;

[0064] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 2.5 mL, and 0.5% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0065] The catalyst performance evaluation is as in Example 1, except that the reaction temperature is 200° C., the conversion rate of dimethyl succinate is 98.2%, and the selectivity of 1,4-butanediol is 95.3%.

[0066] Example 3

[0067] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0068] (1)gC 3 N 4 The preparation of is as described in step (1) of Example 1, except that the calcination temperature is 500°C;

[0069] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 3.5:1:1, and 8.47 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 3.52 g NaOH and 2.12 g Na 2 CO 3 ;

[0070] (3)CuZnAl-LDH@gC 3 N 4See step (3) of Example 1 for the preparation;

[0071] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 0.5 mL, and 0.1% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0072] The catalyst performance evaluation is as in Example 1, except that the reaction pressure is 7 MPa, the conversion rate of dimethyl succinate is 81.3%, and the selectivity of 1,4-butanediol is 84.7%.

[0073] Example 4

[0074] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0075] (1)gC 3 N 4 The preparation method is similar to step (1) of Example 1, except that the calcination temperature is 450°C;

[0076] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 2.5:1:1, and 6.05 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 2.88 g NaOH and 2.12 g Na 2 CO 3 ;

[0077] (3)CuZnAl-LDH@gC 3 N 4 The preparation of is as described in step (3) of Example 1, except that the calcination temperature of CuZnAl-LDH is 450°C;

[0078] (4) Pd / CuZnAl-LDH@gC 3 N 4The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 1 mL, and 0.2% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0079] The catalyst performance evaluation is as in Example 1, except that the hourly space velocity of the dimethyl succinate feed liquid is 3 h -1 The conversion rate of dimethyl succinate was 88.9%, and the selectivity of 1,4-butanediol was 90.5%.

[0080] Example 5

[0081] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0082] (1)gC 3 N 4 The preparation of is as described in step (1) of Example 1, except that the calcination temperature is 400°C;

[0083] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 2:1:1, and 4.84 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 2.65 g NaOH and 2.12 g Na 2 CO 3 ;

[0084] (3)CuZnAl-LDH@gC 3 N 4 See step (3) of Example 1 for the preparation;

[0085] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 2 mL, and 0.4% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0086] The catalyst performance evaluation is as in Example 1, except that the hydrogen-ester ratio is 180, the conversion rate of dimethyl succinate is 98.8%, and the selectivity of 1,4-butanediol is 93.9%.

[0087] Example 6

[0088] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0089] (1)gC 3 N 4 See step (1) of Example 1 for the preparation;

[0090] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 4:1:1, and 9.67 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 3.84 g NaOH and 2.12 g Na 2 CO 3 ;

[0091] (3)CuZnAl-LDH@gC 3 N 4 The preparation of CuZnAl-LDH is as described in step (3) of Example 1, except that the calcination temperature of CuZnAl-LDH is 550°C, and 1.8 g gC 3 N 4 and 0.2 g CuZnAlO;

[0092] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 2.5 mL, and 0.5% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0093] The catalyst performance evaluation is as in Example 1, except that the reaction temperature is 200° C., the conversion rate of dimethyl succinate is 89.3%, and the selectivity of 1,4-butanediol is 87.1%.

[0094] Example 7

[0095] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0096] (1)gC 3 N 4 See step (1) of Example 1 for the preparation;

[0097] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 3.5:1:1, and 8.47 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 3.52 g NaOH and 2.12 g Na 2 CO 3 ;

[0098] (3)CuZnAl-LDH@gC 3 N 4 The preparation method is as described in step (3) of Example 1, except that the calcination temperature of CuZnAl-LDH is 300°C, and 1.6 g gC 3 N 4 and 0.4 g CuZnAlO;

[0099] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 0.5 mL, and 0.1% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0100] The catalyst performance evaluation is as in Example 1, except that the reaction pressure is 4 MPa, the conversion rate of dimethyl succinate is 73.5%, and the selectivity of 1,4-butanediol is 82.7%.

[0101] Example 8

[0102] This embodiment provides an organic-inorganic hybrid catalyst, and the preparation method thereof comprises the following steps:

[0103] (1)gC 3 N 4 See step (1) of Example 1 for the preparation;

[0104] (2) Preparation of CuZnAl-LDH See step (2) of Example 1, except that Cu in solution A 2+ 、Zn 2+ 、Al 3+ The molar ratio is 2.5:1:1, and 6.05 g Cu(NO 3 ) 2 ·3H 2 O, 2.97 g Zn(NO 3 ) 2 6H 2 O, 3.75gAl(NO 3 ) 3 9H 2 O, 2.88 g NaOH and 2.12 g Na 2 CO 3 ;

[0105] (3)CuZnAl-LDH@gC 3 N 4 The preparation of CuZnAl-LDH is as described in step (3) of Example 1, except that the calcination temperature of CuZnAl-LDH is 400°C, and 1.4 g gC 3 N 4 and 0.6 g CuZnAlO;

[0106] (4) Pd / CuZnAl-LDH@gC 3 N 4 The preparation of the catalyst is as described in step (4) of Example 1, except that PdCl 2 The volume of the aqueous solution was 1 mL, and 0.2% Pd / CuZnAl-LDH@gC was obtained. 3 N 4 catalyst.

[0107] The catalyst performance evaluation is as in Example 1, except that the hourly space velocity of the dimethyl succinate feed liquid is 1 h -1The conversion rate of dimethyl succinate was 80.4%, and the selectivity of 1,4-butanediol was 87.2%.

[0108] Comparative Example 1

[0109] (1)gC 3 N 4 See step (1) of Example 1 for the preparation;

[0110] (2) Weigh 1g gC 3 N 4 In a beaker, add 10 mL of deionized water and use a pipette to take 1.5 mL of PdCl with a Pd content of 0.002 g / mL. 2 The aqueous solution was stirred magnetically for 4 h, and then 10 mL of 0.5 mol / L KBH 4 The solution was stirred magnetically for 4 h; after the reduction reaction, it was centrifuged, dried, and ground to obtain 0.3% Pd / gC 3 N 4 catalyst.

[0111] The catalyst performance evaluation was as in Example 1, and the conversion rate of dimethyl succinate was 67.3%, and the selectivity of 1,4-butanediol was 83.5%.

[0112] Comparative Example 2

[0113] (1) Preparation of CuZnAl-LDH See step (2) of Example 1;

[0114] (2) Weigh 1 g of CuZnAl-LDH into a beaker, add 10 mL of deionized water, and use a pipette to transfer 1.5 mL of PdCl with a Pd content of 0.002 g / mL. 2 The aqueous solution was stirred magnetically for 4 h, and then 10 mL of 0.5 mol / L KBH 4 The solution was magnetically stirred for 4 hours; after the reduction reaction was completed, it was centrifuged, dried and ground to obtain a 0.3% Pd / CuZnAl-LDH catalyst.

[0115] The catalyst performance evaluation was as described in Example 1, where the conversion rate of dimethyl succinate was 87.7% and the selectivity of 1,4-butanediol was 90.3%.

[0116] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An organic-inorganic hybrid catalyst, characterized in that The organic-inorganic hybrid catalyst comprises an organic-inorganic composite carrier and an active component; the organic-inorganic composite carrier is composed of g-C3N4 and CuZnAl-LDH; and the active component is Pd.

2. An organic-inorganic hybrid catalyst according to claim 1, characterized in that: The molar ratio of Cu, Zn and Al elements in the CuZnAl-LDH is 1-4:1:

1.

3. An organic-inorganic hybrid catalyst according to claim 2, characterized in that: The mass of the Pd is 0.1-0.6% of the total mass of the organic-inorganic hybrid catalyst.

4. An organic-inorganic hybrid catalyst according to claim 2 or 3, characterized in that: In the organic-inorganic composite carrier, the mass fraction of g-C3N4 is 20-80%; the mass fraction of CuZnAl-LDH is 20-80%.

5. The method for preparing an organic-inorganic hybrid catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: Cu 2+ 、Zn 2+ 、Al 3+ A mixed aqueous solution and CO3 2- OH - The mixed aqueous solution is mixed to undergo a hydrothermal reaction to obtain CuZnAl-LDH; The CuZnAl-LDH is calcined to obtain CuZnAlO; the g-C3N4 and CuZnAlO are mixed in water, and then the water is removed and ground to obtain an organic-inorganic composite carrier; The organic-inorganic composite carrier is dispersed in water, then mixed with an aqueous solution of an active component precursor, and then a reducing agent is added to carry out a reduction reaction to obtain the organic-inorganic hybrid catalyst.

6. The method for preparing an organic-inorganic hybrid catalyst according to claim 5, characterized in that: The Cu 2 + 、Zn 2+ 、Al 3+ A mixed aqueous solution and CO3 2- OH - Cu in mixed aqueous solution 2+ 、Zn 2+ 、Al 3+ 、CO3 2- OH - The amount of substance satisfies the following relationship: in, Cu 2+ 、Zn 2+ The total amount of substance; For Al 3+ The amount of substance.

7. The method for preparing an organic-inorganic hybrid catalyst according to claim 6, characterized in that: The temperature of the hydrothermal reaction is 100 to 180° C.; the time of the hydrothermal reaction is 12 to 24 hours.

8. The method for preparing an organic-inorganic hybrid catalyst according to claim 7, characterized in that: The active component precursor is PdCl2; the reducing agent is one of sodium borohydride, potassium borohydride and hydrogen; and the reduction reaction time is 1 to 5 hours.

9. Use of an organic-inorganic hybrid catalyst according to any one of claims 1 to 4 in catalyzing the hydrogenation of dimethyl succinate to prepare 1,4-butanediol.

10. The use according to claim 9, characterized in that: The reaction conditions for catalytic hydrogenation of dimethyl succinate to prepare 1,4-butanediol are as follows: the reaction temperature is 120-220° C.; the hydrogen pressure is 3-8 MPa; the space velocity is 0.2-3 h -1 ; The hydrogen-ester ratio is 100-200.

Images