NiO-TiO2 / gamma-Al2O3 catalyst, preparation method and application of NiO-TiO2 / gamma-Al2O3 catalyst in preparation of trifluoroethylamine from trifluoroethanol

Abstract

The invention relates to the technical field of pharmaceutical chemicals, in particular to a NiO-TiO2 / gamma-Al2O3 catalyst, a preparation method and application of the NiO-TiO2 / gamma-Al2O3 catalyst in preparation of trifluoroethylamine from trifluoroethanol. The preparation method of the NiO-TiO2 / gamma-Al2O3 catalyst comprises the following steps: dissolving citric acid in absolute ethyl alcohol, adding tetra-n-butyl titanate, stirring, adding nickel nitrate hexahydrate, and stirring until the nickel nitrate hexahydrate is completely dissolved; and adding gamma-Al2O3 into the mixed solution, stirring, evaporating the solvent in an oil bath, drying in a drying oven, grinding a solid sample after drying, putting the solid sample into a crucible, roasting, and cooling and grinding a final product to obtain the NiO-TiO2 / gamma-Al2O3 catalyst. By adopting the NiO-TiO2 / gamma-Al2O3 catalyst prepared by the invention, trifluoroethylamine can be continuously synthesized by catalyzing trifluoroethanol through a fixed bed.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical chemical industry, and specifically relates to a NiO-TiO2 / γ-Al2O3 catalyst and a preparation method thereof, as well as application thereof in the preparation of trifluoroethylamine from trifluoroethanol. Background Art

[0002] Trifluoroethylamine (2,2,2-trifluoroethylamine, TFEN) is a key intermediate in the field of fluorine-containing fine chemicals. It plays an irreplaceable role in pharmaceutical synthesis, pesticide formulations and the development of fluorine-containing polymers. At the same time, it is widely used as a functional monomer in high-end fields such as dye sensitizers and fluorocarbon surfactants. At present, the contradiction between supply and demand of trifluoroethylamine in my country is prominent, and industrial production capacity urgently needs to be broken through. The preparation technology of trifluoroethylamine is mainly divided into two systems: reduction method and amination method: (1) The reduction method uses trifluoroacetonitrile as a raw material through catalytic hydrogenation, or uses trifluoroacetamide as a raw material through lithium aluminum hydride reduction method. Although this process has the advantages of few by-products and high product purity, it is limited by the cost of precious metal catalysts and the high risk of lithium aluminum hydride. Industrial application is subject to dual restrictions of economy and safety; (2) The amination method uses precursors such as trifluoroacetaldehyde and trifluorochloroethane to undergo nucleophilic substitution reaction with ammonia in a solvent system. For example:

[0003] CN201010525312 discloses an ethyl chloride ammonolysis process using trifluoro-2-chloroethane and aqueous ammonia as raw materials. The reaction proceeds in a glycerol solvent at 150-200°C and a pressure of 2-4 MPa for 20-30 minutes to produce the target product. This process uses a batch reaction apparatus, produces harmful byproducts, and uses large amounts of solvent, increasing energy consumption for subsequent distillation and separation.

[0004] CN201310215766 prepares trifluoroethylamine by condensing hydrated trifluoroacetaldehyde with ammonia water and then performing a reduction reaction. This method adopts a batch reaction, and trifluoroacetaldehyde is relatively expensive, so the production cost is high and it is difficult to industrialize.

[0005] The microchannel continuous process reported in CN201910975730 uses 1,1,1-trifluoro-2-chloroethane and liquid ammonia to catalyze amination in a silicon carbide microreactor. Although continuous operation is achieved, there is a risk of microchannel blockage, and scale-up production is difficult.

[0006] In summary, existing trifluoroethylamine processes generally suffer from intermittent reactions, high production costs, and severe pollution. In contrast, the fixed-bed continuous catalytic process offers advantages such as a simple process flow and low by-product production. The direct amination of trifluoroethanol with ammonia is a highly effective green synthesis route for trifluoroethylamine. Summary of the Invention

[0007] The first object of the present invention is to provide a NiO-TiO2 / γ-Al2O3 catalyst and a preparation method.

[0008] The second object of the present invention is to provide a use of a NiO-TiO2 / γ-Al2O3 catalyst in the preparation of trifluoroethylamine from trifluoroethanol.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for preparing a NiO-TiO2 / γ-Al2O3 catalyst comprises: dissolving citric acid in anhydrous ethanol, adding tetra-n-butyl titanate, stirring, and then adding nickel nitrate hexahydrate and stirring until completely dissolved;

[0011] γ-Al2O3 is added to the mixed solution and stirred, and then the solvent is evaporated in an oil bath and dried in an oven. After drying, the solid sample is ground and placed in a crucible and calcined. The final product is cooled and ground to obtain a NiO-TiO2 / γ-Al2O3 catalyst;

[0012] The NiO-TiO2 / γ-Al2O3 catalyst is labeled as xNi-yTi / Al, where x and y represent the loadings of Ni and Ti, respectively, in mmol / gγ-Al2O3. The ratio of the total molar number of nickel oxide and titanium dioxide to the molar number of γ-Al2O3 is 0.1 to 0.3.

[0013] Wherein, the nickel oxide x ranges from 0.2 to 1.8, preferably from 0.45 to 1.35.

[0014] Wherein, the titanium dioxide y ranges from 0.45 to 1.5, preferably from 0.45 to 0.9.

[0015] Wherein, the molar ratio of nickel oxide to titanium dioxide is 0.5-2.

[0016] Wherein, the molar ratio of tetra-n-butyl titanate to citric acid is 0.2-1.2.

[0017] Wherein, the molar ratio of the nickel nitrate hexahydrate to the citric acid is 0.2 to 0.8.

[0018] The oven temperature is 110° C., and the drying time is 2 to 4 hours.

[0019] The calcination temperature is 400-550°C, the calcination time is 2-4 hours, and the heating rate is 2°C / min.

[0020] The present invention also provides the use of NiO-TiO2 / γ-Al2O3 catalyst in the preparation of trifluoroethylamine from trifluoroethanol: the NiO-TiO2 / γ-Al2O3 catalyst is used to continuously synthesize trifluoroethylamine from trifluoroethanol via fixed bed catalysis.

[0021] The specific method is as follows: weigh NiO-TiO2 / γ-Al2O3 catalyst and load it into a fixed bed reactor; before the reaction, the catalyst is heated in a hydrogen atmosphere, and after the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere; trifluoroethanol, hydrogen, ammonia and nitrogen are then fed into a preheater, mixed evenly in a mixer and fed into the catalyst bed at the upper end of the reactor; the reaction is carried out at normal pressure, a reaction temperature of 260-320°C and a liquid space velocity of 0.4h -1 The reaction is carried out under the conditions of , to generate trifluoroethylamine.

[0022] Furthermore, the NiO-TiO2 / γ-Al2O3 catalyst has a mesh size of 40-60.

[0023] Furthermore, the catalyst was heated to 550° C. at a rate of 5° C. / min in a hydrogen atmosphere and maintained at that temperature for 2 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The active components of the γ-Al2O3-supported Ni and Ti catalyst prepared by the method of the present invention have good dispersibility and activity. The interaction between Ti and Ni promotes their dispersion on the γ-Al2O3 carrier, exposing more Ni and Ti atoms, thereby greatly promoting the conversion of trifluoroethanol to trifluoroethylamine and improving the catalytic performance.

[0026] (2) The present invention uses fixed-bed catalysis to continuously synthesize trifluoroethylamine with trifluoroethanol. The reaction pressure is normal pressure, the reaction conditions are mild, there are no organic by-products such as secondary amines and tertiary amines, the product separation is simple, and efficient synthesis of trifluoroethylamine is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1-Figure 3 The catalytic activity of xNi / Al catalysts with different Ni contents. Activity test conditions: 15mL / min NH3, 40mL / min H2, total flow rate 55mL / min, catalyst dosage 1g, trifluoroethanol liquid space velocity 0.4h -1 .

[0028] Figure 4-Figure 6 The catalytic activity of Ti / Al catalyst and xNi-yTi / Al catalyst with different Ti contents. Activity test conditions: 15mL / min NH3, 40mL / min H2, total flow rate 55mL / min, catalyst dosage 1g, liquid space velocity 0.4h -1.

[0029] Figure 7-Figure 9 The effect of different calcination temperatures on the catalytic performance of the x Ni-y Ti / Al catalyst is shown in Figure 2. Activity test conditions: 15 mL / min NH3, 40 mL / min H2, total flow rate 55 mL / min, catalyst dosage 1 g, liquid space velocity 0.4 h -1 .

[0030] Figure 10-12 The effect of feed gas ratio on the catalytic performance of 0.9Ni-0.9Ti / Al catalyst. Activity test conditions: trifluoroethanol liquid space velocity of 0.4h -1 The flow rates of NH3 and H2 were set in a molar ratio, with the remainder being N2, at a total flow rate of 55 mL / min, and the catalyst dosage was 1 g. The ratios in the figure represent trifluoroethanol: hydrogen: ammonia.

[0031] Figure 13 The X-ray diffraction (XRD) test results of the catalyst. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1 Preparation of NiO / Al2O3 Catalyst

[0034] A NiO / Al2O3 catalyst was prepared using a wet impregnation method using γ-Al2O3 powder as a support. Specifically, nickel nitrate hexahydrate was accurately weighed and dissolved in 30 mL of distilled water. 1 g of the γ-Al2O3 powder support was then added and stirred for 30 minutes. The mixture was then heated to 110°C and evaporated to dryness, followed by drying in a drying oven at 110°C for 6 hours. Finally, the NiO / Al2O3 catalyst was calcined at 400°C under static air for 3 hours. The catalyst is labeled as x Ni / Al, with units expressed as mmol / g γ-Al2O3.

[0035] Weigh the prepared catalyst (40-60 mesh) and load it into a fixed bed reactor. Before the reaction, the catalyst is heated to 550°C at 5°C / min in a hydrogen atmosphere and maintained for 2 hours. After the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere. Then, trifluoroethanol, hydrogen, ammonia and nitrogen are sent to the preheater, and then mixed evenly in a mixer and sent to the upper end of the reactor to enter the catalyst bed. At normal pressure, reaction temperature 260-320°C, liquid space velocity 0.4h -1The reaction was carried out under the following conditions to generate trifluoroethylamine.

[0036] The following experiments study the effect of Ni content on the performance of Ni / γ-Al2O3 catalysts:

[0037] The preparation of the Ni / Al2O3 catalyst was essentially the same as in the previous experiment, with the only difference being the amount of nickel nitrate hexahydrate added. The masses of nickel nitrate hexahydrate added were 0.1288 g, 0.2575 g, 0.3863 g, and 0.5150 g, labeled A1, A2, A3, and A4, respectively.

[0038] like Figure 1-Figure 3 As shown, in the temperature range of 200-280 °C, all catalysts showed a trend of increasing trifluoroethanol conversion with increasing temperature, while catalyst A1 had the best yield for trifluoroethylamine at 260 °C.

[0039] Example 2 Preparation of NiO-TiO2 / γ-Al2O3 Catalyst

[0040] Accurately weigh citric acid (the molar ratio of citric acid to (Ti+Ni) is 1) and completely dissolve it in 20 ml of anhydrous ethanol. Then add 0.3063 g of tetrabutyl titanate (C 16 H 36 O4Ti) and magnetically stirred for 10 minutes, then 0.2725g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) was added and stirred for 20 minutes to completely dissolve. 1g of γ-Al2O3 was added to the mixed solution and magnetically stirred for 30 minutes. The solvent was then evaporated in an oil bath at 80°C and dried in an oven at 110°C for 3 hours. After drying, the solid sample was ground and placed in a crucible and calcined at 400°C in static air for 3 hours (heating rate 2°C / min). The final product was cooled and ground to obtain a NiO-TiO2 / γ-Al2O3 catalyst. The catalyst is labeled x Ni-y Ti / Al, where x and y represent the loadings of Ni and Ti, respectively, in mmol / g γ-Al2O3.

[0041] Weigh the prepared catalyst (40-60 mesh) and load it into a fixed bed reactor. Before the reaction, the catalyst is heated to 550°C at 5°C / min in a hydrogen atmosphere and maintained for 2 hours. After the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere. Then, trifluoroethanol, hydrogen, ammonia and nitrogen are sent to the preheater, mixed evenly in a mixer and sent to the upper end of the reactor to enter the catalyst bed. The reaction is carried out under normal pressure, reaction temperature of 260-320°C, and liquid space velocity of 0.4h -1 The reaction was carried out under the following conditions to generate trifluoroethylamine.

[0042] (1) Catalytic activity of Ti / Al catalysts and xNi-yTi / Al catalysts with different Ti contents

[0043] The Ti / Al catalyst was prepared using essentially the same experimental procedures as above, with the exception that nickel nitrate hexahydrate was not added; this catalyst is labeled B1. The Ni-xTi / Al2O3 catalyst was prepared using essentially the same experimental procedures as above, with the exception that the amount of butyl titanate added varied. The amounts of butyl titanate added were 0.3063 g, 0.1532 g, 0.3063 g, and 0.4595 g, respectively; these are labeled B1, B2, B3, and B4.

[0044] like Figure 4-Figure 6 As shown, within the temperature range of 260-340°C, all catalysts showed an increasing trend in trifluoroethanol conversion with increasing temperature, while trifluoroethylamine selectivity decreased with increasing temperature. Notably, catalyst B1 exhibited low trifluoroethanol conversion and zero trifluoroethylamine selectivity within this temperature range. The xNi-yTi / Al catalyst significantly impacted trifluoroethanol conversion and trifluoroethylamine selectivity. Catalyst B3 achieved a 30% trifluoroethylamine yield at 300°C, a 15% increase over catalyst A1.

[0045] (2) Effect of different calcination temperatures on the performance of xNi-yTi / Al catalysts

[0046] Based on the study on the effect of Ti loading on the catalytic preparation of trifluoroethylamine by trifluoroethanol, the effect of calcination at 350℃, 400℃, 500℃ and 550℃ on the catalytic performance was further investigated on the above-mentioned B3 catalyst to obtain C1, C2, C3 and C4 catalyst samples respectively.

[0047] Depend on Figure 7-Figure 9 It can be seen that the conversion rate of catalyst C1 is higher than that of other samples, but the selectivity of trifluoroethylamine is only 20% at most, and the yield is low. However, the yield of trifluoroethylamine over catalyst C2 at 300℃ reaches 30%, which shows the best catalytic performance.

[0048] (3) Effect of different raw material ratios on the performance of xNi-yTi / Al catalysts

[0049] The effect of raw material composition on catalytic performance was further investigated on the above B3 catalyst. Figure 10-12 The results show that the ratio of alcohol hydrogen to alcohol ammonia has an important influence on the conversion rate of trifluoroethanol and the selectivity of trifluoroethylamine. As the alcohol hydrogen ratio decreases, the conversion rate of trifluoroethanol increases, while the selectivity of trifluoroethylamine decreases. Therefore, the hydrogen to alcohol molar ratio should be maintained at 20-24, while the ammonia to alcohol molar ratio should be maintained at 8-12.

[0050] (4) X-ray diffraction (XRD) test of catalyst

[0051] Figure 13 The results showed that no obvious NiO diffraction peaks were observed on the Ni / Al catalyst, while the diffraction peaks at 37.4°, 45.5°, and 67.3° were sharper than those at γ-Al2O3, possibly indicating the formation of a NiAl2O4 spinel phase. The Ti / Al catalyst produced a TiO2 crystalline phase diffraction peak. No TiO2 or NiO crystalline phase diffraction peaks were observed on the B2, B3, and B4 catalysts, indicating that the interaction between TiO2 and NiO promoted their dispersion on the γ-Al2O3 support, which further helped expose more Ni atoms to the catalyst surface, thereby improving the catalytic performance of the catalyst.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a NiO-TiO2 / γ-Al2O3 catalyst, characterized in that: Dissolve citric acid in anhydrous ethanol, add tetra-n-butyl titanate, stir, then add nickel nitrate hexahydrate and stir until completely dissolved; γ-Al2O3 is added to the mixed solution and stirred, and then the solvent is evaporated in an oil bath and dried in an oven. After drying, the solid sample is ground and placed in a crucible and calcined. The final product is cooled and ground to obtain a NiO-TiO2 / γ-Al2O3 catalyst; The NiO-TiO2 / γ-Al2O3 catalyst is marked as xNi-yTi / Al, where x and y represent the loading amounts of Ni and Ti, respectively, and the unit is mmol / gγ-Al2O3.

2. The method for preparing the NiO-TiO2 / γ-Al2O3 catalyst according to claim 1, wherein: The nickel oxide x ranges from 0.2 to 1.8; the titanium dioxide y ranges from 0.4 to 1.5; and the molar ratio of the nickel oxide to the titanium dioxide is from 0.5 to 2.

3. The method for preparing the NiO-TiO2 / γ-Al2O3 catalyst according to claim 1, wherein: The molar ratio of tetra-n-butyl titanate to citric acid is 0.2-1.2; the molar ratio of nickel nitrate hexahydrate to citric acid is 0.2-0.

8.

4. The method for preparing the NiO-TiO2 / γ-Al2O3 catalyst according to claim 1, wherein: The ratio of the total molar number of the nickel oxide and titanium dioxide to the molar number of γ-Al2O3 is 0.1 to 0.

3.

5. The method for preparing the NiO-TiO2 / γ-Al2O3 catalyst according to claim 1, wherein: The oven temperature is 110° C., and the drying time is 2 to 4 hours.

6. The method for preparing the NiO-TiO2 / γ-Al2O3 catalyst according to claim 1, wherein: The calcination temperature is 400° C. to 550° C., the calcination time is 2 to 4 hours, and the heating rate is 2° C. / min.

7. The NiO-TiO2 / γ-Al2O3 catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the NiO-TiO2 / γ-Al2O3 catalyst according to claim 7 in the preparation of trifluoroethylamine from trifluoroethanol, characterized in that: Trifluoroethylamine was continuously synthesized from trifluoroethanol using NiO-TiO2 / γ-Al2O3 catalyst in a fixed bed.

9. Use of the NiO-TiO2 / γ-Al2O3 catalyst according to claim 8 in the preparation of trifluoroethylamine from trifluoroethanol, characterized in that: Weigh NiO-TiO2 / γ-Al2O3 catalyst and load it into a fixed bed reactor; Before the reaction, the catalyst is heated in a hydrogen atmosphere, and after the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere; trifluoroethanol, hydrogen, ammonia and nitrogen are then fed into a preheater, mixed evenly in a mixer and fed into the catalyst bed at the upper end of the reactor. The reaction is carried out at normal pressure, a reaction temperature of 260-320°C and a liquid space velocity of 0.4h -1 The reaction is carried out under the conditions of , to generate trifluoroethylamine.

10. Use of the NiO-TiO2 / γ-Al2O3 catalyst according to claim 8 in the preparation of trifluoroethylamine from trifluoroethanol, characterized in that: The NiO-TiO2 / γ-Al2O3 catalyst has a mesh size of 40-60. The catalyst is heated to 550°C at a rate of 5°C / min in a hydrogen atmosphere and maintained at this temperature for 2 hours.

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