Preparation method of carbon nitride nanosheet catalyst and Knoevenagel condensation reaction method based on catalyst

Abstract

The invention discloses a preparation method of a carbon nitride nanosheet catalyst. The preparation method comprises mixing a chloride salt, a carbon nitrogen source and a solvent in a mass ratio of(0.1-28):(2-6):(100-500), and performing uniform stirring to form a mixture; removing the solvent in the mixture, performing drying and roasting, performing repeated water washing on the roasted solid, performing separation and drying to obtain the carbon nitride nanosheet catalyst. The invention also discloses a condensation reaction method by using the carbon nitride nanosheet catalyst. According to the invention, when the carbon nitride nanosheet is prepared, the reactants are thoroughly mixed in an aqueous solution, and after one-step pyrolysis, the metal cations and chloride ions in the chloride salts destroy the acting force between layers of the laminar carbon nitride to achieve thermal stripping and further to form laminar carbon nitride nanosheets, thereby improving the catalyticperformance. When the catalyst is applied to a condensation reaction of benzaldehyde and ethyl cyanoacetate, the temperature can be as low as 30 DEG C, and the required longest reaction time is 4 h.

Description

technical field [0001] The invention belongs to the technical field of catalyst preparation, in particular to a method for preparing a carbon nitride nanosheet catalyst and a Knoevenagel condensation reaction method based on the catalyst. Background technique [0002] The Knoevenagel condensation reaction is an important reaction for the synthesis of α, β unsaturated carbonyl compounds, and its products are important intermediates in the pharmaceutical, cosmetic and pesticide industries. Generally, the Knoevenagel condensation reaction is carried out under the action of a basic catalyst, and the catalyst mainly includes amines and inorganic bases. [0003] For the Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate to produce ethyl α-cyanocinnamate, there are many schemes, such as Zhang Wenfei et al. (Acta Catalytica Sinica, 2013, 34, 559-566.) reported using MgO as a catalyst to catalyze benzaldehyde Knoevenagel condensation with ethyl cyanoacetate at ...

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Problems solved by technology

[0003] For the Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate to produce ethyl α-cyanocinnamate, there are many schemes, such as Zhang Wenfei et al. (Acta Catalytica Sinica, 2013, 34, 559-566.) reported using MgO as a catalyst to catalyze benzaldehyde Knoevenagel condensation with ethyl cyanoacetate at 80 °C, the conversion rate can reach 72.5% in 2 hours, but the conversion rate in this reaction is low; Cao Yudan et al. ) has good catalytic performance for the Knoevenagel condensation reaction. Specifically, under mild conditions below 100°C, using amino-functionalized molecular sieves as a catalyst, the condensation of benzaldehyde and ethyl cyanoacetate is carried out. The reaction is carried out for 2 hours, and the yield is close to 100%. Yet the reaction temperature in this reaction is on the high side; Application No. is that the Chinese patent of 201210249723.6 discloses " the organic solid base catalyst of synthesizing alpha-cyanocinnamate ethyl ester, its preparation method and its application ", and the catalyst used is N- When butylimidazole basic ionic liquid functionalized silica gel catalyzes the synthesis of ethyl α-cyanocinnamate from benzaldehyde and ethyl cyanoacetate, the catalyst needs to account for 2% of the total weight of the reactants, and the temperature is 80-110°C. The time is 5-12 hours, and the product is obtained by centrifugal sedimentation, and the catalyst in it can be recovered and recycled. However, the reaction temperature of this reaction is too high and the reaction time is too long, which is not conducive to operation.

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