| One step aldol condensation is an interesting route for the synthesis of acrylic acid and its derivative.Raw materials for this reaction are cheaper and energy consumption which uses in this system is lower than other routes.Several papers have been published on the reaction between the propionic acid(PA),methyl propionate(MP)or methyl acetate(MeOAc)with formaldehyde(FA)over a solid catalyst,while the reports on the reaction between ethyl acetate(EtOAc)and formaldehyde are unavailable.Herein,this work presents highly effective catalyst which can be prepared through simple preparation procedure and can be manufactured on a commercial scale for aldol condensation of ethyl acetate with formaldehyde.This thesis summarizes the method for catalyst preparation,catalyst characterization,aldol condensation activity in different types of reactor and reaction parameter,and correlation of catalyst properties and synthesis condition to their catalytic activities.This research explores the use of commercial ?-Al2O3 as support due to it is easy to apply on the commercial scale.Cesium and phosphorus were chosen as an active phase which exhibited basic and acid properties,respectively.Further,lanthanum metal(La,and Ce)and transition metal(Y,Zr,Nb,W)were investigated as a promoter to enhance the catalytic activity.All catalysts were characterized with different techniques such as X-ray diffraction(XRD),X-ray photoelectron(XPS),scanning electron microscopy and energy dispersive spectroscopy(SEM-EDS),transmission electron microscopy(TEM),temperature program desorption(TPD),Fourier transform infrared(FT-IR),N2 adsorption-desorption,and thermogravimetric analysis(TGA).The aldol condensation of ethyl acetate with formaldehyde activities was performed in a tubular fixed-bed reactor under atmospheric pressure at the temperature between 250 to 400?.Phosphorus-cesium over alumina(P-Cs/?-Al2O3)catalysts were developed with highly improved catalytic performance with the influence of acidity and basicity.Key reaction parameters,such as reactant ratio,the amount of metal loading,reaction temperature,were optimized.The optimum condition was EtOAc:FA of 5:1 with 3%-10%P-Cs/?-Al2O3 at 350?,which demonstrated a maximum yield of 25.1%.Phosphorus-cesium over alumina(P-Cs/?-Al2O3)catalysts were developed with highly improved catalytic performance with the influence of acidity and basicity.Key reaction parameters,such as reactant ratio,the amount of metal loading,reaction temperature,were optimized.The optimum condition was EtOAc:FA of 5:1 with 3%-10%P-Cs/?-Al2O3 at 350?,which demonstrated a maximum yield of 25.1%.Further,3%-10%P-Cs/?-Al2O3 catalyst was modified with different metals and employed for the reaction of acetic acid ester(MeOAc and EtOAc)with formaldehyde.The Zr-P-Cs/?-Al2O3 catalyst exhibited maximum yield(53.5%)and selectivity(57.2%)of methyl acrylate(MA)+ acrylic acid(AA).The W-P-Cs/?-Al2O3 catalyst showed good performance on production of ethyl acrylate(EA),with the yield of 41.2%and selectivity of 59.8%.The addition of small amount of metal improved the catalytic performance as compared to P-Cs/?-Al2O3catalyst.Thus,the addition of metal influenced the acidity and basicity of the surface of the catalyst and exhibited significantly enhanced aldol condensation activity.Moreover,the stability of Zr-P-Cs/?-Al2O3 and W-P-Cs/?-Al2O3 catalysts were tested.Yields declined by nearly 60%after reaction at 60 h,due to the formation of carbon deposition on the surface of the catalyst.Moreover,the scale up of the aldol condensation of ethyl acetate with formaldehyde was performed in the moving-bed reactor with 5 L of P-Cs/?-Al2O3 catalyst.The best catalytic activity was exhibited under reaction temperature at 350 ? with LHSV of 0.441 mL·g-1·h-2,which was produced 9.5%of EA yield and 32.2%of EA selectivity. |
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