Title : Effect of performance of different catalysts on the conversion of acrylic acid- Kinetics and thermodynamics
Abstract:
Esters are aromatic compounds, widely used as solvent, plasticizers, sealants, medicinal and flavoring agents. Esterification is a reversible reaction having low reaction rate (yield less than 15%) due to which a suitable catalyst is employed to enhance the reaction rate. In the present work, esterification of acrylic acid with ethanol was presented to study the effect of type of catalyst and temperature on the conversion. Three homogeneous catalysts (sulphuric acid(H2SO4), hydrochloric acid (HCl), and hydroiodic acid (HI)) and two heterogeneous catalysts (Dowex 50W and Amberlyst 15) were employed in amount of 2% v/v (with equivalent for solid catalyst) of reaction mixture as the temperature was varied from 40-70 oC. It were observed that homogeneous catalyst were better than heterogeneous catalysts with the trend of conversion as H2SO4> HCl> Dowex 50W >HI> Amberlyst 15. However, since homogeneous catalyst are corrosive and do cause side reaction, it’s proposed to employ the heterogeneous catalyst for the study. Performance of Dowex 50W and Amberlyst 15 were evaluated at reaction temperature of 60 oC, catalyst loading of 10% w/w% and molar ratio of 1:1. The conversion was found to be 47.6% and 41.2% as the reaction was carried out for 400 min. Catalyst reusability is studied on the conversion obtained for three runs. Conversion was found to decrease from 33.5% and 25.4% after third run. Deposition of reactions on active site along with the leaching of active sites leads to decrease in catalytic activity. Kinetics parameters for the two heterogeneous catalysts were found to yield rate constant values between 0.0073-0.0204 and 0.0115-0.033 m3/mol.min as temperature was varied from 40-70 oC for Amberlyst 15 and Dowex 50W, respectively. These outcomes provide an approach to understand the significant effect of each catalyst on the esterification of acrylic acid with ethanol.
