Informatics Publishing Limited

Edidiong Okon ¹, Habiba Shehu ¹, Ifeyinwa Orakwe ¹, Ngozi Nwogu ¹, Mohammad Kajama ¹, Edward Gobina ¹

Affiliations
1 Center for Process Integration and Membrane Technology (CPIMT), School of Engineering. The Robert Gordon University Aberdeen, AB10 7GJ, GB

Abstract

In this work, resin catalysts used for lactic acid esterification was analysed using liquid N₂ adsorption-desorption isotherm measured at 77 K using an automated adsorption instrument (Quantachrome 2013). The surface area and pore size distribution were obtained using the BET (Brunauer-Emmett-Teller) and BJH (Barrette - Joyner Halenda) methods of the N₂ desorption isotherm respectively. The N₂ vapour adsorption data was determined at the vapour pressure range (P/P_o) of 0.05 - 0.1. An autosampler Gas chromatograph equipped with mass spectrometer (GC-MS) was used for the analysis of the esterification reaction product. Fourier Transform Infrared - Attenuated Total Reflection (FTIR-ATR) was used for the structural identification of the component with the strongest adsorption strength on the surface of the resin catalysts. The results of the N₂ adsorption isotherm for the resin catalysts showed a type IV adsorption isotherm with hysteresis confirming a mesoporous layer in pore size the range of 2 - 5 nm. The multipoint method exhibited a straight line curve with a positive slope (552.42) and intercept (1.607). The BET surface area of the amberlyst 36 was found to be higher (20.171 m2/g) than that of dowex 50W8x (0.497 m2/g). These results were further confirmed by the gas chromatograph analysis where products of the amberlyst 36 was found to elute faster at the retention time of 1.521 mins in contrast to those of dowex50W8x resin catalysts. The result of the FTIR analysis of the resin catalysts showed that the band at 1731 cm-1 correspond to C-O stretching with strong adsorption bond while the band at 2992 cm-1 representing O-H corresponds to stretching vibration bond suggesting ethanol and lactic acid as the adsorption components on the surface of the resin catalysts. The gas chromatograph NIST library spectra of the esterification reaction products exhibited the structure of ethyl lactate (45) on the mass spectra with other compounds with their respective ions including formic acid (71) formic acid and 2,3-butanediol (73).

Keywords

Heterogeneous Catalysts, Characterisation, Esterification, Adsorption, Ethyl Lactate And Cation-Exchange Resin.

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Ngozi Nwogu ¹, Edidiong Okon ¹, Edward Gobina ¹

Affiliations
1 Center for Process Integration and Membrane Technology (CPIMT), School of Engineering, The Robert Gordon University, Aberdeen, AB10 7GJ, GB

Abstract

This work presents the transport behaviour of carrier gases with inorganic ceramic membrane used for environmental gas separations at 289K and 0.01-1 bar. The gases tested include: Helium (He), Nitrogen (N₂) Carbon dioxide (CO₂) and Argon (Ar). The Knudsen ideal selectivity ratio of 0.95, 0.3 and 0.79 for Ar/CO₂, He/CO₂ and N₂/CO₂ gas respectively was slightly higher than the theoretical selectivity of the gases. The gas permeance was found to decrease with increase in gauge pressure indicating mass transfer limitations. However, at a relatively low pressure of 0.1 bar, Knudsen diffusion mechanism was dominant for He and N₂ gases flow across the modified ceramic membrane in relation to the inverse proportionality of the square ischolar_main of their molecular weights. Scanning electron microscopy (SEM) was used to determine the pore size distribution of the α-Al₂O₃ ceramic support.

Keywords

Permeance, Selectivity, Knudsen Diffusion and Inorganic Ceramic Membrane.

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