Experimental Characterisation of Cation-exchange Resin for Biomass Green Solvent Production

?In this work, resin catalysts used for lactic acid esterification was analysed using liquid N2 adsorptiondesorption 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/Po) of 0.05 ? 0.1. An auto sampler 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 m 2 /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-butandiol (73).