Esterification, a reaction leading to varied industrial products, is conventionally catalysed by homogeneous catalysts like sulfuric or p-toluenesulfonic acid. However, due to the ease of catalyst separation, heterogeneous catalysts are desired for this reaction. To overcome the challenges of tedious synthesis protocols of heterogeneous catalysts, a novel catalyst in form of geopolymers are being explored. This study explores structure-property relationships in geopolymers with reference to their application as esterification catalysts. Being amorphous in nature, geopolymers cannot be represented by periodic models. Instead, in this study, fundamental interacting units of geopolymers have been used as molecular models of representative active sites. Acidity and basicity of catalysts govern their activities. Therefore, adsorption of acidic (NH3) and basic (CO2) probes was carried out giving insights into acidic and basic sites on the catalyst along with their relative strengths. Figure 1 shows the adsorption of NH3 and CO2 over the geopolymer indicating strong acidic and weak basic sites. Adsorption of alcohols was further studied and energetics were determined. Further computational studies are being undertaken to develop mechanistic insights into esterification.

Probes into acid-base sites on geopolymeric catalyst: A DFT study

2019 Spring National Meeting

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