Greener and higher conversion of esterification via interfacial photothermal catalysis

Reversible chemical reactions such as industrial production of esters are governed by the equilibrium law. To improve the productivity of esterification, superfluous reactants and dehydrants are usually used to drive the reaction forward. However, these methods are not only energy intensive but also cause extra difficulty in the separation of final products. Here we propose a photothermal catalysis system based on a sulfonic acid-functionalized graphene oxide aerogel to increase the yield rate of esterification without excess reactants or dehydrants. As a result of local photothermal heating and different molecular bond affinities, the generated products are evaporated out of reactive sites, leading to a local excess of reactants and thereby thermodynamically driving the reaction in favour of ester generation. Specifically, an acetic acid conversion rate of 77% is achieved, which is significantly higher than the theoretical limit of 62.5%. Theoretical analysis reveals its substantial advantage in saving the energy for separating products when applied to the real industrial esterification reaction. Our strategy could find applications in various fields such as thermal catalysis, nitration, acylation and the synthesis of other chemicals.