Brønsted acid functionalized phthalocyanine on perylene diimide framework knotted with ionic liquid: An efficient photo-catalyst for production of biofuel component octyl levulinate at ambient conditions under visible light irradiation

Abstract

NovelBrønsted acid functionalized phthalocyanine on perylene diimide framework knotted with ionic liquid (BAFPcPDIL) was synthesized and confirmed by instrumentation techniques. DRS-spectrum and Hammett value has been determined to confirm band-gap and proton levels of photo-catalyst respectively. The photo-catalytic performance was evaluated by production of octyl levulinate (OL) using levulinic acid (LA) with n-octyl alcohol (OA) under visible light irradiations. Response surface methodology (RSM)with Box–Behnken design (BBD) with 29 experiments was applied to explore consequences of four crucial process variables: catalyst loading (A), molar ratio of reactants (B) andpower of visible light (C), duration in hour (D) on OL yield. From the model, the optimum conditions for the utmost conversion were found as: 10 mg catalyst with (1:1) alcohol to LA molar ratio under 12 W lamp, in 12 h for completing esterification reaction with 95.58% yield of OL. With optimum conditions, various alkyl esters such as methyl levulinate 92.14%, ethyl levulinate 93.12%, n-propyl levulinate 91.45%, iso-propyl levulinate 92.38%, n-butyl levulinate 85.13%, n-pentyl levulinate 86.35%, n-hexyl levulinate 89.57%, tert-butyl levulinate 91.58%, were successfully synthesized with excellent yields. The plausible photocatalytic mechanismof the esterification reaction was also described. The study was extended on blending of OL with diesel sample in 10–30%, found comparable result of density, kinematic viscosity, calorific values, cetane number, flash, fire and pour point of the blended samples with blank diesel sample and appreciable changes in exhaust gases of 25% blended diesel sample. Additionally, BAFPcPDIL displayed good recyclability without loss of photo reactivity after four runs.