The Synthesis of Dimethyl Adipate from Organic Carbonates and Cyclopentanone using Zinc-based heterogenous catalysts

The purpose of this project was to synthesise novel mixed oxide heterogenous catalysts in the pursuit of maximising the efficiency of the reaction between organic carbonates (dimethyl carbonate, DMC) and cyclic ketones (cyclopentanone, CPO), yielding an industrially utilised product, such as dimethyl adipate (DMA). Conditions were set at 260 °C, 20 bar, molar ratio DMC:CPO of 15:1, stirring of 800rpm – as these previously determined to be optimal. The parameters which were investigated were the composition of the mixed oxide used as catalyst (e.g. the molar ratio of Zn:Mg) and the reaction time. Initially, Zn/Mg mixed oxides were tested, varying the catalyst preparation procedure (coprecipitation and microemulsion), calcination temperature, and Zn/Mg atomic ratio in order to tune the acid/base properties of the catalyst. The ZnMgO (1:2) catalyst calcined at 450 °C produced better results in terms of CPO conversion and DMA yield, 98% and 39%, respectively, after 5 h at 260 °C. The addition of a trivalent cation, namely Al and Fe, into the mixed oxide structure was also studied, yielding comparable results in terms of both of these parameters with conversion and DMA yield of 89% and 26%, respectively, considering the much lower catalyst loading percentage by weight, however favouring DMC decomposition to light compounds.