Optimisation of Ru-promoted Ir-catalysed methanol carbonylation utilising response surface methodology

In this study, central composite design (CCD) at five levels (−1.63, −1, 0, +1, +1.63) combined with response surface methodology (RSM) have been applied to optimise methanol carbonylation using a ruthenium-promoted iridium catalyst in a homogenous phase. The effect of seven process variables, including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations, as well as their binary interactions, were modelled. The determined R2 values greater than 0.9 for the rate and methane formation data confirmed that the quadratic equation properly fitted the obtained experimental data. The optimum conditions for maximum rate and minimum methane formation were obtained via the RSM to be: temperature of 191 °C, pressure of 32.48 barg, iridium concentration of 939.40 ppm, ruthenium concentration of 2099.22 ppm, methyl iodide concentration of 14.46 wt.%, methyl acetate concentration of 17.55 wt.% and water content of 7.60 wt.%. The results predicted by the developed correlation at the optimum determined conditions, 28.63 mol/l h for the reaction rate and 1.97 mol% CH4, were reasonably compared with the experimental data obtained for the reaction rate and methane formation of 27.10 mol/l h and 3.06 mol% CH4, respectively.

Figure optionsDownload high-quality image (82 K)Download as PowerPoint slideResearch highlights▶ Response surface methodology applied to optimise the carbonylation process. ▶ Temperature and pressure had most effects on the reaction rate. ▶ Most effective factors on methane formation are pressure and water concentration. ▶ Developed empirical correlation satisfactorily verified experimental results.