Optimization on the etherification of glycerol with tert-butyl alcohol

Abstract

The etherification of glycerol with tert-butyl alcohol (TBA) on solid acid catalysts provides a promising way to transform glycerol into a value added product to be used as an oxygenated additive to diesel fuels. Systematic optimization on this etherification reaction was carried out based on the small-scale experimental data (with a 35 cm 3 reacting mixture loaded in a 50 cm 3 stainless steel sampler shaken by a high rotational shaker). Effects of the possible processing variables were optimized via the proposed optimizing algorithm to reach the global optimum. The optimizing algorithm consists of the following two steps. Initially, the experiments designed by the global optimizer (rbfSolve routine in TOMLAB/CGO) are conducted before the region surrounding the global extreme is reached. When the region of global extreme is approaching, additional-optimizing experiments designed by the identified RBF model are then carried out to accelerate the rate to achieve the global optimum. The objective function was chosen as the total weight of the products glycerol mono-buthoxy ethers (GMBEs) and glycerol di-buthoxy ethers (GDBEs). Performing the designed experiments for the three control variables including the reacting temperature, the catalyst loading, and the solvent loading at the constant recipe and operating conditions, the global optimal operating condition was found using 24 experiments.