Synthesis and characterization of a K/K2CO3-based solid superbase as a catalyst in propylene dimerization

A novel solid superbase 3%K/K2CO3 was prepared by loading metallic potassium on K2CO3. The optimized preparation conditions included a loading time of 1.5 h, loading temperature of 150 A degrees C, loading amount of 3wt% and average carrier size of 120 mu m. Under the optimum conditions, the conversion of propylene is about 60% with the selectivity of dimers 98.5% and the selectivity of 4MP1 86.3%. In addition, the superbase 3%K/K2CO3 has a base strength of H (-)>= 37, and the concentration of basic sites of H (-)>= 35 is approximately 0.3mmol center dot g (CAT) (-1) . The microcrystal of metallic potassium was determined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was assumed that the oxygen species, which are adjacent to lattice defects, such as the crystalline corners, edges and vacancies of metallic potassium micro-crystals, constituted the superbasic sites.