Synthesis and characterization of MgO-B2O3 mixed oxides prepared by coprecipitation; selective dehydrogenation of propan-2-ol

Abstract

The synthesis of MgO-B ₂ O ₃ mixed oxides by coprecipitation from Mg(OH) ₂ and B(OH) ₃ (0-10 wt%) led to solids with textural and acid-base properties rather different from pure magnesium oxide. DRIFT and ¹¹ B MAS NMR studies showed that boron atoms are in a flat trigonal environment, as part of the magnesium oxide structure. Titration of acid and basic sites by TPD-MS of probe molecules (pyridine and 2,6-dimethylpyridine for acid sites, and carbon dioxide for basic ones) indicates that the presence of boron leads to an increase in the acid sites surface density as well as to a decrease in surface density of basic ones, together with a change in strength distribution profile of the later. Propan-2-ol conversion over MgO-B ₂ O ₃ mixed oxides showed an increase in the selectivity to the dehydrogenation process with an increase in the amount of boron in the catalyst.