Qualitative and quantitative assessments of acid and base sites exposed on polycrystalline MgO surfaces: Thermogravimetric, calorimetric, and in-situ FTIR spectroscopic study combination

Impact of the parent material used to yield magnesia on its surface properties was the prime objective of the present investigation. Accordingly, four test magnesias were obtained by calcination at 600 degreesC of four different parents: magnesium oxalate (to yield MgO-OX), carbonate (MgO-CA), hydroxide (MgO-HY), and perchlorate (MgO-PC). The surface accessibility was determined by N-2 sorptiometry at liquid nitrogen temperature, whereas the surface acid and base properties were assessed qualitatively and quantitatively by means of thermogravimetry, differential scanning calorimetry, and in-situ infrared spectroscopy of adsorption/ desorption of pyridine and CO2 at RT-400degreesC. The reactivity of the surface acid and base sites thus revealed was gauged versus the decomposition of methylbutynol at 100 degreesC. The results obtained have shown the surface accessibility, basicity, and base site reactivity to assume the following descending order: MgO-OX > MgO-HY > MgO-CA > MgO-PC. Moreover, the results emphasize the importance of implementing the above-indicated combination of studies, if the nature, amount, and strength of surface acid and base sites are to be exhustively assessed.