Quantitative measurement of Brönsted acidity by TPD of ammonia on H 3 [PMo 12 O 40 ] and its Cs1 salt, in bulk and supported on SBA-15

摘要: The method for acidity measurement through temperature programmed desorption (TPD) of ammonia was adapted simultaneous TG/DTG–DTA analysis the H3[PMo12O40] and its Cs acid salts, in bulk supported on SBA-15 support. NH3 consists H2O release steps as a result increase. last step corresponds to expelling by decomposition species strong bonded like ammonium cation, simultaneously with constitutive water, within 300–600 °C range. MS showed that oxidation N2O NO during had occurred reduction Mo6+. reoxidation samples air all cases done finally. In order separate water (water formed condensation hydroxyl groups belonging SBA-15) from samples, TPD every sample. case pure compounds, mass loss corresponding stage (after correction reduction, equal increase owing reoxidation) gives amounts which correspond stoichiometrically Bronsted acidity. subtraction corrected (because reduction) amount acidic strength estimated basis temperatures DTG peaks.