Kim, SJ Kim, MH Hong, SB Uh, YS Choi, YS 2024-01-21T19:04:42Z 2024-01-21T19:04:42Z 2021-09-05 1997-01 1011-372X https://pubs.kist.re.kr/handle/201004/144152 Temperature-programmed desorption (TPD) and electron spin resonance (ESR) techniques have been employed to investigate the oxygen adsorbed on the paramagnetic defect centers in dehydroxylated AlPO4-20, AlPO4-11, AlPO4-5, and VPI-5 molecular sieves. Two different adsorption sites are observed for the small-pore AlPO4-20, where oxygen is entrapped within the intracrystalline voids generated during the calcination step, as well as within the beta-cages. However, the unidimensional molecular sieves AlPO4-11 AlPO4-5, and VPI-5 have only one type of adsorption site within their inner pores. The apparent activation energies of desorption (12.0-21.7 kcal mol(-1)) determined from the oxygen TPD results demonstrate that, as the pore size of the AlPO4 molecular sieve is larger, the interaction between the adsorbed oxygen and the molecular sieve framework becomes weaker. English BALTZER SCI PUBL BV TEMPERATURE PROGRAMMED DESORPTION METAL-OXIDE CATALYSTS MFI-TYPE ZEOLITES Adsorption of oxygen on the paramagnetic defect centers in aluminophosphate molecular sieves Article 10.1023/A:1018977025472 1 CATALYSIS LETTERS, v.44, no.3-4, pp.165 - 169 CATALYSIS LETTERS 44 3-4 165 169 scie scopus A1997WY72900004 2-s2.0-0006618352 Chemistry, Physical Chemistry Article TEMPERATURE PROGRAMMED DESORPTION METAL-OXIDE CATALYSTS MFI-TYPE ZEOLITES oxygen adsorption AlPO4 molecular sieves paramagnetic defects TPD ESR