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Tracking the structural changes in pure and heteroatom substituted aluminophosphate, AIPO-18, using synchrotron based X-ray diffraction techniques

DOI: 10.1039/c3cp00015j DOI Help

Authors: Martin Martis (University College London) , Andy Smith (University College London) , Chiu Tang (Diamond Light Source) , Julia Parker (Diamond Light Source) , Tim Hyde (Johnson Matthey) , Michael J. Watson (Johnson Matthey Technology Centre) , Xavier Baucherel (Johnson Matthey Technology Centre) , Shinji Kohara (Spring8) , Toru Wakihara (Yokohama National University) , Gopinathan Sankar (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics , VOL 15 (28)

State: Published (Approved)
Published: April 2013

Abstract: We report the structural changes that occur during the thermal removal of organic template molecules that occlude the pores of small pore nanoporous zeolitic solids, AlPO-18, SAPO-18, CoAlPO-18, ZnAlPO-18 and CoSAPO-18. The calcination process is a necessary step in the formation of active catalysts. The studies performed using time-resolved High Resolution Powder Diffraction (HRPD) and High Energy X-ray Diffraction (HEXRD) techniques at various temperatures reveal that changes that take place are dependent on the type of heteroatom present in the nanoporous solids. While time-resolved HRPD shows clear changes in lattice parameters during the removal of physisorbed water molecules and subsequent removal of the organic template, HEXRD data show changes in various near neighbour distances in AlPO-18, SAPO-18, CoAlPO-18, CoSAPO-18 and ZnAlPO-18 during the calcination process. In particular HEXRD reveals the presence of water molecules coordinated to Al(III) ions in the as-synthesised materials. Upon removal of the template and water, these solids show contraction in the cell volume at elevated temperatures while first and second neighbour distances remained almost unchanged.

Subject Areas: Chemistry, Materials

Instruments: I11-High Resolution Powder Diffraction

Other Facilities: Spring8 - Beamline BL04B2

Added On: 20/08/2013 12:00

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