Highly Porous Zirconium Aryldiphosphonates and Their Conversion to Strong Bronsted Acids
✍ Scribed by Abraham Clearfield; Zhike Wang; Paul Bellinghausen
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 365 KB
- Volume
- 167
- Category
- Article
- ISSN
- 0022-4596
No coin nor oath required. For personal study only.
✦ Synopsis
IN HONOR OF PROFESSOR GALEN STUCKY ON THE OCCASION OF HIS 65TH BIRTHDAY
Porous inorganic+organic hybrids have been prepared by the reaction of 4,4-biphenylbis(phosphonic acid) with Zr(IV) in organic solvents. The resultant products consist of -zirconium phosphate-type layers crosslinked by biphenyl pillars. By using an excess of Zr in the synthesis, surface areas of &400 m 2 /g have been obtained and the pores can be controlled to be the micro-type with diameters of 10+20 A s and a relatively narrow pore size distribution. The aromatic rings are readily sulfonated by SO 3 under pressure to produce very strong Bronsted acid catalysts. An NMR procedure, utilizing the shift of the carbonyl carbon of acetone-2-13 C sorbed onto the sulfonated products, indicated an acid strength for the Bronsted acid sites equal to that of 100% sulfuric acid. Unpillared Zr(O 3 PC 6 H 4 SO 3 H) 2 has a somewhat lower acid strength, but still has a higher acid strength than zeolites HX and HY. The particles of this layered acid exfoliate in water and light-scattering data show that they are in 5 nm size range. They also exhibit high proton conductivity as solid membranes. These sulfonated materials have a potential as strong acid catalysts for a variety of reactions at a low temperature.
2002 Elsevier Science (USA)