Microemulsion-assisted synthesis of catalysts based on aluminiurn and magnesium phosphates

Various materials consisting of magnesium (mMgPO-1 and mMgPO-2) or aluminium phosphates (mAlPO-1 and mAlPO-2) were synthesized from microemulsions and characterized in structural terms using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), thermal analysis, and solid-state P-31 and Al-27 NMR spectroscopies. The morphology of the solids was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and their surfaces properties were determined from N-2 adsorption-desorption isotherms. The new materials thus prepared are structurally and compositionally similar to solids obtained by precipitation from solutions; their specific surface areas, however, are substantially greater and their pore size distribution more narrow. The catalytic activity of the materials in the dehydration-dehydrogenation of isopropyl alcohol was found to be similar to or greater than that of catalysts obtained by precipitation from aqueous solutions. The magnesium orthophosphates yielded acetone (the major product) and propene from 2-propanol; the aluminium orthophosphates, which possess dehydrating activity only, yielded propene alone. (C) 2002 Elsevier Science B.V. All rights reserved.