Synthesis and characterization of mixed silica/zirconia and silica/titania porous phospate heterostructures (PPH)

New stable mesoporous phosphate heterostructure materials with tunable acidity, consisting of expanded zirconium phosphate with silica galleries doped with zirconium or titanium, have been prepared using as precursor zirconium phosphate, expanded with cetyltrimethylammonium as the surfactant, hexadecylamine as the co-surfactant, tetraethylorthosilicate (TEOS) as the silica source, and zirconium(IV) propoxide or titanium(IV) propoxide as Zr or Ti sources, respectively. The solids were characterised by XRD, XPS, DTA-TG, and their acidity was studied by ammonia thermal programme desorption, iso-propanol decomposition and 1-butene isomerisation. The incorporation of Zr or Ti produces a decrease of the Brönsted acidity and an increase of the Lewis acidity.