Ethanol dehydration activity on hydrothermally stable LaP _xO _y catalysts synthesized using CTAB template

Nanocrystalline LaP _xO _y with various starting P to La ratios from 0.5 to 2.0 catalysts were prepared by a sol-gel method using cetyl trimethylammonium bromide (CTAB) as template. The catalysts were thoroughly characterized by N ₂ physisorption, powder X-ray diffraction (XRD), temperature programmed desorption (TPD) of NH3, solid state ₃₁P and ₁H nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM) techniques. XRD results indicate the presence of predominantly monazite LaPO ₄ with minor amounts of (≤B3.0 wt%) rhabdophane LaPO ₄ phase in the samples with starting P/La ratios of 1.0 and 1.5. NH ₃-TPD results show an increasing trend in the total acidity with increase in P/La ratio. These catalysts were tested in the selective ethanol dehydration in the temperature range between 250 and 400 °C. The catalyst activity (lmol/h/m ²) is increased with P/La ratio and the catalyst with highest P/La ratio of 2.0 exhibiting the highest ethanol dehydration activity. The ethanol conversion increased with reaction temperature, reaching 100% at 350 °C and remains unchanged at higher temperatures. On the other hand, the ethylene selectivity is also increased up to 350 °C and then decreased with further increase of reaction temperature. At a P/La ratio of 2, the CTAB templated LaP _xO _y catalyst showed higher catalytic activities compared to the LaP _xO _y by hydrothermal method without any template.