Effect of yttrium on catalytic performance of Y-doped TiO2 catalysts for propane dehydrogenation

Defective bulk catalysts based on TiO2 have superior catalytic performance for propane dehydrogenation (PDH). The oxygen vacancy concentration and the number of active sites on the catalyst surface can be effectively tuned by doping metal in TiO2. Herein, yttrium (Y)-doped titanium dioxide (nY/TiOx) catalysts were in-situ synthesized via the coprecipitation method to study the effect of rare earth metal Y doping on the structure of TiO2 and the catalytic performance for PDH. Experimental results demonstrate that Y-doped TiO2 exhibits higher catalytic activity, propylene selectivity and stability than bare TiO2. Full characterizations with X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy of pyridine adsorption (Py-IR), temperature-programmed desorption of ammonia (NH3-TPD), H2 temperature-programmed reduction (H2-TPR), and Raman techniques on these catalysts reveal that Y3+ can enter TiO2 lattice, and the lattice stability of the catalyst can be enhanced by replacing Ti4+ to form Y–O–Ti structure. Meanwhile, the introduction of an appropriate amount of Y can obviously promote the PDH reaction by adjusting the acidity of the catalyst, improving the release capacity of TiO2 lattice oxygen and increasing the formation of active centers. Nevertheless, excessive Y doping will lead to pore clogging, and the exposure of active sites will be reduced, resulting in the degradation of catalytic performance.