Ultrasonic-assisted fabrication of LaNiOx composite oxide nanotubes and application to the steam reforming of ethanol

A novel ultrasonic-assisted route for the preparation of LaNiOx composite oxide nanotubes was developed in this study. A nickel–lanthanum composite oxide with a 1:1 molar ratio was prepared by the co-precipitation–oxidation method (PO) and assisted with 240 W ultrasonic irradiation (assigned as U-LaNiOx). The composite oxide nanorods were synthesized by the co-precipitation–oxidation method (assigned as LaNiOx) without ultrasonic irradiation. Both samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), BET and temperature-programmed reduction (TPR). Catalytic activity toward the steam reforming of ethanol (SRE) was tested in the temperature range of 300–450 °C in a fixed-bed reactor. The results indicated that U-LaNiOx nanotubes have better activity which enables 100% ethanol conversion at 325 °C; while a conversion temperature of above 425 °C is required for the LaNiOx nanorods. The distribution of CO is minor for both samples. This demonstrated that the water gas shift reaction (WGSR) is an important side-reaction in the SRE reaction over both composite oxides to produce H2 and CO2.