Key Role of Lanthanum Oxychloride: Promotional Effects of Lanthanum in NiLaO_y/NaCl for Hydrogen Production from Ethyl Acetate and Water

The hydrogen economy is accelerating technological evolutions toward highly efficient hydrogen production. In this work, the catalytic performance of NiO/NaCl for hydrogen production via autothermal reforming of ethyl acetate and water is further improved through lanthanum modification, and the resulted 3%-NiLaO_y/NaCl catalyst achieves as high as 93% H₂ selectivity and long-term stability at 600 °C. The promoting effect is caused by the strong interactions between lanthanum and NiO/NaCl, by which LaNiO₃ and a novel LaOCl phase are formed. The key role of LaOCl in promoting low-temperature hydrogen production is highlighted, while effects of LaNiO₃ are well known. The LaOCl (010) facet possesses high adsorption capacity toward co-chemisorbing ethyl acetate and water. LaOCl strongly interacts with ethyl acetate and H₂O in the form of hydrogen bonding and coordination effect. The interactions induce tensions inside ethyl acetate and H₂O, activate the molecules, and hence decrease the energy barrier for reaction. In situ Fourier transform infrared spectroscopy (FTIR) reveals that LaOCl along with NaCl enhances the adsorption ability of NiO/NaCl. Moreover, LaOCl improves the dispersion of Ni species in NiO–LaNiO₃–LaOCl nanosheets, which possess abundant active sites. The effects together promote hydrogen evolution. Furthermore, the NiLaO_y/NaCl catalyst can be easily reborn after deactivation due to the water solubility of NaCl.