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

Abstract

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%-NiLaOy /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 H2 O in the form of hydrogen bonding and coordination effect. The interactions induce tensions inside ethyl acetate and H2 O, 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 NiLaOy /NaCl catalyst can be easily reborn after deactivation due to the water solubility of NaCl.