Effects of CeO2, TiO2, and TiO2-CeO2 Supports on Catalytic Performance of Ni2P in Hydrodeoxygenation of Anisole

This work examined the effects ofsupports for nickel phosphide(Ni2P) catalysts on anisole hydrodeoxygenation (HDO) usingsynthesized CeO2, TiO2, and TiO2-CeO2 supports and commercial supports (denoted as CeO2-L and TiO2-L) along with bulk Ni2P. Characterizationrevealed that Ni2P nanoparticles were well dispersed onthe synthesized CeO2. Ni2P/CeO2 exhibitedthe highest activity on a catalyst weight basis among those Ni2P on synthesized supports as well as the common materialssuch as SiO2, Al2O3, and activatedcarbon. Ni2P/TiO2-CeO2 (at a Ti/Cemolar ratio of 0.98) afforded superior reactivity to Ni2P/CeO2 based on turnover frequency (TOF, h(-1)), which points to more active sites on Ni2P/TiO2-CeO2 than on Ni2P/CeO2. The TOFof anisole on catalysts decreased in the following order: Ni2P/Ti0.98Ce0.02O2 > Ni2P/TiO2 > Ni2P/CeO2 > bulkNi(2)P. The type of supports employed for Ni(2)Palsoinfluenced the product distributions and thus HDO pathways. Ni2P/CeO2 favored benzene selectivity, and this maybe related to the relative electron enrichment on the Ni delta+ site of Ni2P/CeO2 that facilitated benzenedesorption from the catalyst surface after demethoxylation of anisole.Ni2P/TiO2-CeO2 exhibited significantlyhigher cyclohexane selectivity, which may be attributed to the lowerelectron density on Ni delta+ of Ni2P/TiO2-CeO2 and the acidity of binary support, promotingthe deep hydrogenation of benzene to cyclohexane. The presence ofphenol when Ni2P/TiO2 and Ni2P/TiO2-CeO2 were employed in anisole HDO could be correlatedwith the acidity of TiO2, which led to methylation of anisole.Adding a small amount of CeO2 in TiO2 and usingit as support synergistically improved the TOF and suppressed phenolformation while increasing cyclohexane selectivity. Both Ni2P/CeO2 and Ni2P/TiO2-CeO2 are promising catalysts in anisole HDO for the tunable target productsof benzene and cyclohexane, respectively.