Bimetallic Ni‐Re catalysts for the efficient hydrodeoxygenation of biomass‐derived phenols

Abstract

The development of non-noble metal-based catalysts for the hydrodeoxygenation (HDO) upgrading of biomass pyrolysis oils is crucial for realizing the cost-effective biofuel production. In this paper, we report on the enhanced HDO activity of the rhenium-promoted nickel catalysts (Ni-Re) for the HDO of a pyrolysis oil model compound, guaiacol. The catalyst screening studies revealed that the Ni-Re displayed a considerably higher HDO activity than other monometallic (Ni, Re, Cu, Co) and bimetallic catalysts (Cu-Re, Co-Re), highlighting its unique catalytic property. In order to optimize the catalytic activity and reveal the structure-activity relationship of the Ni-Re catalysts, the effects of the Ni/Re ratio and type of support (SiO 2 , TiO 2 , and ZrO 2 ) on the catalyst structure and HDO activity were investigated in detail. The results showed that the addition of rhenium to nickel altered both geometric and electronic structures of nickel significantly. The Ni-Re/SiO 2 catalyst with a Ni/Re ratio of 0.315 achieved~95% yield of the desired deoxygenation product, cyclohexane, at 523 K and 30 bar-H 2 after 5 hours. Novelty StatementThe upgrading of biomass pyrolysis oils to hydrocarbon fuels oftentimes requires the use of noble metal catalysts and harsh reaction conditions (e.g., high H 2 pressure), all of which greatly increase the process cost. In this work, a highly active and nonprecious metal-based catalyst, bimetallic Ni-Re/SiO 2 , is developed for the cost-effective upgrading of biomass-derived phenols to deoxygenated hydrocarbon fuels at low temperature and low pressure.

Utilization of Ni as a Non-Noble-Metal Co-catalyst for Ceria-Supported Rhenium Oxide in Combination of Deoxydehydration and Hydrogenation of Vicinal Diols

“…This is probably due to the small particle size of Ni and/or oxidation of Ni species by exposure to air. In the literature, a strong interaction between reduced Ni and Re species has been reported for the supported Ni–Re bimetallic catalysts; − , however, detailed characterization is lacking for the reduced state without exposure to air. The intensity and peak width of XRD for the CeO 2 phase were not changed, indicating that the bulk CeO 2 phase was not changed during the pre-reduction or catalytic reaction.…”

Effect of the Support Functionalization of Mono- and Bimetallic Ni/Co Supported on Graphene in Hydrodeoxygenation of Guaiacol

“…44−46 Over NiRu bimetallic systems, the selectivity to phenol was improved, 47 while the addition of Re modified both geometric and electronic structures of nickel, significantly improving HDO activity. 48 Finally, bimetallic Ni−Co has also been investigated over several acidic supports (HZSM-5, 49 Al-MCM-41, 50 Al 2 O 3 , 51 and ZrP 29 ), and in all the cases, over the bimetallic systems, HDO activity was enhanced. Specially, Co has shown to stabilize the Ni active phase 49 by improving mainly the metal dispersion 50 and the reducibility of the NiO particle, resulting in higher HDO activity.…”

“…As far as Ni is concerned, the promotion with Cu led to smaller particle size inhibiting the hydrogenolysis and deoxygenation reaction . On the other hand, the addition of Fe shows that an alloy was formed, rendering the C–O cleavage energetically easier. − Over NiRu bimetallic systems, the selectivity to phenol was improved, while the addition of Re modified both geometric and electronic structures of nickel, significantly improving HDO activity . Finally, bimetallic Ni–Co has also been investigated over several acidic supports (HZSM-5, Al-MCM-41, Al 2 O 3 , and ZrP), and in all the cases, over the bimetallic systems, HDO activity was enhanced.…”

Guaiacol Hydrodeoxygenation and Hydrogenation over Bimetallic Pt-M (Nb, W, Zr)/KIT-6 Catalysts with Tunable Acidity

“…The introduction of a second metal has been reported to improve guaiacol HDO. Bimetallic Ni-Re/SiO 2 catalyst showed a higher guaiacol HDO activity compared to monometallic (Ni, Re, Cu, Co) and other bimetallic (Cu–Re and Co–Re) catalysts, yielding cyclohexane as the major product at 250 °C and at 3 MPa H 2 pressure . Pd–Co and Pd–Fe supported on Al-MCM-41 were also reported for atmospheric guaiacol HDO at ∼400 °C, with the yield of fully deoxygenated products being <20% .…”