On the Feasibility of Using Hierarchical ZSM‐5 and Beta Zeolites as Supports of Metal Phosphides for Catalytic Hydrodeoxygenation of Phenol

Abstract

Hierarchical ZSM‐5 and beta zeolites are assessed and compared as supports for the preparation of Ni and Co phosphide‐based hydrodeoxygenation (HDO) catalysts. Zeolites are first impregnated with the metals and P precursors, followed by temperature‐programmed reduction, to obtain the corresponding Ni2P and Co2P phases. In the HDO tests, phenol is used as a model compound typically present in pyrolysis bio‐oils. Me2P deposition affects the textural and acidic properties of the zeolitic supports, especially in the case of h‐beta, because a collapse of its mesoporosity and the formation of aluminophosphate species are observed. For both zeolites, Ni2P is the most active phosphide phase. In particular, Ni2P/h‐ZSM‐5 exhibits outstanding results (almost full phenol conversion, complete deoxygenation, and narrower compound yield distribution), even when compared with other Ni2P‐supported materials reported in the literature. Moreover, this catalyst can be effectively regenerated by calcination and subsequent reduction treatment, so that the catalytic performance remains hardly unaltered. The superior catalytic activity for phenol HDO of the h‐ZSM‐5 support is assigned mainly to the preservation of the secondary mesoporosity, which provides a good dispersion of the Ni2P nanoparticles and a good accessibility to the zeolite acid sites.

Hydro(deoxygenation) Reaction Network of Lignocellulosic Oxygenates

“…Nickel and cobalt phosphide HDO catalysts with hierarchical ZSM‐5 first undergo impregnation with metals and P precursors, followed by reduction, resulting in Ni 2 P and Co 2 P phases. Ni 2 P/h‐ZSM‐5 offers complete deoxygenation and narrow selectivity with unaltered catalyst performance . Efficient HDO of phenol by h‐ZSM‐5 results from secondary mesoporosity, which promotes good dispersion of Ni 2 P particles and remarkable accessibility of the zeolite acid sites.…”

Selective Production of Phenol on Bifunctional, Hierarchical ZSM-5 Zeolites

“…Many catalysts have been studied in hydrodeoxygenation reactions, including supported noble and transition metals (Ru, Rh, Pd, Pt, Ni, Co, Fe) on different types of acidic supports (Al 2 O 3 , USY, MCM-22, BEA, ZSM-5, etc.) [17][18][19][20][21][22][23].…”

“…The preparation of zeolites with a hierarchical pore structure by direct synthesis and by post-synthesis treatments has been exhaustively investigated through the years by many researchers. Acidic treatment with a mixture of NH 4 F and HF leads to simultaneous removal of Si and Al, which is very important for preservation of structure and Si/Al ratio [23][24][25]. Zeolites modified by this method show greater accessibility to the active acidic sites, promoting higher catalytic activity, especially in the case of bulky and branched molecules, where the diffusion restrictions limit the reaction rate.…”

Catalytic hydro-deoxygenation of acetic acid, 4-ethylguaiacol, and furfural from bio-oil over Ni 2 P/HZSM-5 catalysts

“…as catalysts for HDO attracted researcher's attention since acid supports can promote synergic interactions between the metal active phase and their intrinsic acid sites [13][14][15]. Furthermore, the use of acid supports also favored sequential hydrogenation-dehydration-hydrogenation reactions in HDO of molecules [16,17].…”