Metal-zeolite catalysts are promising for hydrodeoxygenation of bio-oils, but they always encounter sluggish diffusion kinetics due to sole micropores and inferior metal stability. Here, highly stable sub-nanoscale Pt-Ni bimetals confined in a hierarchical ZSM-5 zeolite ([email protected]) are constructed. The formed [email protected] species create framework-bonding metal sites with zeolite in a confined microenvironment, thereby establishing strong interactions and generating uniform distribution of Pt-Ni bimetals. In the [email protected] hydrodeoxygenation of phenolics, sub-nanometric Pt-Ni facilitates the adsorption and transfer of hydrogen, and hierarchical pores promote the diffusion kinetics of reactants. The designed [email protected] with small metal particles and high coordination numbers of Pt-Ni bonds, favors the complete deoxygenation of phenolics, with a higher yield of cyclohexane than conventional catalysts prepared by impregnation. Benefiting from the protection of the zeolite framework, the [email protected] catalyst exhibits high thermal stability and low leaching of metal active sites, with only 4.4% catalyst deactivation after five reaction cycles. 

Dynamics-driven Tailoring of Sub-nanometric Pt-Ni Bimetals Confined in Hierarchical Zeolite for Catalytic Hydrodeoxygenation

Uniform Ni species encapsulated in nanocrystalline ZSM–5 with enhanced catalytic performance for upgrading of fatty acids

Zeolites based material are very popular in refining and petrochemicals industries due to their unique properties such as uniform shape and size of pores, moderately higher surface area, and tuneable acidic and basic properties for catalysis. The cavity of a zeolite is an important space for shape selective catalysis as it is accessible to reactants molecules for interaction and adsorption of reactant molecules with active sites available in the pores followed by chemical reaction and diffusion of products. In the present review article, fine tuning of acidic properties and porosity of zeolites on the activity of catalyst and selectivity to desired product for alkylation, trans-alkylation, isomerization reactions, and production of olefins from methanol and syngas are discussed in details. 

Selective Production of Petrochemicals through Reactions in Confined Space of Zeolites

Synthesis of high-density bio-jet fuel by one-pot Mannich-Michael reaction and subsequent hydrodeoxygenation over alkali-treated zeolite catalysts

The confinement of metal species within hierarchical zeolites combines the acidic/basic sites of zeolites, the enhanced mass transfer of mesoporous system, and the inside active metal sites, leading to high activity, unique selectivity, and superior stability in chemicals synthesis, energy and environment catalysis. To date, review on this emerging topic is rarely reported. Herein, we classify five metals-hierarchical zeolites composite (metal@hierarchical zeolites) according to the location of metals on hierarchical structure, including metals located on micropores, intercrystalline mesopores, intracrystalline mesopores, hollow nanobox and mesoporous shells. The synthesis and catalysis applications of metal@hierarchical zeolites composite are provided, highlighting the rational design of catalyst preparation, the improved catalytic efficiency and stability of metal species. Finally, we discuss the current limitations and future opportunities for this emerging field. This Review is expected to inspire more developments and applications of metal@hierarchical zeolites.

Peng Sun

Papers

Hierarchical Zeolites-confined Metal Catalysts and Their Enhanced Catalytic Performances.