Single-site zinc on silica catalysts for propylene hydrogenation and propane dehydrogenation: Synthesis and reactivity evaluation using an integrated atomic layer deposition-catalysis instrument

Abstract

Alkyl-zinc and zinc oxide-type sites were synthesized via atomic layer deposition on highsurface-area silica using an integrated atomic layer deposition-catalysis instrument (I-ALD-CAT). One-cycle ALD experiments using diethylzinc (DEZ) afforded Zn/SiO 2 systems that provided key insights into the reactivity and stability of Zn sites as a function of dispersion at the submonolayer level. The I-ALD-CAT tool design allowed for systematic comparison of the reactivity of different grafted zinc sites. Open-shell 16-electron, tricoordinate ethyl zinc-silica sites exhibit higher activity in propane hydrogenation-dehydrogenation compared to 18-electron, tetracoordinate zinc oxide-type centers. Silica surface saturation with Zn(II) sites (~75% of a monolayer) results in facile zinc agglomeration and catalyst deactivation under reaction conditions. Reduced DEZ dosing coupled with thermal substrate pretreatment techniques (e.g., dehydration under vacuum) resulted in increased Zn dispersion and produced Zn/SiO 2 catalysts with improved activity and stability under propylene hydrogenation (200°C) and propane dehydrogenation (550°C) conditions.

Role of Co2C in ZnO‐promoted Co Catalysts for Alcohol Synthesis from Syngas

“…Similar to this result, Camacho‐Bunquin et al . found that for thin ZnO ALD films deposited on SiO 2 , Zn−O short‐range scattering was present with no second shell scattering . Prior work found that with increasing ZnO film thickness deposited by ALD, the magnitude of the second shell Zn−Zn scattering increased as expected for a ZnO structure,, but due to the low amount of ZnO deposited in this study we did not observe this.…”

ZnO Nanoclusters Supported on Dealuminated Zeolite β as a Novel Catalyst for Direct Dehydrogenation of Propane to Propylene

“…Among them, Zn based materials are found to be one of the most promising catalysts due to the low price, environmental‐friendly‐ness and high catalytic performance in PDH ,,. Several studies have verified that isolated Zn 2+ and Zn(OH) + species are the catalytically active sites in PDH,, while very few investigations put attention on the catalytic activity of small ZnO clusters or nanoparticles. It is reported that ZnO supported on Al 2 O 3 could serve as Lewis acid sites (LAS), which can efficiently catalyze PDH .…”

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

“…Alternatively, the propylene can also be easily separated from liquid phase aer HTL to be upgraded through a downstream catalytic bed. 19,20 Further studies will be needed to test these ideas. Based on the high propylene yield from PHB in HTL process we hypothesized that mcl-LAO can be produced from mcl-PHA via the similar pathway.…”