Catalysis at the interface of nano-oxides and nanozeolites

Abstract

The catalysts that can efficiently hydro-reform higher n-paraffin to lower isoparaffins for environmentally friendly gasoline were studied. The catalysts were examined by the conversion of n-hexadecane, n-C 16 H 34 to i-C 6 H 14~i -C 12 H 26 . The tri-modally nanoporous (nanometer-size) catalysts composed of (Ni-Mo)/[γ-Al 2 O 3 ], nano-oxide, and nanocrystalline zeolite have some active and selective performances because of the cooperation between (Ni-Mo)/[γ-Al 2 O 3 ] and the composite of nano-oxide-nanozeolite. The (Ni-Mo)/[γ-Al 2 O 3 ] component holding the skeletal isomerization activity enhances the cracking activity on the composite of nanoporous (np)-Al 2 O 3 -USY (ultra-stable Y-type zeolite) to result in i-C 6 H 14~i -C 12 H 26 as the isomerization of n-hexadecane followed the cracking reaction. The catalyst composed of nanocrystalline BEA (beta-type zeolite) or MFI (ZSM-5-type zeolite) zeolite can be more activated with the nano-SiO 2 than with the nano-Al 2 O 3 . The catalyst composed of the dealuminated zeolite, USY (SiO 2 /Al 2 O 3 = 12) cannot be activated with the nano-SiO 2 but with the nano-Al 2 O 3 . This activation depends on the SiO 2 /Al 2 O 3 ratio of the USY.It is considered that the catalytic property of the three components is partially due to the novel active sites formed concertedly at the interface of the nano-oxides and the nanozeolites. The novel sites have a major role for the isomerization and cracking as the moderate and strong acids and are generated when Si-OH in the nanopores of the USY resulted from the dealumination catches Al-OH in the nano-Al 2 O 3 to form Si-O-Al-O-Al-O-Si instead of Si-O-Al-O-Si-O-Si-O.

NiMo/Al₂O₃ Promoted Hybrid Catalysts of Nanosized Alumina and Beta Zeolite for Hydrocracking with Isomerization

“…This indicates that a concerted reaction occurs on the three-component catalyst. Just like for a three-component catalyst containing USY zeolite (NiMo/γ-Al2O3 _ ns Al2O3 _ USY zeolite) 32) , a combined effect was confirmed for a threecomponent catalyst containing beta zeolite (NiMo/ γ-Al2O3 _ ns Al2O3 _ beta zeolite). Moreover, the threecomponent catalyst containing beta zeolite has a higher cracking activity and a higher selectivity despite beta zeolite having a higher SiO2/Al2O3 molar ratio (approximately 25) than USY zeolite (about 12).…”

“…They are generated when Si _ OH in the nanopores of the USY zeolite produced by dealumination traps Al _ OH in the ns Al2O3 precursor. On the other hand, we found that catalysts composed of beta zeolite or ZSM-5 (hereafter, MFI) zeolite are activated more by ns SiO2 than ns Al2O3 and that they have higher activities than a catalyst composed of USY zeolite 32) . Overcracking that produced a gaseous component was observed when a catalyst composed of MFI zeolite was used.…”

“…In our recent research on catalysts, we have intentionally focused on zeolite catalysts containing various subnanometer pores and unimodal nanoporous oxides with pore sizes ranging from about 1 nm to several tens of nanometers. This research has resulted in some advances in catalyst designing in various industrial applications, including hydrodesulfurization 28), 29) , N2O decomposition 30) , hydrocracking 31), 32) , and catalytic cracking 33)～35)…”

“…As hydrocracking catalysts, we studied efficient hydro-reform catalysts that have a high selectivity for producing lower isoparaffins from higher nparaffin; this promises to produce an environmentally friendly gasoline 32) . We studied the catalytic performance of these catalysts in converting n-hexadecane (n-C16H34) into isoparaffins with carbon numbers in the range 6 to 12.…”

Catalyst of Palladium Supported on H-Beta Zeolite with Nanosized Al₂O₃ for Isomerization of <i>n</i>-Heptane

“…Cracking of hydrocarbon may be driven by formation of an intermediate of carbenium ion on solid acid sites. Usage of ns Al2O3 as a binder for high silica zeolite particle leads to formation of acid sites on the surface of the zeolite catalyst, to produce carbenium ions on the sites, and to promote the cracking reaction 19) . The basic structure of zeolite is a chain of tetrahedrons consisting of silicon cations, aluminum cations and oxygen anions.…”