Sachio Asaoka

31P-MASNMR spectroscopic studies with zirconium phosphate catalysts

Zirconium phosphates are crystallized during the removal of hydration water in the zirconium phosphate gel with phosphoric acid solution under reduced pressure. Several forms of crystallites are obtained by this procedure, depending on the temperature and process time, for a given concentration of phosphoric acid. Synthetic ZrP2O7 and e-Zr(HPO4)2 catalysts, which were evacuated at 773 K, showed higher catalytic activities for butene isomerization than other forms of zirconium phosphates or other conventional solid acid catalysts. In order to elucidate those higher catalytic activities, 31P magic angle spinning NMR (31P-MASNMR) has been employed to study zirconium phosphates after evacuation at different temperatures. The 31P chemical shifts move towards higher magnetic fields as the layer separations become smaller. The catalysts which showed higher activities showed higher chemical shifts at around −38 ppm from H3PO4. These results suggest that the phosphate groups remaining after evacuation at around 800 K may enhance the protonic characteristics, since the accumulation of electrons moves from the phosphate groups on the surface to phosphorus atoms which are located between Zr atom planes.

Structure and surface chemistry of crystalline zirconium phosphate catalysts

Abstract The catalytic activities for isomerization of butenes and cyclopropane on crystalline zirconium phosphates(ZrP) have been examined. The ZrP catalyst, when calcined at higher temperatures( ca. 800K), exhibited higher catalytic activities. The coisomerization of d0- and ds-1-butene suggests that isomerization would proceed on protonic acid sites even after heat treatment at 1100K. After evacuation at ca. 800K, most of the phosphate groups were removed, with consequent loss of water, due to the condensation of phosphate groups between each Zr atom layer. However, a trace amount of residual phosphate groups still remained on the surface. In order to elucidate those higher catalytic activities on the phosphate protons, 31P magic angle spinning NMR (31P-MASNMR) has been employed to study the phosphorus micro-environments. The catalysts which showed higher activities showed higher 31P chemical shifts. The NMR results suggest that the phosphate groups remaining after evacuation at around 800 K may enhance the protonic acidity.

Hydroconversion of Triglycerides to Hydrocarbons Over Mo–Ni/γ-Al2O3 Catalyst Under Low Hydrogen Pressure

The hydroconversion of coconut oil to saturated hydrocarbons under low hydrogen pressure was demonstrated, using a sulfur-free Mo–Ni/γ-Al2O3 catalyst prepared by the co-impregnation of Ni and Mo species. The Mo–Ni/γ-Al2O3 catalyst exhibited remarkably high conversion of coconut oil as well as high selectivity for the generation of the hydrocarbon fraction associated with jet fuel. Examining variations in product distributions with contact time showed that hydrocarbons were produced primarily through the hydrogenolysis of triglycerides followed by hydrodecarboxylation of fatty acids. Increases in the contact time led to improvements in the proportion of hydrocarbons via the hydrodeoxygenation of fatty acids.Graphical Abstract

Selective synthesis of LPG from synthesis gas

Abstract LPG synthesis from synthesis gas was investigated over hybrid catalysts composed of a Cu-Zn methanol synthesis catalyst and several kinds of zeolites at 523–623 K under pressure. Combination of Cu-Zn catalyst and USY or β zeolite gave high catalytic performances for LPG formation; above 70% of CO conversion and LPG selectivity were obtained at 598 K and 2.1 MPa.

Catalysis at the interface of nano-oxides and nanozeolites*

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-C16H34 to i-C6H14~i-C12H26. The tri-modally nanoporous (nanometer-size) catalysts composed of (Ni-Mo)/[γ-Al2O3], nano-oxide, and nanocrystalline zeolite have some active and selective performances because of the cooperation between (Ni-Mo)/[γ-Al2O3] and the composite of nano-oxide-nanozeolite. The (Ni-Mo)/[γ-Al2O3] component holding the skeletal isomerization activity enhances the cracking activity on the composite of nanoporous (np)-Al2O3-USY (ultra-stable Y-type zeolite) to result in i-C6H14~i-C12H26 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-SiO2 than with the nano-Al2O3. The catalyst composed of the dealuminated zeolite, USY (SiO2/Al2O3 = 12) cannot be activated with the nano-SiO2 but with the nano-Al2O3. This activation depends on the SiO2/Al2O3 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-Al2O3 to form Si-O-Al-O-Al-O-Si instead of Si-O-Al-O-Si-O-Si-O.

RECENT ADVANCES IN APPLICATIONS OF MULTINUCLEAR SOLID-STATE NMR TO HETEROGENEOUS CATALYSIS AND INORGANIC MATERIALS

Abstract The interface between heterogeneous catalysis and the science of inorganic materials and high-resolution solid-state NMR is recently an area of much activity. A wide variety of novel techniques in multinuclear solid-state NMR have provided attractive possibilities in the mechanistic studies in catalysis as well as the design of catalysts and functional materials. Current state-of-the-art topics, by means of significant multinuclear solid-state NMR techniques, were selected to illustrate the scope of applications to the studies in the field of heterogeneous catalysis and inorganic materials.

Recent trends of industrial catalysts for resid hydroprocessing in Japan

To meet the gradual changes in petroleum demand, in particular a reduced demand for heavy fuel oil, advanced technology for resid hydroprocessing is now extremely necessary. The catalyst technology for resid hydroprocessing in Japan, especially fixed bed type of hydrodesulfurization and hydroconversion, is reviewed in this article.

Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al2O3/H-USY and ns Al2O3/H-GaAlMFI; HC: [Ni-Mo/γ-Al2O3]/ns Al2O3/H-beta) were studied. The major product from CC on ns Al2O3/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products.

Preparation of nanosized and structured oxides for catalyst

Abstract Precipitation control and impregnation into the precipitate were developed for nanosized and structured Al2O3, SiO2–Al2O3, ZnO–Al2O3, TiO2–Al2O3, etc. The nanosized and structured oxides dispersed on nanoporous oxides can be expected to generate various types of functional nanosites.

Role of nanosized oxide in catalysis on the nanoporous surface of zeolite particles

Based on our studies on the hybrid catalysts of nanosized (ns) oxide with zeolite, products obtained from the isomerization and hydrocracking of heavier n-paraffins and the role of ns oxide were investigated using a tricomponent catalyst of [Ni-Mo/γ-Al2O3], ns oxide, and H-beta zeolite catalyst, which showed high activity, high isomerization selectivity, and mild cracking ability. A concerted effect of the three components was observed. From the observed hybridization state of the catalyst, it was suggested that the concerted effect was obtained because the components become attached to each other. The individual and concerted effects of each component and two components, respectively, were investigated based on the ratio of [Ni-Mo/γ-Al2O3]/[H-beta zeolite], the content of ns oxide, the amount of metal, the type of ns oxide species, and the reduction state of metal. It was confirmed that in order to obtain the highest concerted effect, the ratios of [Ni-Mo/γ-Al2O3]/[H-beta zeolite] and/or ns oxide/zeolite are important. Furthermore, among the ns oxide species, nsAl2O3-nsTiO2 displayed the highest activity and cracking ability with an over-cracking suppression. In addition to increasing the concerted effect in the tricomponent catalyst, the performance of this catalyst could also be further increased by controlling the amount and reduction state of metal.