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We report the design and synthesis of nanosized ZnxZryOz mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (83%). ZnO is addded to ZrO2 to selectively passivate zirconia's strong Lewis acidic sites and weaken Brnsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brønsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized ZnxZryOz mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene. [ABSTRACT FROM AUTHOR]

Dispersion and quantitative characterization of supported catalysts is a grand challenge in catalytic science. In this paper, heteropoly acid H3PW12O40 (HPA) is dispersed on mesoporous zeolite silicalite-1 derived from hydrothermal synthesis using carbon black nanoparticle templates, and the catalytic activity is studied for 1-butene isomerization. The HPAs supported on conventional zeolite and on mesoporous zeolite exhibit very different activities and thus provide good model systems to investigate the structure dependence of the catalytic properties. The HPA on mesoporous silicalite-1 shows enhanced catalytic activity for 1 -butene isomerization, while HPA on conventional silicalite-1 exhibits low activity. To elucidate the structural difference, supported HPA catalysts are characterized using a variety of techniques, including 31P magic angle spinning nuclear magnetic resonance, and are shown to contain a range of species on both mesoporous and conventional zeolites. However, contrary to studies reported in the literature, conventional NMR techniques and chemical shifts alone do not provide sufficient information to distinguish the dispersed and aggregated surface species. The dispersed phase and the nondispersed phase can only be unambiguously and quantitatively characterized using spin-lattice relaxation NMR techniques. The HPA supported on mesoporous zeolite contains a fast relaxation component related to the dispersed catalyst, giving a much higher activity, while the HPA supported on conventional zeolite has essentially only the slow relaxation component with very low activity. The results obtained from this work demonstrate that the combination of spinning sideband fitting and spin-lattice relaxation techniques can provide detailed structural information on not only the Keggin structure for HPA but also the degree of dispersion on the support. [ABSTRACT FROM AUTHOR]

Silanized dry gel prepared by solvent evaporation was subjected to steam treatment to synthesize hierarchically porous zeolite Beta. With well dispersed sodium cations (Na+) in ethanol solution and dry gel, zeolite Beta with high degree of crystallinity can be obtained by the steam-assisted crystallization method. Two types of organosilanes, short-chain phenylaminopropyltrimethoxysilane (PHAPTMS) and long-chain hexadecyltrimethoxysilane (HDTMS), were applied to prepare the silanized dry gel and inhibit the crystallization of zeolite Beta. PHAPTMS does not generate appreciable mesopores, whereas HDTMS can successfully create abundant mesopores ranging from 3 to 10nm, which indicates a greater spatial separation effect of the long-chain moiety than the short-chain counterpart. [ABSTRACT FROM AUTHOR]

The tetrairon(III)-substituted polytungstates [Fe4(H2O)10(β-XW9O33)2]n- (n = 6, X = AsIII, SbIII; n = 4, X = SeIV, TeIV) were immobilized on (3-aminopropyl)triethoxysilane-modified SBA-15 and showed an excellent catalytic performance for solvent-free aerobic oxidation of long-chain n-alkanes using air as the oxidant under ambient conditions through a classical free-radical chain autoxidation mechanism. [ABSTRACT FROM AUTHOR]

α-Fe[sub2]O[sub3] nanowires were prepared using mesoporous silica SBA-15 as a template and showed a remarkable catalytic activity for the hydroxylation of phenol with 30% H[sub2]O[sub2] in aqueous solution at 343 K. [ABSTRACT FROM AUTHOR]

An abstract of the article "A Facile Synthesis of NiO Nanosheet with High-energy (111) Surface," by Kake Zhu, Weiming Hua, and Xingyi Wang is presented.