Daniel Fodor

Differences Between Individual ZSM‐5 Crystals in Forming Hollow Single Crystals and Mesopores During Base Leaching

After base treatment of ZSM-5 crystals below 100 nm in size, TEM shows hollow single crystals with a 10 nm shell. SEM images confirm that the shell is well- preserved even after prolonged treatment. Determination of the Si/Al ratios with AAS and XPS in combination with argon sputtering reveals aluminum zoning of the parent zeolite, and the total pore volume increases in the first two hours of base treatment. In corresponding TEM images, the amount of hollow crystals are observed to increase during the first two hours of base treatment, and intact crystals are visible even after 10 h of leaching; these observations indicate different dissolution rates between individual crystals. TEM of large, commercially available ZSM-5 crystals shows inhomogeneous distribution of mesopores among different crystals, which points to the existence of structural differences between individual crystals. Only tetrahedrally coordinated aluminum is detected with (27) Al MAS NMR after the base leaching of nano-sized ZSM-5.

Synthesis of Single Crystal Nanoreactor Materials with Multiple Catalytic Functions by Incipient Wetness Impregnation and Ion Exchange

ZSM-5 hollow crystals are functionalized with multiple catalytic sites, the structure of which resembles a cell-like structure on the nanometer scale. The crystal size of the nanoreactor is below 100 nm. The material is functionalized with metal oxide particles within the hollow or on the external crystal surface. Additionally, Bronsted acid sites are present in the zeolite channels.

Non-uniform spatial distribution of tin oxide (SnO2) nanoparticles at the air–water interface

Depth resolved X-ray photoelectron spectroscopy (XPS) combined with a 25 μm liquid jet is used to quantify the spatial distribution of 3 nm SnO2 nanoparticles (NPs) from the air-water interface (AWI) into the suspension bulk. Results are consistent with those of a layer several nm thick at the AWI that is completely devoid of NPs.

Catalytic hydrogenation of liquid alkenes with a silica-grafted hydride pincer iridium(III) complex: support for a heterogeneous mechanism

The previously reported silica-grafted iridium(III) hydride complex [IrH(O–SBA-15)(POCOP)] (2), prepared by treating [IrH2(POCOP)] (1) (POCOP is 1,3-bis((di-tert-butylphosphino)oxy)benzene) with SBA-15 (mesoporous silica), hydrogenates liquid alkenes (1-decene, trans-5-decene, cyclohexene, styrene, and 4-phenyl-1-butene) at room temperature and under 1 atm H2. Internal alkenes react at a lower rate than the terminal ones. For the sake of comparison, the hydrogenation of the same substrates was studied with the homogeneous catalyst [IrH2(POCOP)] (1). The heterogeneous catalyst 2 hydrogenates 1-decene, cyclohexene, and 4-phenyl-1-butene faster than 1, whereas the opposite is true for styrene and trans-5-decene, which suggests that different active species are involved in the heterogeneous and homogeneous reactions. Catalysis by a truly heterogeneous species is supported by a series of “hot filtration tests”. NMR spectroscopic studies showed that 2 does not undergo degrafting upon longer exposure to alkenes compared to ethene under hydrogenation conditions.