Size-activity threshold of titanium dioxide-supported Cu cluster in CO oxidation.

Development of non-noble metal cluster catalysts, aiming at concurrently high activity and stability, for emission control systems has been challenging because of sintering and overcoating of clusters on the support. In this work, we reported the role of well-dispersed copper nanoclusters supported on TiO in CO oxidation under industrially relevant operating conditions. The catalyst containing 0.

Synthesis of Mg-Al Mixed Oxides with Markedly High Surface Areas from Layered Double Hydroxides with Organic Sulfonates.

Mg-Al mixed oxides with record-high surface areas and basic site concentrations were synthesized from Mg-Al layered double hydroxides with interlayer isethionate (Ise) or 3-hydroxy-1-propanesulfonate (HPS). Anion exchange of interlayer CO in synthetic hydrotalcites with the organic sulfonates induces disorders in layer stacking as characterized by powder X-ray diffraction and enables facile delamination in water. Thermal treatment of materials anion-exchanged by Ise (MgAl-Ise) and HPS (MgAl-HPS) in N and H resulted in the formation of Mg-Al mixed oxides with marked enhancement in Brunauer-Emmett-Teller (BET) surface area relative to those treated in air.

Development of TiO-SiO Photocatalysts Having a Microhoneycomb Structure by the Ice Templating Method.

Immobilization of TiO-based photocatalysts usually suffers from lowered surface area and mass transfer limitation compared with their suspended counterpart. In this work, TiO-SiO monolithic photocatalysts having straight macropores, called microhoneycombs, were synthesized. The obtained samples had straight macropores with a diameter in the range of 15-40 μm formed by walls having a thickness up to 5 μm.

Carbon Paper with a High Surface Area Prepared from Carbon Nanofibers Obtained through the Liquid Pulse Injection Technique.

To improve the performance of carbon paper used for applications such as electrodes for electrochemical devices and air filters, two types of long carbon nanofibers (CNFs) with average diameters of 20 and 49 nm were prepared by the liquid pulse injection (LPI) technique by adjusting reaction conditions. Carbon paper was made from the CNFs through a simple filtration process. The paper prepared from the CNFs with an average diameter of 20 nm (LPI-CNF(20) paper) was firm and flexible even though it was prepared without using any binders.

Genesis of Delaminated-Zeolite Morphology: 3-D Characterization of Changes by STEM Tomography.

Zeolite delamination increases the external surface area available for catalyzing the conversion of bulky molecules, but a fundamental understanding of the delamination process remains unknown. Here we report morphological changes accompanying delamination on the length scale of individual zeolite clusters determined by 3-D imaging in scanning transmission electron microscopy. The results are tomograms that demonstrate delamination as it proceeds on the nanoscale through two distinct key steps: a chemical treatment that leads to a swelled material and a subsequent calcination that leads to curling and peeling off of delaminated zeolite sheets over hundreds of nanometers.

Immobilization of magnesium ammonium phosphate crystals within microchannels for efficient ammonia removal.

Magnesium ammonium phosphate was formed in flow-through microchannels of silica monoliths using two different methods to fabricate materials that show efficient ammonia adsorption performance from wastewater with low hydraulic resistance. Magnesium ammonium phosphate crystals in these materials release ammonia when heated at 378 K, yielding primarily magnesium hydrogen phosphate. When this material was used for ammonia removal from an aqueous solution containing 100 ppm ammonia in a flow system, the material readily removed ammonia, decreasing the ammonia concentration to 25 ppm.

Delamination of layered zeolite precursors under mild conditions: synthesis of UCB-1 via fluoride/chloride anion-promoted exfoliation.

New material UCB-1 is synthesized via the delamination of zeolite precursor MCM-22 (P) at pH 9 using an aqueous solution of cetyltrimethylammonium bromide, tetrabutylammonium fluoride, and tetrabutylammonium chloride at 353 K. Characterization by powder X-ray diffraction, transmission electron microscopy, and nitrogen physisorption at 77 K indicates the same degree of delamination in UCB-1 as previously reported for delaminated zeolite precursors, which require a pH of greater than 13.5 and sonication in order to achieve exfoliation.

A zeolite-supported molecular ruthenium complex with eta6-C6H6 ligands: chemistry elucidated by using spectroscopy and density functional theory.

An essentially molecular ruthenium-benzene complex anchored at the aluminum sites of dealuminated zeolite Y was formed by treating a zeolite-supported mononuclear ruthenium complex, [Ru(acac)(eta(2)-C(2)H(4))(2)](+) (acac=acetylacetonate, C(5)H(7)O(2)(-)), with (13)C(6)H(6) at 413 K. IR, (13)C NMR, and extended X-ray absorption fine structure (EXAFS) spectra of the sample reveal the replacement of two ethene ligands and one acac ligand in the original complex with one (13)C(6)H(6) ligand and the formation of adsorbed protonated acac (Hacac). The EXAFS results indicate that the supported [Ru(eta(6)-C(6)H(6))](2+) incorporates an oxygen atom of the support to balance the charge, being bonded to the zeolite through three Ru-O bonds.

Zeolite-supported metal complexes of rhodium and of ruthenium: a general synthesis method influenced by molecular sieving effects.

A general method for synthesis of supported metal complexes having a high degree of uniformity is presented, whereby organometallic precursors incorporating acetylacetonate (C(5)H(7)O(2)(-), acac) ligands react with zeolites incorporating OH groups near Al sites. The method is illustrated by the reactions of Rh(acac)(CO)(2) and of cis-Ru(acac)(2)(eta(2)-C(2)H(4))(2) with zeolites slurried in n-pentane at room temperature. The zeolites were H-Beta, H-SSZ-42, H-Mordenite, and HZSM-5.

Role of the support in catalysis: activation of a mononuclear ruthenium complex for ethene dimerization by chemisorption on dealuminated zeolite Y.

A set of supported ruthenium complexes with systematically varied ratios of chemisorbed to physisorbed species was formed by contacting cis-[Ru(acac)(2)(C(2)H(4))(2)] (I; acac = C(5)H(7)O(2) (-)) with dealuminated zeolite Y. Extended X-ray absorption fine structure (EXAFS) spectra used to characterize the samples confirmed the systematic variation in the loadings of the two supported species and demonstrated that removal of bidentate acac ligands from I accompanied chemisorption to form [Ru(acac)(C(2)H(4))(2)](+) attached through two Ru-O bonds to the Al sites of the zeolite. A high degree of uniformity in the chemisorbed species was demonstrated by sharp bands in the infrared (IR) spectrum characteristic of ruthenium dicarbonyls that formed when CO reacted with the anchored complex.

Molecular chemistry in a zeolite: genesis of a zeolite Y-supported ruthenium complex catalyst.

Dealuminated zeolite Y was used as a crystalline support for a mononuclear ruthenium complex synthesized from cis-Ru(acac)2(C2H4)2. Infrared (IR) and extended X-ray absorption fine structure spectra indicated that the surface species were mononuclear ruthenium complexes, Ru(acac)(C2H4)2(2+), tightly bonded to the surface by two Ru-O bonds at Al(3+) sites of the zeolite. The maximum loading of the anchored ruthenium complexes was one complex per two Al(3+) sites; at higher loadings, some of the cis-Ru(acac)2(C2H4)2 was physisorbed.

Structure-directing agent location and non-centrosymmetric structure of fluoride-containing zeolite SSZ-55.

Single crystals of pure silica zeolite SSZ-55 were prepared using the fluoride route. Single-crystal X-ray diffraction at a synchrotron source revealed the framework structure of the material, but the unit cell (orthorhombic a = 12.905(2) A, b = 21.