Christopher C. H. Lin

Anion-controlled pore size of titanium silicate molecular sieves.

Titanium silicate molecular sieves contain structural units that are fundamentally different from classical aluminosilicates. In addition to ordered octahedral titanium chains, members of the zorite family contain pentagonal titanium units which project into the main adsorption channels of the framework. We report that the effective pore size of these materials can be controlled by substituting halogens at the O7 sites that cap the pentagonal pyramids projecting into the channel. The quantity and type of halogen used determines the adsorptive properties of the molecular sieve. Barium exchange stabilizes these materials over a wide temperature range (nominally 200-400 degrees C). The barium-exchanged materials do not contract appreciably with calcination, as is observed in related Molecular Gate materials, and thus halogen content can control the pore size of the materials. This new approach to pore size control may have important implications for the purification of multiple classes of compounds, including light hydrocarbons and permanent gases.

CHEMICAL UPGRADING OF SEDIMENTARY Na-CHABAZITE FROM BOWIE, ARIZONA

Natural zeolites may represent one of the greatest under-utilized resources of the mineral world. Even with their unique character and properties, issues of consistency, homogeneity and purity preclude them from many premium applications. We report a simple method to upgrade mineral sedimentary Na-chabazite from the well known Bowie, Arizona, deposit to near synthetic purity and consistency. During this alkaline-silicate digestion process, initially soft chabazite ore granules gain substantial mechanical strength. This may allow direct employment in adsorption and purification processes without the need for binding and forming. These granules manifest significantly improved adsorption properties, including enhanced water and CO2 adsorptivity.

THE SYNTHESIS OF A PLATY CHABAZITE ANALOG FROM DELAMINATED METAKAOLIN WITH THE ABILITY TO SURFACE TEMPLATE NANOSILVER PARTICULATES

Mineral chabazite has shown the unusual ability to surface template nanometal particles, especially Ag. A chabazite analog was synthesized from delaminated metakaolin. The chabazite formed retained the platy morphology of the base clay. This morphology is ideal for displaying surface-supported nanometal particles. The synthetic chabazite analog demonstrated the ability to form and support large concentrations of Ag nanoparticles, as observed in the related natural mineral. Due to greater Al content, the synthetic chabazite manifests significantly improved capacity for the formation of such Ag nanoparticles. As in the case of the mineral chabazite, surface Ag nanoparticles of high uniformity were observed in the range of 5–6 nm.

Chabazite-Clay Composite for Bitumen Upgrading

Abstract The Alberta oilsands resource is increasingly recognized as a strategic source for North American energy supply. We synthesized a novel chabazite-clay composite for improved oilsand bitumen upgrading by growing chabazite on kaolin under alkaline conditions. XRD, SEM, TEM, N 2 physical adsorption, and XPS surface elemental analysis confirmed that the chabazite-clay composite has a unique exterior surface, accessible to large hydrocarbon molecules, that could moderate bitumen upgrading reaction with high performance contaminant (sulfur, nitrogen, nickel, and vanadium) removal.