Martin D. Foster

Modeling the framework stability and catalytic activity of pure and transition metal-doped zeotypes

We present a thorough computational study of transition metal-doped zeolite and aluminophosphate (AIPO) frameworks. The structural and electronic chemistry of the dopants is examined with ab initio quantum mechanical calculations, and the results correlated with the Bronsted and Lewis acid strength, and with the redox potential of the dopant ions in the framework. The energetics of doping is provided, and is employed to analyze the mode of dopant incorporation, and its site ordering in the microporous framework. In total, 23 dopant ions are examined in the isostructural framework of chabasite and AlPO-34. These cover most of the isomorphous framework replacements known to occur experimentally, but also framework replacements that have not yet been achieved. In this case, ab initio modeling techniques are employed in a predictive way. Finally, we present a computational study of the alkene epoxidation on titanosilicates, that covers the whole catalytic cycle

A systematic topological search for the framework of ZSM-10

The application of a new technique for zeolite framework structure solution is described that exhaustively enumerates every possible topology consistent with known unit-cell dimensions and space-group symmetry. It is shown that computer-generated on-line databases of hypothetical crystal structures can radically augment structure building in the pre-refinement stage.

Characterisation and evaluation of hypothetical zeolite frameworks

Abstract A series of hypothetical zeolites, derived from the results of tiling theory, has been evaluated using computational chemistry techniques. Simulated heats of formation (i.e. the lattice energy with respect to α-quartz or α-berlinite for silica polymorphs and AlPO 4 polymorphs, respectively) are used as an initial criterion for the chemical “feasibility” of these structures. This data is further correlated with various structural and topological properties, such as framework density, coordination sequences, accessible volume and internal surface. Uninodal frameworks have been treated both as silica and AlPO 4 polymorphs, and comparisons made between the two compositions. Finally, we discuss three hypothetical structures with respect to their feasibility, structural properties and secondary/periodic building units.

Progress towards an atlas of designer zeolites

Our online Atlas of prospective zeolite structures presents the zeolite community with a powerful resource. It provides the ability to search a vast collection of structures, view the structures and use tools to analyze them. We foresee increasingly important uses for the database in areas of materials design and structure solution. This paper will promote the website by discussing its contents and uses.

16-P-13 - Characterisation of hypothetical zeolite frameworks

Publisher Summary This chapter presents a characterization of hypothetical zeolite frameworks. A series of hypothetical zeolite structures have been evaluated based on calculated lattice energies and structural properties. The structures are those generated by Delgado and coworkers, using recent advances in tiling theory. Treating each structure as a silica polymorph, relative lattice energies, framework densities, and coordination sequences are calculated. An automated procedure uses these quantities and correlations between them to make an initial selection of likely candidate zeolite structures.