Frank W. Lai

High-flux MFI membranes

The synthesis and evaluation of high performance MFI-type membranes is described. These systems exhibit fluxes that are one to two orders of magnitude higher than previous literature reports, with ...

Structure of a Three-Dimensional, Microporous Molybdenum Phosphate with Large Cavities

The synthesis, single-crystal x-ray structural characterization, and sorption properties of a microporous molybdenum phosphate, (Me4N)1.3(H3O)0.7[Mo4O8(PO4)2] � 2H2O (Me, methyl), are presented. The three-dimensional framework is built up from Mo4O84+ cubes and PO43- tetrahedra that are connected in such a way that large, cation-filled voids are generated; these voids constitute 25% of the volume of the solid. Absorption isotherms for water show the completely reversible uptake of 4 to 5 percent by weight water into the micropores of this compound, which corresponds to 10 to 12 percent by volume.

Synthesis and structure of Cs4Mo10P18O66

Abstract The crystal structure of Cs 4 Mo 10 P 18 O 66 was determined from single crystal X-ray diffraction data with the following unit cell parameters: space group P 1 with a = 14.395(1), b = 15.600(1), c = 6.4571(6) A, α = 98.316(6)°, β = 90.824(7)°, γ = 90.073(6)°, V = 1434.6(4)A 3 , R ( R w ) = 0.054 (0.066). Important features of the structure include nonintersecting, orthogonal Cs + -filled tunnels and two pairs of cornersharing MoO 6 octahedron, with Mo in the +4 oxidation state, bridged together by a P 2 O 4− 7 group and a P 3 O 5− 10 group coordinated to a Mo 3+ center.

Parallel, segregated Cs+- and K+-filled one-dimensional tunnels in Cs2K2Mo8P12O52

Abstract The reaction of Cs2MoO4, K2MoO4, MoO3, Mo, and P2O5 in a mole ratio of 1:1:4.33:1.33:6 in an evacuated silica tube for 48 hr at 900°C yields dichroic crystals (green when viewed parallel to the normal of the {010} sets and yellow when viewed parallel to the normal of the {001} sets) of Cs2K2Mo8P12O52. The crystals are monoclinic, space group P2 1 c (#14) with a = 6.388(2), b = 18.901(2), c = 18.805(2)A, β = 92.07(2)°, and V = 2269.11(9)A3. The framework consists of (MoO6) octahedra, (PO4) phosphate, and (P2O7) pyrophosphate groups and contains two different types of parallel tunnel: a large tunnel in which an ordered array of Cs+ and voids are found and a smaller one filled with K+.