A gas permeable CHA-type aluminophosphate molecular sieve membrane was ionothermally synthesized on a porous d-alumina substrate through the so-called “substrate surface conversion” method. The synthetic conditions for this specific membrane were optimized. The temperature, time and the amounts of H3PO4 and HF in the initial synthesis solution were investigated. X-ray diffraction (XRD), scannin...

In this paper, we demonstrate the potential of pulsed field gradient (PFG) NMR spectroscopy to reveal detailed knowledge of self-diffusion of light gases and light gas mixtures in carbon molecular sieve membranes on small length scales. PFG NMR is used to investigate intra-membrane diffusion of carbon dioxide and methane for a broad range of temperatures and mean square displacements in a carbo...

Studies of chemically reacting systems of macromolecules by conventional transport experiments are subject to inherent ambiguities. These uncertainties often prohibit an unequivocal determination of the explicit reactions which give rise to the average propexties being measured. Such difficulties may be circumvented with molecular sieve chromatography in which subunit dissociation curves are ob...

changed under ambient condition for at least 40 h, time to which these measurements were carried out. To investigate the absorption behavior as a function of time, the absorption spectrum at 100 OC was taken at regular intervals over 40 h for poled/cured A204/DR1. An absorption peak at A, , = 508 nm existed before poling/curing. After poling/curing &shifta to 493 nm with a decrease of absorbanc...

Highly purified preparations of D-aIIIiII0 acid oxidase were obtained by removal of high molecular weight components after purification by established procedures. Molecular sieve studies were carried out on the size characterization of the highly purified apoenzyme molecule. In the microgram per ml concentration range the apoenzyme was shown to dissociate to a subunit with a molecular Stokes ra...

zeolites due to their structures can be used as molecular sieves for purification of materials and solutions. zeolites with phi and sod structure are so common and applicable for this purpose. hydroxy sodalite and phillipsite are the more abundant members of zeolites which display good selectivity for very small molecules and some ions such as sr, pb, zn, cu and rb. there is not any pure natura...

Applications of zeolite membranes in separation, chemical sensors, and catalytic membrane reactors have led to extensive studies on their fabrication. To date, mainly silicatebased zeolite membranes of the structure types MFI, DDR, LTA, and FAU have been synthesized on different substrates and evaluated for singleor multiple-gas permeation. Routes for the synthesis of zeolite membranes can be b...