Zeolites/molecular sieves with uniform, molecular-sized pores are important for many adsorption-based separation processes. Pore size gaps, however, exist in the current zeolite family. This leads to a great challenge of separating molecules with size differences at ~0.01 nm level. Here, we report a novel concept, pore misalignment, to form a continuously adjustable, molecular-sieving "gate" at...

A natural zeolite (Z-N), rich in clinoptilolite, was modified (Z-Al) by incorporation of hydrated aluminum oxide (HAlO) for the simultaneous phosphate and ammonium removal. The incorporation of surface hydroxyl groups (≅Al-OH) into the zeolite structure, as active groups for phosphate removal, was characterized by acid-base titrations (pHPZC=4.5±0.2). The phosphate sorption increases from 0.6 m...

m-Xylene transformation has been studied on as-prepared H-Y and a series of dealuminated Y zeolite catalysts. The conversion of m-xylene was found to increase initially with acidity, however, decreases subsequently. It has been proposed that the high concentration of acid sites in the H-Y catalyst increases paring reaction, in addition to the well-known isomerization and disproportionation path...

Zeolite Rho is able to successfully separate CO(2) from CH(4) with the highest selectivity ever observed on the basis of pore diameter and surface polarity. The adsorption of CO(2) provokes structural changes in the zeolite Rho.

The studies were carried out on heavy metal bioavailability and leachability during water hyacinth composting mixed with cattle manure, sawdust and natural zeolite. The water hyacinth, cattle manure and sawdust were taken in the 6:3:1 ratio with 5, 10 and 15% natural zeolite and composted for 30 days. The concentrations of nutrients and total heavy metals were increased during the process. Due ...

This study reports on the EPR of C r 5 + and C u 2 + ions, introduced by solidand liquid-state reactions with the synthetic zeolites 3A, 4A and 5A, and the natural zeolite clinoptilolite. C r 3 + was oxidized to Cr 5 + in the samples, the coordination around Cr 5 + being square pyramidal. Superhyperfine (shf) interaction of Cr with A1 nucleus was observed in both solidand liquid-stateintroduced...

Zeolite Beta/MCM-41 composites have been prepared with various crystallinities of zeolite Beta through a twostep crystallization process involving the combination of low crystallinity zeolite Beta synthesis gel with cetyltrimethylammonium bromide surfactant solution. The composites are characterized by XRD, SEM, Si and Al MAS NMR, N2 adsorption, NH3-TPD and catalytic cracking. The experimental ...

The present work introduces the study of the CO2 capture process by zeolites synthesized from paper sludge and scrap glass. Zeolites ZSM-5, analcime and wairakite were produced by means of two types of Structure Directing Agents (SDA): tetrapropilamonium (TPA) and ethanol. On the one hand, zeolite ZSM-5 was synthesized using TPA; on the other hand, analcime and wairakite were produced with etha...

Zeolite nanoblock (ZNB), prepared by hydrochloric acid decomposition of Na-A type zeolite, works as a highly efficient hydrogen-permeable membrane. Si and Al K-edge X-ray absorption near edge structure (XANES) spectra were measured for ZNB to clarify the local structures. The Si K-edge XANES spectrum is similar to that of the Na-A type zeolite, but the Al K-edge XANES spectrum is interpreted as...

lta zeolite nanoparticles was successfully synthesized from clear solution under controlled conditions using hydrothermal method using tetramethyl ammonium hydroxide as a structural directing agent. the as-synthesized lta zeolite particles were characterized by powder x-ray diffraction (xrd) analysis, scanning electron microscopy (sem), fourier transform infrared (ft-ir) spectroscopy, energy di...