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...

The emission control of NOx in exhaust gases is one of the greatest engineering challenges to extend the practical and commercial application of diesel and lean burn engines. One solution is selective NOx reduction using hydrocarbons in an oxidizing atmosphere. We mainly focused on catalytic reactions under temperature excursion because of the resemblance to conditions prevailing in real automo...

Knowledge of the framework topology of zeolites is essential for multiple applications. Framework type determination relying on the combined information of coordination sequences and vertex symbols is appropriate for crystals with no defects. In this work we present an alternative machine learning model to classify zeolite crystals according to their framework types. The model is based on an ei...

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...

Fluid catalytic cracking (FCC) is a major process in oil refineries to produce gasoline and base chemicals from crude oil fractions. The spatial distribution and acidity of zeolite aggregates embedded within the 50-150 μm-sized FCC spheres heavily influence their catalytic performance. Single-molecule fluorescence-based imaging methods, namely nanometer accuracy by stochastic chemical reactions...

Introduction i 1 1. The Principles of Simulated Moving Bed Chromatography 3 1.1 Continuous counter current adsorption systems 3 1.2 The simulated moving bed process 4 1.2.1 The four-section SMB cascade 5 2. Modeling of SMB Column 2.1 Equivalent counter-current model 8 8 3. Characteristics of Adsorbents and Modeling Results 11 3.1 Ca2+ exchanged ion exchange Non-polar dealuminated Faujasite zeol...

the purpose of this study is comparison of manganese absorption capacity by natural and modified zeolite. for this purpose used by from semnan mines zeolite with mean particle diameter of 360 micrometer. for modified zeolite, 5 g amount of natural zeolite with 100 ml of 1 m sodium chloride solution mixed and maintained at 24 hours in room temperature. for measure specific surface of absorbents,...

In this study, Response Surface Methodology (RSM) using Central Composite Design (CCD) was employed to optimize the conditions of independent variables (adsorption time and ion solution concentration) for the removal of Zinc (II) and Ag ions from the aqueous solutions using analcime and modified analcime zeolites (Fe-ANA and Ni-ANA) as efficient and low cost adsor...