Microporous and Mesoporous Materials

Progress reports are a new type of article in Advanced Engineering Materials, dealing with hot current topics, and providing readers with a critically selected overview of important progress in these fields. It is not intended that the articles be comprehensive, but rather insightful, selective, critical, opinionated, and even visionary. We have approached scientists we believe are at the very forefront of these fields to contribute the articles, which will appear on an annual basis. The article below describes the latest advances in Microporous and Mesoporous Materials.     

Advances in Microporous and Mesoporous Solids—Highlights of Recent Progress

This report highlights developments in the fields of microporous and mesoporous materials that were published mostly during the year 2002. Selected examples are provided to illustrate new zeolite structures, porous coordination materials, mesoporous solids with new compositions, controlled morphologies, and increased hydrothermal and thermal stabilities, as well as porous solids with tunable pore openings or other structural features that can be dynamically modified. A number of applications are discussed, including stabilization of reactive guests, separations, electronic materials, and sensors.     

Hybrid Inorganic–Organic Mesoporous Silicates—Nanoscopic Reactors Coming of Age

This review describes methods of preparing hybrid inorganic–organic mesoporous silicates with uniform channel structures, as well as some of their applications. Both reactive and passive organic groups can be incorporated in the porous solids by grafting methods or by co‐condensation under surfactant control. Functional groups have been placed selectively on the internal or external pore surfaces or even within the walls of the mesoporous solids. Organic functionalization of these solids permits tuning of the surface properties (hydrophilicity, hydrophobicity, binding to guest molecules), alteration of the surface reactivity, protection of the surface from attack, and modification of the bulk properties (e.g., mechanical or optical properties) of the material. Recent applications of hybrid mesoporous silicates are highlighted, including catalysis, sorption of metals, anions, and organics, reactors for polymerization, fixation of biologically active species, and optical applications.     

Recent Progress in the Synthesis of Porous Carbon Materials

In this review, the progress made in the last ten years concerning the synthesis of porous carbon materials is summarized. Porous carbon materials with various pore sizes and pore structures have been synthesized using several different routes. Microporous activated carbons have been synthesized through the activation process. Ordered microporous carbon materials have been synthesized using zeolites as templates. Mesoporous carbons with a disordered pore structure have been synthesized using various methods, including catalytic activation using metal species, carbonization of polymer/polymer blends, carbonization of organic aerogels, and template synthesis using silica nanoparticles. Ordered mesoporous carbons with various pore structures have been synthesized using mesoporous silica materials such as MCM‐48, HMS, SBA‐15, MCF, and MSU‐X as templates. Ordered mesoporous carbons with graphitic pore walls have been synthesized using soft‐carbon sources that can be converted to highly ordered graphite at high temperature. Hierarchically ordered mesoporous carbon materials have been synthesized using various designed silica templates. Some of these mesoporous carbon materials have successfully been used as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for enzyme immobilization. Ordered macroporous carbon materials have been synthesized using colloidal crystals as templates. One‐dimensional carbon nanostructured materials have been fabricated using anodic aluminum oxide (AAO) as a template.     

Synthetic Inorganic Materials

Catalysts, coatings, and structural components are some of the applications of the synthetic inorganic materials described here, which range from zeolites to carbides and nitrides. The in‐situ growth of β‐Si₃N₄ whiskers from α‐Si₃N₄ grains is depicted the Figure. Self‐reinforced silicon nitride results, as the whiskers impart increased fracture toughness to the ceramic.     

Particle Size Distribution and Characterization of High Siliceous and Microporous Materials

Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate (SAPO) microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer (PSA) and scanning electron microscope (SEM). The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test (F-test) methods were performed for the significance of results by the analysis of variance (ANONA) and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett & Teller (BET) volumetric technique and v-as plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.