Synthesis of mordenite using kaolin as Si and Al source

The main purpose of this work was to study mordenite synthesis using kaolin as a Si and Al source. The influence of crystallization time and seed addition were studied. The obtained zeolites were characterized by: XRD, SEM, nitrogen adsorption and chemical analysis. Kaolin showed to be a promising source of Si and Al for mordenite synthesis. Seed addition led to more highly crystalline phases. Kaolin yielded mordenite whereas ZSM-5 was obtained from calcined kaolin. Longer synthesis times and seed addition favored mordenite formation.     

Shape Selective Chemistries with Modified Mordenite Zeolites

This is a review of work carried at Dow Chemical on the design and characterization of novel mordenite catalysts with a unique micro and meso-porous structure characterized by a variety of methods including, TEM, BET surface area and pore size distribution, and n-decane hydro-conversion. The catalytic performance of these catalysts in shape selective reactions is illustrated with results from n-decane hydro-conversion and applications to alkylation and trans-alkylation reactions of mono and polynuclear aromatic hydrocarbons and other chemistries. Juan M. Garcés and G. John Lee both retired from The Dow Chemical Company.     

Thin-layer template-free polycrystalline mordenite membranes on cylindrical mullite supports

Continuous nanoporous mordenite membranes were reproducibly fabricated on tubular microporous mullite supports. The ceramic supports were prepared during calcination of kaolin clay, followed by a leaching post-treatment. A template-free seeded hydrothermal synthesis in a brass autoclave was used to prepare the zeolite membranes. The membranes and the powder crystals collected from the bottom of the autoclave were characterized with XRD, SEM and EDAX. PV properties of the membranes were assessed using dehydration of different ethanol–water mixtures. XRD patterns showed that mordenite was the only zeolitic material present in the membrane. SEM examination of the membrane revealed that thickness of the mordenite crystals filling the voids as a dense thin-layer among the mullite support was 5–10 μm. The continuous top-layer of the membrane was formed by many large and oriented crystals. EDAX analysis showed a Si to Al ratio of 6 for the mordenite powder. The polycrystalline membranes were found to be selective for dehydration of different ethanol/water mixtures. It was concluded that selective adsorption of water on the zeolite pores, small intercrystalline defects and a pinhole-free structure of the membrane layer leaded to high water selectivity of the mordenite membranes studied.     

Study on RE-Modiffied Mordenite Catalysts for Amination Reaction

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Effect of superfine particles of alumina incorporated in the cavities of mordenite in enhancing selectivity

Alumina has been incorporated in the cavities of mordenite by the hydrolysis of Al³⁺ ions in the cavities with moist ammonia gas, following calcination at 450°C. The incorporation of the superfine particles of alumina into the cavities of the mordenite is assessed on the basis of the data of MAS ²⁷Al NMR measurements, X-ray powder diffraction and the amount of saturated adsorption of nitrogen for FAL/MZ. The acid properties, assessed using NH₃ TPD and FTIR studies, show the presence of Brønsted and Lewis acid sites on the catalyst, and an increase in acidic sites on incorporating alumina. The dehydrogenation selectivities of FAL/MZ, Al³⁺/MZ, H⁺/MZ, and Na⁺/MZ have been investigated. Brønsted acid sites largely enhance the ring-cleavage, whereas this incorporation of superfine particles of alumina significantly suppresses the ring-cleavage. Therefore, the incorporation of the superfine particles increases remarkably in the cyclohexene selectivity.     

Fe-mordenite/cordierite monolith for the catalytic decomposition of nitrous oxide

Mordenite zeolites were coated on cordierite support by in situ hydrothermal method or dip-coating method. The mordenite/cordierite was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques and their stability was studied. The mordenite/cordierite monolith prepared by in situ synthesis showed much better stability than that prepared by dip-coating. Iron was introduced into mordenite/cordierite by ion exchange and Fe-mordenite/cordierite catalyst was prepared. Fe-mordenite/cordierite prepared from in situ synthesis exhibited good activity and stability for N₂O catalytic decomposition, with great potential for future application.     

Enhanced n-hexane hydroisomerization over bicontinuous lamellar silica mordenite supported platinum (Pt/HM@KCC-1) catalyst

A bicontinuous lamellar silica mordenite (HM@KCC-1) has been successfully synthesized by microemulsion technique assisted with mordenite-seed recrystallization, followed by protonation and impregnation with platinum (Pt). The catalysts were extensively characterized by XRD, N₂ adsorption, FTIR, FESEM, TEM and ESR and the activity was tested in hydroisomerization of n-hexane. Fourier Transform-Infrared Spectroscopy (FT-IR) study through pyridine and 2,6- dimethylpyridine adsorption revealed that Pt/HM@KCC-1 possessed abundant Lewis acid sites and moderate Brønsted acid sites while Pt/HM possessed strong Lewis and Brønsted acid sites. At 300 °C, the conversion of n-hexane on Pt//HM@KCC-1 reached 75% with 98% isomer selectivity and 74% isomer yield. The enhancement of catalytic performance is attributed to the well-dispersed Pt nanoparticles, tuned acidic properties and improved textural properties which provided a well balance in the acid/metal functions. Thus, favours the reaction towards higher hydroisomerization selectivity, limiting the undesired consecutive cracking reaction.     

掺天然沸石粉水泥及其混凝土的性质

以沸石为主要造岩矿物的岩石称为天然沸石岩（或称为天然沸石）。沸石是具有架状结构含水铝硅酸盐矿物,含有碱及碱土金属离子。在建筑材料中最常用的有斜发沸石和丝光沸石。掺天然沸石粉的水泥（或称沸石水泥）具有许多特殊的性能：提高抗渗性、预防碱———骨料反应膨胀、抗冻性好等。天然沸石在中国贮量大,分布面广。靠近沸石矿床的水泥厂都用沸石为水泥掺合料     

Stabilization of flavylium dye by incorporation into the pore of protonated zeolites

Flavylium dye, a model compound of natural anthocyanin, has a defect that its color stability is very poor. We have complexed the flavylium dye with protonated zeolites and succeeded to enhance both the thermal and chemical stability of the dye. The aqueous dispersion of the flavylium/zeolite complex maintains its color even at 353 K or at pH 9, under which conditions the aqueous solution of the flavylium loses its color immediately. The stability is enhanced when the dye is incorporated into the pore of the zeolites, and a large stabilization effect is obtained by a tight adsorption with a narrow pore, as long as the dye is incorporated into the pore. Because of its enhanced color stability, the flavylium dye incorporated in the zeolite pore can be a candidate for an environmentally friendly coloring material.