Zeolite based trace humidity sensor for high temperature applications in hydrogen atmosphere

We present a humidity sensor based on H-ZSM-5 type zeolite that is suitable to detect traces of humidity (10–110 ppm_V) under harsh conditions, e.g. reducing atmosphere (H₂) and high temperature (up to 600 °C). By means of complex impedance spectroscopy (IS) we show that the zeolite sensor responds linearly towards minimal changes in humidity. Therefore this result indicates that the zeolite sensor is capable to detect traces of humidity in processes where high temperatures in a hydrogen environment are required.     

Adsorption of 2,4,6‐Trinitrotoluene on MFI Zeolite

2,4,6‐Trinitrotoluene (TNT) was adsorbed onto all silica MFI zeolite. These TNT doped zeolite samples were examined using Fourier Transform Infrared Spectroscopy (FTIR) and X‐ray Diffraction (XRD). Results indicate that, using FTIR with an Attenuated Total Reflection (ATR) accessory, mass loading percentages as low as 2.5 mass percent TNT in zeolite are detectable. It was also observed that adsorption of TNT onto MFI did not suppress the IR absorbing vibrations of TNT. TNT doped zeolite samples were washed, using vacuum aspiration, with water and acetone, both of which stripped the TNT from the zeolite samples, indicating that the adsorption of TNT onto MFI zeolite is a physisorption, rather than chemisorption, phenomenon. Finally, a lack of strain‐induced peak broadening from XRD studies indicate that TNT does not enter the zeolitic pore structure, rather, it is adsorbed onto the zeolite surface.     

Fe-Zeolite as on-Site Regenerable Adsorber for Chlorohydrocarbons in Groundwater – from Laboratory to Pilot Test

This study describes the design and upscaling of an on-site regenerable adsorbent fixed bed of Fe-loaded MFI zeolite for removal of chlorinated hydrocarbons (CHCs) from contaminated groundwater from laboratory studies to pilot scale. The zeolite has an excellent adsorption performance for the hydrophilic CHCs and can be regenerated on-site by flushing with H₂O₂ to degrade adsorbed contaminants by a catalytic Fenton-like reaction. In the pilot test, the Fe-zeolite (30 kg) maintained its performance over treatment of 1470 m³ of groundwater in 12 adsorption/regeneration cycles.     

Preparation of MFI type tubular membranes by steam-assisted crystallization

Zeolite MFI membranes were successfully prepared on both alumina and stainless steel tubular supports by crystallization of previously deposited silicate layers under a steam atmosphere. The resultant membranes were able to separate n/isobutane mixtures at relatively high temperatures, displaying separation selectivities of 11.3, 8.9 and 2.5 at 100, 230 and 330 °C, respectively.     

轻质高强沸石烧结砖的研制

我国沸石资源丰富，量多面广。以沸石为主要原料生产的烧结砖，是一种新型的节能墙体材料，它的最显著特点是：轻质、高强，节能效果好。     

沸石/纤维素复合材料保水保肥性能研究

以沸石、羧甲基纤维素、丙烯酸等为原料,用水溶液交联共聚法合成了吸水保水复合材料。利用红外光谱分析复合材料的官能团,通过淋溶和蒸发试验研究了沸石∕纤维素复合材料的水肥调控性能。结果表明沸石、纤维素与单体聚合良好,沸石∕纤维素复合材料具有显著的保水保肥性能,可明显减少氮、钾的流失,具有良好的应用前景。     

废塑料油化技术

本文介绍了废塑料油化技术的现状及典型工艺流程.指出废塑料油化技术工业化的制约因素是经济性,而环保意识增强和资源管理的要求将促进油化技术工业化的实现.     

Zeolite formation in alkali-activated cementitious systems

Autoclaved aerated concrete (AAC) is a unique building material. Because of its cellular nature, it is lightweight, self-insulating, sound- and fireproof, as well as insect and mold resistant. Furthermore, AAC is free of VOCs and various fibers associated with wood and glass wool construction. In an attempt to toughen AAC and make it less prone to on-site damage, a conventional fly-ash-based AAC formulation is being supplemented with sodium hydroxide (NaOH). The introduction of sufficient alkali promotes the growth of crystalline zeolites in the tobermorite matrix during autoclave curing. It is postulated that in situ grown zeolites will serve the same purpose as added fibers. Inasmuch as fly-ash-based AAC reactions often do not go to completion, a phase study of the development of tobermorite and zeolites from a gel-like slurry made from reagent grade chemicals was undertaken. Mixtures were studied as a function of time and temperature. Phase development depends on bulk composition and curing conditions. Longer curing at higher temperatures causes the Na-P1 that forms initially to change to analcime. Whereas Na-P1 is bladelike in habit and is seen to intermingle with the slightly larger blades of tobermorite, the Na-P1 gradually undergoes a phase change to analcime that forms very large cubes. This change has the potential to disrupt the AAC matrix.     

Advanced photon-harvesting concepts for low-energy gap organic solar cells

Organic semiconductors usually show high absorption coefficients only over a limited spectral range. This has to be taken into account when designing organic solar cells with low-energy gap absorbers, as it is likely that these cells will have reduced harvesting abilities for photons of higher energy. We will present two routes to tackle this problem via luminescence and energy transfer and outline three novel concepts of how to integrate these mechanisms. We use an efficient low-energy gap organic solar cell based on zinc-phthalocyanine and fullerene C₆₀ as a model system.