Сучасний університет в умовах викликів глобалізованого світу

In this work, three industrially relevant zeolites with framework topologies of MOR, FAU and FER have been explored on their ability to form an AlPO4 phase by reaction of a phosphate precursor with expelled framework aluminum. A detailed study was performed on zeolite H-mordenite, using in situ STXM and soft X-ray absorption tomography, complemented with 27Al and 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, XRD, FT-IR spectroscopy, and N2 physisorption. Extraframework aluminum was extracted from steam-dealuminated H-mordenite and shown to dominantly consist of amorphous AlO(OH). It was found that phosphoric acid readily reacts with the AlO(OH) phase in dealuminated H-mordenite and forms an extraframework amorphous AlPO4 phase. It was found that while AlPO4 crystallizes outside of the zeolitic channel system forming AlPO4 islands, AlPO4 that remains inside tends to stay more amorphous. In the case of ultrastable zeolite Y the FAU framework collapsed during phosphatation, due to extraction of framework aluminum from the lattice. However, using milder phosphatation conditions an extraframework AlPO4 α-cristobalite/tridymite phase could also be produced within the FAU framework. Finally, in steamed zeolite ferrierite with FER topology the extraframework aluminum species were trapped and therefore not accessible for phosphoric acid; hence, no AlPO4 phase could be formed within the structure. Therefore, the parameters to be taken into account in AlPO4 synthesis are the framework Si/Al ratio, stability of framework aluminum, pore dimensionality and accessibility of extraframework aluminum species

Ionic liquid-based, liquid-junction-free reference elctrode

In this paper, we describe a new type of polymer membrane-based reference electrode (RE) based on ionic liquids (ILs), in both liquid-contact (LCRE) and solid-contact reference electrode (SCRE) forms. The ILs used were bis(trifluoromethane sulfonyl)amid with 1-alkyl-3methyimidazolium as well as phosphonium and ammonium cations. In addition to their charge stabilisation role, it was found that the ILs also functioned as effective plasticizers in the PVC matrix. The LCREs and SCREs were prepared using the same design as their corresponding indicator electrodes. LCREs were prepared by casting in glass rings while SCREs were prepared on platforms made using screen-printing technology, with poly(3-octylthiophene-2,5 diyl) (POT) as the intermediate polymer. After potentiometric characterization of the response mechanism, the practical performance of the REs was studied using potentiometric titrations (Pb2+ and pH), and characterised using cyclic voltammetry and impedance spectroscopy. All results were compared via parallel experiments in which the novel RE was substituted by a conventional double junction Ag/AgCl reference electrode. The mechanism of response is most likely based on a limited degree of partitioning of IL ions into the sample thereby defining aquo-membrane interfacial potential. Despite their simple nature and construction, the REs showed excellent signal stability, and performed well in the analytical experiments. The identical mode of fabrication to that of the equivalent indicator (or Ion-Selective) electrode (ISE) will facilitate mass-production of both indicator and reference electrode using the same fabrication line, the only difference being the final capping membrane composition

Real-time Analysis of a Working Triethylaluminium-Modified Cr/Ti/SiO2 Ethylene Polymerization Catalyst with In Situ Infrared Spectroscopy

A diffuse reflectance infrared Fourier‐transform (DRIFT) study has been conducted at 373 K and 1 bar on an industrial Cr/Ti/SiO(2) Phillips‐type catalyst modified with, and without, triethylaluminium (TEAl) as co‐catalyst. The reaction rate of the polymerization of ethylene, as monitored by the increase in the methylene stretching band of the growing polyethylene (PE), has been investigated as a function of the titanium content. After an initial period of mixed kinetics, with the reaction rate significantly higher for the TEAl‐modified catalysts compared with the non‐modified catalysts, the polymerization proceeded as a pseudo‐zero‐order reaction with a reaction rate that increased as a function of titanium loading. Furthermore, it was found that the higher Ti loading caused the appearance of more acidic hydroxyl groups and modified the Cr sites by making them more Lewis acidic, ultimately shortening the induction time and increasing the initial polymerization rate

Aluminum-Phosphate Binder Formation in Zeolites as Probed with X‑ray Absorption Microscopy

In this work, three industrially relevant zeolites with framework topologies of MOR, FAU and FER have been explored on their ability to form an AlPO₄ phase by reaction of a phosphate precursor with expelled framework aluminum. A detailed study was performed on zeolite H-mordenite, using in situ STXM and soft X-ray absorption tomography, complemented with ²⁷Al and ³¹P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, XRD, FT-IR spectroscopy, and N₂ physisorption. Extraframework aluminum was extracted from steam-dealuminated H-mordenite and shown to dominantly consist of amorphous AlO­(OH). It was found that phosphoric acid readily reacts with the AlO­(OH) phase in dealuminated H-mordenite and forms an extraframework amorphous AlPO₄ phase. It was found that while AlPO₄ crystallizes outside of the zeolitic channel system forming AlPO₄ islands, AlPO₄ that remains inside tends to stay more amorphous. In the case of ultrastable zeolite Y the FAU framework collapsed during phosphatation, due to extraction of framework aluminum from the lattice. However, using milder phosphatation conditions an extraframework AlPO₄ α-cristobalite/tridymite phase could also be produced within the FAU framework. Finally, in steamed zeolite ferrierite with FER topology the extraframework aluminum species were trapped and therefore not accessible for phosphoric acid; hence, no AlPO₄ phase could be formed within the structure. Therefore, the parameters to be taken into account in AlPO₄ synthesis are the framework Si/Al ratio, stability of framework aluminum, pore dimensionality and accessibility of extraframework aluminum species