DeNOxDeNO_{x} abatement modelling over sonically prepared copper USY and ZSM5 structured catalysts

Metallic supports play an important role as structured reactor internals. Due to their specific properties including enhanced heat and mass transport, high mechanical resistivity and elimination of local hot-spots, they are commonly used in gas exhaust abatement from stationary and automotive industries. In this study, the performance of three structured supports with deposited Cu/USY (Ultrastabilised Y—zeolite) for deNOx abatement were modelled. Based on kinetic and flow resistance experimental results, the one-dimensional (1D) model of structured reactor was developed. The performance of the structured reactors was compared by the length of the reactor necessary to achieve an arbitrary 90% NOx conversion. The performed simulations showed that the sonochemically prepared copper USY and ZSM-5 zeolites deposited on metallic supports may be successfully used as catalysts for deNOx process

Non-noble metal oxide catalysts for methane catalytic combustion : sonochemical synthesis and characterisation

The aim of this study was to obtain nanocrystalline mixed metal-oxide–ZrO2 catalysts via a sonochemically-induced preparation method. The effect of a stabiliser’s addition on the catalyst parameters was investigated by several characterisation methods including X-ray Diffraction (XRD), nitrogen adsorption, X-ray fluorescence (XRF), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and µRaman. The sonochemical preparation method allowed us to manufacture the catalysts with uniformly dispersed metal-oxide nanoparticles at the support surface. The catalytic activity was tested in a methane combustion reaction. The activity of the catalysts prepared by the sonochemical method was higher than that of the reference catalysts prepared by the incipient wetness method without ultrasonic irradiation. The cobalt and chromium mixed zirconia catalysts revealed their high activities, which are comparable with those presented in the literature

DeNOxDeNO_x abatement over sonically prepared iron-substituted Y, USY and MFI zeolite catalysts in lean exhaust gas conditions

Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C

Experimental and theoretical studies of sonically prepared Cu-Y, Cu-USY and Cu-ZSM-5 catalysts for SCR deNO(x)

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNO(x) reaction. The faujasite-based catalysts were fully active at 200-400 degrees C, whereas the ZSM-5-based catalysts reached 100% activity at 400-500 degrees C. Our in situ DRIFTS experiments revealed that Cu-O(NO) and Cu-NH3 were intermediates, also indicating the role of Bronsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNO(x) reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).Web of Science117art. no. 82

Sonically modified zeolites with MFI and USY type structure as catalysts for methane combustion. Preparation and physicochemical characterisation

The objectives of our study were to prepare of ZSM-5 and USY-based catalysts by hydrothermal method, containing metallic active phase, deposited by both conventional ionic-exchange or ultrasonic irradiation. Prepared materials were characterized by various physicochemical methods, such as XRD, BET, SEM, UV-VIS and the sorption of ammonia monitored by FT- -IR spectroscopy. The XRD data confirmed pure MFI or USY type structure zeolite. BET and ammonia sorption results have shown that the presented method leads to preparation of highly porous and acidic systems. Metallic active phase was found as cations and oxides with hexagonal and octahedral coordination

Synthesis and Effect of Structure on Swelling Properties of Hydrogels Based on High Methylated Pectin and Acrylic Polymers

The aim of the research was to develop new pectin-based hydrogels with excellent swelling properties. Superabsorbent hydrogels composed of high methylated pectin and partially neutralized poly(acrylic acid) was obtained by free radical polymerization in aqueous solution in the presence of crosslinking agent—N,N’-methylenebisacrylamide. The effect of crosslinker content and pectin to acrylic acid ratio on the swelling properties of hydrogels was investigated. In addition, the thermodynamic characteristic of hydrogels was obtained by DSC. Furthermore, the structure of pectin-based hydrogels was characterized by FTIR and GPC. It was also proved that poly(acrylic acid) is grafted on pectin particles. The results showed that introduction of small amount of pectin (up to 6.7 wt %) to poly(acrylic acid) hydrogel increase the swelling capacity, while further increasing of pectin ratio cause decrease of swelling