Barbara Dudek

Investigation on the Low-Temperature Transformations of Poly(furfuryl alcohol) Deposited on MCM-41

MCM-41-type mesoporous silica was used as a support for poly(furfuryl alcohol) deposition. This material was produced by precipitation-polycondensation of furfuryl alcohol (FA) in aqueous slurry of the SiO2 support followed by controlled partial carbonization. By tuning the FA/MCM-41 mass ratio in the reaction mixture, various amounts of polymer particles were introduced on the inner and outer surface of the MCM support. The thermal decomposition of the PFA/MCM-41 composites was studied by thermogravimetry (TG) and spectroscopic techniques (DRIFT, XPS), whereas the evolution of textural parameters with increasing polymer content was investigated using low-temperature adsorption of nitrogen. The mechanism of thermal transformations of PFA deposited on the MCM-41 surface was discussed in detail. It was found that heating at a temperature of about 523 K resulted in opening of the furan rings and the formation of γ-diketone moieties, which were found to be the highest effective surface species for the adsorption of polar volatile organic compounds. A further increase in calcination temperature caused a drop in the amounts of surface carbonyls and the appearance of condensed aromatic domains.

Montmorillonite intercalated with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by surfactant-directed method as catalytic supports for DeNOx process

The intercalation of natural montmorillonite with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by the surfactant-directed method resulted in the formation of high surface area porous materials; these were tested as catalytic supports for the process of selective catalytic reduction of NO (DeNOx). The incorporation of titanium or aluminium into the structure of the silica pillars significantly increased the surface acidity of the clay samples. Iron and copper were deposited onto the surface of the pillared clays mainly in the form of monomeric isolated cations and oligomeric metal oxide species. The contribution of the latter species was higher in the clay intercalated with SiO2-TiO2 pillars than in the samples modified with SiO2 and SiO2-Al2O3 pillars. The pillared clay-based catalysts were active in the DeNOx process but, in this group, the best results were obtained for the clay intercalated with SiO2-TiO2 pillars and doped with iron and copper. The catalytic performance of the samples is discussed in respect of their surface acidity and active forms of transition metal species deposited.

Oxidative Dehydrogenation of Ethylbenzene Over Poly(furfuryl alcohol)-Derived CMK-1 Carbon Replica

Poly(furfuryl alcohol) was introduced into a pore system of MCM-48 silica by the precipitation polycondensation of furfuryl alcohol (FA). The complete filling of the pores without the deposition of significant amounts of polymer on the external surface of MCM-48 was obtained at the FA/MCM-48 mass ratio close to 1.0. The final structure of carbon replica was formed by subsequent carbonization and extraction of SiO2 with HF. The carbonization temperature strongly influenced the surface composition of the formed carbon replicas. The highest catalytic activity in the oxidative dehydrogenation of ethylbenzene was observed for CMK-1 with the highest concentration of phenol and carbonyl groups, recognized as active sites of the studied reaction.Graphical Abstract

Hierarchical materials originated from mesoporous MCF material and Beta zeolite nanoparticles – synthesis and catalytic activity in N2O decomposition

Hierarchical micro-mesoporous materials with the properties of Beta zeolite and mesoporous cellular foam (MCF) material were prepared by impregnation of MCF with a suspension of zeolite nanoparticles. Four different methods were used for MCF modification: (1) wet impregnation, (2) wet impregnation with acidification of Beta nanoseeds suspension, (3) incipient wetness impregnation, (4) incipient wetness impregnation with acidification of Beta nanoseeds suspension. The obtained materials were characterized using nitrogen sorption measurements, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform (DRIFT) techniques. The use of different impregnation methods resulted in introduction of various forms of iron species to the samples. The iron modified samples (iron was introduced using ion-exchange method) as well as mesoporous MCF silica and Beta zeolite (as reference samples) were tested as catalysts in the N2O decomposition reaction.

Physicochemical properties of hydrogel template-synthesized copper(II) oxide-modified clay influencing its catalytic activity in toluene combustion

CuO-modified montmorillonite was synthesized by the template-assisted route. Poly(acrylic acid) was intercalated into the interlayer gallery of natural clay. Subsequently, various amounts of Cu2+ cations were introduced into the prepared hydrogel–clay composite using adsorption in different volumes of aqueous Cu(NO3)2 solution at constant pH = 6. The resulting materials were finally calcined at 550 °C (chosen using the results of TGA-IR analyses) to transform them into thermally stable oxide systems. The changes in the structural properties of the clay during the progressive modification were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Moreover, porosity, reducibility and surface composition of the calcined materials were determined by means of low-temperature N2 adsorption, temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). It was shown that a high concentration of CuO nanoparticles, which were well-dispersed and protected against sintering between montmorillonite grains, and weak interaction between CuO and the clay support (resulting in easy reducibility of CuO) were the most important features influencing the catalytic activity of the synthesized materials in the total oxidation of volatile organic compounds (VOCs).

Morphology and electrical conductivity of carbon nanocoatings prepared from pyrolysed polymers

Conductive carbon nanocoatings (conductive carbon layers—CCL) were formed on α-Al2O3 model support using three different polymer precursors and deposition methods. This was done in an effort to improve electrical conductivity of the material through creating the appropriate morphology of the carbon layers. The best electrical properties were obtained with use of a precursor that consisted of poly-N-vinylformamide modified with pyromellitic acid (PMA). We demonstrate that these properties originate from a specific morphology of this layer that showed nanopores (3-4 nm) capable of assuring easy pathways for ion transport in real electrode materials. The proposed, water mediated, method of carbon coating of powdered supports combines coating from solution and solid phase and is easy to scale up process. The optimal polymer carbon precursor composition was used to prepare conductive carbon nanocoatings on LiFePO4 cathode material. Charge-discharge tests clearly show that C/LiFePO4 composites obtained using poly-N-vinylformamide modified with pyromellitic acid exhibit higher rechargeable capacity and longer working time in a battery cell than standard carbon/lithium iron phosphate composites.

INFLUENCE OF DEFECT STRUCTURE ON CATALYTIC ACTIVITY OF NANOMETRIC MATERIALS BASED ON CERIA-DOPED COPPER

A series of nanometric materials based on copper-doped cerium (IV) oxide was synthesized using a reverse (w/o) microemulsion method. The obtained powder precursors were tested by the thermal analysis methods coupled with evolved gas analysis (EGA-TGA/DTG/SDTA). Morphology and structure of the samples were characterized by XRD and BET analysis. The content of copper ions was determined using a ICP-OES spectrometer. The electronic structure of the catalysts was characterized by high-temperature electrical conductivity measurements at different pO2. The obtained materials were tested in catalytic incineration of the selected VOCs (methanol and ethylene). The correlation between the activity of the catalysts and copper content as well as electrical properties has been confirmed.