Alicja Rafalska-Łasocha

Preparation and characterization of new Mg–Al–Fe oxide catalyst precursors for dehydrogenation of ethylbenzene in the presence of carbon dioxide

Abstract New catalysts based on hydrotalcite-like precursors (Mg–Fe and Mg–Al–Fe) were synthesized. The structure of catalyst precursors was confirmed by XRD, FT–IR and TG. Appearance of separate brucite phase was observed for Mg–Fe precursors with excess of Mg, while for Mg–Al–Fe precursors, increase in Al content led to a formation of MgAl 2 (OH) 8 and mixed Al–Fe hydroxides apart from hydrotalcite phase. During calcination, the hydrotalcite like precursors spread their surface area and transform into mixed oxide. The mixed oxides were applied in ethylbenzene (EB) dehydrogenation with CO 2 . The activity losses with time-on-stream were completely restored by oxygen pulses.

SYNTHESIS AND PROPERTIES OF Li2MnSiO4 COMPOSITE CATHODE MATERIAL FOR SAFE Li-ION BATTERIES

Lithium silicates Li2MnSiO4 (where M is a 3d metal) with their theoretical capacity up to 333 mAh⋅g-1 and high chemical stability, thanks to a presence of strong covalent bonds Si–O, seem to be a good potential cathode material for Li-ion batteries. The main drawback of those materials is their low electric conductivity which can be enhanced by coating the material with conductive carbon layer (CCL). This work concerns the synthesis of CCL/Li2MnSiO4 composite material and investigation of its physicochemical properties. The material was successfully produced using sol-gel Pechini method. In order to find the best way of receiving Li2MnSiO4 product various synthesis conditions were applied. CCL/Li2MnSiO4 composite was produced in a one-step process using organic precursor matrix as a source of carbon. Both Li2MnSiO4 material and CCL/Li2MnSiO4 composite were investigated using thermal analysis (EGA-TGA/DTG/SDTA), X-ray diffraction (XRD) and electrical conductivity measurements to find the relations between structure, morphology and electrochemical properties.

SUBSTITUTION OF Fe3+ FOR Al3+ CATIONS IN LAYERED DOUBLE HYDROXIDE [LiAl2(OH)6]2 CO3·nH2O

Synthesis of the Li-Al-Fe layered double hydroxides was performed by the coprecipitation method at constant pH (11.0±0.2) and temperature (40±2°C). Structural features of the as-synthesized samples were investigated by X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy and Mössbauer spectroscopy. The samples consisted of well crystallized [LiFexAl2-x(OH)6]2CO3·nH2O phases with strict ordering of M+ and M3+ cations in the sheets. However, only a proportion of Al3+ could be substituted by Fe3+ ions. The excess Fe3+ cations formed a separate ferrihydrite phase. Incorporation of Fe into the hydrotalcite-like structure resulted in an increase in the a lattice parameter determined by XRD. In addition, a shift of IR absorption bands, ascribed to the stretching vibrations of interlayer CO32− anions as well as the transitional motions of oxygen in the layers, to lower frequencies was observed. The presence of Fe3+ in the octahedral sheets caused a splitting of the band assigned to the stretching vibrations of the layer OH groups. Mössbauer experiments revealed that Fe exists in the synthesized samples in two different chemical environments. A proportion of the Fe3+ cations is incorporated as isolated ions in the [LiFexAl2-x(OH)6]2CO3.nH2O crystal structure. However, Fe3+ ions forming the ferrihydrite phase are dominant in the Fe-rich materials.

Synthesis and investigations of new strontium dicarboxylates

Abstract Using simple methods of synthesis without template agents, 6 new compounds of strontium and dicarboxylic acids have been obtained. The resulting salts are: {1} strontium glutarate pentahydrate, {2} strontium adipate, {3} strontium pimelate monohydrate, {4} strontium suberate, {5} strontium azelate and {6} strontium dodecanedioate hemihydrate. Similarly to the known barium compounds, starting from the salt of azelaic acid, strontium compounds with longer dicarboxylic acids form acidic salts. Metal centers have the coordination number C.N. = 8, and the coordination polyhedra are dodecahedra. Glutaric acid form layered material, whereas with use of longer acids 3D systems are formed. Acids such as dodecanedioic and azealic form systems in which Sr-O polyhedra do not share edges or vertices. Isolated SrO8 polyhedra are joined by carboxylic groups of dicarboxylic acids. Strontium salts {2, 4, 5} are anhydrous, but {1} is pentahydrate, {3} is monohydrate, and {6} is hemihydrate. During thermal decomposition strontium salts of dicarboxylic acids decompose through an unknown intermediate product to strontium carbonate.

Investigations of new barium dicarboxylates

Abstract Structures of new barium dicarboxylates (salts of glutaric, adipic, pimelic, suberic, azelaic and dodecanedioic acids {1–6}) were characterized. Structure solution from powder data was performed in the cases of barium adipate {2}, pimelate monohydrate {3} and dodecanedioate {6}. Structures of barium glutarate pentahydrate {1}, suberate {4} and azelate {5} were obtained from single crystal analysis. Even though these compounds are salts of homologus series of dicarboxylic acids [HOOC—CnH2n—COOH; n = (3–10)], the obtained materials are characterized by broad structural diversity. The synthesized salts form layered (2D) or three-dimensional (3D) structures. Coordination polyhedra of BaOn(8 or 9) – create layers or linear systems of polyhedra connected by edges or edges and vertices, or layers formed by isolated polyhedra linked by carboxylic acids. The degree of hydratation ranges from 5 to 0; the obtained materials crystallize in various crystallographic systems, from triclinic to tetragonal.

Potassium Ferrites Formation in Promoted Hematite Catalysts for Dehydrogenation. Thermal and structural analyses

K-promoted hematite catalysts for ethylbenzene dehydrogenation were studied by thermal analysis (TG/DTG) and high-temperature XRD. The formation of potassium ferrite (K2Fe2O4), considered to be a catalytically active phase, was observed during calcination of the Ce-promoted catalysts. A linear correlation of the catalytic activity and the temperature of potassium ferrites formation was found.

Powder diffraction data of novel complexes Cd X 2 -2(NH 2 -Ph Y ), part I

Four new compounds with general formula CdI 2 -2(NH 2 -Ph X ) (Ph represents phenyl radical; X represents Cl or H atoms) were obtained and characterized. Two of them, bisaniline diiodidecadmium(II) — CdI 2 ⋅2[NH 2 –C 6 H 5 ] {1} and bis(2-chloroaniline) diiodidecadmium(II) — CdI 2 ⋅2[NH 2 –C 6 H 4 Cl] {2}, crystallize in monoclinic system, whereas another two, bis(3-chloroaniline) diiodidecadmium(II) — CdI 2 ⋅2[NH 2 –C 6 H 4 Cl]{3} and bis(4-chloroaniline) diiodidecadmium(II) hemi(4-chloroanilate) — CdI 2 ⋅2[NH 2 –C 6 H 4 Cl]½[NH 2 –C 6 H 4 Cl] {4}, crystallize in triclinic system. The investigated compounds, from chemical point of view, are similar to the so-called cisplatin—a compound used as a chemotherapy drug to treat many types of cancers. Their syntheses and results of X-ray powder diffraction studies at room and elevated temperatures are described in this paper.

µ-XRPD investigations of pigments in 17th-century panel paintings from Gdańsk and the northern region of Poland

µ-XRPD investigations of pigments in 17th-century panel paintings from Gdansk and the northern region of Poland

Badania u-XRPD i SEM-EDS pigmentów i zapraw w trzech obrazach z kolekcji Muzeum Pałacu Króla Jana III w Wilanowie

Badania μ-XRPD i SEM/EDS pigmentow i gruntow w trzech obrazach z kolekcji Muzeum Palacu krola Jana III w Wilanowie

Badania zapraw i bieli w warstwach malarskich w dziełach artystów dworskich króla Jana III Sobieskiego za pomocą rentgenowskiej dyfraktometrii proszkowej (XRDP)

Badania zapraw i bieli w warstwach malarskich w dzielach artystow dworskich krola Jana III Sobieskiego za pomocą rentgenowskiej dyfraktometrii proszkowej (XRDP)