S. A. Hodorowicz

Stability and excitation of potassium promoter in iron catalysts – the role of KFeO2 and KAlO2 phases

Well‐characterized catalyst model compounds of KAlO2 and KFeO2 are investigated by thermal desorption of potassium from the material. The desorbing fluxes of ions, atoms and highly excited states (field ionizable Rydberg states) were studied with surface and field ionization detectors in a vacuum apparatus. From the Arrhenius plots the activation energies for desorption of K and K+ were determined. The chemical state of potassium at the surfaces is concluded to be: ionic on KAlO2 (with the K desorption barrier of 1.76 eV) and covalent on KFeO2 (barrier of 2.73 eV). These results agree with the data obtained earlier for industrial catalysts for ammonia and styrene production. They are interpreted in terms of the Schottky cycle, which is completed for KAlO2 and fails for KFeO2. This failure indicates a non‐equilibrium desorption process. K Rydberg states are only found to desorb from KFeO2, in agreement with the suggestion that such states in some way are responsible for the catalytic activity.

Synthesis, X-ray structure and spectroscopic investigation of an eight-coordinate cadmium(II) complex

Reaction of 4-methylimidazole-5-carbaldehyde (L) with cadmium(II) nitrate (M : L = 1 : 2; EtOH) yields a novel eight-coordinate mononuclear complex, [CdL2(NO3)2]. X-ray structural analysis indicates that the Cd(II) ion possesses what can be described as a double coordination sphere. The inner coordination sphere is pseudo-tetrahedral and consists of four atoms, N(1), N(11), O(21) and O(42), with bond lengths ranging from 2.252(2) to 2.371(2) Å. The second or outer coordination sphere is composed of four oxygen donors, O(7), O(17), O(22) and O(41), with Cd–O distances of 2.543(2) to 2.756(2) Å. The atoms of the external coordination sphere form pyramids with the pseudo-tetrahedral faces of the inner coordination sphere. IR and Raman spectra confirm the stabilization of the Nπ–H isomer of the ligand.

Motion of cations and phase situation in solid tetrabutylammonium octacyanomolybdate(V)

SummaryStudies of the i.r. spectra, lattice parameters and the proton second moment in [n-Bu4N]3[Mo(CN)8] over the 77K to 383 K region are reported.1Hn.m.r. data provide evidence for different rotational processes which are discussed in some detail. Atca. 260 K and 295 K the compound exibits anomalous changes in i.r. spectra and lattice parameters. The results reveal the existence of polymorphism in solid tetrabutylammonium octacyanomolybdate(V).

Novel features in the stereochemistry of octacyanides: Phase transition in tetra-n-butylammonium octacyanotungstate(V)

Abstract Tetra- n -butylammonium octacyanotungstate(V) has been found to exist in three phases at the temperature range 90–353 K. The IR and 1 H-NMR spectra as well as thermogravimetric and powder diffraction studies support these structural changes. The phase transitions were found in the temperature range 273–283 K (T 1 ) and 333–343 K (T 2 ).

Synthesis and characterization of sodium-tetramethylammonium decamolybdate

Abstract Sodium-tetramethylammonium decamolybdate in acidified solution has been crystallized. Chemical analysis, thermogravimetric and X-ray studies have been performed.

Novel intelligent hybrid thick-film sensors of temperature and flow

The paper presents the results of investigations carried out in the Research Centers in Cracow concerning intelligent sensors of temperature and flow. Design assumptions and technological details of manufacturing process are described. Final characteristics of sensor prototypes are given. Some examples of application of sensors are demonstrated and the development trends are discussed.