Pilot tests of the microspherical aluminochromium KDI-M catalyst for <Emphasis Type="Italic">iso</Emphasis>-butane dehydrogenation

Results from pilot tests of microspherical aluminochromium KDI-M catalyst mixed with IM-2201 in a large-scale unit (Nizhnekamskneftekhim) for iso-butane dehydrogenation are discussed. Compared to KDI catalyst, its modified analogue KDI-M is more active and selective; the optimized grain-size composition and mechanical strength ensures higher yields of iso-butylene and longer nonstop operation (up to 400 days) of the reactor unit.     

Two-electron exchange between impurity centers of tin in PbS<Subscript><Emphasis Type="Italic">z</Emphasis></Subscript>Se<Subscript>1–<Emphasis Type="Italic">z</Emphasis></Subscript> solid solutions

Using emission Mössbauer spectroscopy on ^119mmSn(^119mSn) and ¹¹⁹Sb(¹¹⁹mSn) isotopes, the electron exchange process between neutral and doubly ionized U ^– tin centers is studied in partially compensated PbS _z Se_1–z solid solutions. The activation energy of this process for compositions with z ≈ 1 is comparable to the deposition depth of the tin energy levels in the band gap of PbS (~0.11(1) eV, and for compositions with z ≈ 1, it is comparable with the correlation energy of donor U ^– tin centers in PbSe (~0.05(1) eV). For all compositions of solid solutions, the exchange is realized by the simultaneous transfer of two electrons with the use of the delocalized states of the valence band.     

Genesis of the structure and the phase and elemental compositions of an aluminum oxide catalyst in the isomerization process of n-butylenes

An investigation of the changes in the characteristics of the porous structure, phase, and elemental compositions of catalyst samples for the isomerization of n-butylenes using a set of physicochemical methods has been conducted. In has been established that under hydrothermal conditions of the isomerization process, aluminum oxide recrystallization takes place, resulting in a decrease of its specific surface value and a displacement of the maximum of the distribution of pore diameters to the region of greater values. A porous structure transformation scheme has been suggested while operating the isomerization catalyst for n-butylenes. It has been supposed that the partial phase change of γ-Al₂O₃ into δ-Al₂O₃ occurring under industrial conditions of the isomerization of n-butylenes is caused by an accumulation of metal compound admixtures supplied with the feed flow.