Transformations of isobutylene in the presence of various types of zeolites

Conclusions In contrast to zeolites with ultrahigh silica content, type A, X, Y, and M zeolites in the Na form and also those modified by decationization, cation exchange, and addition of-Al₂O₃, Al₂O₃-SiO₂, Pt, and Rh show a low activity in the aromatization reaction of C₃-C₄ olefins at 450–550°C at times of contact of 2–14.4 sec. The zeolites studied become rapidly deactivated as the result of intense coke formation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1300–1304, June, 1981.     

Catalytic properties,surface composition,and acidity of Ga-ZSM-5 catalysts for aromatization of lower paraffins

A study has been made of the catalytic and acidic properties together with the surface composition of the zeolite HZSM-5 modified by gallium by hydrothermal treatment with a sodium gallate solution and also by impregnation with gallium nitrate solution. It has been established that the first method of introducing gallium produces a more selective catalyst for aromatization of n-butane. It has been shown that under the conditions of the catalytic reaction several types of active centers incorporating Ga are formed: Ga₂O₃ on the zeolite surface, gallium ions inside the zeolite canals, and gallium atoms at the surface of and in the lattice that are bonded to OH groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2726–2732, December, 1991.     

Hard X-ray compton polarimetry with the PENGUIN-M instrument in the spaceborne experiment CORONAS-PHOTON

We describe the main parameters of the PENGUIN-MD detector unit of the PENGUIN-M instrument designed to measure the degree of linear polarization of X-ray radiation from solar flares in the energy range 20–150 keV and the X-ray spectra of solar flares in the energy range 2–500 keV. The method for measuring the X-ray polarization employed in the PENGUIN-MD unit is based on registration of coincidences in an active scatterer and scattered-radiation detectors. This method makes it possible to substantially reduce the background and to increase the sensitivity and reliability of the measurements.     

Generation of picosecond pulses with a large axial interval in the IR and visible spectral regions

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 1, pp. 20–24, January, 1990.