Catalytic synthesis of triazine compounds using a flexible technology

Based on laboratory pilot studies, we have developed a flow sheet for the catalytic synthesis of triazine compounds from carbamide using a flexible technology and a catalyst for this process. The main process parameters are as follows: a carbamide melt is fed into the reactor under a pressure of 0.8 MPa at 140–160°C; the volume rate of feeding the circulating gas into the reactor is 500–750 h⁻¹, its temperature is 350–500°C, and the melt-to-gas mass ratio is 1: (7–9). The temperature of synthesis in the reactor is 350–450°C; the pressure in the reactor is 0.1–0.2 MPa. The sublimation temperature is 180–200°C. The conversion of carbamide is ∼98%. The content of the target component in the product is ∼98.8%. Depending on the composition of the circulating gas, it is possible to obtain products of melamine, cyanuric acid, or melamine cyanurate. A catalyst in the form of promoted active aluminum oxide with an inner surface of 300 to 400 m²/g and a technique for its preparation have been developed.     

Resonant scattering and absorption in the titanate-based nanoplatelet dispersions in near ultraviolet region

Extinction enhancement and nonlinear near-resonant absorption of potassium polytitanate nanoplatelets were experimentally studied in the near-UV region. Phenomenological models such as the one-oscillator Lorentz model for dielectric function and the two-level model with the depleted ground state were used to interpret the experimental data. The introduced model parameters demonstrate the adequately high sensitivity to variations in nanoplatelet morphology and chemical environment.     

Radiation Conditions during Decontamination of an Experimental Facility for Reprocessing Nuclear Fuel

The basic characteristics of the changes occuring in the radiation conditions in an experimental facility for reprocessing spent nuclear fuel during decontamination of the facility after reprocessing irradiated uranium and uranium–plutonium BOR-60 reactor fuel and plutonium tetrafluoride into dioxide by the pyroelectrochemical method are examined. An expression is obtained experimentally for calculating the decrease in the power of photon radiation from contaminated surfaces as a function of the number of decontamination cycles. It is shown that for one-time processing of the surfaces of stainless steel equipment by the two-bath method the decontamination coefficient varies over the range 2.5–25 for emitters and 5–30 for and , emitters.     

Random media characterization using the analysis of diffusing light data on the basis of an effective medium model

The transport properties of dense random media such as rutile powder layers and polyball suspensions are analyzed in visible and near infrared on the basis of experimental data on coherent backscattering, diffuse transmittance, and low-coherence interferometry. The developed technique of retrieval of the transport parameters of examined scattering media allows the evaluation of the transport mean free path l* and the effective refractive index n(ef) of the medium without a priori knowledge of the optical properties of the scattering particles. It is found that with decreasing wavelength lambda(0) the value of localization parameter 2pin(ef)l*/lambda(0) of the studied rutile samples abruptly drops and approaches approximately 2.6 at 473 nm. This peculiarity is caused by the very large scattering efficiency of scatterers in the vicinity of the first Mie resonance.     

Transverse nonuniformity in the distribution of inhomogeneity in systems incorporating a pseudo-fluidized bed

The effect of a variety of factors (gas velocity, catalyst grain size, initial height of the bed, and resistance of the gas distributor) on the transverse nonuniformity in the distribution of inhomogeneity in a pseudo-fluidized bed is considered. A method is proposed for analyzing experimental data so as to estimate the degree of this nonuniformity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 6, pp. 1016–1020, December, 1969.