Heterogeneous oligomerization catalysts: properties and efficiency

A number of heterogeneous acid type catalysts of silica-alumina nature, which are proposed to be used for petrochemistry by-product oligomerization, have been investigated. Particularly, such key indicators as active site concentration and strength have been determined. These parameters have been determined by the method based on potentiometric titration that is relatively seldom used in heterogeneous catalysis. The number of active site types present in investigated catalysts, as well as concentrations of each type of site, has been determined by mathematical processing of potentiometric titration data. The sequence of mathematical processing of titration data is described. The relationship between the properties of the investigated catalysts and their effectiveness in heterogeneous catalytic cooligomerization of the C₉ fraction of liquid products of diesel fuel pyrolysis has been analyzed. The relationships between yields achieved in the presence of various catalysts and the properties of these catalysts have been defined. Namely, it was determined that the product yield is almost proportional to the active site??s concentration of the catalysts (activated clay materials). The relationship between the strength of active sites and average molecular weight of the cooligomers has been found. The causes of obtained regularities have been analyzed and explained.      

Jost functions for quarkonium

We examine the interaction in quarkonium by means of the potential V(r)=–/r+ r+V_o. Within the framework of the Fuda generalization of the van Leeuwen-Reiner approach, the off-shell Jost functions and the off-shell and half-off-shell T-matrices are derived.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 57–60, May, 1986.     

Cooligomerization of dominant monomers of C9 fraction of liquid pyrolysis products: comparison of heterogeneous catalytic approach with common methods

Cooligomerization of liquid products of the C9 fraction of diesel fuel pyrolysis to produce cooligomers of wide application is suggested to be carried out with silica-alumina catalysts, among which the activated bentonite clay seems to be optimal. Cooligomerization of the mixture simulating the C₉ fraction composition was studied to compare the suggested heterogeneous catalytic method with other methods of cooligomers production. Different methods have been compared in terms of yield of cooligomers and their properties, namely molecular weight and its distribution, density, unsaturation and colour. The ratio of monomer units in cooligomer has been determined and the monomers conversion degrees have been calculated for different cooligomerization methods. Reasons of structure and composition differences of cooligomers obtained by different methods are suggested.      

Use of a kinetic model for selecting the optimal conditions for the reaction of unsaturated aldehydes with peracids

The selectivity of the formation of unsaturated acid on the concentration, reagent ratio, temperature, conversion, and solvent was determined using a kinetic model for the reaction of unsaturated aldehydes with organic peracids and the kinetic parameters of this reaction were calculated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 5, pp. 298–302, September–October, 1995.