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A series of samples of zeolite-containing microspheres (ZCMS) and fluid catalytic cracking (FCC) catalysts based on Prosyana (Ukraine) kaolin were synthesized in situ. Their adsorption and chemisorption characteristics were recorded using a nitrogen low-temperature adsorption/desorption method and temperature programmed desorption (TPD) of ammonia, respectively. It was shown that changes in the synthesis conditions had a considerable impact on the microand meso-porosity of the samples. A low-temperature band dominated the ammonia TPD spectra of the ZCMS samples, reflecting the retention of ammonia by the sodium cations of the zeolite acting as weak Lewis acid sites. ZCMS was found to display an appreciable activity in cumene cracking at 723 K.It was shown that during the conversion of ZCMS to FCC catalysts through the decationization and ultra-stabilization of the zeolite phase, the latter is appreciably destroyed giving rise to a considerable increase in the mesoporosity of the samples without any change in the average diameters of such mesopores.It was concluded that the catalyst stability is characterized by pores of an intermediate (20-30 Å) diameter, thereby demonstrating the strength of the linkage between the zeolite and matrix phases.The zeolite phase content and adsorption characteristics of catalysts prepared on the basis of Prosyana kaolin meet the demands of modern FCC catalysts.

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ABSTRACT:The results obtained for the pulse cracking of cumene in the presence of zeolite-containing acidic catalysts were analyzed taking into account data complications arising because of the chemisorption of the components of the reaction mixture on the acid sites of the catalyst samples. The propene/benzene (P/B) molar ratios in the reaction mixtures, which amounted to 0.60-2.7, deviated considerably from the expected stoichiometry depending on the nature of the samples, their mode of preparation, their preliminary thermal treatment and steaming as well as on the experimental conditions employed. At the same time, the total yields of cracking products and non-converted cumene were, as a rule, 1.5-3-times less than the amounts of cumene fed into the system.The infringement of the stoichiometry and the considerable material imbalance observed may be attributed to the chemisorption of both cumene and the final conversion products on Lewis acid sites, i.e. coordinatively unsaturated aluminium atoms and zeolite cations, present on the catalyst surface. Chemisorption of the intermediates -phenyl carbocations -on Brönsted acid sites, as well as coke formation as a result of propene polymerization on these sites, must also be taken into consideration. The balance between these various processes and interactions leads to the overall reaction situation observed, thereby enabling conclusions to be drawn regarding both the nature of the catalyst surface and the individual processes, which appear to depend on the strength, amount and correlation between the Brönsted and Lewis acid sites on the samples studied.

Nickel-containing mordenite samples were synthesized by impregnation from aqua's solution of nickel nitrate. Porous and catalytic characteristics of the catalysts were studied by means of low temperature nitrogen adsorption/desorption and micropulse n-hexane isomerisation. The maximum isomer yields are 10-12 wt % for 1-5 wt % Ni content at 523-573 K.