Oscillatory Adsorption as the Determinant of the Fluctuating Behaviour of Different Heterogeneous Systems

Abstract

Heterogeneous, catalytic oscillatory reactions as well as the oscillatory process of complex formation based on solid urea have been analysed in an attempt to ascertain the cause of such oscillatory mechanisms. In this context, oscillatory adsorption/desorption, phase transitions of the supported metal employed as the catalyst in the relevant oscillatory oxidation-reduction reactions as well as the reactions themselves have been considered.Based on an analysis of two oscillatory systems, of which one (i.e. the oscillatory alkylation of isobutane with butenes on a metal-free zeolite catalyst) is not complicated by any phase transitions, whilst the other (i.e. the oscillatory formation of an urea-octane complex via the interaction of urea with a binary vapour mixture of octane and non-complex-forming hydrocarbons) is not complicated by any chemical reactions, it is possible to infer that the source of the oscillatory properties of heterogeneous systems which involve the chemical interaction of their components is oscillatory adsorption which occurs as an uncomplicated selfsupporting process which appears to proceed without any increase in the entropy of the system.The occurrence of oscillatory adsorption in a heterogeneous system leads to an oscillatory behaviour in the corresponding process, involving its simultaneous retardation in a similar manner as does the pendulum of a clock with respect to the untwisting of a spring or the oscillatory circuit of an electromagnetic system with respect to the discharge of a dry battery.

Investigation of the Features of Nickel-Modified Mordenite Zeolites

“…3, Table 2). The ratio of R 560/440 of band intensities for samples synthesized from MOR zeolite decreases monotonically with increasing content of nickel in the samples compared to the original NaMOR from 100 % to 85%, which obviously indicates a slight destruction of the crystal structure (up to 15%) in the process of applying a large amount of metal component (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) wt. %) on zeolite of this structural type.…”

“…[1][2][3][4]. Being the materials with unique properties [5][6][7] they are the effective catalysts and sorbents, in particular, they have high efficiency towards extraction of heavy and radioactive metals from the aqua medium [8][9][10][11]. The most used in industry are LTA, FAU, MFI, and MOR-type zeolites.…”

Catalytic Synthesis of Methyl Glycolate from Glyoxal Methanol Solution over Base Catalysts

“…Since during the conversion of carbohydrates over zeolite catalysts two competing processes of the conversion of hexoses into 5-HMF and oligomerization to humins simultaneously proceeds, this reaction is similar to the alkylation of isobutane with butenes over acid catalysts, which also involves two competing reactions of isobutane alkylation and butenes oligomerization. 42 It was previously found that the proceeding of alkylation in the oscillating mode allows increasing the time of effective work of the catalyst. It is possible that similarly with alkylation, in the case of conversion of simple carbohydrates, the proceeding of the reaction in the oscillation regime could also be a promising way to increase the efficiency and selectivity of the target process.…”