The chemical process accompanying the hydrogenation of fats I. Geometrical isomerization
Summary1. It has been shown for numerous examples that the catalytic hydrogenation of fats is accompanied by the cis-trans isomerization of the radicals of the unsaturated acids.2. A scheme is proposed which explains the mechanism of the isomerization through a process of the hydrogenation-dehydrogenation of the olefinic compounds.
Modern State of the Multiplet Theor of Heterogeneous Catalysis
Publisher Summary This chapter reviews the modern state of the multiplet theory of heterogeneous catalysis. The multiplet theory deals with numerical values of bond lengths and bond energies, as well as with the geometrical form of reacting molecules and the crystal lattices of catalysts. This allows definite results to be obtained for many reactions on an atomic level. This is how the multiplet theory differs from a number of other theories on catalysis. The theory of the structure of matter is based on both electronic theory and quantum mechanics—the basis for the multiplet theory. Bond lengths and energies represent a stable complex of electronic properties essential for catalysis. The multiplet theory proceeds from the premise that catalysis is a chemical phenomenon and that covalent bonds require catalytic activation.
The Atomization of Diatomic Molecules by Metals by Metals
Publisher Summary The atomization occurs by the evaporation of adatoms from a dilute layer. The atomization of diatomic molecules is one of the simplest heterogeneous processes that can be devised, and it exemplifies, with corresponding clarity, the problems of heterogeneous catalysis. There is now an agreed kinetic description for the atomization of hydrogen over tungsten, derived from the application of independent experimental techniques. Much information is also available concerning the adsorbed state for this system. It is possible to deduce the numerical consequences of certain limiting models and develop a fairly definitive analysis of the reaction. The chapter describes the kinetics of the atomization of hydrogen over platinum and gold and of oxygen over platinum. The pressure dependence of the atomization rate varies with the temperature of the metal and the pressure of the gas. If the temperature of the metal is sufficiently low, the pressure dependence of the atomization rate is accurately half order over a wide range of pressure.