Homogeneous gas reactions

Ethylene is made by pyrolysis of hydrocarbon vapors in tubes of 50-100 mm dia and several hundred meters long with a reaction time of several seconds heat is supplied by mixing with superheated steam and by direct contact of the tube with combustion gases. 

Reactors to make polyethylene are 34-50 mm dia with 10-20 m long turns totalling 400-900 m in length. The tube is jacketed and heated or cooled at different positions with pressurized water. 

A flow reactor is used for the production of synthesis gas, CO + H2, by direct oxidation of methane and other hydrocarbons in the presence of steam. Preheated streams are mixed and react in a 

Almost innumerable instances of such reactions are practiced. Single-batch stirred tanks, CSTR batteries, and tubular flow reactors are all used. Many examples are given in Table 17.1. As already pointed out, the size of equipment for a given purpose depends on its type. A comparison has been made of the production of ethyl acetate from a mixture initially with 23% acid and 46% ethanol these sizes were found for 35% conversion of the acid (Westerterp, 1984, pp. 41-58)  

Some of the homogeneous liquid systems of Table 17.1 are numbers 2, 16, 22, 28, 42, 53, 54, and 96, some in batch, mostly continuous. 

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The most common situation studied is that of a film reacting with some species in solution in the substrate, such as in the case of the hydrolysis of ester monolayers and of the oxidation of an unsaturated long-chain acid by aqueous permanganate. As a result of the reaction, the film species may be altered to the extent that its area per molecule is different or may be fragmented so that the products are soluble. One may thus follow the change in area at constant film pressure or the change in film pressure at constant area (much as with homogeneous gas reactions) in either case concomitant measurements may be made of the surface potential. 

Kassel L S 1928 Studies in homogeneous gas reactions. II. Introduction of quantum theory J. Phys. Chem. 32 1065-79... 

His researches and those of his pupils led to his formulation in the twenties of the concept of active catalytic centers and the heterogeneity of catalytic and adsorptive surfaces. His catalytic studies were supplemented by researches carried out simultaneously on kinetics of homogeneous gas reactions and photochemistry. The thirties saw Hugh Taylor utilizing more and more of the techniques developed by physicists. Thermal conductivity for ortho-para hydrogen analysis resulted in his use of these species for surface characterization. The discovery of deuterium prompted him to set up production of this isotope by electrolysis on a large scale of several cubic centimeters. This gave him and others a supply of this valuable tracer for catalytic studies. For analysis he invoked not only thermal conductivity, but infrared spectroscopy and mass spectrometry. To ex-... 

We thus arrive at the same equation as for a homogeneous gas reaction, except that the heat of reaction refers to all the phases, gaseous and condensed. 

Fig. 7-11 Compilation of the most important photochemical processes in the atmosphere, including estimates of flux rates expressed in moles per year between the earth s surface and the atmosphere and within the atmosphere. (Modified with permission from P. J. Crutzen, Atmospheric interactions - homogeneous gas reactions of C, N, and S containing compounds. In B. Bolin and R. Cook (1983). "The Major Biogeochemical Cycles and Their Interactions," pp. 67-112, John Wiley, Chichester.)...

Laidler, K.J., Reaction Kinetics Volume 1 Homogeneous Gas Reactions Volume 2 Reactions in Solution, Perg-amon, London, 1963 Chemical Kinetics, McGraw-I Iill, New York, 2nd ed., 1965. 

L. S. Kassel, The Kinetics of Homogeneous Gas Reactions, Chemical Catalogue Co., New York, 1932. 

In theoretical kinetics today there are still no serious competitors to the transition state theory of Eyring and co-workers (Glasstone et al., 1941). In its most stringent sense it applies only to simple homogeneous gas reactions. The treatment of simple reactions in solution requires additional knowledge of the properties of liquids, and the theory becomes less rigorous and less fundamental. In the extension... 

A high molecular weight hydrocarbon gas A is fed continuously to a heated high temperature mixed flow reactor where it thermally cracks (homogeneous gas reaction) into lower molecular weight materials, collectively called R, by a stoichiometry approximated by A 5R. By changing the feed rate different extents of cracking are obtained as follows ... 

Crutzen, P. J., Atmospheric Interactions—Homogeneous Gas Reactions of C, N, and S Containing Compounds, in The Major Biogeochemical Cycles and Their Interactions (B. Bolin and R. B. Cook, Eds.), Chap. 3, pp. 67-114, Wiley, New York, 1983. 

What may be the equilibrium constant expression for a homogeneous gas reaction whose mole number-time relationship is given in the graph ... 

L.S. Kassel. Studies in Homogeneous Gas Reactions II Introduction of Quantum Theory. J. Phys. Chem., 32 1065-1079,1928. 

As example of the caculation of the equilibrium composition of a homogeneous gas reaction the ammonia synthesis reaction at 450 °C will be considered ... 

The homogeneous gas reaction, A = 3B, follows second order kinetics. For a feed rate of 4 m3/hr of pure A at 5 atm and 350 C, a pilot reactor... 

Kassel, Kinetics of Homogeneous Gas Reactions. The Chemical Catalog Co. New York. (1932). Chapters V and X. 

L. S. Kassel, Kinetics of Homogenous Gas Reactions, chap. 5, Reinhold (ACS Monograph),... 

L. S. Kassel, J. Phys. Chem., 32, 225, 1065 (1928). See also L. S. Kassel, Kinetics of Homogeneous Gas Reactions, chap. 5, ACS Monograph, Reinhold Publishing Corporation, New York, 1932, for a fuller account of these developments. 

M. Bodenstein and Ramstetter, Z. physik. Chem., 100,106 (1922). L. Kassel, Kincticsof Homogeneous Gas Reactions, Reinliold Publishing Corp., New York, 1932, has shown that an equation which fits the data for the equilibrium constant and reverse rate over a broader range is log k = — 5.480/T + 0.5 log T + 7.604 (liters/molo sec), which gives FiMt = 25.07 Kcal/mole and reduces P to 7 X 10"<. This latter also agrees better with the thermal data. Note Kassel has erroneously divided rate constants by factor of 2. 

Hickman still, molecular distillation, 427 HIGEE fractionator, 399 Homogeneous gas reactions, 592 HTU (height of a transfer unit), 401,404, 422... 

Mainly homogeneous gas reactions will be discussed, including elementary steps taking place at the walls. In spite of the incompleteness of the information available, an attempt will be made to present a comparatively detailed discussion of the results obtained from investigations in the liquid phase and in solution as well. 

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