Propane decomposition

Calculated Rate Constants for Propane Decomposition C3HS — CjH + CHj... 

Figure 3. Reduced time curve propane decomposition at one atmosphere fraction unreacted vs. t...

Near atmospheric pressure, propane decomposition rate increases slightly with increasing total pressure. n-Butane is probably not sensitive to pressure. 

We shall consider first the nature of the carbonaceous species produced by propane decomposition on the nickel/ -alumina catalyst. From TEM, this was found to be fil mental in nature. The mechanism of the growth of these filaments is proposed to involve diffusion of carbon through a metal particle and eventual precipitation at the rear of the metal crystallite (Ref 3,4). 

Karagiannakis G, Kokkofitis C, Zisekas S and Stoukides M (2005), Catalytic and electrocatalytic production of H2 from propane decomposition over Pt and Pd in a proton-conducting membrane-reactor , Catal Today, 104,219-224. 

Karagiannakis G, Zisekas S, Kokkofitis C and Stoukides M (2006), Effect of H2O presence on the propane decomposition reaction over Pd in a proton conducting membrane reactor , AppZ Catal A-Gen, Mil, 265-271. 

B. L. CRYNES and L. F. ALBRIGHT (14) have noted that the course of the propane decomposition at 700°C is different after a stainless steel reactor has been treated with oxygen. The product composition and propane conversion change significantly, especially in the initial stages of the run. 

Here, the conversion of propylene In the copyrolysls of propane and propylene could not be calculated straightforwardly since propylene Is one of the major products of propane decomposition. Therefore, the conversion of propylene was evaluated by the same way as reported by Robinson et al (8). From the preliminary pyrolysis of propane. It was found that the relationship between propane conversion, and Its selectivity to propy-... 

Figure 2. Arrhenius plots for propane decomposition rate in pyrolysis of propane-propylene mixtures...

Table 2. Arrhenius kinetic parameters of propane decomposition rates in pyrolysis of propane—propylene mixtures ...

The dotted lines of Figure 5 show the calculated results us ng only the rate constants given in Table 4 and the dots are the observed concentrations for each component. It can be seen from this figure that the calculated values deviate from the observed values as the amount of propylene produced increases. Consequently, the numerical calculations were tried again using the interactions between propane and propylene in addition to the rate constants in Table 4. In this calculation, it was assumed that the ratios of rate constants for the stoichiometric reactions of propane decomposition (k k ) and of propylene... 

Using the experimental results of the pyrolysis of propane-propylene mixtures under the conditions of temperatures near 900 C, atmospheric pressure and hydrogen dilution, the relation between the decomposition rate constant of propane or propylene and the ratio of both reactants was obtained. It was found from the results that propylene had an inhibition effect on propane decomposition, and conversely, propane had an acceleration effect on propylene decomposition. 

C3H6, H2O Pd/SCY/Pd H" 4-fold increase in the rate of propane decomposition. During the electrochemical pumping of hydrogen, the rate of hydrogen pumped to the outer chamber over I/2F reaches values up to 0.9 [24]... 

Thermal decomposition of propane in the fuel supply has to be avoided for a stable ejector operation because solid depositions will immediately plug the nozzle and thus cut fuel supply. Tests with propane fed through the ejector nozzle at different ejector temperatures are conducted to determine the stability limit for the propane fuel. Propane decomposition can be detected by measuring the concentration of the decomposition products hydrogen and methane in the exhaust gas. Results of these measurements are shown in Figure 11, the concentrations were measured by gas chromatography. 

Figure 11 Concentration of hydrogen and methane as products of propane decomposition for different nozzle inlet temperatures...

Table 3. A 2 factorial design for computer experimentation with the 11-reaction mechanism for propane decomposition.

The author wishes to express his thanks to the editor, Professor W. C. Gardiner, Jr., for his valuable aid and encouragement throughout the preparation of this manuscript. Also, appreciation is extended to Mr. D. Miller for preparing the example on propane decomposition, to Ms. N. Duffy for drawing the figures, and to Mrs, J. Easley for typing the manuscript. 

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