Apparent activation energy, measurement

The reaction rate constant and activation energy are also apparent in the presence of intraparticle diffusion effects. Through Arrhenius equation, we have an apparent activation energy measured, i.e. ... 

Measuring tire pressure dependence of k at different temperatures shows that the apparent activation energy at constant viscosity decreases with increasing viscosity [46, ( figure A3,6,8). From a detailed analysis one... 

Calculate bout IcLtn for the reversible reaction in Example 5.2 in a CSTR at 280 K and 285 K with F=2h. Suppose these results were actual measurements and that you did not realize the reaction was reversible. Fit a first-order model to the data to find the apparent activation energy. Discuss your results. 

The presence of diffusion limitations has a strong effect on the apparent activation energy one measures. We can express both the rate constant, k, and the diffusion constant, Defr, in the Arrhenius form ... 

The apparent activation energy is now measured under conditions where the surface is estimated to be dean, i.e. 0, = 1. 

Figure 13. Dependence of ethane hydrogenolysis TOF and apparent activation energy on Pt particle size. TOFs decrease by two orders of magnitude over the size range, while the apparent activation energy increases. Coordinatively unsaturated surface atoms in small particles have a higher reactivity and subsequently a smaller barrier for hydrogenolysis than highly coordinated surface atoms of larger particles. TOFs were measured at 20 Torr C2H6, 200 Torr H2, and 658 K [16]. (Reprinted from Ref [16], 2006, with permission from American Chemical Society.)...

Vreactor=70 ml VCh=Vrcn=10 ml (0.045 mole) 111 1 =0.3 g PH2=80 bar (at RT) was not maintained during reaction NH3/RCN=0.25 without ammonia, selectivity of SB is higher at lower temperatures. The selectivity to RNH2 decreased with reaction time for the experiment performed without NH3. The apparent activation energy of the hydrogenation of RCN on RNi-L catalyst was 30.5 kJ/mol, which is close to the value 46 kJ/mol measured in the liquid phase hydrogenation of acetonitrile on CoB amorphous alloy catalyt [7], RNi-C is more active than RNi-L catalyst (compare Table 1 No 4 and 6 and Table 2 No 7 and 8). 

The overall stoichiometric equation for this decomposition leading to equilibrium depends on the temperature. A considerable amount of the final products are H, OH, and O. Bauer et al.3 were the first to report an investigation of the water dissociation by the shock-tube method. The temperature range for this study was 2400-3200 °K. They followed the reaction by measuring the uv absorption of the hydroxyl radical produced during the decomposition. The apparent activation energy for the parameter (1/ [H20])(d [OH]/df) of about 50 kcal.mole-1 seemed to indicate that the reaction... 

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