Kinetic Parameters for HDS and HDM Reactions

All the kinetic parameters were derived by using three levels of temperature (380 C, 400°C, and 420°C), six levels of LHSV (0.33, 0.5, 0.75, 1.0, 1.25, and 1.5h- ), at a fixed hydrogen-to-oil ratio of 5000ft /bbl and 6.9MPa of total initial pressure. 

FIGURE 9.2 Variation of as function of liquid flow rate (400°C and 6.9 MPa). 

no available correlations are known to predict catalyst wetting efficiency for such diluted beds, and consequently there is no way to determine the liquid holdup and residence times under these conditions by means of mathematical expressions. 

Modeling of Processes and Reactors for Upgrading of Heavy Petroleum 

Once the pseudointrinsic kinetic rate constant was estimated at each temperature, the Arrhenius equation was used to determine activation energy (Ej, as can be seen in Ligure 9.4. Low apparent values for HDS reaction were obtained (11.73 kcal/ gmol), which is attributed to some mass-transfer limitations (Vrinat, 1983). The preexponential factor was found to be 3.3 x 10 (cmVg-s) (cmVgmol)°  

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In the aforementioned equations, z = 0 is located at the entrance of the reactor, and z = L means the end of catalytic bed. All data available at 6.9 MPa were used to derive the kinetic parameters for HDS and HDM reactions. Eighteen experimental points were employed for each reaction, that is, six data points for different space velocities at three different temperatures. Equations 9.3 through 9.7 were solved for each LHSV at constant temperature for obtaining the apparent rate constant. The domain (L) was divided into 220 increments in order to improve accuracy. After verification of the effect of LHSV on apparent constant, a relationship between the liquid fiux and the rate constant was developed in order to derive the parameter values of Equation 9.25 following a linear approach, where y = Mk pp, m = A x= 1/Gf, and b = 1/. ... 

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