Gas‐phase catalytic isomerization of n‐heptane using Pt/(CrO_x/ZrO₂)‐HMS catalysts: A kinetic modeling

Abstract

A systematic study has been conducted to optimize the process conditions and to evaluate the kinetic parameters for the isomerization reaction of n‐heptane on the novel platinum‐chromium/zirconium‐ hexagonal mesoporous silica (Pt/(CrOx/ZrO2)‐HMS) catalysts (PCZH). The kinetic experiments were performed in a fixed‐bed reactor at the reaction temperatures of 200–350°C, Cr/Zr molar ratio of 5–35, the n‐C7 flow rate of 2–4.5 cc h−1, and H2 flow rate of 20–45 cc min−1. The statistical analysis of all experimental data was carried out using analysis of variance to optimize the operating conditions for n‐heptane reactions. The results show that the incorporation of Cr into the Pt‐Zr‐HMS structure promotes the kinetic rate of the isomerization reaction. Sharp elevation from 0.08 to 0.3 mol g−1 s−1 in the isomerization kinetic rates can be observed in the PCZH(35) and a temperature of 350 °C, when the H2 flow rate increases from 20 to 45 cc min−1 at a constant flow rate of n‐C7 (4.5 cc h−1). The surface and contour plot verifies that the kinetic rate does not significantly vary with respect to studied temperatures and Cr/Zr ratio when the flow rate of isomerization feeds is considerably low. The experimental kinetic rate obtained on the optimum condition is in good agreement with the prediction of the response surface method. The kinetic model of Langmuir–Hinshelwood as well as a power‐law model was developed for this reaction. A reasonably good fit of the obtained data shows that the Langmuir–Hinshelwood model has a better performance to define the isomerization of the n‐heptane process.

Kinetic modeling and optimization of n-heptane catalytic isomerization using Box-Behnken experimental design

“…A good correlation between predicted and actual experimental data of n-C 7 isomerization are presented in Fig. 1 Furthermore, the Root Mean Square Error (RMSE) that is the standard deviation of the residuals, [12] obtained RMSE = 0.03 for these data. The signal to noise ratio greater than 4 is another major factor for model evaluation.…”

“…well. [12] In this case B, D, AC, BD, A 2 B, A 2 D are signi cant model terms. Values greater than 0.1000 indicate the model terms are not signi cant.…”

Study on the preparation and n-heptane isomerization performance of MoOx-Pd/Ce-MCM-48 catalyst

“…A lower activation energy indicated a faster adsorption rate of the catalyst, Langmuir–Hinshelwood seemed to be a suitable model for this reaction. 34 …”

Kinetic Modeling of Light Naphtha Hydroisomerization in an Industrial Universal Oil Products Penex™ Unit

“…The initial mathematical model step characterization of the subject is to build scheme reactions for hydrocarbon during the isomerization process [15]. The mathematical model assumptions were considered as the following [39][40][41][42][43]:…”