Kinetics of the oxidative coupling of methane over perovskite-type lanthanum aluminate and sodium tungstate catalysts

Abstract

This study developed a kinetic model of the oxidative coupling of methane over perovskite-type lanthanum aluminate and sodium tungstate catalysts According to the catalytic results we found that the methane conversion of LaAlO3 increased milder than Mn-Na2WO4/SiO2 with increasing temperature It might be due to lower C-H bond activation energy of LaAlO3 We also found that in the case of C2 products the ethylene selectivity of Mn-Na2WO4/SiO2 increased more significant than LaAlO3 with increasing CH4/O2 ratio at a given WHSV and high temperature (> 750°C) Increased temperature at a fixed CH4/O2 ratio resulted in reducing of ethane selectivity where Mn-Na2WO4/SiO2 showed significant trend Therefore comparing to LaAlO3 we suggested that Mn-Na2WO4/SiO2 was easier to be affected by temperature to promote the dehydrogenation of ethane to ethylene In order to gain an in-depth understanding of these two catalysts kinetic analysis has been performed The reaction mechanism considered the formation of ethylene ethane carbon monoxide and carbon dioxide including homogeneous gas-phase reaction and heterogeneous surface reaction The kinetic parameters was estimated via nonlinear regression The results showed that LaAlO3 had a lower activation energy of methane (180 8 kJ/mol) and a lower activation energy of ethane dehydrogenation (333 7 kJ/mol)

Date of Award	2020
Original language	English
Supervisor	Yu-Chuan Lin (Supervisor)