Catalytic combustion of methane in simulated PSA offgas over Mn-substituted La–Sr-hexaaluminate (LaxSr1−xMnAl11O19)

Mn-substituted La, Sr-hexaaluminate was studied as a catalyst for the catalytic combustion of pressure swing adsorption (PSA) offgas from a hydrogen station based on steam reforming of petroleum gas. The catalytic activity and thermal stability were tested under simulated PSA offgas condition and the catalysts were characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), CO2-temperature programmed desorption (TPD) and N2 physisorption for BET. All the LaxSr1−xMnAl11O19 catalysts prepared by co-precipitation method contained hexaaluminate structure as the major phase after 5 h calcination at 1200 °C. Partial substitution of La for Sr in SrMnAl11O19 increased the specific surface area and consequently the catalytic activity for oxidation of methane. The CO2 in the simulated PSA offgas was found to suppress the catalytic activity in methane oxidation if the catalyst had appreciable surface basicity. The most active catalyst, La0.6Sr0.4MnAl11O19, retained its lattice structure and chemical composition even after 40-h thermal aging at 1000 °C under PSA offgas composition.

Throughout a 40 h thermal aging test at 1000 °C under simulated PSA offgas composition, the activity of La0.6Sr0.4MnAl11O19 remained almost constant with no signs of phase deformation and elemental loss.Figure optionsDownload high-quality image (70 K)Download as PowerPoint slideResearch highlights▶ The combustion activity of hexaaluminate was dependent on its surface area. ▶ Throughout a thermal aging test, the activity of La0.6Sr0.4MnAl11O19 remained constant. ▶ La0.6Sr0.4MnAl11O19 was stable after the thermal aging test under simulated PSA offgas.