Screening of single and binary catalysts for oxidative coupling of methane to value-added chemicals

Abstract A combinatorial approach was applied to explore active binary catalysts for oxidative coupling of methane (OCM) to value-added hydrocarbons (C 2+ ). A screening of 25 selected single components on SiO 2 for OCM reaction identified the top-14 single active components as follows: La > Ce > Ga > Al > Ca > Cr > Ba > Na 2 WO 4 > Mn > Cu > Ti > Zn > Rb > Ni. Binary catalyst screening was then performed and resulted in a combination of Na 2 WO 4 and Mn producing the most active binary catalyst. X-ray powder diffraction measurement of the Na 2 WO 4 -Mn/SiO 2 catalyst revealed that the presence of α-cristobalite phase was essential for the activation of methane. Moreover, the X-ray photoelectron spectroscopy spectrum of the Na 2 WO 4 -Mn/SiO 2 catalyst showed that the binding energy of W4f and Mn 2p shifted toward a lower binding energy, thereby enhancing the catalytic activity. Optimization of C 2+ production of the catalyst by varying Na 2 WO 4 :Mn weight ratios, total metal loadings, catalyst weights, and feeding gas compositions, achieved maximum C 2+ yield of 23.54% with 60.5% selectivity and 39.67% methane conversion. Furthermore, the activity of the Na 2 WO 4 -Mn/SiO 2 catalyst was monitored with time-on-steam for 50 h, revealing good catalyst stability.