PRODUCTION OF C2 HYDROCARBONS VIA OXIDATIVE COUPLING OF METHANE REACTION OVER 3%LI/LA2O3-MGO-CEO2 MIXED OXIDE CATALYSTS: EFFECT OF LANTHANUM CONTENT ON THE CATALYTIC PERFORMANCE

Methane is one of the main components in biogas and can be considered as “bridge fuel”, facilitating the transition to a global economy with low carbon footprint and it can also be utilized as transportation fuel, as energy carrier in the electricity sector or as raw material, participating in the productionof high value products, such as ethylene and/or ethane. Among various chemical processes, the most promising method is the direct conversion of CH4 into C2 hydrocarbons through the process of methane oxidative coupling. This experimental study reports for the first time on the catalytic performance of 3%Li/La2O3-MgO-CeO2catalytic samples during the OCM process, which were synthesized via a citrate sol-gel method, while the moral ratio between the metals La, Mg and Ce was varied. Moreover, Li was also added as promoter via the wet impregnation method. Different characterization techniques, including BET, XRD, and Raman spectroscopy were conducted in order to study the influence of La³⁺ content on the physicochemical characteristics and catalytic performance. From the catalytic activity experiments, the increase of La³⁺ concentration reinforced the catalytic performance as to the conversion of CH4 at lower reaction temperature, while decreased the desirable C2 hydrocarbons yield. At temperatures higher than 750^oC, the 3%Li/La0.45Ce0.45Mg0.1O1.7catalytic samples showed the highest activity in terms of C2selectivity (>80%) and C2 yield (>10%). It could be argued that the increased population of oxygen vacancies and electrophilic oxygen species, improved the OCM process.