(600bp) Oxidative Coupling of Methane Using Solution Combustion Synthesized Catalytic Materials

Oxidative Coupling of Methane (OCM) to C₂ hydrocarbons (ethane and ethylene) is an attractive opportunity for valorization of methane, which is the main constituent of natural gas (typically > 95%), for which the reserves are estimated to far exceed those of crude oil¹. Solution combustion synthesis, a novel one-step technique for the preparation of nanostructured complex metal oxides ^2-4, was used successfully for synthesis of several promising OCM catalyst series with varying metal ratios: (a) Strontium–Aluminum mixed oxides (b) Sodium–Lanthanum oxides (c) Strontium-Aluminum-Lanthanum mixed oxides (d) Na₂WO₄-Mn/SiO₂.

The various catalyst series were optimized by varying the temperature, flowrates and feed CH₄/O₂ ratios. All these catalysts exhibit C₂ yields among the highest in the literature, a superior C₂ selectivity and a higher desired ethylene/ethane ratio. Among the four catalyst series tested, the Na₂WO₄-Mn/SiO₂ series showed the best performance, for which detailed characterization was conducted to understand the basis for catalyst performance.

References:

(1) Kondratenko E.V., Baerns M., Handbook of Heterogeneous Catalysis, Viley-VCH Verlag 2008, 3010-3023.

(2) Deshpande, K.; Mukasyan, A.; Varma, A., Journal of the American Ceramic Society 2003, 86 (7), 1149-1154.

(3) Deshpande, K.; Mukasyan, A.; Varma, A., Chemistry of Materials 2004, 16 (24), 4896-4904.

(4)  Erri, P.; Dinka, P.; Varma, A., Chemical Engineering Science 2006, 61 (16), 5328-5333.