AUTHOR=Garcia-Fayos Julio , Lobera Maria P. , Balaguer Maria , Serra Jose M. 

TITLE=Catalyst Screening for Oxidative Coupling of Methane Integrated in Membrane Reactors

JOURNAL=Frontiers in Materials

VOLUME=5

YEAR=2018

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2018.00031

DOI=10.3389/fmats.2018.00031

ISSN=2296-8016

ABSTRACT=<p>Increased availability of methane from shale gas and stranded gas deposits in the recent years may facilitate the production of ethylene by means of potentially more competitive routes than the state-of-the-art steam cracking processes. One appealing route is the oxidative coupling of methane (OCM), which is considered in this work for the production of ethylene by means of the use of catalytic membrane reactors (CMR) based on Ba<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>0.8</sub>Fe<sub>0.2</sub>O<sub>3−δ</sub> (BSCF) ceramic material. In a first approach, a screening of 15 formulations as catalysts for the ethylene-ethane production was conducted on CMR consisting of disk-shaped planar BSCF membranes. At 900°C, the maximum C<sub>2</sub> selectivity was 70%, reached with Ba<sub>0.5</sub>Sr<sub>0.5</sub>FeO<sub>3−δ</sub> and La<sub>0.5</sub>Ce<sub>0.1</sub>Sr<sub>0.4</sub>Co<sub>0.8</sub>Fe<sub>0.2</sub>O<sub>3−δ</sub> catalysts. On the other hand, low CH<sub>4</sub> conversions (X<sub>CH4</sub>) resulted in C<sub>2</sub> yields below 3%. Operation at 1,000°C significantly shifted X<sub>CH4</sub> for all the activated membranes due to the decrease in CH<sub>4</sub>/O<sub>2</sub> ratios, thus obtaining C<sub>2</sub> yields close to 9% and productivities of ca. 1.2 ml·min<sup>−1</sup>·cm<sup>−2</sup> with Ce<sub>0.9</sub>Gd<sub>0.1</sub>O<sub>2−δ</sub> and Ba<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>0.8</sub>Fe<sub>0.2</sub>O<sub>3−δ</sub> impregnated with Mn-Na<sub>2</sub>WO<sub>4</sub> catalysts. The performance of OCM reaction was also studied in a tubular catalytic membrane reactor. Tubular configuration improved C<sub>2</sub> yield by minimizing CH<sub>4</sub>/O<sub>2</sub> ratios up to 1.7, obtaining a maximum of 15.6% at 900°C with a BSCF capillary membrane activated with a packed bed of 2 wt% Mn/5 wt% Na<sub>2</sub>WO<sub>4</sub> on SiO<sub>2</sub> catalyst.</p>