In situ Generation of Intimacy in MnO_x+SAPO‐34 Mechanical Mixture for the Conversion of Syngas to Light Olefins

Abstract

Bifunctional MnO x + SAPO-34 catalysts were evaluated for the conversion of syngas to light olefins (OXZEO process). They were prepared, either by mechanical mixing of 100 μm-scale particles agglomerates, or by mixing of ethanol suspensions, containing homogeneously distributed micrometer-scale primary particles of oxide and zeolite. The selectivity to light olefins, initially lower for the mechanical mixture, reached the value of the suspension mixture after a 14 h on-stream period.This convergence was explained from SEM images by in situ breaking of SAPO-34 agglomerates present in the mechanical mixture and dispersion of SAPO-34 crystals among MnO x primary particles, decreasing the contact distance between the two catalytic functions. These results evidence the importance of intimacy at the micrometer scale to improve the catalytic properties in the OXZEO process.

Reply to the Comment on “Direct Conversion of Syngas into Light Olefins with Low CO2 Emission”

“…The preparation method of metal oxide also has a great effect on the catalytic performance. Upon coupling with H-SAPO-34, MnO x oxides prepared by precipitating an aqueous manganese nitrate solution with sodium carbonate, by precipitating a manganese sulfate water-glycerol solution with ammonium carbonate, and by precipitating an aqueous manganese nitrate solution with ammonium bicarbonate show a CO 2 selectivity of 24.3%, ∼33% and 43.4%, respectively, at similar conditions (380–410 °C, 2.5 MPa and H 2 /CO = 2.0–2.5) due to the different electronic structure and/or particle size of MnO x oxides. − …”