Abstract
Due to the surge of natural gas production, feedstocks for chemicals shift towards lighter hydrocarbons, particularly methane. The success of a Gas-to-Chemicals process via synthesis gas (CO and H2) depends on the ability of catalysts to suppress methane and carbon dioxide formation. We designed a Co/Mn/Na/S catalyst, which gives rise to negligible Water-Gas-Shift activity and a hydrocarbon product spectrum deviating from the Anderson–Schulz–Flory distribution. At 240 °C and 1 bar, it shows a C2-C4 olefins selectivity of 54%. At 10 bar, it displays 30% and 59% selectivities towards lower olefins and fuels, respectively. The spent catalyst consists of 10 nm Co nanoparticles with hcp Co metal phase. We propose a synergistic effect of Na plus S, which act as electronic promoters on the Co surface, thus improving selectivities towards lower olefins and fuels while largely reducing methane and carbon dioxide formation.
Highlights
Due to the surge of natural gas production, feedstocks for chemicals shift towards lighter hydrocarbons, methane
Methane may be converted to synthesis gas, which can be used to produce chemicals and fuels via the Fischer-Tropsch synthesis (FTS) process[3]
The X-ray diffraction (XRD) pattern of calcined Co1Mn3–Na2S (Supplementary Figure 1) consisted of Mn2O3, MnO2 and CoMnO3 phases, and the addition of promoters did not result in change of crystalline phases
Summary
An SEM image (Supplementary Figure 2) of calcined Co1Mn3–Na2S, showed its morphology and the homogeneity of Co and Mn elemental loadings was confirmed by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEMEDX, Supplementary Table 2). Methane selectivity at 17% was lower than what was predicted by the ASF distribution (Supplementary Figure 4 and Supplementary Table 3). The effects of reaction pressures and temperatures on the catalytic performance of Co1Mn3–Na2S are shown in Fig. 1 and detailed information can be found in Supplementary Tables 4–7. Only with Na2S promotion this is achieved, while in literature catalysts always produce more methane than expected
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