Direct production of olefins from syngas with ultrahigh carbon efficiency

Abstract

Syngas conversion serves as a competitive strategy to produce olefins chemicals from nonpetroleum resources. However, the goal to achieve desirable olefins selectivity with limited undesired C1 by-products remains a grand challenge. Herein, we present a non-classical Fischer-Tropsch to olefins process featuring high carbon efficiency that realizes 80.1% olefins selectivity with ultralow total selectivity of CH4 and CO2 (<5%) at CO conversion of 45.8%. This is enabled by sodium-promoted metallic ruthenium (Ru) nanoparticles with negligible water-gas-shift reactivity. Change in the local electronic structure and the decreased reactivity of chemisorbed H species on Ru surfaces tailor the reaction pathway to favor olefins production. No obvious deactivation is observed within 550 hours and the pellet catalyst also exhibits excellent catalytic performance in a pilot-scale reactor, suggesting promising practical applications.

Identifying the Performance Descriptor in Direct Syngas Conversion to Long-Chain α-Olefins over Ruthenium-Based Catalysts Promoted by Alkali Metals

“…On increasing the K content, the CO conversion decreased significantly, while the olefin selectivity increased remarkably (Figure a). However, as reported in a previous work, excessive alkali metal additives would suppress the olefin production and promote the C1 byproduct formation . The CO 2 selectivity gradually increased from 0.2 to 7.4% on increasing the K/Ru molar ratio.…”

“…Xie et al used Na and its counter-ion S as electronic promoters to modulate the metallic Co and greatly improve selectivity to lower olefins . In our previous work, the addition of Na could stabilize the formation of Co 2 C nanoprisms with exposed facets of (101) and (020), which achieved a high selectivity to lower olefins with suppressed CH 4 selectivity. , Especially, the sodium-promoted metallic ruthenium nanoparticles exhibited high selectivity to α-olefins with ultralow C1 byproduct selectivity . However, the underlying role of alkali metal promoters for Ru-based FTO remains unclear and there still lacks a detailed descriptor for a quantitative study on the electronic effect of alkali metal promoters.…”

“…However, as reported in a previous work, excessive alkali metal additives would suppress the olefin production and promote the C1 byproduct formation. 28 The CO 2 selectivity gradually increased from 0.2 to 7.4% on increasing the K/Ru molar ratio. The CH 4 selectivity was maintained at about 2.0% for samples with K/Ru molar ratio in the range of 0.1−0.5, while it increased to 5.5% for the 1K-Ru/ SiO 2 catalyst (Figure 8b).…”

“…26,27 Especially, the sodiumpromoted metallic ruthenium nanoparticles exhibited high selectivity to α-olefins with ultralow C1 byproduct selectivity. 28 However, the underlying role of alkali metal promoters for Rubased FTO remains unclear and there still lacks a detailed descriptor for a quantitative study on the electronic effect of alkali metal promoters.…”

Direct synthesis of extra-heavy olefins from carbon monoxide and water

“…1d-f). Notably, the Ru 3d 5/2 peak located at 280.4 eV suggested negligible electronic interaction between PEG and Ru particles 25 . Supplementary Figure S3 shows scanning transmission electron microscopy-energy diffraction X-ray (STEM-EDX) elemental , we still need the kinetic feasibility.…”