Selective and Stable In-Promoted Fe Catalyst for Syngas Conversion to Light Olefins

Abstract

A selective and stable alumina-supported In-promoted Fe catalyst (10 mol % In based on Fe) was discovered for converting syngas (2:1 H2/CO ratio) to olefins with high selectivity (45% with CO2 included) and a remarkable stability (72 h run) at a CO conversion of 10% at 400 °C and 5 bar. The X-ray photoelectron spectroscopy results indicated that incorporating In into Fe catalysts changed the chemical bonding state of Fe and Fe/In composition near the surface layers, which affected the catalytic reactivity. Steady-state isotopic transient kinetic analysis showed that more stable CHx fragments are present on the catalyst surface when incorporating In into Fe, which can promote C–C coupling reaction toward olefins. Our study demonstrates that introducing In into Fe catalysts on Al2O3 support can lower CO activation abilities. It has more impacts on lowering hydrogenation activity, which permits more C–C couplings and like of “ene” hydrogenation. Moreover, weakening CO adsorption both in terms of sites and strength encouraged CO toward hydrocarbons rather than CO2.

Advances in Selectivity Control for Fischer–Tropsch Synthesis to Fuels and Chemicals with High Carbon Efficiency

“…Similarly, the cofeeding of 8% CO 2 over an FeZn catalyst produced very limited CO 2 selectivity (15%) with 53.5% lower olefin selectivity at a CO conversion of 95.1%. 90 Several recent works also suggest that the introduction of promoters such as In, 97 Cu, 98 Mg and K, 99 Zn and Zr, 100 and Mg and Al 101 into Fe-based components can tailor the surface Fe sites and electronic structure as well as the adsorbed intermediates to favor the formation of olefins while suppressing CO 2 production. Under a high temperature of 400 °C, the In-promoted Fe-based (Fe10In/Al 2 O 3 ) catalyst showed a CO 2 selectivity as low as 16% with 45% lower olefin selectivity and ∼22.0% CH 4 selectivity in total products at ∼11% CO conversion.…”

“…Under a high temperature of 400 °C, the In-promoted Fe-based (Fe10In/Al 2 O 3 ) catalyst showed a CO 2 selectivity as low as 16% with 45% lower olefin selectivity and ∼22.0% CH 4 selectivity in total products at ∼11% CO conversion. 97 The strong electronic interaction between In and Fe promoted Fe dispersion, reducibility, and the formation of an extra Fe 7 C 3 phase. Meanwhile, the incorporation of In also weakened the hydrogenation activity and CO adsorption strength and produced more stable surface-bound CH x species that can promote C−C coupling to form olefins.…”

Challenges and Opportunities of Fe‐based Core‐Shell Catalysts for Fischer‐Tropsch Synthesis

“…The acidic zeolite properties can be exploited to control active metal-support interactions and secondary cracking, isomerization and oligomerization reactions that occur over the zeolite acid sites. [6] The tunability and functionality of zeolite-based catalysts has attracted interest in studying catalysts comprised of Fe deposited onto or within a zeolite support. [7] The three-dimensional framework of zeolites allows for the encapsulation of metal nanoparticles, while providing access to the metal active sites via the porous structure.…”

“…For achieving high olefin selectivity, it is necessary to include tunable acid‐base properties that can be obtained with a zeolite support. The acidic zeolite properties can be exploited to control active metal‐support interactions and secondary cracking, isomerization and oligomerization reactions that occur over the zeolite acid sites [6] …”

Enhancing Low-Temperature Syngas Production via Surface Tailoring of Supported Intermetallic Nanocatalysts

“…Catalytic dry reforming of methane (DRM) is a promising strategy to transform CO 2 and CH 4 into a CO-rich syngas (H 2 + CO) stream for large-scale production of renewable fuels and chemicals . DRM enables high CO 2 utilization and has potential for economic feasibility. , Integrating DRM with CO liquefaction processes such as Fischer–Tropsch and direct dimethyl ether synthesis can produce liquid fuel, − potentially reducing CO 2 emissions by 30% . At present, reforming is carried out at very high temperature to avoid catalyst deactivation , and pore blockage due to coke formation.…”