The pivotal role of bromine in FeMnKBr/YNa catalyst for CO2 hydrogenation to light olefins

Light olefins are key intermediates in the synthesis of petrochemicals, and the conversion of stabilized carbon dioxide to light olefins using catalysts containing halogenated elements such as chlorine is a major challenge. Building on previous reports emphasizing the toxic effects of halogen elements on catalysts, we present the synthesis of FeMnKBr/YNa catalysts. This involved the synthesis of the catalyst by melt permeation using Br-containing potassium salts, other metal nitrates and YNa zeolites. The catalyst performed well in converting syngas (H2/CO2 = 3) to light olefins with a selectivity of 56.2%, CO2 conversion of 34.4%, and CO selectivity of 13.6%. Adding Br aids in reducing the Fe phase, boosts catalyst carburization, and produces more iron carbide species. It also moderately deposits carbon on the active center's surface, enhancing active phase dispersion. Br's electronegativity mitigates the influence of K, reducing catalyst's carbon-carbon coupling ability, leading to more low-carbon olefins generation.

Highly robust and efficient MnZnFe2O4 decorated fibrous KCC-SiO2 catalyst for the synthesis of light olefins from syngas

In this study, high light olefin (C2–C4) selectivity is obtained through FTS reaction and using a novel and robust catalyst of KCC-SiO2 fibrous nanospheres decorated with MnZnFe2O4 NPs.

Effect of the Zr promoter on precipitated iron-based catalysts for high-temperature Fischer–Tropsch synthesis of light olefins

FeMnxZr and FeMnxZr2Na catalysts prepared by coprecipitation and impregnation methods were applied to investigate the promoting effects of Zr on iron-based catalysts for high-temperature Fischer–Tropsch synthesis (HTFT).

Controlled Nanostructure of Zeolite Crystal Encapsulating FeMnK Catalysts Targeting Light Olefins from Syngas

Light olefins (C₂⁼-C₄⁼) are important basic raw materials in chemical industries. Direct production of light olefins from syngas using zeolite encapsulation catalysts shows great potential due to their regulation of product distribution in the Fischer-Tropsch process. Herein, we report a series of silicalite-1 zeolite-encapsulated FeMnK catalysts with distinct nanostructures, including FeMnK@S-1, FeMnK@Hol-S-1, and FeMnK@HM-S-1. It was found that the FeMnK@HM-S-1 catalyst (encapsulation of FeMnK oxide in hollow mesoporous silicalite-1 crystal) had an enhanced C₂⁼-C₄⁼ selectivity of 49% at a CO conversion of 12%. Our results revealed that superior light olefins selectivity of the FeMnK@HM-S-1 catalyst was achieved by the synergic effect between the inherent silicalite-1 micropores and the hollow mesoporous structure, which is responsible for restricting heavy hydrocarbon (C₅⁺) formation, maximizing C₂-C₄ hydrocarbons selectivity, quickly removing the primary light olefin products, and increasing the O/P ratio. We demonstrated that the enhanced CO adsorption and the declined H₂ adsorption (lower [H*]/[C*] ratio) over the FeMnK@HM-S-1 catalyst could also facilitate the olefin synthesis. This work provides guidance for reasonable designing of F-T catalysts to tailor product selectivity.