Wang Chuanhao,Du Junjie,Zeng Lin,Li Zhongling,Dai Yizhou,Li Xu,Peng Zijun,Wu Wenlong,Li Hongliang,Zeng Jie
Extra-heavy olefins (C 12+ = ), feedstocks to synthesize a wide range of value-added products, are conventionally generated from fossil resources via energy-intensive wax cracking or multi-step processes. Fischer-Tropsch synthesis with sustainably obtained syngas as feed-in provides a potential way to produce C 12+ = , though there is a trade-off between enhancing C-C coupling and suppressing further hydrogenation of olefins. Herein, we achieve selective production of C 12+ = via the overall conversion of CO and water, denoted as Kölbel-Engelhardt synthesis (KES), in polyethylene glycol (PEG) over a mixture of Pt/Mo 2 N and Ru particles. KES provides a continuously high CO/H 2 ratio, thermodynamically favoring chain propagation and olefin formation. PEG serves as a selective extraction agent to hinder hydrogenation of olefins. Under an optimal condition, the yield ratio of CO 2 to hydrocarbons reaches the theoretical minimum, and the C 12+ = yield reaches its maximum of 1.79 mmol with a selectivity (among hydrocarbons) of as high as 40.4%.
Haripal Singh Malhi,Zhenzhou Zhang,Yanling Shi,Xinhua Gao,Wenqi Liu,Weifeng Tu,Yi-Fan Han
The multi-walled carbon nanotubes (MWNTs) supported Fe-based catalysts, including FeZnNa/MWNTs, FeZnK/MWNTs, and FeZnRb/MWNTs were synthesized through co-precipitation, and incipient wetness impregnation approaches. The physicochemical results demonstrated that the addition of MWNTs had significantly influenced the morphology, reduction, phase structure, adsorption behavior of Fe-based catalysts, and consequently, the reactivity of CO 2 hydrogenation to olefins. Furthermore, adding MWNTs to the alkali metal-promoted FeZn catalysts inhibits the synthesis of CH 4 and CO and favors an improved selectivity for olefins. With the incorporation of MWNTs, the heavy olefins (C 5- C 8 = ) selectivity over FeZnNa, FeZnK, and FeZnRb catalysts increased from 27.1 to 32.2, 27.0–31.1, and 24.2–28.6 %, respectively. The results proved that the superior selectivity of heavy olefin over the MWNTs-supported catalysts might be accomplished by the electron-donating ability of the MWNTs surface, the presence of extra Hägg carbide, and higher adsorption strength with light olefins. In addition, the catalyst supported by MWNTs demonstrated exceptional stability throughout the 100-hour test at 593 K.
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