Janus Au–Fe_2.2C Catalyst for Direct Conversion of Syngas to Higher Alcohols

Abstract

Higher alcohol synthesis (HAS) direct from syngas using Febased catalysts is quite promising, but there are still problems in the construction of intimate-contact and stable dual sites to obtain satisfactory higher alcohol selectivity and space time yield (STY). Herein, a series of Au−Fe 2.2 C catalysts derived from monodisperse Janus Au−Fe 3 O 4 nanoparticles with different Fe/Au ratios were prepared. The optimal catalyst with a Fe/Au molar ratio of 11.6 achieved the most Janus nanoparticles and exhibited the highest STY toward higher alcohols of 0.195 g g cat −1 h −1 and excellent catalytic stability over 200 h. The superior performance of this catalyst was attributed to the unique Au−Fe 2.2 C Janus structure, which could enhance both CO insertion and CO dissociation as well as their synergistic effect. The correlation of the CO adsorption behavior and STY toward alcohols was established as well, indicating that the balance between CO nondissociated adsorption and CO dissociated adsorption played an important role in enhancing the alcohol formation. Moreover, the strong interaction between Au and iron species in Janus nanoparticles could facilitate the formation of ε′-Fe 2.2 C and benefit the stability of the catalyst. These results may provide new ideas for the design and fabrication of high-performance catalysts with dual sites for HAS.

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

“…To achieve a high selectivity to HA, it is pivotal to introduce a second active site for CO nondissociative adsorption and insertion. The effective sites for CO nondissociative adsorption and insertion include oxides (i.e., Co x O, Fe 3 O 4 ), carbides (i.e., Co 2 C, − Fe 2 C, ε′-(Co x Fe 1– x ) 2.2 C), and some metal elements (i.e., Fe, Cu, , Au, Ru, Rh, Mo). Recent advances mainly focused on the trial to strengthen the CO insertion function by constructing a synergistic dual-site structure and tuning the local chemical environment. , Various types of promoters (i.e., alkali metal, , alkaline earth, La, , Zn, Mn), supports (i.e., CNT, AC), and catalyst precursors [i.e., alloy, layered double hydroxide (LHD), perovskite] are introduced to facilitate the formation of a stable dual-site structure with abundant contact boundary or interfacial sites.…”

“…Some recent works also explore other types of bimetallic active sites such as Fe 2.2 C–Au, CoFe alloy bimetallic carbide, , binary Co/Mo carbide, bimetallic CoGa, , and Co 2 C–Mn 5 O 8 . To strengthen CO insertion, binary CO nondissociative metal sites such as Co 0 –Co 2 C/Ru δ+ (or Rh δ+ ) and Co 0 –Co 2 C/Cu 0 are also proposed. , Zeng et al fabricated an α-Al 2 O 3 -supported Janus-structured Fe 2.2 C–Au dual-site for HAS, which achieved a selectivity to total alcohols of 52.5% with 60.4% being C 2+ OH under 20% CO conversion.…”

“…To achieve a high selectivity to HA, it is pivotal to introduce a second active site for CO nondissociative adsorption and insertion. The effective sites for CO nondissociative adsorption and insertion include oxides (i.e., Co x O, 139 Fe 3 O 4 140 ), carbides (i.e., Co 2 C, 141−143 Fe 2 C, 144 ε′-(Co x Fe 1−x ) 2.2 C 145 ), and some metal elements (i.e., Fe, 144 Cu, 146,147 Au, 148 Ru, 149 Rh, 149 Mo 150 ). Recent advances mainly focused on the trial to strengthen the CO insertion function by constructing a synergistic dual-site structure and tuning the local chemical environment.…”

“…146 kinetic coordination between chain growth and CO insertion, which largely benefits the production of C 5+ OH. Some recent works also explore other types of bimetallic active sites such as Fe 2.2 C−Au, 148 CoFe alloy bimetallic carbide, 145,169 binary Co/Mo carbide, 170 bimetallic CoGa, 171,172 and Co 2 C−Mn 5 O 8 . 142 To strengthen CO insertion, binary CO nondissociative metal sites such as Co 0 −Co 2 C/Ru δ+ (or Rh δ+ ) and Co 0 −Co 2 C/Cu 0 are also proposed.…”

Enhanced Effect of the Mesoporous Carbon on Iron Carbide Catalyst for Hydrogenation of Dimethyl Oxalate to Ethanol

“…33‐0664) [30] simultaneously, indicating the weak interaction between microporous carbon supports and metal particles. The different kinds of supports have obvious influence on the used catalysts in Figure 1(b), and the iron carbides are assigned to Fe 5 C 2 (JCPDS no.36‐1248) [31] and Fe 2.2 C (JCPDS no.17‐0897) [32] . Besides, for the Fe/mesC catalyst, the diffraction peaks ascribed to Fe (JCPDS no.…”