Even
though many studies have been done in the direct transformation
of syngas to aromatics, developing catalysts to achieve high space
time yield (STY) for aromatics (over 1.0 g·gFe
–1·h–1) remains a bottleneck
of this process. Herein, we designed a type of catalyst with FeMn
nanoparticles as the yolk and hollow HZSM-5 zeolite as the shell,
which displayed a surprisingly high aromatics STY of 1.9 g·gFe
–1·h–1, outperforming
previously reported catalytic systems significantly. The enhanced
catalytic performance was attributed to the spatially and temporally
ordered effect of the yolk@shell structure, which fully exploited
the shape-selective effect and aromatization ability of HZSM-5 zeolite.
The elemental composition of the yolk, the hollow structure combined
with mesoporous channels, as well as the acidity of the nanoreactor
could be tuned rightly, which played significant roles in enhancing
the production of aromatics and suppressing the coke deposition. These
findings provided a strategy for constructing highly efficient multifunctional
catalysts, which could be potentially applied to other tandem catalysis
systems.
Exploiting new carbon supports with adjustable metal-support interaction and low price is of prime importance to realize the maximum active iron efficiency and industrial-scale application of Fe-based catalysts for Fischer-Tropsch synthesis (FTS). Herein, a simple, tunable, and scalable biochar support derived from the sugarcane bagasse was successfully prepared and was first used for FTS. The metal-support interaction was precisely controlled by functional groups of biosugarcane-based carbon material and different iron species sizes. All catalysts synthesized displayed high activities, and the iron-time-yield of Fe 4 /C bio even reached 1,198.9 mmol g Fe À1 s À1 . This performance was due to the unique structure and characteristics of the biosugarcane-based carbon support, which possessed abundant CÀO, C=O (h 1 (O) and h 2 (C, O)) functional groups, thus endowing the moderate metal-support interaction, high dispersion of active iron species, more active ε-Fe 2 C phase, and, most importantly, a high proportion of Fe x C/Fe surf , facilitating the maximum iron efficiency and intrinsic activity of the catalyst.
An
in-depth understanding of the influence mechanism of the nonprecious
metal Fe promoter on CO2 methanation is of great significance
to the optimal design of high-efficiency CO2 methanation
catalysts. In this research, CeO2 and Al2O3-supported Ni-based catalysts were prepared and evaluated
for the CO2 methanation reaction. Interestingly, it was
found that the addition of Fe into the CeO2-supported Ni
catalyst lowered the CO2 methanation performance, while
it greatly enhanced the performance of the Al2O3-supported Ni catalyst. A variety of factors over Fe-modified catalysts
were explored, in which surface basicity along with oxygen vacancies
could contribute to the adjustment of the CO2 methanation
performance.
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