The Catalyst Review February 2020 - 16

EXPERIMENTAL
DUT-5-BPyDC(10)-Mn2+ was reduced, the conversion of trans-stilbene decreased from 54 to 19% and the selectivity increased from
83 to 90%. Turnover numbers (TON) were calculated to compare the activity of the catalysts. Despite the small catalyst amount, high
yields were obtained resulting in very high turnover numbers. For DUT-5-BPyDC(10)-Co, an increase from 1300 for 0.05 mol% to
3000 for 0.01 mol% was observed. The lowest TON (500) was achieved by using 0.05 mol% of DUT-5-BPyDC(10)-Mn2+. Nevertheless,
these values are significantly higher than for other MOF-based catalysts previously used for epoxidation reactions. Hot filtration and
recycling tests revealed that the reaction proceeded mainly via a heterogeneous pathway. Source: Yildiz C, Kutonova K, Oßwald S, et
al. (2020). ChemCatChem, 12: 1-10.
Hybridization of ZSM-5 with Spinel Oxides for Biomass Vapour Upgrading...
The growing demand for liquid fuels, coupled with increasing environmental concerns, is driving efforts to develop efficient processes for
converting alternative feedstocks such as lignocellulosic biomass into
renewable energy sources and chemicals. Herein, the authors report a
catalytic fast pyrolysis (CFP) of biomass using multifunctional hybrid spineloxide@zeolite catalysts which combine the advantages of hierarchical
ZSM-5 zeolite acid sites with the deoxygenating and depolymerizing
properties of spinel oxides.

Figure 1. (a) bio-oil yield vs. oxygen content and (b) carbon
efficiency vs. effective H:C molar ratio. Reaction conditions:
temperature - 500°C, wt. biomass feed - 1.5 g, cat. wt. - 0.5 g,
carrier gas - N2.

Multiple spinel oxides MgB2O4 (where B = Fe, Al, Ce, Ga, Cr) were screened
as catalysts for the pyrolysis of pinewood sawdust and the resultant biooil (bio-oil on a water-free basis) in terms of carbon efficiency, oxygen
content and chemical composition (Figure 1). While all the candidates
deoxygenated the pyrolysis vapor, MgAl2O4 and MgFe2O4 were found to
the best results producing bio-oil with acceptable carbon efficiency.
Catalyst fast pyrolysis (CFP) over MgFe2O4@ZSM5 and MgAl2O4@ZSM5
was then carried out under similar reaction conditions (Table 1). It was
found that the MgAl@ZSM5 was more effective in the production of
aromatic compounds, whereas MgFe@ZSM5 promoted the formation
of ketones/aldehydes. With MgAl@ZSM5 catalysts, zeolite active sites
were more accessible, thus facilitating condensation of small chains into
aromatics. The lower reduction of aliphatic C-O compounds observed
with MgAl@ZSM5 indicates a higher depolymerization efficiency of
MgAl@ZSM5 materials versus MgFe@ZSM5. The substantial reduction
of aliphatic C-O in the MgAl@ZSM5 oil may be correlated with the
increased aromatic compounds due to catalytic transformation, with
Ar-H as the dominant aromatic species being generated.

Table 1. Proton NMR of chemical functional groups present
in the bio oil based on chemical shift range.

In conclusion, the results obtained from this study indicate that careful
control of the CFP catalyst with a mild hydrogenation step in one-pass
may improve the conversion of lignocellulose to pyrolysis oil with a
hydrocarbon-rich organic fraction. Source: Konarova M, Atanda L, Batalha
N, et al. (2019). ChemCatChem, DOI: 10.1002/cctc.201902023.
Chemist Synthesizes Gold-based Electrocatalysts...
A RUDN chemist has synthesized an electrocatalyst based on gold nanoparticles with organic ligands that can trigger both hydrogen
production reactions and oxygen reduction reactions in fuel cells. The yield of products with the new catalyst was twice as high as
when using a traditional platinum-based catalyst. Rafael Luque, a RUDN chemist, synthesized a catalyst based on gold nanoparticles
stabilized with citrate, a salt of citric acid. To obtain gold nanoparticles in complex with other organic substances, an exchange of
ligands was carried out based on a concentration gradient. For this, nanoparticles were incubated in a solution of a new ligand, and
then centrifuged to precipitate formed nanoparticles with attached ligands. During the experiment in oxygen reduction reactions, the
chemists found a significant effect of the type of ligand and its interaction with the gold surface on the absorption of O2 molecules.
Gold nanoparticles with citrate proved to be the best in these reactions. The limiting current density of this type of catalyst-5.58
milliamps per square centimeter-was two times higher than that of nanoparticles with other ligands. This means that with the
same energy consumption, this catalyst will produce more oxygen. In hydrogen production reactions, the best catalytic activity, as
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The Catalyst Review

February 2020

The Catalyst Review February 2020

Table of Contents for the Digital Edition of The Catalyst Review February 2020