In this study, we explored the feasibility
of using base metal
catalysts for three-way catalysis. The catalysts contain up to three
base metals that were chosen to replace or reduce use of platinum
group metals (Rh, Pd, and Pt). The aim was to develop catalysts with
high activities at low temperatures having robustness against oxygen
concentration fluctuations. Various base metal catalysts supported
on alumina [10 wt % X/Al2O3 (X = Fe, Co, Ni, or Cu), 10 wt % CuY/Al2O3 (Y = Mn, Fe, Co, or Ni; Cu/Y = 1:1 in atomic ratio), and 10 wt % CuNi–5 wt % Z/Al2O3 (Z = Mn, Fe, or Co; Cu/Ni
= 1:1 in atomic ratio)] were tested by temperature-programmed reaction
in NO–CO–C3H6–O2 flow and under fluctuating oxygen concentration conditions. We found
that the rate of reduction of NO over the 10 wt % CuNi–5 wt
% Fe/Al2O3 catalyst in the low-temperature region
was comparable to that of 1 wt % Pt/Al2O3, and
this catalyst was also tolerant to oxidative conditions to some extent.
Ex situ characterization of the catalysts before and after the three-way
catalytic reaction was carried out via powder X-ray diffraction, X-ray
absorption spectroscopy, scanning transmission electron microscopy
with an energy-dispersive X-ray spectrometer, and in situ diffuse
reflectance infrared Fourier transform measurements and revealed that
the presence of Fe species resulted in the significantly improved
oxidation of C3H6 and, thus, an increased rate
of reduction of NO.
Cyclobutene Ring! A cobalt complex with dppf as the ligand catalyzed the synthesis of cyclobutenes from alkynes and acrylates bearing a leaving group at the α position. The formation of cyclobutenes was facilitated by a suitable proton source. In the presence of a Lewis acid, acetonitrile participated in the reaction, affording the corresponding acetylated cyclobutenes. More information can be found in the Communication by Tetsuaki Fujihara, Yasushi Tsuji et al. on page 2456 in Issue 12, 2018 (DOI: 10.1002/ajoc.201800561).
This study reports a cobalt-catalyzed synthesis of cyclobutenes using alkynes and acrylates bearing a leaving group at the α position. The cyclobutene formation was facilitated by an appropriate proton source. In the presence of a Lewis acid, acetonitrile participated in the reaction, affording the corresponding functionalized cyclobutenes.[a] Prof.
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