Four
distinct crystalline Mo3VO
x
catalysts comprising the same structural units were tested for the
selective oxidation of methacrolein (MCR). Crystalline orthorhombic
Mo3VO
x
(Orth-MoVO), trigonal
Mo3VO
x
(Tri-MoVO), and amorphous
Mo3VO
x
(Amor-MoVO) having pentagonal,
hexagonal, and heptagonal channels in the crystal structure showed
far better catalytic activity and selectivity to methacrylic acid
(MAA) than those of various Mo–V-based mixed oxide catalysts.
Tetragonal Mo3VO
x
(Tet-MoVO)
having pentagonal and hexagonal but no heptagonal channels in the
crystal structure provided minor MCR oxidation activity, and the MAA
selectivity was lower than that of the other crystalline Mo3VO
x
catalysts with heptagonal channels.
In situ Fourier transform infrared (FT-IR) measurements revealed that
Orth-MoVO and Tri-MoVO were active with respect to MCR, forming methacrylate
as a reaction intermediate, while no infrared (IR) bands related to
surface compounds were observed over Tet-MoVO after the MCR injection.
Based on these results, we concluded that the crystal structure of
crystalline Mo3VO
x
catalysts
significantly affects the catalytic MCR oxidation activity. Orth-MoVO
catalyzed the MCR oxidation at low reaction temperatures (<240
°C), where the conventional catalyst used for the industrial
MCR oxidation process, a heteropoly acid (HPA)-based catalyst, displayed
poor catalytic activity.
High
dimensionally structured niobium oxide (HDS-NbO) containing
fluoride (F–) was prepared by a hydrothermal synthesis.
F– could be introduced into HDS-NbO by replacing
lattice oxygen up to a solid F–/Nb ratio of 0.55.
The introduction of an appropriate amount of F– promoted
the crystal growth of HDS-NbO, while niobium oxyfluoride having the
hexagonal tungsten bronze structure (HTB-Nb(F,O)
x
) was concomitantly formed by excess F– addition.
HAADF-STEM analysis suggested that the number of micropores (hexagonal
and heptagonal channels) in HDS-NbO was increased by the introduction
of an appropriate amount of F–. The catalytic activity
for Brønsted acid reactions was evaluated by Friedel–Crafts
alkylation. The catalytic activity was significantly increased by
the introduction of F–, while excess introduction
of F– significantly decreased the activity. Catalytic
activity for the Lewis acid reaction in the presence of water was
evaluated by the transformation of pyruvaldehyde into lactic acid.
The catalytic activity was changed by the introduction of F– in a manner similar to that observed in the Friedel–Crafts
alkylation. On the basis of the results obtained, we propose that
the local catalyst structure around the micropores of HDS-NbO is crucial
for the acid reactions.
The development of novel effective antibacterial agents is crucial due to increasing antibiotic resistance in various bacteria. Poly (alkyl cyanoacrylate) nanoparticles (PACA-NPs) are promising novel antibacterial agents as they have shown antibacterial activity against several Gram-positive and Gram-negative bacteria. However, the antibacterial mechanism remains unclear. Here, we compared the antibacterial efficacy of ethyl cyanoacrylate nanoparticles (ECA-NPs), isobutyl cyanoacrylate NPs (iBCA-NPs), and ethoxyethyl cyanoacrylate NPs (EECA-NPs) using five Gram-positive and five Gram-negative bacteria. Among these resin nanoparticles, ECA-NPs showed the highest growth inhibitory effect against all the examined bacterial species, and this effect was higher against Gram-positive bacteria than Gram-negative. While iBCA-NP could inhibit the cell growth only in two Gram-positive bacteria, i.e., Bacillus subtilis and Staphylococcus aureus, it had negligible inhibitory effect against all five Gram-negative bacteria examined. Irrespective of the differences in growth inhibition induced by these three NPs, N-acetyl-L-cysteine (NAC), a well-known reactive oxygen species (ROS) scavenger, efficiently restored growth in all the bacterial strains to that similar to untreated cells. This strongly suggests that the exposure to NPs generates ROS, which mainly induces cell growth inhibition irrespective of the difference in bacterial species and cyanoacrylate NPs used.
We present a 10 wt% WO3/ZrO2 catalyzed monoallylation reaction of anilines to give various N-allyl anilines in good yields. The developed catalytic reaction is applicable to the continuous flow synthesis of N-allyl aniline with 97% selectivity.
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