Sorbents for high temperature CO2 capture are under intensive development owing to their potential applications in advanced zero emission power, sorption-enhanced steam methane reforming for hydrogen production and energy storage systems in chemical heat pumps. One of the challenges in the development is the prevention of sintering of the sorbent (normally a calcium oxide derivative) which causes the CO2 capture capacity of the material to deteriorate rapidly after a few cycles of utilization. Here we show that a simple wet mixing method can produce sintering-resistant sorbents from calcium and magnesium salts of d-gluconic acid. It was found that calcium oxide was well distributed in the sorbents with metal oxide nanoparticles on the surface acting as physical barriers, and the CO2 capture capacity of the sorbents was largely maintained over multiple cycles of utilization. This method was also applied to other organometallic salts of calcium and magnesium/aluminum and the produced sorbents showed similarly high reversibility.
A series of endohedral fullerenes Sc3-
x
Y
x
N@C80 (x = 0−3) with variable encaged moieties and the same C80
cage were synthesized, isolated, and spectroscopically characterized by the laser desorption time-of-flight
mass spectrometry (LD-TOF−MS), differential pulse voltammetry (DPV), Fourier transform infrared (FTIR),
visible-near-infrared (vis-NIR) absorption spectrometry, and so forth. It was revealed that Sc3-
x
Y
x
N@C80 (x
= 0−3) have a similar electronic structure, (Sc3-
x
Y
x
N)6+@(C80)6-. However, because of the relatively larger
van der Waals radius of yttrium to that of scandium which induces the size increase of Sc3-
x
Y
x
N from x =
0 to x = 3, the frontier orbitals of this series of endohedral fullerenes dramatically change. For example,
Sc2YN@C80 shows similar electronic property with its left neighbor Sc3N@C80 but is quite different with its
right neighbor ScY2N@C80. The cycloaddition reactions of N-enthylazomethine ylide with Sc3-
x
Y
x
N@C80 (x
= 0−3) were carried out, and the regioselectivity of endohedral fullerenes shows the same trend of variation
to that of their electronic properties along with the size of endohedral moiety increasing. It was found that
Sc3N@C80 and Sc2YN@C80 produce only the [5,6]-pyrrolidine regioisomers, and a critical change in fullerene
regioselectivity occurs from ScY2N@C80 where the [6,6]-pyrrolidine regioisomer appears as a minor regioisomer
and finally becomes the major regioisomer in the case of Y3N@C80.
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