The separation of acetylene from ethylene is of paramount importancei nt he purification of chemicalf eedstocks fori ndustrial manufacturing. Herein, an isostructural series of gallate-based metal-organic frameworks (MOFs), Mgallate (M = Ni, Mg, Co), featuring three-dimensionallyi nterconnected zigzag channels, the aperture size of which can be finely tunedw ithin 0.3 by metalr eplacement. Controlling the apertures ize of M-gallate materials slightly from 3.69 down to 3.47 could result in ad ramatic enhancement of C 2 H 2 /C 2 H 4 separation performance.A st he smallest radius amongt he studied metal ions, Ni-gallate exhibits the best C 2 H 2 /C 2 H 4 adsorption separation performance owingt ot he strongestc onfinement effect,r ankinga fter the state-of-theart UTSA-200a with aC 2 H 4 productivity of 85.6 mol L À1 from 1:99 C 2 H 2 /C 2 H 4 mixture. The isostructural gallate-based MOFs, readilys ynthesized from inexpensive gallic acid, are demonstratedt ob ean ew
To
recover zirconium (Zr) from LiCl-KCl molten salt, the electro-reduction
mechanisms and dynamic and thermodynamic properties of Zr(IV) on W
and Fe electrodes were investigated using a series of electrochemical
techniques. Zr(IV) was reduced by a continuous two-step process to
form metallic Zr on the W electrode and a one-step process to form
various Zr–Fe alloy compounds on the Fe film electrode. The
deposition potentials pertaining to the formation of various Zr–Fe
intermetallics were found more positive than those of Zr(II)/Zr and
Zr(IV)/Zr(II)pairs. Furthermore, the dynamic data of the Zr(II)/Zr
pair on the W electrode and the ZrFe3/Zr(IV) pair on the
Fe film electrode were measured by linear polarization and Tafel methods.
The results indicated that, with an increasing temperature, the value
of the exchange current density for the two pairs increased, while
the charge transfer resistance and transfer coefficient of the two
pairs decreased. The thermodynamic data, for instance, the activities
of Zr in Zr–Fe alloys and Gibbs free energies of the formation
of Zr–Fe intermetallic compounds, were estimated using open-circuit
chronopotentiometry. Furthermore, electrochemical recovering Zr was
conducted using an Fe electrode by potentiostatic and galvanostatic
electrolysis, which proved that the products were only ZrFe2 intermetallic compounds. The recovery efficiencies were 98.05% and
98.97%, respectively.
An isostructural family of M‐gallate (M=Mg, Co, Ni) MOFs not only afforded excellent separation performances for the removal of C2H2 from C2H4, but also a remarkably high C2H4 productivity of 85.6 mol L−1 from an 1/99 C2H2/C2H4 mixture. Metal‐ion substitution, with different lengths of the metal–oxygen bonds, significantly enhanced the interaction between the C2H2 molecules and frameworks as a result of precisely controlling the pore aperture size from 3.69 to 3.47 Å. More information can be found in the Full Paper by Z. Bao, Q. Ren, et al. on page 15516.
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