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To prepare anion exchange membranes which permeate specific anions selectively in electrodialysis, anion exchange membranes with various anion exchange groups were prepared and the relative transport number of various anions compared with chloride ions was examined. Anion exchange groups introduced in the membranes were trimethylbenzylammonium, triethylbenzylammonium, tri-n-propylbenzylammonium, tri-nbutylbenzylammonium, and tri-n-pentylbenzylammonium, in order of increasing hydrophobicity. The relative transport number of various anions compared with chloride ions changed remarkably with increasing chain length of alkyl groups (increasing hydrophobicity of the groups). The relative transport number of highly hydrated anions, such as sulfate ions and fluoride ions, compared with chloride ions decreased with increasing hydrophobicity of the groups. On the other hand, less hydrated anions such as bromide ions and nitrate ions compared with chloride ions permeate selectively through the membrane with increasing hydrophobicity of the groups. For example, the relative transport number of nitrate ions compared with chloride ions increased from 1.58 (membrane with trimethylbenzylammonium groups) to 16.5 (membrane with tri-n-pentylbenzylammonium groups) in electrodialysis of a 1:1 mixed solution of sodium nitrate and sodium chloride (0.04 N as sodium ion concentration). However, the increase in hydrophilicity of the membrane by further reaction of the remaining chloromethyl groups of the membrane with trimethylamine caused the relative transport number between them to decrease.

We study an asymmetric J1-J2 zigzag ladder consisting of two different spin-1 2 antiferromagnetic (AFM; J2, γJ2 > 0) Heisenberg legs coupled by zigzag-shaped ferromagnetic (FM; J1 < 0) inter-leg interaction. On the basis of density-matrix renormalization group based calculations the ground-state phase diagram is obtained as functions of γ and J2/|J1|. It contains four kinds of frustration-induced ordered phases except a trivial FM phase. Two of the ordered phases are valence bond solid (VBS) with spin-singlet dimerization, which is a rather conventional order by disorder. Still, it is interesting to note that the VBS states possess an Affleck-Kennedy-Lieb-Tasaki-type topological hidden order. The remaining two phases are ferrimagnetic orders, each of which is distinguished by commensurate or incommensurate spin-spin correlation. It is striking that the ferrimagnetic orders are not associated with geometrical symmetry breaking; instead, the global spin-rotation symmetry is broken. In other words, the system lowers its energy via the FM inter-leg interaction by polarizing both of the AFM Heisenberg legs. This is a rare type of order by disorder. Besides, the incommensurate ferrimagnetic state appears as a consequence of the competition between a polarization and a critical Tomonaga-Luttinger-liquid behavior in the AFM Heisenberg legs. arXiv:1911.05270v1 [cond-mat.str-el]

Dehydrogenation of ethylbenzene to styrene under excess carbon dioxide flow was carried out over activated carbon-supported metal oxide catalysts (Cr, Mn, Co, Ni, Mo, Ru, La, and Ce) at 823 K and W/F ) 35 g of catalyst‚h/mol. The highest yield of styrene (about 40%) with selectivity of above 80% was obtained using activated carbon-supported chromium oxide (Cr/AC) and cerium oxide (Ce/AC) catalysts. The initial activities of the Cr/AC and Ce/AC catalysts were comparable to that of an iron-loaded activated carbon catalyst reported previously. Only chromium(III) oxide and cerium(IV) oxide were detected by X-ray diffraction before and after reactions at higher loading levels, and these species might have been active forms. However, a reduced chromium oxide species was detected by X-ray photoelectron spectroscopy after reaction under argon. In addition to the produced styrene, equivalent amounts of carbon monoxide and water were formed. These results suggest that the dehydrogenation of ethylbenzene to styrene proceeds via two reaction paths. One is the simple dehydrogenation and an oxidation reaction of hydrogen formed with carbon dioxide. The other is the oxidative dehydrogenation of ethylbenzene through the redox cycle of chromium(III) oxide.

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Composite membranes composed of commercial anion exchange membranes and polypyrrole were prepared by chemical oxidation of pyrrole in the membrane matrix. Two different procedures were used:  immersing the anion-exchange membranes equilibrated with a ferric chloride solution into an aqueous pyrrole solution; immersing the anion-exchange membranes equilibrated with the pyrrole solution into the ferric chloride solution. Polypyrrole homogeneously existed throughout the membranes in the former composite membranes, and the polymer existed on the membrane surfaces as layers in the latter membranes. Electrical conductivity parallel to the plane and that across a cross section of the membrane also demonstrated different morphology of the composite membranes. After evaluating the electrochemical properties of the composite membranes, transport properties in electrodialysis, transport number of sulfate ions, nitrate ions, and bromide ions relative to chloride ions and current efficiency were evaluated. Permeation of sulfate ions through the composite membranes was difficult; permeation of nitrate ions was enhanced by the existence of polypyrrole on and in the membranes and the relative transport number of bromide ions decreased depending on morphology of the membranes. The polypyrrole in the anion-exchange membranes markedly affected the transport number of anions relative to chloride ions.