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At least 775 records · Page 43

Structure and adsorption properties of a porous cooper hexacyanoferrate polymorph

The key questions addressed here were: the structure elucidation and the investigation of the adsorption space and framework expansion effect of a Cu(II) hexacyanoferrate (III) polymorph (labeled Cu-PBA-I). The structural analysis was performed with a broad set of characterization methods. In addition, a low and high pressure carbon dioxide adsorption investigation was performed, assuming, to comprehend the adsorption experiments, that the adsorbent plus the adsorbed phase were a solid solution. The Cu-PBA-I presented the following composition, K 1/4 Cu (II) [Fe (III)(CN) 6 ] 3/4 ∙ 1/4 nH 2 O, exhibited an antiferromagnetic behavior and displayed a thermally stable I4 2 m space group lattice in the degassed state. Furthermore, the low pressure adsorption study allowed the calculation of the micropore volume, W¼0.09 cm 3 /g and the isosteric heat of adsorption, q iso =19 kJ/mol; further, the high pressure adsorption data revealed an extremely high adsorption capacity owing to a framework expansion effect. Finally, the DRIFTS spectrum of adsorbed CO 2 displayed peaks corresponding to carbon dioxide physically adsorbed and interacting with electron accepting Lewis acid sites. Hence, was produced an excellent adsorbent which combine porosity and anti-ferromagnetism, antagonist properties rarely found together.

36 MATERIALS SCIENCE↗

Cooperative roles of water and metal-support interfaces in the selective hydrogenation of cinnamaldehyde over cobalt boride catalysts

Chemoselectivity in the hydrogenation of carbonyl over alkene bonds is valuable for producing industrial chemicals. In this study, we investigate the role of water in the selective hydrogenation of cinnamaldehyde on cobalt and cobalt boride catalysts by combining rate measurements, in situ characterization, and computational calculations. Ex situ and in situ spectroscopic analyses indicate that the boron species do not significantly modify the intrinsic electronic properties of cobalt. However, during thermal treatments, they exsolve from the bulk phase and become enriched on the surface, forming acidic species that enhance the activity and selectivity of carbonyl bond hydrogenation by three and two times, respectively. A small amount of water is able to promote hydrogenation. When titania, ceria, and zirconia are used as supports, metal-support interactions result in smaller particles that show a drop in selectivity toward the desirable unsaturated alcohol. Overall, the combination of the presence of boron species and strong metal-support interactions protects the catalysts from water attack, resulting in enhanced stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗