756456-88-9Relevant articles and documents
Fluorite-like hydrolyzed hexanuclear coordination clusters of Zr(IV) and Hf(IV) with syn-syn bridging N,N,N-trimethylglycine in soft crystal structures exhibiting cold-crystallization
Matsuoka, Moe,Takao, Koichiro,Tsushima, Satoru
, (2021/09/27)
Tetravalent metal ions are hydrolyzed under presence of N,N,N-trimethylglycine hydrochloride (betaine hydrochloride, [Hbet]Cl) in aqueous solutions to afford [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ (M4+ = Zr4+ (1), Hf4+ (2)) as hydrated perchlorate salts. These compounds were characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. As a result, we have found that fluorite-like [M6O8] coordination clusters are formed through octahedral arrangement of six M4+ linked by μ3-O atoms. Additionally, each pair of neighboring M4+ are connected by the μ-bet ligand through a syn-syn bridging coordination of its carboxylate moiety. This interaction seems to prevent further growth of the fluorite structure leading to formation of MO2. It was difficult to directly distinguish each μ3-O atom to be μ3-OH? or μ3-O2? due to its strongly anisotropic thermal displacement in the obtained structures. Bond valence sum analysis suggested that four μ3-OH? and four μ3-O2? are alternately arranged in the [M6O8] core motifs. Indeed, such a symmetric structure of [M6(μ3-O)4(μ3-OH)4] was confirmed in another phase of 1 at 296 K, where 1 transforms to a monoclinic structure (1′). The number of ClO4? counteranions found in the structure determination is not enough to compensate + 12 charge of [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ in any unit cells of 1, 1′ and 2. Instead, large solvent/ion accessible voids have been actually observed in their crystal structures, indicating that the missing ClO4? are located therein and are significantly disordered to make them invisible in the crystallography. DSC analysis revealed that ClO4? and H2O/H3O+ in the crystal lattice of 1 undergo unique structure relaxation and rearrangements pronounced by cold-crystallization to induce the phase transition from 1 to 1′ with elevating temperature.
Transfer hydrogenation of furfural to furfuryl alcohol over modified Zr-based catalysts using primary alcohols as H-donors
Wang, Yantao,Zhao, Deyang,Liang, Rui,Triantafyllidis, Konstantinos S.,Yang, Weiran,Len, Christophe
, (2020/12/07)
Catalytic transfer hydrogenation is gaining increasing attention as a promising alternative to conventional hydrogenation with H2. In present work, a series of modified Zr-based catalysts were synthesized and tested for furfural catalytic transfer hydrogenation into furfuryl alcohol (FA). The results indicated that more than 13 % of furfural conversion and furfuryl alcohol yield could be achieved with modified zirconium hydroxide (mZrH) at 140 °C when compared with zirconium hydroxide (ZrH) using ethanol as H-donor and solvent in continuous flow regime, and the activity could be further enhanced by increasing the reaction temperature or Ru loading on the catalyst. The best result of 92 % furfural conversion with ～99 % FA selectivity was obtained at 150 °C with 6% Ru/mZrH as catalyst, and the productivity of FA is 5.5 mmol g?1 h?1 which is 2 times higher than that reported with ZrH in batch. Moreover, long-term stability study of the catalysts indicated that 6% Ru/mZrH not only performs a better activity, but also a better stability than 6% Ru/ZrH. Characterizations of the catalysts by BET, XRD, EA, IR, SEM-EDS, XPS and CO2 adsorption indicated that zirconium hydroxide (ZrH) was successfully modified with hydroxylamine, leading to significantly change of its morphology and basic sites. And the deactivation of the catalysts was due to both the leaching of Ru and the deposition of side-products on its surface.
Metal-reinforced sulfonic-acid-modified zirconia for the removal of trace olefins from aromatics
Kong, Decun,Peng, Qian,Shi, Li,Wang, Xin,Meng, Xuan,Hu, Xiude,Liu, Naiwang
, p. 1644 - 1653 (2020/04/28)
Metal-reinforced sulfonic-acid-modified zirconia catalysts were successfully prepared and used to remove trace olefins from aromatics in a fixed-bed reactor. Catalysts were characterized by ICP-OES, N2 adsorption–desorption, X-ray diffraction, thermogravimetric analysis (TGA), and pyridine-FTIR spectroscopy. Different metals and calcination temperatures had great influence on the catalytic activity. Alumina-reinforced sulfated zirconia exhibited outstanding catalytic performance, stable regeneration activity, and giant surface area, and are promising in industrial catalysis. TGA showed that the decomposition of methyl could be attributed to Br?nsted acid sites, and pyridine-FTIR spectroscopy proved the weak Br?nsted sites on these synthesized metal-reinforced sulfated zirconia. Also, a relation between the reaction rate and weak Br?nsted acid density is proposed.
