Yanshu Liu,Guanyun Zhang,Dexin Wang,Guanjie Chen,Fangfang Gao,Chen-Ho Tung,Yifeng Wang
A cryptand-like Ti-coordination compound, namely Ti12Cs, comprising two Ti6-salicylate cages and hosting two Cs+ ions, was synthesized by the solvothermal method. It exhibits strong visible-light absorption with an absorption band edge of 652 nm, attributed to the electron transition from salicylate ligands to Ti ions. Electrochemical impedance, visible-light transient photocurrent response, and photoluminescence spectra confirm that Ti12Cs has excellent visible-light response and charge-separation properties. Ti12Cs can be used as a heterogeneous and recyclable photocatalyst for CO2/epoxide cycloaddition, with high utilization efficiency of visible-light under mild conditions. The mechanism investigation points to a synergistic effect of photocatalysis and Lewis acid catalysis.
The activities of several Lewis acid catalysts such SnCl 2 , FeCl 3 , ZnCl 2 , AlCl 3 , and NbCl 5 for the in situ transesterification/esterification of lipid contained within a microalga ( Chlorella pyrenoidosa ) in ethanol at 350 °C were examined to identify the most suitable catalyst in term of crude biodiesel (CBD) yield. Of those catalysts tested, ZnCl 2 showed the highest performance toward the CBD production. Using ZnCl 2 as catalyst, effects of reaction temperature (200–370 °C), time (0–120 min), ethanol to microalga ratio (EtOH:MA) (5/5–40/5), catalyst loading (0–30 wt.%), and algae moisture (0–80 wt.%) on the yields of product fractions and the properties of CBD were studied. The presence of ZnCl 2 not only promoted the production of CBD but also showed activities toward the deoxygenation and denitrogenation of CBD. The moisture content in the starting material is the most influential factor affecting the yield and properties of CBD.
A lanthanide metal–organic framework (MOF) Yb(BTC)(H 2 O)·(DMF) (BTC = 1,3,5-benzenetricarboxylate, DMF = N , N -dimethylformamide) was prepared from Yb(NO 3 ) 3 ·5H 2 O and H 3 BTC using the solvothermal method and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, N 2 adsorption–desorption technology, and temperature-programmed desorption. The results show that Yb(BTC)(H 2 O)·(DMF) is a lanthanide MOF with an excellent thermal stability. The coordinated water molecules and DMF guest molecules were removed from the channels by calcination to form a porous solid Yb (BTC) with coordinatively unsaturated Yb 3+ sites. The BET surface area and pore size of Yb(BTC) are 695 m 2 /g and 0.68 nm, respectively. As a heterogeneous Lewis acid catalyst, the activity of Yb(BTC) for the synthesis of polycarbonate diol (PCDL) via transesterification between diphenyl carbonate and diol was investigated. Compared with nine reported catalysts, Yb(BTC) exhibits the highest catalytic activity for the synthesis of PCDL.
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