Type IV deep eutectic solvent(DES) involves the formation of metal-based eutectics from metal salts or metal salt hydrate in combination with various hydrogen-bond donors(HBDs) such as urea, ethylene glycol or acetamide. In current study, two distinguished approaches were used to synthesize potential DESs, given as the direct heating and the evaporating methods. Successful synthesized DESs were subjected for physical properties characterization by Fourier Transform Infrared(FTIR) Spectroscopy, thermal stability, viscosity,and conductivity analyses. Five novel manganese(II)-based DESs were successfully synthesized as reported in this study. Data obtained indicated that the Mn Cl2á4H2Oáacetamide DES exhibits the lowest freezing point(27.5℃), highest thermal stability(193℃ point of dehydration), lowest viscosity(E = 112.8cP) and the highest conductivity(0.12723 mS/cm). The findings obtained reveal the characteristics, nature or features of synthesized DESs as potential industrial solvents. 相似文献
Ceria-zirconia nanophase with structural defects and high thermal stability was synthesized by a surfactant-templated method.
The 0.5 wt.% Rh/ceria-zirconia catalyst shows high activity for NO reduction by CO under an oxygen-rich condition, and the
selectivity to 100% N2 below 200°C was achieved. 相似文献
The selective oxidation of CO in the presence of hydrogen on CuO/CeO2 systems containing Fe and Ni oxides as promoters was studied. The catalysts containing 1–5 wt % CuO and 1–2.5 wt % Fe2O3 supported on CeO2 and the CuO/CeO2 systems containing 1–2.5 wt % NiO were synthesized, and their catalytic activity as a function of temperature was determined. It was found that the additives of Fe and Ni oxides increased the activity of the CuO/CeO2 catalysts with a low concentration of CuO. In this case, the conversion of CO at 150°C approached 100%. At the same time, these additives had no effect on the activity of the CuO/CeO2 systems at a CuO concentration of 5 wt % or higher, which exhibited an initially high activity in the above temperature region. The forms of CO adsorption and the amounts of active sites for CO adsorption and oxidation were studied using temperature-programmed desorption. It was found that the introduction of Fe and Ni additives in a certain preparation procedure facilitated the formation of an additional amount of active centers associated with CuO. Data on the temperature-programmed reduction of samples (the amount of absorbed hydrogen and the maximum temperature of hydrogen absorption) suggested the interaction of all catalyst components, and the magnitude of this interaction depended on the sample preparation procedure. With the use of Mössbauer spectroscopy, it was found that the procedure of iron oxide introduction into the CuO/CeO2 system was responsible for the electron-ion interactions of catalyst components and the reaction mixture. 相似文献
Melt/solid polycondensation (MP/SSP) is deemed as an alternative synthetic route besides ring-opening polymerization (ROP) in synthesizing poly(l-lactic acid) (PLLA). However, it is found that PLLA synthesized by MP/SSP has much poorer thermal stability than that by ROP due to more residual Sn(II) metallic catalyst in the former, but sulfonic acids does not show any detrimental effect on the thermal stability of PLLA. To synthesizing PLLA with good thermal stability by MP/SSP, a variety of commercially available sulfonic acids were screened as catalysts in MP/SSP of PLLA. Among these nonmetallic catalysts, it was found that 1,3-propanedisulfonic acid (PSA) and 1,5-naphthalene disulfonic acid (NSA) exhibited satisfactory catalytic reactivity and PLLAs with excellent thermal stability, high molecular weight, little coloration and good optical purity were successfully synthesized by MP/SSP. The decomposition temperature was increased by 80–100 °C in comparison to SnCl2-catalyzed PLLA, and the thermal stability is comparable to commercial PLLA produced by ROP. 相似文献
The present work aims to investigate the feasibility of oxalic acid-choline chloride deep eutectic solvent (OA-ChCl DES), which serves as a promising green solvent that utilized in the acidic deep eutectic solvent (DES) hydrolysis. Oxalic acid-choline chloride DES cellulose nanocrystal (OA-ChCl DES CNC) was isolated from the bleached DES treated pulp (BP) through the acidic DES hydrolysis using 1:1 molar ratio of OA-ChCl DES. The functional groups, crystallinity index, morphological structure, particle size, zeta potential, thermal stability and surface chemistry of the OA-ChCl DES CNC were compared with the sulphuric acid cellulose nanocrystal (SA-CNC) that prepared via sulphuric acid hydrolysis. The findings revealed the presence of negatively charged carboxyl groups on OA-ChCl DES CNC surface after the acidic DES hydrolysis. The physicochemical analyses verified that the OA-ChCl DES CNC was in nano-sized range with polydispersity index (PdI) of 0.56, indicating slightly monodispersed nanoparticles. A stable OA-ChCl DES CNC colloidal suspension with zeta potential value of ?52.1?±?5.2 mV was obtained. The OA-ChCl DES CNC outweighed the SA-CNC in term of thermal stability (288 °C) despite having a slightly lower crystallinity index (76.7%). In fact, the OA-ChCl DES CNC with a yield of 55.1% was achieved through the acidic DES hydrolysis, suggesting that the OA-ChCl DES was capable of promoting efficient cleavage of strong hydrogen bonds in BP.
A series of novel pyrimidinedione- and pyrimidinetriones-based compounds were synthesized by different techniques such as with conventional Knoevenagel condensation alone, with a Rhizopus oryzae lipase biocatalyst, and with a deep eutectic solvent (DES). The yield was found to be maximum by using lipase and DES. Reuse of the lipase and DES was possible up to four consecutive cycles. These methods are mild, highly efficient, and amenable to scaleup. The products were found to exhibit appreciable in vitro antibacterial activity against Echerichia coli, Pseudomonas neumoniae, and Micrococcus and in vitro antifungal activity against Aspergillus niger and Candida albicans. All the compounds exhibited appreciable in vitro activity against the tested strains. The photophysical properties and thermal stability of the products were also investigated. 相似文献