ZnCl2 Content Research Articles

ZnCl2-assisted Synthesis of ZnSe Polycrystal

A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature (∼1000 °C). ZnSe polycrystal was obtained in the closed-tube systems with Zn-Se, Zn-Se-Zn(NH3)2Cl2, Zn-Se-NH4Cl and Zn-Se-ZnCl2. The as-synthesized samples were tested by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and analyzed by thermodynamic numerical method. The results demonstrate that the synthesis efficiency is higher than 99.96% for Zn-Se-ZnCl2 system at around 1000 °C for 3 weeks. It also exhibits that not only temperature, but also low apparent ratio of volume and surface area of the source materials and higher ZnCl2 content are required to achieve high synthesis efficiency. A SeCl transporting reaction synthesis process is proposed based on the thermodynamic analysis.

Deep oxidative desulfurization of diesel fuels by Lewis acidic ionic liquids based on 1-n-butyl-3-methylimidazolium metal chloride

A series of Lewis acidic ionic liquids (ILs) based on 1-n-butyl-3-methylimidazolium metal chloride, i.e., [C4mim]Cl/MCl2 (M=Zn, Fe, Cu, Mg, Sn, Co), are synthesized and used to investigate the oxidative removal of sulfur compounds (S-compounds) from diesel fuels, with ILs serving as both extractant and catalyst and 30wt% H2O2 solution as oxidant. It is observed that metal chloride species affect S-removal, as S-removal efficiency follows the order: [C4mim]Cl/ZnCl2>[C4mim]Cl/FeCl2>[C4mim]Cl/CoCl2>[C4mim]Cl/MgCl2>[C4mim]Cl/CuCl2>[C4mim]Cl/SnCl2. The highly efficient [C4mim]Cl/ZnCl2 is selected to investigate the effects of ZnCl2 content on desulfurization. It is interesting to find out that ZnCl2 content has a significant influence on desulfurization; specifically, 99.9% S-removal is observed for [C4mim]Cl/3ZnCl2 after 3h at 45°C, O/S molar ratio of 8, IL/oil mass ratio of 1/2. [C4mim]Cl/3ZnCl2 then undergoes series of parallel experiments to systematically investigate the influence of factors such as temperature, molar ratio of O/S, mass ratio of IL/oil, and ILs recycling. The incorporation of real diesel fuel into this study demonstrates the efficacy of this IL in desulfurization. This work shows that oxidative desulfurization using Lewis acidic ILs may be a new option for producing cleaner diesel fuels.

Selective fast pyrolysis of biomass impregnated with ZnCl2 to produce furfural: Analytical Py-GC/MS study

A new technique was proposed to produce furfural (FF) through low-temperature fast pyrolysis of biomass impregnated with ZnCl2. Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed in this study to reveal the ZnCl2-catalyzed biomass pyrolysis and FF formation characteristics. The results revealed that the presence of ZnCl2 decreased the temperature for the complete decomposition of biomass, inhibited the devolatilization of lignin and pyrolytic ring scission of holocellulose. Meanwhile, it promoted the depolymerization and dehydration of holocellulose to form the FF and three anhydrosugars (levoglucosenone (LGO), 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC) and 1,4:3,6-dianhydro-α-d-glucopyranose (DGP)) as the major primary pyrolytic products. With the increase of the ZnCl2 content, the three anhydrosugars were firstly increased and then decreased, while the FF was increased steadily. Moreover, these anhydrosugars could be converted to FF through the secondary catalysis by ZnCl2, leaving the FF as the predominant product. In addition, the acetic acid (AA), which was not inhibited by the ZnCl2, was formed as the only important liquid by-product.

Evaporation Behavior of Zinc Chloride in Ar–O2–H2O Atmosphere

Evaporation behavior of ZnCl2 melts and ZnCl2–ZnO mixtures in Ar–O2–H2O atmosphere was observed at 873 K by measuring change of weight and chemical composition. When water vapor or oxygen was added, weight loss of ZnCl2 decreased, and the effect of water vapor on repression of weight loss was much stronger than that of oxygen. Especially, weight loss stagnated after 20 min at 40% of weight loss in Ar–5%H2O atmosphere. It is considered that the reaction product between zinc chloride and water vapor covered the surface of melt.In the case of ZnCl2–ZnO melt, weight loss reached and stagnated at about 60% of initial weight in Ar and Ar–O2 atmospheres. This value is close to initial ZnCl2 content. However, weight loss reached and stagnated at about 50% of initial weight in Ar–H2O atmosphere, and the residue was converted to zinc oxide after 60 min experiments. From these results, formation of zinc oxide by the reaction between zinc chloride and water vapor in Ar–H2O atmosphere was confirmed. It is concluded that zinc oxide formed by the reaction on surface of melt prevented the contact between zinc chloride and gas phase, and the evaporation of zinc chloride. This phenomenon caused the stagnation of weight loss with atmosphere containing water vapor.

Oxychloride glasses based on the TeO2-ZnO-ZnCl2 system

A series of glasses based on the TeO2-ZnO-ZnCl2 system was prepared and their physical, thermal and optical propeties were investigated. This system provides a wide and stable glass formation range in which a Tc-Tg gap beyond 140°C can be achieved. An infrared cut-off edge up to 6.5 μm can be obtained, while the optical energy gap was found to be in the range of 2.0–2.5 eV. Most properties are observed to be dependent in a systematic manner on the ZnCl2 content.

Catalyzed degradation of poly(vinylchloride). III. Zinc(II) chloride catalysis

AbstractWhen PVC films containing zinc(II) chloride were heated in the temperature range 65–95°C, broad absorptions developed in the 250–900 nm region with maxima around 610 nm. The development of the color, the rate of which was proportional to the ZnCl2 content, was preceded by an induction period, the length of which depended on the temperature. The activation energy of the process decreased as the ZnCl2 content of the film increased. Color developments in air and in vacuum were compared.

Vibrational spectra of some glasses of alkali-metal nitrates with Group IIA and IIB metal nitrates and with zinc chloride and water

Raman and infrared spectra are reported for mixed alkali metal–bivalent metal nitrate glasses, M1NO3–M2(NO3)2, with M1 being Na, K, Rb, and Cs when M2 is Mg, with M1 being K and Rb when M2 is Ca, with M2 being K and Cs when M2 is Zn, and with M1 being Na, K, and Cs when M2 is Cd. Spectra also are reported for mixed ZnCl2–KNO3 and ZnCl2–CsNO3 glasses, and for variably hydrated equimolar KNO3–Mg(NO3)2 glasses. In each case the spectra show the presence in the glasses of nitrate groups strongly perturbed by association with the bivalent metal. The nature of this perturbation is analysed and its magnitude is shown to vary systematically with the constitution of the glasses. Low-frequency Raman lines given by the ZnCl2-containing glasses are interpreted as showing the presence of polymeric species, which give way to simpler zinc–chloride–nitrate mixed complexes as the ZnCl2 content is lowered.