Redox behavior of nanohybrid material with defined morphology: Vanadium oxide nanotubes intercalated with polyaniline

Vanadium oxide/polyaniline nanotubes were produced by cationic exchange between hexadecylamine and polyaniline after the synthesis of vanadium oxide nanotubes by sol–gel method followed by hydrothermal treatment. The local structure of this hybrid material was studied by high-resolution transmission electron microscopy, infrared and Raman spectroscopy and small angle X-ray diffraction technique. The results show that polyaniline is intercalated in the interlamellar space of the vanadium oxide nanotube forming a hybrid material with defined morphology. Electrochemical impedance spectroscopy experiments have shown that the apparent diffusion coefficient for nanotubes with template was approximately 1 × 10⁻⁹ cm² s⁻¹. Nanotubes with polyaniline presented an apparent diffusion coefficient at least one order in magnitude higher than the parent material “with template”, comparable with other vanadium oxide described in the literature, revealing a promising material for utilization as cathode for ion-Li batteries.     

t-ZrO2/SAPO-34质量比对t-ZrO2/SAPO-34复合催化剂物化性质及其甲醇制烯烃催化性能的影响

采用介孔t-ZrO2对微孔SAPO-34分子筛进行复合改性,利用水热包覆技术制备了t-ZrO2/SAPO-34复合催化剂,研究了t-ZrO2与SAPO-34质量比对复合催化剂物化性质和MTO催化性能的影响。采用XRD、FT-IR、SEM、NH3-TPD和BET等手段对不同复合催化剂的晶相组成、骨架结构、微观形貌、表面酸性及孔结构进行分析表征。结果表明,质量比对t-ZrO2/SAPO-34复合催化剂的物化性质和催化性能影响较大。过高或过低t-ZrO2:SAPO-34质量比制得复合催化剂中SAPO-34分子筛结晶度和骨架结构特征均有所减弱,分别呈现以介孔为主和以微孔为主的孔结构特征;当质量比为1:1时,制得复合催化剂形成了包覆相结构和微-介孔层级结构（微孔比表面积112.91 m2·g-1,介孔比表面积176.02 m2·g-1,总比表面积为288.93 m2·g-1,总孔容0.19 cm3·g-1）,总酸量较大（0.344 mmol/g）;在常压、反应温度380 ℃、N2流速20 mL·min-1、进料空速2 h-1MTO反应条件下,复合催化剂表现出优越催化性能、稳定性及反应寿命,甲醇转化率和低碳烯烃选择性分别达100%和90.54%,催化寿命达1130 min,与单一SAPO-34分子筛相比,催化寿命延长了768 min。     

ZSM-5/MgO质量比对复合催化剂物化性质及合成甲硫醇反应的影响

采用介孔碱性MgO对微孔酸性ZSM-5分子筛进行复合改性,利用液相沉淀包覆技术制备了ZSM-5/MgO复合催化剂,研究了ZSM-5与MgO质量比对复合催化剂物化性质和合成甲硫醇催化性能的影响。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积及孔隙分析仪(BET)和化学吸附分析仪(CO₂/NH₃-TPD)等手段对不同复合催化剂的晶相组成、微观形貌、孔结构及表面酸碱性进行分析表征。结果表明：ZSM-5/MgO质量比对ZSM-5/MgO复合催化剂的物化性质和催化性能影响较大。过高或过低ZSM-5/MgO质量比制得复合催化剂中MgO结晶度都有所降低,且未形成包覆相结构;ZSM-5/MgO质量比为1/3时制得复合催化剂形成了均匀包覆相结构和微 介孔结构(总比表面积为162 m²/g,总孔体积0.46 cm³/g),同时具有酸碱特性;在反应压力1.0 MPa、反应温度370  ℃、H2S/CH₃OH摩尔比2/1、N₂流速80 mL/min、H₂S流速4.9 mL/min反应条件下合成甲硫醇,复合催化剂表现出优越的催化性能、稳定性及寿命,CH₃OH转化率、CH₃SH选择性和CH₃SH收率分别达到90.48%、90.04%和81.47%,催化剂寿命达到18 h。与单一ZSM-5分子筛相比,复合催化剂寿命延长了7 h,CH₃SH收率提高了13.97百分点。     

Effect of anions from calcium sources on the synthesis of nano-sized xonotlite fibers

The xonotlite fibers were synthesized via the hydrothermal synthesis method with CaO and SiO2 as the raw materials and the molar ratio of Si/Ca of 1.0. Effect of anions from various calcium sources on the microstructure of the xonotlite fibers is studied in this paper. These obtained products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM) techniques to investigate their crystalline phase, crystal structure and morphology. The results indicate that anion from various calcium sources has little influence on the crystalline phases of xonotlite fibers but poses a great impact on their morphologies. Xonotlite fibers with single crystal characteristics and large aspect ratio of 50—100 were successfully fabricated from CaCl2 as calcium material at 225 °C for 15 h. The existence of Cl? anion in the CaO-SiO2-H2O system significantly contributes to the formation of xonotlite crystal.     

Effective regulation of electronic structures and luminescence properties of LiGd9(SiO4)6-x(GeO4)xO2:Dy3+ phosphors by tetrahedral substitution

A series of Dy³⁺-activated phosphors with the general formula LiGd₉(SiO₄)_6-x(GeO₄)_xO₂:Dy₃₊(0 ≤ x≤ 3)characterized by an apatite-type structure were successfully synthesized via a simple solid-state technique involving a partial substitution of [SiO₄]^4-with [GeO₄]^4- species.The effects of homovalent[GeO₄]^4--[SiO₄]^4- substit...     

Synergistic effect for co-coking of sawdust and coal blending based on the chemical structure transformation

Biomass was used as additives in coal blending for making coke in terms of widening the alternative raw materials and reducing CO₂ emissions. To obtain the influences of biomass incorporation on the semicoke formation, the chemical structure transformation as well as the gas evolution during sawdust (SD)/coal blending (BC) co-coking were investigated using in-situ Fourier transform infrared spectroscopy coupled with mass spectrometry (In-situ FTIR-MS). Meanwhile, the role of biomass in the semicoke formation was also characterized by several analytical techniques. The transformation of the five main functional groups between SD and BC exhibited the largest difference, and the synergistic effect based on the chemical structure transformation was also proposed for the SD/BC blends co-coking. The synergistic effect based on the chemical structure transformation was divided into two stages during semicoke formation. One stage occurred at 100–280 °C that was assigned to the physical effect that inhibited the BC decomposition. Another stage happened at 280–500 °C that was mainly attributed to the hydrogen transfer that enhanced the aromatization of semi-coke. In addition, it was also noted that the thermoplastic properties decreased proportionately to the quantity of the SD, and the non-agglomeration between BC and SD was clearly observed by SEM.     

Bulk flotation of auriferous pyrite and arsenopyrite by using tertiary dodecyl mercaptan as collector in weak alkaline pulp

Laboratory and industrial scale experiments were conducted to investigate the effect of tertiary dodecyl mercaptan (TDM) as a collector on the flotation of auriferous pyrite and arsenopyrite. The optimum recovery of gold associated with auriferous sulphides was obtained by adding a mixture of TDM and sodium butyl xanthate, together with only a little CuSO₄ as an activator in a weak alkaline pulp adjusted by NaOH. A two-month industrial trial at the Liumei plant in Guangxi, China showed that an average gold recovery of 90.8% into a concentrate assaying 81.1 g/t Au from a feed assaying 2.9 g/t Au could be achieved at pH 8–8.5 using TDM as a collector.     

Incorporating polyimide cathode materials into porous polyaniline xerogel to optimize the zinc-storage behavior

Polyimide is a kind of promising organic-based electrode material for zinc ion batteries (ZIBs), with the merits of resource sustainability, environmental friendliness and structural diversity. At present, however, the study on polyimide-based electrode for ZIBs is fairly few, and the limited conductivity and capacity are also needed to be overcome. Here, a polyimide cathode material denoted as PUI is synthesized by using perylene-3,4,9,10-tetracarboxylic dianhydride and urea, and the zinc-storage performance is comprehensively optimized by taking advantage of a 3-D porous polyaniline (PANI) xerogel carrier, for instance, the specific capacity of PUI/PANI composite is 72 % higher than that of PUI, and the rate performance and cycling stability are both improved as well. The analysis of electrochemical kinetics reveals that the 3-D porous PANI can facilitate fast electron/ion transportation and high capacitive contribution during discharging and charging. Moreover, the mechanism analysis demonstrates the synergistically enhanced zinc-storage capacity of CO (in PUI) and N (in PANI) in PUI/PANI. This work promotes the application potential of polyimide-based cathode materials, and also highlights the valuable role of porous conducting polymer (e.g., PANI) in constructing high-performance cathode materials for ZIBs.     

氯乙烯活性自由基聚合研究进展

活性自由基聚合(LRP)是一种有效的高分子设计手段,氯乙烯(VC)属于非活性单体,实施LRP较为困难。综述了目前成功应用于VC聚合的LRP体系,即SET-LRP、NMP和RAFT,详细介绍了其调控机理和控制效果,探讨了各法的优缺点,并展望了VC-LRP未来的发展方向。     

工艺条件对K_2WO_4-ZnCl_2/γ-Al_2O_3催化剂上合成甲硫醇的影响

采用浸渍法制备了K2WO4-Zn Cl2/γ-Al2O3催化剂,利用XRD,SEM,BET,TPD等方法对该催化剂进行了表征。表征结果显示,K2WO4-Zn Cl2/γ-Al2O3催化剂保持了典型γ-Al2O3晶体结构的特征,活性组分的分散度较高,孔道为典型的圆柱型介孔结构且孔分布较集中,同时具有弱酸位和弱碱位。考察了工艺条件对硫化氢和甲醇在K2WO4-Zn Cl2/γ-Al2O3催化剂上生成甲硫醇的影响。实验结果表明,硫化氢和甲醇在该催化剂上生成甲硫醇适宜的条件为:n(硫化氢)∶n(甲醇)=2∶1、空速2.0 h-1、反应温度400℃、反应压力1.0 MPa。在此条件下,甲醇转化率、甲硫醇选择性和甲硫醇收率分别为87.85%,91.43%,80.32%。