水热合成Cu-BiVO4催化剂及用于光催化氧化脱硫的研究

采用水热法合成了可见光催化剂Cu-BiVO4,并对其进行X射线粉末衍射（XRD）、紫外-可见漫反射 (UV-Vis DRS)表征。以噻吩的正辛烷溶液模拟轻质油品为目标物,以催化剂的pH值、用量、光照时间、通气量等工艺条件为考察对象,研究了Cu-BiVO4光催化氧化去除模拟汽油中硫化合物的性能。结果表明,Cu的复合使BiVO4的可见光吸收带发生红移,吸收强度也有较大幅度的提高。在中性条件下制备的催化剂的活性最高,在空气通入量为300mL/min,催化剂加入量为0.5mg/L时, 400W金卤灯照射180min,Cu-BiVO4光催化氧化脱硫效果较好,模拟汽油的脱硫率可达到95%以上。     

Preparation, characterization, and catalytic properties of the Mo2C/SBA-15 catalysts

A series of Mo₂C/SBA-15 catalysts with different Mo contents were prepared by temperature-programmed carburization (TPC). The materials obtained and their oxide precursors (MoO₃/SBA-15) were characterized by Nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy. The activities of the catalysts for deep hydrodesulfurization (HDS) of thiophene were evaluated. The results of N₂ adsorption-desorption isotherms indicated that the surface area and pore diameter of the oxide precursors increase after carburization. The XRD patterns show that Mo₂C particles are highly dispersed in the SBA-15 ordered mesoporous. The test results show that Mo₂C/SBA-15 catalysts have an excellent performance for the deep HDS under the lower temperature region.     

Synthesis,characterization, and photovoltaic performance of the polymers based on thiophene-2,5-bis((2-ethylhexyl)oxy) benzene-thiophene

Three novel conjugated copolymers based on thiophene-2,5-bis((2-ethylhexyl)oxy)benzene-thiophene (TBT) as electron-donating units, either isoindigo or both isoindigo and diketopyrrolopyrrole (DPP) as electron-withdrawing units have been designed and synthesized by Stille-coupling reaction. All the polymers exhibit high thermal stability, broad absorption in the range of 300–800 nm, and the low-lying energy level of highest occupied molecular orbits (HOMO) (−5.47 to −5.19 eV). After introduced with additional hexylthiophenes and further introduced with DPP units, the polymers PTBT-HTID and PTBT-HTID-DPP show smaller lamellar distance and π–π stacking distance, and the morphology of the corresponding photoactive layers possess more appropriate microphase separation and smaller domain size, which lead to high short circuit current densities (J_sc) and power conversion efficiency (PCE). The polymer photovoltaic devices based on PTBT-HTID-DPP/PC₆₁BM exhibit a high J_sc value of 11.13 mA cm⁻², a fill factor (FF) of 0.57, and the PCE of 4.2%.     

The molecular structure of plasma polymerized thiophene and pyrrole thin films produced by double discharge technique

Production of polythiophene (PTH) and polypyrrole (PPY) thin films via double discharge plasma system has been studied. The double discharge system is a superposition of an ordinary low-pressure dc glow discharge and a high-current pulsed one. The glass substrates were located simultaneously at three different positions in the reactor and the thin films were synthesized at constant plasma parameters to evaluate the influence of the position on the molecular structure. And, the as-grown and iodine doped thin films were investigated to find out the correlation between molecular structure variation of the iodine–film interactions, too. The PTH (C₄H₄S) and PPY (C₄H₅N) monomers without using any carrier gases have been used as plasma precursors, each at 1 mbar operating pressure. The thin films were compared by using Fourier transform infrared (FTIR), X-ray photoelectron (XPS), and UV–visible absorption spectroscopy. It is found that the thin films obtained at the pulsed plasma region where the gas phase polymerization is dominated resemble to conventional polymeric structure. The XPS depth profiles revealed that while the stoichiometry of the monomer was almost preserved with the successive depth of PTH samples, but at the PPY one was not preserved. Moreover, the atomic concentration of oxygen and nitrogen observed at the surface of the films significantly drops down beneath the surface which indicates that they could be employed as anti-corrosive materials. It is found that chemical bonding with iodine take place after doping and the value of the optical band gap of polymers (E_g) are reduced proportionally with doping time.     

Synthesis and characterization of silver/thiophene nanocomposites by UV-irradiation method

Silver/thiophene (Ag/Th) nanocomposites have been prepared by UV-irradiation method. The resulting products were characterized by Elemental Analysis (EA), X-ray Photoelectron Spectroscopy (XPS), optical absorption spectroscopy, Fourier Transform Infrared (FT-IR), Thermal Gravimetric Analysis (TGA), X-ray Diffraction (XRD), transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM). We prepared Ag/Th nanocomposites successfully for the first time without any reducing or binding agent. XRD patterns are consistent with that of silver and thiophene molecules are present in the final products. A SEM image shows the uniform particles distribution. The particles are spherical in nature and seem to be nanosized, typically in the range of < 100 nm. Finally, we observed a strong interaction between the Ag⁺ ion and sulfur atom of thiophene ring. This work provides a simple route for the synthesis of Ag/Th nanocomposites.     

Simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene over dimolybdenum nitride catalysts

A series of unsupported dimolybdenum nitride (γ-Mo₂N) catalysts differing in surface area were prepared by temperature programmed reduction of MoO₃ with a mixture of NH₃:N₂ (90:10). Characterization of catalysts by BET, XRD, TPR and XPS techniques was carried out. The samples were used as catalysts in hydrotreating reactions (simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene). Low surface area γ-Mo₂N materials show much higher specific conversions than those with higher surface area. These results indicate that HDS and HYD reactions over γ-Mo₂N seem to be structure-sensitive. The relative exposure extent of crystalline planes (1 1 1) and (2 0 0) over the different catalysts can be associated with their hydrogen adsorption capacities and with their catalytic performances. The catalytic activities are significantly affected by the catalyst pretreatment conditions.     

Effect of lanthanum addition on the thiophene hydrodesulfurization activity over Al-MCM-41 supported molybdenum catalysts

A series of Al-MCM-41 modified with 1–7% lanthanum were used as supports to prepare the Mo/La–Al-MCM-41 catalysts containing 10 wt.% molybdenum. The supports and catalysts were characterized with XRD, BET, XPS, TPD, TEM and SEM, and their catalytic activities were tested for thiophene hydrodesulfurization. The La addition did not cause any significant collapse of the structure and morphology of Al-MCM-41 samples, and increased the acidity of Al-MCM-41 samples. The Mo/La–Al-MCM-41 catalysts showed higher thiophene HDS activity than non-modified catalysts. The La-modified catalysts showed an enhanced butene selectivity but a decreased tetrahydrothiophene selectivity, indicating that the La–Al-MCM-41 supports contained a larger amount of acid sites.     

Electrochemistry of conductive polymers 44: A comparative study on electrochemically polymerized polythiophenes from thiophene, bithiophene, and terthiophene

Polythiophenes obtained by electrochemical polymerization of thiophene, 2,2′-bithiophene, 2,2′:5′,2″-terthiophene in 1.0 M LiClO₄ propylene carbonate solutions have been studied using various experimental techniques including UV–vis absorption spectroscopic, electrochemical quartz crystal microbalance, and current sensing atomic force microscopic (CS-AFM) experiments. The polythiophene films were obtained by repeated potentiodynamic voltage scans on gold electrodes. Clear differences were observed from the polymer films obtained from the monomers in their electrical, electrochemical, and optical properties due to various factors such as degradation of the polymer at high anodic potentials, conjugation lengths of polymers, incorporated oligomers, and solvated ion pairs in the polymer matrix. The poly(bithiophene) displayed the best conductivity, while the polythiophene showed almost no electrical conductivity.     

Effects of selenium substitution on optical,electrochemical, and photovoltaic properties of oxindole-based π-conjugated polymers

Two oxindole based π-conjugated polymers with same structures except the positions of selenium atoms in the main chains have been synthesized. The effects of heavy atom substitution on optical, electrochemical, and photovoltaic properties have been investigated. The polymer solar cell devices based on the new polymers as electron donors also have been studied. The oxindole based polymers showed intramolecular non-bonded interactions between divalent sulfur/selenium and carbonyl oxygen. The selenophene based polymers showed narrow optical band gaps. However, the introduction of selenophene led to the decline of optical absorption in both the monomer and the polymers compared with the thiophene based counterparts. The diminution of absorption in selenium containing polymers can have adverse effect on solar photon harvesting.     

Hybrid plasma-sono-coprecipitation dispersion of NiMo nanocatalyst over functionalized multiwall carbon nanotube used in hydrodesulfurization of thiophene

To evaluate the effect of non-thermal plasma and ultrasound treatment on the catalytic physicochemical properties and hydrodesulfurization activity, a series of NiMoW/FMWCNT nanocatalysts (4%NiO, 12%MoO₃, and 6% WO₃) were prepared via co-precipitation method. The co-precipitated and treated by ultrasound or plasma-ultrasound nanocatalysts were characterized using XRD, FESEM, EDX dot-mapping, BET and FTIR techniques. The XRD data confirmed the formation of NiO, WO_3, and Mo₂C as the crystalline phase on carbon support. The results indicated ultrasound irradiation and non-thermal plasma treatment have significant influences on phase structure, morphology, and surface area. The optimum amount of applied voltage of plasma was found to be 500?V in which the maximum surface area and well-dispersion of the active phase were found. Further applied plasma voltage led to a decrease in catalytic activity due to the higher support-metal interaction and unpleasant distribution of the particles on nanocatalyst surface. The plasma–ultrasound hybrid synthesis method was able to eliminate 100% of sulfur in the initial solution of thiophene during hydrodesulfurization process.