Hβ/Al-SBA-15介微孔复合分子筛负载Ni-W催化剂对萘加氢裂化制BTX的催化性能

采用后合成法制备Hβ/Al-SBA-15复合分子筛,利用XRD、N_2吸附、Py-IR、NH_3-TPD、SEM和TEM等手段进行表征。用浸渍法将Ni-W活性组分担载在Hβ/Al-SBA-15载体上,制备Ni-W/Hβ/Al-SBA-15催化剂,以萘为模型化合物,考察该催化剂的加氢裂化性能。结果表明,所合成的Hβ/Al-SBA-15复合分子筛既有介孔结构又有微孔结构,并同时具有B酸和L酸中心,酸性强于SBA-15。具有适度酸性位和介微孔结构的Ni-W/Hβ/Al-SBA-15催化剂,对萘加氢裂化具有较高的萘转化率和BTX选择性,分别为96%和61.1%。     

电沉积Ni-W梯度镀层及耐磨性研究

通过电沉积技术并调节镀液中镍钨离子配比浓度在铝合金基体表面制备了Ni-W梯度镀层,研究了镀层中W质量分数的变化对梯度镀层性能的影响.结果表明:所制备梯度镀层表面均匀平整,与基体结合良好,沿镀层生长方向W质量分数逐层增加;相比于Ni-W均质合金,Ni-W梯度镀层具有较低的摩擦系数,磨损形貌较为平整,表面剥落少,表现出较好的耐摩擦磨损性能.     

The effect of BZO doping concentration and thickness dependent properties of YBCO films grown by PLD on buffered NiW substrates

The effect of BaZrO₃ (BZO) doping is systematically studied in YBa₂Cu₃O_6+x (YBCO) thin films deposited by pulsed laser deposition (PLD) on buffered NiW substrates. Based on the structural and magnetic properties, the optimal BZO doping concentration is obtained to vary between 4 and 7.5 wt.%, depending mainly on applied magnetic field. This relatively high optimal concentration is linked to the nanograined target material and metal substrate that cause low-angle grain-boundaries and in-plane spread of YBCO crystals on NiW. Thickness dependent analysis of undoped and BZO-doped YBCO films predicts differences in growth mechanisms where early growth next to the substrate interface is 2D-type in BZO-doped films. This leads to the situation where crystallographic structure as well as superconducting properties are improved when the film develops and the thickness is increased. Therefore from the resistivity measurements a threshold thicknesses where reasonable properties occur are determined for both set of films. Measurements in thermally activated flux-flow regime (TAFF) indicate that above the threshold thickness relatively strong and isotropic vortex pinning is realized in BZO-doped YBCO films. Generally, this paper demonstrates that especially for thin film applications on NiW substrates even more compatible buffer layer structures should be utilized.     

镍基溅射钨注碳电极的催化性能

镍基溅射钨注碳电极的催化性能张季爽，吕瑶姣，李青莲（湖南大学化学化工系环境工程系，长沙４１００８２）沈报恩（杭州大学化学系，杭州３１００２８）析氢反应研究涉及到氢能、燃料电池、氯碱工业等的能源开发及节能技术，并具有重要的理论意义￣［１～５］．本工作研...     

A study on magnetic properties and structure of SmCo5 thin films on Ni-W underlayers

A systematic study on Ni-W alloy underlayers has shown that a highly textured (2 1 1)-Ni₄W can be formed after deposition at room temperature. Highly textured (0 0 0 1)-SmCo₅ with a high out-of-plane coercivity (over 10 kOe) and large perpendicular anisotropy can be obtained after deposition on the (2 2 1)-Ni₄W underlayer probably due to a small mismatch between (2 2 1)-Ni₄W and (0 0 0 1)-SmCo₅. Our study indicates that the surface roughness of the underlayers also plays a crucial role, that a smooth surface is favorable for a good crystallinity and high coercivity of SmCo₅. Moreover, we found that a highly textured Ni-(1 1 1) can be obtained on the top of the (2 1 1)-textured Ni₄W. The film structure of SmCo₅/Ni/Ni₄W may be interesting as the hard/soft double-layered film for perpendicular magnetic recording or for other applications after a further development.     

Preparation and wear resistance of pulse electrodeposited Ni-W/Al2O3 composite coatings

The aim of this work is to obtain the electroplating parameters for preparation of Ni-W/Al₂O₃ composite coating with high tungsten content, high micro-hardness and excellent wear resistance by pulse plating procedure. Our results showed that the duty cycle is a dominant parameter for the tungsten content in the coating and the tungsten content increases significantly with increasing duty cycle. The further analysis showed the great influence of tungsten content on micro-hardness of the coating. A maximum micro-hardness of about 859 Hv was obtained in pulse electrodeposited Ni-W/Al₂O₃ composite with tungsten content of 40 wt.% at a peak current density of 20 A/dm², a duty cycle of 80%, a pulse frequency of 1000 Hz and a particle loading of 10 g/L alumina in the plating bath. Although the hardness of Ni-W/Al₂O₃ composite coating was only slightly affected by the alumina content of the deposits prepared in present investigation, the alumina content effect on the tribological characteristic of Ni-W/Al₂O₃ composite coatings is significant. The friction coefficient was lowered to 0.25 and the wear loss was reduced to 1.05 mg by setting the control factors according to the values mentioned above for obtaining the coating with the highest micro-hardness.     

高温超导Ni—W基带的织构研究

涂层超导是目前国际超导界的研究热点和重点，所采用的韧性金属基带多为Ni和NiW合金．本文采用粉末冶金方法制备了Ni-3 at．％W和Ni-5 at．％W合金．利用轧制辅助双轴织构基带（咖TS）技术制备了Ni-W合金基带，系统研究了Ni-W合金形变和再结晶织构转变规律．研究表明：通过大变形量的冷轧和高温再结晶退火，可以得到强立方织构的Ni-W合金基带．     

纤维素在Ni-W/MCM-41下的催化液化

用水热法合成了MCM-41介孔分子筛,通过浸渍法合成含Ni和W的负载型催化剂,并用X射线粉末衍射(XRD)和紫外漫反射(UV-Vis/DRS)等进行表征.以天然纤维素为原料,考察了反应温度、催化剂用量、反应时间、液固比对原料残渣率的影响.实验结果表明,在温度250 ℃,催化剂0.05 g,反应时间2 h,液固比60:1的条件下,原料的残渣率为14.01% .     

Ni-W Catalysts Supported on Mesoporous SBA-15: Trace W Steering CO2 Methanation

Aseries of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(Ni_xW/SBA-15, Ni-5%, x=1,10,50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H₂-temperature programmed reduction(H₂-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H₂-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H₂WO₄ can significantly improve Ni dispersion on SBA-15 (Ni₅₀W/SBA-15) with Ni⁰ andnon-stoichiometric WO_x species as small as ca. 3.6 nm. The prepared Ni_xW/SBA-15 was utilized for CO₂ hydrogenation, which showed that a higher W content restrained the CO₂ hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni₅₀W/SBA-15 catalyst showed the best performance with a 93.3% CO₂ conversion rate and 99.7% selectivity for methane at 400 ^oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH₄. This work provides a new clue to fabricating efficient CO₂ conversion bimetallic materials.     

制备因素对Ni－W／C催化剂活性及结构的影响

研究了以沥青活性炭为载体的Ｎｉ－Ｗ催化剂制备参数与其加氢脱硫（ＨＤＳ）、加氢脱氮（ＨＤＮ）和加氢脱芳（ＨＤＡ）活性的关系,并利用广延Ｘ射线吸收精细结构．（ＥＸＡＦ）、透射电镜（ＴＥＭ）研究了金属原子的近程配位情况及金属的分散状况．发现金属原子比、催化剂焙烧气氛和温度等对催化剂活性有较大影响．浸渍液ＰＨ值与载体ＰＨＩＥＰ的相对关系对催化活性的影响与浸渍方式有关．表征结果表明,“类ＷＳ２”结构的完整性影响了催化剂活性,焙烧气氛温度影响了金属硫化物的分散度．