TiO_2直接电解还原过程的研究

采用SEM、EDS、XRD等方法对TiO2直接电化学还原产物进行分析,指出TiO2电极的还原是从外向内由高价到低价再到金属逐步进行的。对还原过程中电流、还原气相产物的分析结果表明:还原过程电流效率低,并且电流效率随电解时间延续而降低,阳极产物CO、CO2与阴极中间产物Ca发生副反应以及副反应产物炭黑造成电流短路是电流效率低的主要原因。提高电流效率的途径有两条:一是增大阴、阳极间距,减小副反应的发生;二是使电解池表面熔盐不断导出,或采取某一隔离措施,使副反应产生的炭黑在阴、阳极之间不造成电流短路。     

用原料添加法提高钼粉粒度的探讨

叙述了在钼粉的工业化生产条件下采用原料添加法来提高最终粉末粒度，改善原料工艺性能的试验。研究表明：在钼酸铵原料中添加一定组份的钥粉，能有效地改善钼酸铵在动态焙解还原时的分散性和流动性，选择不同的添加量和添加粉粒度，可有效地把钼粉的ＦＳＳＳ粒度从２．５μｍ提高到４．２μｍ，从而可根据用粉要求，选择合适的添加工艺，来制取理想的钼粉。     

铝电解槽TiB2涂层阴极技术

将含有ＴｉＢ２、碳纤维和热固性粘结剂的涂料，涂敷到铝电解槽的阴极基体上，制备出可润湿的阴极表面。经固化和碳化后，涂层和碳质基体材料的粘结力强，热膨胀匹配性好。每台硼化钛涂层阴极试验槽能节省ＮａＦ２５０～３００ｋｇ，试验槽的电流效率高出对比槽１．４４％，能耗降低１７５～２１１ｋＷ·ｈ／ｔＡ     

稀燃车用催化剂的研究进展

稀燃车用催化剂是汽车尾气净化催化剂今后发展的方向，在稀燃条件下如何处理NOx是稀燃车用催化剂面临的巨大挑战。本文详细地评述了近年来国内外在这方面的研究工作，包括选择催化还原催化剂、存储还原催化剂和组合多功能催化剂的研究进展。     

AlF3贮仓料位计在线监控系统开发与应用

针对铝电解原材料中AlF3与Al2O3自动配料不准和难于观察及控制的现象，我厂开发应用了AlF3贮仓料位计，并与微机网络相连，实现了远程测量与在线监控，使AlF3配料更准确更均匀，电解质分子比更稳定，电解槽生产低耗高效。     

Electrocatalysis of oxygen reduction on a carbon supported platinum-vanadium alloy in polymer electrolyte fuel cells

The electrocatalysis of the oxygen reduction reaction (ORR) on carbon supported Pt:V 1:1 catalyst in polymer electrolyte fuel cells (PEFC) was investigated. At an oxygen pressure of 1 atm results indicate a lower electrocatalytic activity for the ORR in the presence of vanadium. However, at an O₂ pressure ≥2 atm an enhanced electrocatalytic property of PtV/C compared with Pt/C is revealed. This result indicates the occurrence of a different electrocatalytic mechanism for the ORR on Pt/C and PtV/C. An increase of mass transport overpotentials is observed for the PtV/C catalyst, and this was related to the presence of vanadium oxide. Indeed, XRD analysis revealed that only about 30% of V present in the catalyst is alloyed with Pt, forming a face centred cubic (fcc) Pt₃V solid solution. A thermal treatment at 850 °C under reducing atmosphere leads to the formation of an ordered fcc Pt₂V phase. After this, the ORR activity of PtV/C at O₂ pressure 1 atm is higher than that of Pt/C.     

Enhancement by SO2 of initial activity for selective catalytic reduction of NO with CH3OH over \gamma-alumina

The effect of SO₂ on catalytic activity for NO reduction to N₂ by methanol in excess oxygen over $\gamma$ -alumina has been investigated. SCR activity increased initially upon exposure of a fresh $\gamma$ -alumina catalyst to SO₂ which is attributed to formation of Brønsted acid sites. Longer exposure to SO₂ leads to a decline in catalytic activity to a lower steady-state NO_x reduction activity which is independent of the SO₂ content in the feed gas.     

化学还原法制备导电涂料用片状超细铜粉的研究

以CuSO4·5H2 O为原料 ,抗坏血酸为还原剂 ,NH3 ·H2 O为络合剂 ,将络合剂在反应温度加到CuSO4·5H2 O溶液中 ,再加入还原剂 ,制备了粒径分布为 1～ 10 μm的片状铜粉。探索与分析NH3 ·H2 O的用量、反应温度和CuSO4浓度对铜粉形貌及产率的影响。结果表明 :络合剂的使用是制备片状超细铜粉的关键 ,其与Cu2 + 形成络合物 ,减少溶液中游离Cu2 + 的浓度 ,控制铜的生成速度 ,并影响铜的成核和生长 ,最终形成片状铜粉。     

High Throughput Screening of Low Temperature SCR and SCD De-NOx Catalysts in Scanning Mass Spectrometer

High-throughput synthesis and screening methods have been developed for the discovery of highly active lead compounds for the selective catalytic reduction as well as direct decomposition of NO in the temperature range 200–300 °C. The discovery libraries for primary screening consisted of 16 × 16 catalyst arrays on 4in. square quartz wafers. Catalysts were prepared by robotic liquid dispensing techniques and screened for catalytic activity in Symyx' scanning mass spectrometer. The scanning mass spectrometer is a fast serial screening tool that uses flat wafer catalyst surfaces, local laser heating, a scanning/sniffing nozzle and a quadrupolar mass spectrometer to compare relative catalytic activities. The feed consisted of NO/NH₃ mixtures with optional O₂ cofeed and Kr as the internal standard in Ar carrier gas. QMS detection allowed for tracking of H₂O, N₂, NO, O₂, N₂O and Kr. Screening protocols for catalytic materials encompassed metal precursors and carriers for supported vanadia systems, extensive doping of V₂O₅/TiO₂, and broad screening of mixed redox metal oxides and supported base and noble metal systems. More than 500 samples could be screened in a single day. Active hits (high NO consumption accompanied by corresponding N₂ production) identified in discovery libraries were re-synthesized as focus libraries for lead confirmation and further optimization. These libraries used shallower compositional gradients, for example 56 points (compositions) per ternary, with four 56-point ternaries per 4in. wafer. Broad screening ternaries were generally 8 or 15 points. The focus libraries more clearly reveal the trends and provide guidelines for secondary screening and scale-up. High conversions were achieved in scanning mass spectrometer so the scalability risk is small for the short contact time reactions.     

Electrochemical promotion of Rh catalyst in gas-phase reduction of NO by propylene

The concept of non-faradaic electrochemical modification of catalytic activity (NEMCA) has been applied for the in situ control of catalytic activity of a rhodium film deposited on YSZ (yttria stabilized zirconia) solid electrolyte towards reduction of 1000 ppm NO by 1000 ppm C₃H₆ in presence of excess (5000 ppm) O₂ at 300 °C. A temporary heating at this feed composition results in a long-lasting deactivation of the catalyst under open circuit conditions due to partial oxidation of the rhodium surface. Positive current application (5 A) over both the active and the deactivated catalysts gives rise to an enhancement of N₂ and CO₂ production, the latter exceeding several hundred times the faradaic rate. While active rhodium exhibits a reversible behaviour, electrochemical promotion on the deactivated catalyst is composed of a reversible and an irreversible part. The reversible promotion results from the steady-state accumulation of current-generated active species at the gas exposed catalyst surface whereas the irreversible effect is due to the progressive reduction of the catalyst resulting in an increased recovery rate of lost catalytic activity. The results are encouraging with respect to application of rhodium for the catalytic removal of NO from auto-exhaust gases under lean-burn conditions.