玻璃纤维工业与铂铑金属

探讨了玻纤工业选择铂铑合金的原因;介绍了铂铑的资源贮存量、性质及用途;分析了铂铑金属多年的价格走向;针对铂铑金属的价格波动,提出了玻纤工业的应对策略。     

微波辅助萃取废烟叶中茄尼醇工艺研究

研究了微波辅助萃取废烟叶中茄尼醇的工艺条件, 对微波功率、辐射时间和萃取溶剂等影响微波萃取的条件进行了筛选和分析, 优化条件为:以正己烷+乙醇为萃取溶剂, 固液比为1∶45, 物料水分 3%以下, 微波功率 280w, 辐射时间 25min。     

酸浸-置换工艺回收废甲醇催化剂中铜的研究

对酸浸-置换工艺回收废甲醇催化剂中的铜进行了研究。酸浸实验中考察了酸浸时间、液固比、酸浸温度对铜浸出量的影响;置换实验中考察了pH、置换时间、置换温度对铜回收量的影响。研究表明,酸浸-置换工艺回收废甲醇催化剂中铜的最佳工艺条件为：酸浸时间80 min、液固比20：1、酸浸温度80℃、置换pH=5、置换时间60 min、置换温度65℃。每克废甲醇催化剂可回收铜0.4531 g。     

磷酸活化焙烧-酸浸法富集低品位还原钛渣

以钒钛磁铁矿经煤基直接还原-电炉熔分工艺生产的钛渣为原料,采用磷酸活化焙烧-稀硫酸浸出方法去除杂质提高钛渣品位. 钛渣的物相包括黑钛石、辉石(玻璃相)、塔基洛夫石、镁铝尖晶石等. 考察了磷酸焙烧活化过程中各因素对钛渣晶型转化的影响及稀硫酸浸出过程中各因素对主要杂质(Ca, Mg, Al, Si)浸出的影响,得到优化的工艺条件为：焙烧温度1273 K,焙烧时间100 min,磷酸加入比例7.1%(w),酸浸温度110℃,硫酸浓度5%(w),液固质量比10:1,浸出时间120 min,在该条件下钛渣中TiO2含量由52.54%提高至68.31%.     

复杂硫化铜精矿微波活化预处理-加压浸出工艺

研究了以黝铜矿为主的复杂硫化铜精矿微波活化预处理-加压浸出工艺.结果表明,该精矿在微波功率82W、每批处理量95g及辐照时间120s条件下预处理后,矿石浸出性能显著改善.预处理过程中未见铅、锌、硫、砷等元素挥发损失.实验确定了微波活化铜精矿加压浸出工艺条件为:浸出温度453K,氧分压0.6MPa,初始硫酸浓度1.23mol/L,液固比5mL/g,浸出时间2.0h,木质素磺酸钙用量为精矿质量的1.25%,搅拌速度500r/min.在此条件下,铜、锌、铁浸出率分别达到86.36%,92.33%和27.64%.加压浸出渣经高温煤油溶解单质硫后返回作浸出配矿使用,可保障有价金属铜锌收率.     

微波-超声波联用从醋酸乙烯废触媒中回收活性炭

采用微波、超声波联用技术对醋酸乙烯废触媒进行脱附处理,同时采用微波技术加热活化回收活性炭,测定了不同技术回收的活性炭的亚甲蓝脱色力。结果表明,一次微波两次超声波联用技术处理醋酸乙烯废触媒,即微波高火力、时间15 min、固液比1∶4(质量比)和超声波功率120 W、时间60 min、固液比1∶4(质量比)、作用面积91.56 cm2时,锌的洗脱率最高、活性炭的脱色力最高,与传统的煅烧法相比,采用微波高火力,15 min活化回收的活性炭其亚甲蓝脱色力为9.5 mL/0.1 g,达到国家林业局粉状活性炭二级标准(LY216—79)。     

微波消解-火焰原子吸收法测定硅橡胶催化剂中铂的含量

采用微波消解系统消解硅橡胶催化剂,再用火焰原子吸收法测定了其中铂的含量。考察了消解试剂种类、无机酸、共存离子对测定结果的影响及抑制方法。结果表明,采用HNO3+HF或HCl+HF或王水+HF为消解试剂对硅橡胶催化剂进行微波消解时效果好,消解时避免使用H2SO4;为防止消解液爆沸,需进行预消解。常见共存离子K+、Na+、Fe2+、Cu2+、Pb2+、Zn2+、Ca2+、Mg2+、Si对铂含量测定结果的影响很大,无机酸HCl、HNO3及HF对铂含量的测定结果也有一定的影响;采用CuSO4作干扰抑制剂不仅能有效抑制无机酸和共存离子的影响,而且具有明显的增敏作用。此方法的相对标准偏差小于2%,回收率为92.43%~109.05%。     

热分解-汞齐化富集-冷原子吸收分光光度法测定工业废盐中的汞含量

本研究尝试建立利用热分解-汞齐化富集-冷原子吸收分光光度法测定工业废盐中汞含量的方法。本研究方法在进样量为0.1g,样品干燥温度为150℃,干燥时间为20s,热分解温度为750℃,分解时间为180s,汞齐化时间为12s,读数时间为30s的条件下用直接测汞仪检测工业废盐中的汞含量。实验结果显示,方法测定范围为0.001μg/g～5μg/g,相关系数R2优于0.9999,汞含量的检出限为0.0002μg/g,相对标准偏差（RSD）在6.34%～7.55%范围内,工业废盐样品加标回收率在89.8%～121.4%范围内。该方法操作简便、耗时较短、无基体干扰、重现性好、准确度高,适用于生态环境损害鉴定评估、固体废物鉴别等工作中工业废盐的汞含量测定。     

A comparison of CO oxidation on ceria-supported Pt,Pd, and Rh

Steady-state, CO-oxidation kinetics have been studied at differential conversions on model, ceria-supported, Pt, Pd, and Rh catalysts, from 467 to 573 K, and the results compared to the alumina-supported metals. On each of the ceria-supported metals, there is a second mechanism for CO oxidation under reducing conditions which involves oxygen from ceria reacting with CO on the metals. The rates of this second process are independent of which metal is used. The process has a significantly lower activation energy (14±1 kJ/mol compared to 26±2 kJ/mol on alumina-supported catalysts) and different reaction orders for both CO (zeroth-order compared to –1) and 02 (0.40 to 0.46 compared to first-order). This second process leads to significant rate enhancements over alumina-supported catalysts at low temperatures, especially for Pt. The implications of these results for automotive catalysis are discussed.     

Extraction and separation of Pt(IV)/Rh(III) from acidic chloride solutions using Aliquat 336

Extraction and separation of Pt(IV)/Rh(III) from chloride solutions using Aliquat 336 (Quaternary ammonium salt made by the methylation of mixed tri octyl/decyl amine) diluted in kerosene as an extractant/synergist alone and mixed with organophosphorous extractants as synergists/extractants were carried out from an aqueous feed containing 0.0005 mol L⁻¹ Pt(IV)/Rh(III).Variation of hydrochloric acid concentration of aqueous phase from 0.005 to 10.0 mol L⁻¹ increased the percentage extraction of platinum up to 5.0 mol L⁻¹ there after it decreases. Whereas in the case of rhodium, from 0.005 to 1.0 mol L⁻¹ acid range the percentage extraction was decreased from 1.0 to 10.0 mol L⁻¹ acid range is favorable for extraction. Platinum(IV)/rhodium(III) separation factor of 279.2 was obtained at 1.0 mol L⁻¹ HCl concentration with 0.005 mol L⁻¹ Aliquat 336 and separation factor of 612.3 was obtained at 3.0 mol L⁻¹ HCl concentration with 0.01 mol L⁻¹ Aliquat 336. The present study optimized the various experimental parameters like phase contact time, effect of extractant, salts, temperature, loading capacity of extractant, stripping studies with various mineral acids/bases, recycling and reusing capacity of extractant up to ten cycles.     

Hydrogenative transformations of methylcyclobutane over silica-supported Rh,Ni, Pt and Pd catalysts at different temperatures

The effect of temperature on the transformations of methylcyclobutane over silica-supported Rh, Ni, Pt and Pd catalysts was studied in a wide temperature range (323–723 K) in a pulse system. The transformations taking place were cracking (hydrogenolysis), hydrogenative ring opening and ring enlargement. The reaction directions were found to depend strongly on the nature of the metal. Over Pt and Pd, hydrogenative ring opening was the main reaction at all temperatures studied. In contrast, Rh and Ni promoted hydrogenolysis at high temperature, and this reaction occurred exclusively above 573 K. The selectivity data on the ring-opening reaction were different over Pt and Pd from those over Rh and Ni. The ring-opening selectivity (ratio of isopentane to both ring-opened products) was close to statistical over Pt and Pd, while sterically less hindered bond scission was the main direction of the ring opening over Rh and Ni.     

Electrochemical promotion of the CO2 hydrogenation reaction using thin Rh, Pt and Cu films in a monolithic reactor at atmospheric pressure

A monolithic electropromoted reactor (MEPR) with up to 22 thin Rh/YSZ/Pt or Cu/TiO₂/YSZ/Au plate cells was used to investigate the hydrogenation of CO₂ at atmospheric pressure and temperatures 220–380 °C. The Rh/YSZ/Pt cells lead to CO and CH₄ formation and the open-circuit selectivity to CH₄ is less than 5%. Both positive and negative applied potentials enhance significantly the total hydrogenation rate but the selectivity to CH₄ remains below 12%. The Cu/TiO₂/YSZ/Au cells produce CO, CH₄ and C₂H₄ with selectivities to CH₄ and C₂H₄ up to 80% and 2%. Both positive and negative applied potential significantly enhance the hydrogenation rate and the selectivity to C₂H₄. It was found that the addition of small (0.5 kPa) amounts of CH₃OH in the feed has a pronounced promotional effect on the reaction rate and selectivity of the Cu/TiO₂/YSZ/Au cells. The selective reduction of CO₂ to CH₄ starts at 220 °C (vs 320 °C in absence of CH₃OH) with near 100% CH₄ selectivity at open-circuit and under polarization conditions at temperatures 220–380 °C. The results show the possibility of direct CO₂ conversion to useful products in a MEPR via electrochemical promotion at atmospheric pressure.     

Reduction of NO by hydrogen versus reduction by CO over Pt, Pd and Rh clusters in NaX zeolite

The activation of hydrogen and CO was examined using D₂+H₂ equilibration at room temperature and by ¹³CO+C¹⁸O scrambling at 170°C, respectively, the adsorption of NO at room temperature and its TPD were used to characterise the activation of NO. These reactions were compared with the NO reduction by carbon monoxide and by hydrogen. It appeared that the M/NaX clusters (M=Pt, Rh or Pd) exhibit opposite behaviour in the NO reduction by these two reductants: with CO the sequence was RhPdPt, while platinum (Pt/NaX) was the most active catalyst (PtPd>Rh) when hydrogen was employed.

The CO scrambling was found to be most rapid over Pt, while the adsorption and dissociation of NO was most extensive over Rh; in the NO reduction by CO the weak CO activation over Rh was overwhelmed by the strong NO dissociation. On the other hand, the extensive NO adsorption and dissociation over Rh hindered the dissociation of hydrogen, which resulted in the lowest activity in the NO reduction by H₂ accompanied by an intermediate formation of N₂O. This was not the case with Pt, over which easily dissociated hydrogen reacted with probably molecularly adsorbed NO.

The reduction of N₂O by hydrogen proceeded readily over all metallic clusters at room temperature, being thus, either of the same activity as that of NO+H₂ reaction, or even of higher activity over Pd and especially over Rh. The easy reduction of N₂O by hydrogen does not agree with the reduction by CO, which was found to proceed worse than that of NO.

In some cases, also bimetallic species (PtRh/NaX, PtPd/NaX, PdRh/NaX) were employed, as well as oxidized M clusters.     

Noble Metal (Pt, Rh, Pd) Promoted Fe-ZSM-5 for Selective Catalytic Oxidation of Ammonia to N2 at Low Temperatures

We have reported previously the excellent performance of Fe-exchanged ZSM-5 for selective catalytic oxidation (SCO) of ammonia to nitrogen at high temperatures (e.g., 400-500 °C). The present work indicates that the reaction temperature can be decreased to 250-350 °C when a small amount of noble metal (Pt, Rh or Pd) is added (by both doping and ion exchange) to the Fe-ZSM-5. The SCO activity follows the order: Pt/Fe-ZSM-5 > Rh/Fe-ZSM-5 > Pd/Fe-ZSM-5. The noble metal promoted Fe-ZSM-5 catalysts also show higher activity for NH₃ oxidation than Ce-exchanged Fe-ZSM-5 at low temperatures. On the Pt promoted Fe-ZSM-5, near 100% of NH₃ conversion is obtained at 250 °C at a high space velocity (GHSV = 2.3 × 10⁵ h^-1) and nitrogen is the main product. The presence of H₂O and SO₂ decreases the SCO performance only slightly. This catalyst is a good candidate for solving the ammonia slip problem that plagues the selective catalytic reduction (SCR) of NO with ammonia in power plants.