Noble-free potassium-bimetallic catalysts supported on beta-zeolite for the simultaneous removal of NOx and soot from simulated diesel exhaust

This paper deals with the activity of the KCu and KCo catalysts supported on beta-zeolite for the simultaneous NO_x/soot removal from a simulated diesel exhaust, containing C₃H₆ as model hydrocarbon. In order to reveal the effect of potassium, the corresponding monometallic catalysts (Co/beta and Cu/beta) were analyzed and different potassium loadings were used. In addition, for comparative purpose, the performance of a platinum based catalyst (Pt/beta) was studied. All noble-free catalysts show, at 450 °C, a high activity for the simultaneous NO_x/soot removal. Among them, K1Cu/beta presents the best global performance at 350 and 450 °C achieving a high soot consumption rate (comparable to platinum catalysts) and the highest NO_x reduction. In contrast to platinum catalysts, K1Cu/beta has the advantage that the main reaction products are N₂ and CO_2.     

Metal effects in the Fischer-Tropsch synthesis: Bond-order-conservation-morse-potential approach

We have applied the BOC-MP method to theoretically analyze the metal effects in the Fischer-Tropsch (FT) synthesis by calculating the energetics of conceivable elementary steps (the relevant heats of chemisorption and the reaction activation barriers) during CO hydrogenation over the periodic series Fe(110), Ni(111), Pt(111), Cu(111). The basic steps such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH₂ versus CO into the metal-alkyl bonds, and chain termination leading to hydrocarbons (alkanes versus -olefins) or oxygenates are discussed in detail. It is shown that the periodic trends in the ability of metal surfaces to dissociate chemical bonds and those to recombine the bonds are always opposite. In particular, we argue that metallic Fe is necessary to produce the abundance of carbidic carbon from CO but the synthesis of hydrocarbons and oxygenates can effectively proceed only on carbided Fe surfaces which resemble the less active metals such as Pt. More specifically, we project that the C-C chain growth should occur predominantly via CH₂ insertion into the metal-alkyl bond and the primary FT products should be -olefins. These and other model projections are in agreement with experiment.     

均匀沉淀法制备AI／ZnS复合粒子

介绍了以硫代乙酰胺(TAA)和乙酸锌[Zn(Ac)2]为主要原料，在片状铝粉表面包覆一层ZnS，制备出包覆式复合粒子Al／ZnS，改变母粒子Al粉的加入量及反应温度，确定制备包覆完全致密复合粒子的最佳条件，通过SEM、XRD及粒度测试等分析方法对复合粒子进行表征。     

火焰原子吸收光谱法测定硅粉中的铜

介绍了用火焰原子吸收法测定工业硅粉中微量铜的具体方法和过程，同时也给出了最佳实验条件。实验中采用新的样品处理方法，得到了令人满意的结果。其中样品回收率为99．8％—104．0%，相对标准偏差为0．31％—0.38％。本方法在实际应用过程中，简单、快速、     

交联壳聚糖微球树脂对Cu（Ⅱ）的吸附动力学研究

通过交联壳聚糖微球树脂对Cu（Ⅱ）的静态吸附实验,研究树脂对cu（Ⅱ）的吸附特性．结果表明,pH5—6时,树脂对Cu（Ⅱ）的吸附量较高;Cu（Ⅱ）在交联壳聚糖树脂上的吸附动力学过程符合Lagergren一级动力学吸附方程;吸附速率常数随吸附温度的增加而增大;表观吸附活化能为20．702kJ／mol．     

蒙脱土多孔异构材料对水溶液中Cu2＋的吸附

以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为柱撑前躯体,合成大片层间距的蒙脱土多孔异构吸附材料,考察其对水溶液中Cu2+的吸附效果.WAXD结果显示片层间距由原土的1.26 nm增加到4.89 nm.利用分光光度计测试溶液中Cu2+的浓度.确定本吸附材料吸附Cu2+的平衡时间为180 min;去除率随Cu2+初始浓度的增大而减小;随着吸附材料用量的增加,对Cu2+的去除率增大,确定最佳的吸附材料投放量为20 g/L;pH值对Cu2+的吸附具有明显的影响作用,在5.00～6.00范围内去除率最高,为99%.     

超分散稳定纳米ZnS的非水原位构筑及摩擦学性能

设计并合成了油溶性环烷酸锌和异氰酸酯类超分散稳定剂,采用原位构筑方法获得了非水纳米ZnS分散系,用冷冻蚀刻电镜对其进行了表征,用离心实验对其分散稳定性进行了考察.对纳米粒子的形成过程、分散稳定机理进行了阐述.用环块和四球摩擦试验机对纳米ZnS分散系的摩擦学性能进行了研究.结果表明:ZnS为40 nm的粒状颗粒,大小均匀,在介质中呈单粒子分散;纳米分散系经72 h普通离心和56 h非连续超离心均未发生沉降,表现出理想的分散稳定性;试验显示超分散稳定纳米ZnS的存在,能明显改善油样的抗磨减摩性能和承载能力.在试验范围内,添加的纳米ZnS的量越大,其抗磨减摩性能也越好,但当n-ZnS的质量分数大于0.25%时,其承载能力趋于稳定.     

Cu（Ac）2-Co（Ac）2-KBr催化SPC氧化对甲基苯甲醚

研究了无机复合催化剂催化SPC氧化对甲基苯甲醚的反应性能：以Cu（Ac）2-Co（Ac）2-KBr为催化剂,利用过碳酸钠氧化对甲酚甲基化产物对甲基苯甲醚,系统研究了催化剂组成比例、催化剂用量、溶剂、反应温度、反应时间等因素对反应的影响,结果表明,Cu（Ac）2-Co（Ac）2-KBr具有较高的催化活性和选择性,体现出金属离子之间的协同作用,对甲基苯甲醚在m（Cu（Ac）2）：m（Co（Ac）2）：m（KBr）=0．1：0．5：0．1（质量比）,n催化剂：n底物=0．14,冰醋酸作溶剂,稍过量的过碳酸钠,65℃条件下的转化率可达45．9％,生成对甲氧基苯甲醛的选择性为68．3％。提出了氧化反应的H原子转移机理。     

CdSe/ZnS量子点的合成及表征

本文于水溶液中采用3-巯基丙酸作为稳定剂,成功合成了CdSe/ZnS核壳型量子点。透射电子显微镜观察表明,所合成的量子点尺寸均一,形貌近似球形,粒子大小在5 nm以下。紫外吸收光谱和荧光光谱分析表明,所合成的CdSe/ZnS核壳型量子点较之CdSe量子点更具良好光学特性。