热处理对高硫化氢合成气一步法制甲硫醇K2MoO4-NiO/SiO2催化剂结构及性能的影响

 在不同焙烧温度和焙烧气氛下对共浸渍法制备的 K2MoO4-NiO/SiO2 催化剂进行热处理, 并采用 X 射线衍射、热重-差示扫描量热、氢气程序升温还原、拉曼光谱和电子自旋共振波谱等手段对催化剂进行了表征, 同时考察了催化剂催化高硫化氢合成气一步法制甲硫醇的性能. 结果表明, 由于催化剂中所含柠檬酸氧化放热, 空气中焙烧的催化剂发生严重烧结. 随着焙烧温度的升高, 八面体配位的 Mo(Oh) 逐渐向四面体配位的 Mo(Td) 转变, 导致催化剂的还原能力降低, 配位不饱和 Mo (CO 吸附位) 减少, 因而 CO 转化率降低. 甲硫醇的生成与 Mo–S–K 相密切相关, 而 MoS2 晶相表面主要生成烃类. 与氮气中焙烧的催化剂相比, 空气中焙烧的催化剂表面的 MoS2 相较多, 而 Mo–S–K 相较少, 因此具有更高的烃类选择性和更低的甲硫醇选择性.     

丙烷脱氢反应中焙烧温度和反应气氛对 Pt-Sn/SAPO-34 催化性能的影响

 在不同的焙烧温度下制备了 Pt-Sn/SAPO-34 催化剂, 并使用 X 射线衍射、N2 吸附、X 射线荧光光谱、O2 脉冲烧炭、H2 程序升温还原和透射电镜等手段对催化剂进行了表征. 在微型反应器中评价了 Pt-Sn/SAPO-34 催化剂对丙烷脱氢制丙烯反应的催化性能, 考察了焙烧温度和反应气氛对催化剂性能的影响. 结果表明, 焙烧温度为 500 oC 时, 催化剂具有最佳的反应活性. 当焙烧温度高于 500 oC 时, 催化剂出现不希望的表面变化, 例如活性 Pt 位点的聚集、Pt 的团聚、Sn 的流失等. 当反应温度为 595 oC 时, Pt-Sn/SAPO-34 催化性能稳定, 且能够保持表面金属状态.     

AT‐Specific DNA Binding of Binuclear Ruthenium Complexes at the Border of Threading Intercalation

The binuclear ruthenium complex [μ‐bidppz(phen)₄Ru₂]⁴⁺ has been extensively studied since the discovery of its unusual threading intercalation interaction with DNA, a binding mode with extremely slow binding and dissociation kinetics. The complex has been shown to be selective towards long stretches of alternating AT base pairs, which makes it interesting, for example, as a model compound for anti‐malaria drugs due to the high AT content of the genome of the malaria parasite P. falciparum. We have investigated the effect of bridging ligand structure on threading intercalation ability and found that length and rigidity as well as the size of the intercalated ring system are all factors that affect the rate and selectivity of the threading intercalation. In particular, we discovered a new DNA‐threading compound, [μ‐dppzip(phen)₄Ru₂]⁴⁺, which appears to be just at the border of being capable of threading intercalation and displays even greater selectivity for AT‐DNA than the parent compound, [μ‐bidppz(phen)₄Ru₂]⁴⁺.     

用于水中有机磷农药检测的离子迁移率谱仪预富集进样方法

建立了检测水中有机磷农药的离子迁移率谱仪预富集进样方法。预富集器由表面覆盖有吸附薄膜的微热板、聚四氟乙烯电路板和管座组成,具有操作简单,无需有机溶剂,自加热,热容小,功耗低等优点。以马拉硫磷检测为例,分析了富集器解吸升温速率和离子迁移率谱仪半透膜温度对检测结果的影响。采用高温短时脉冲加热和低温维持加热相结合的解吸方式,既可形成较高的进样浓度脉冲,又可减少进入漂移管的杂质,有利于提高离子迁移率谱仪检测灵敏度。实验表明:采用所述预富集及两阶段加热解吸进样方法,对水中马拉硫磷的检出限为3.9μg/L,达到了国家标准对水中有机磷检测的要求。     

微波法合成一维结构Cd(OH)2螺旋形纳米线

通过微波辐照法一步合成了长1~3 μm, 直径30~100 nm的螺旋形纳米线, 实验结果表明它是由更细的纳米线组装成束的. 通过改变反应物浓度可以调控螺旋纳米线的直径和长度, 不同的镉盐对产物的结构与形貌有较大的影响. 讨论了螺旋形纳米线可能的形成机理.     

SQSQh: 1H‐detected SQ–SQ experiment for determination of signed silicon–carbon coupling constants

A new variant of SQ–SQ pulse sequence (SQSQh) for relative sign determination and detection of small silicon–carbon couplings over more than one bond is presented. In the SQSQh sequence, proton detection replaces carbon detection used in the original SQ–SQ pulse sequence (SQSQc). The theoretical gain in sensitivity was experimentally tested on two samples (trimethylsiloxyethane, 1, and 1,2,4‐tris(trimethylsiloxy)benzene, 2), the experimentally found gain provided by the SQSQh over the SQSQc method varied between 6 and 8. The method can be applied to linear spin systems, i.e. to systems where the silicon is coupled to the carbon in question and to any hydrogen not necessarily bonded to the carbon. Copyright © 2010 John Wiley & Sons, Ltd.     

Palladium-catalyzed cyclization of 1,6-enyne with 2-bromoarylaldehyde: domino sequence to [5-7-6] tricyclic ring systems

A domino sequence of cyclization of 1,6-enyne with 2-bromoarylaldehyde followed by the intramolecular Aldol-condensation has been realized in the presence of 5 mol % of palladium catalyst. This sequence provides a convenient protocol to access polycyclic ring systems with readily available starting materials under simple Pd(0)-catalyzed conditions. The intramolecular Aldol-condensation has been proposed as the key step for the catalytic cycle.     

微波场中T型分子筛的合成及晶化研究

研究了微波场中T型分子筛的结晶过程。考察了微波加热体系中合成参数如合成时间、溶胶组成、反应压力和模板剂用量对分子筛晶化的影响。微波加热的主要优点是减少合成时间,无模板剂的溶胶在普通加热条件下的晶化时间需要120 h,而在微波场中则仅需要20～25 h。另一方面,由于微波的快速加热特性促进了稳定相钙十字沸石的生成,从而减小了次稳定相T型分子筛的结晶区间。在未添加模板剂条件时,100 ℃下微波水热合成T型分子筛的结晶区间为：20≤n_SiO2/n_Al2O3≤22和0.31≤ n_M2O/n_SiO2≤0.33(其中M₂O=Na₂O+K₂O, n_Na/n_K=3和n_M2O/n_SiO2=11.70)。在普通加热和微波加热合成体系中,添加模板剂均能扩大结晶区间,同时还可以进一步减少合成时间。