Preparation,Characterization and Catalytic Performance of Carbon Nanotubes Promoted Ni‐B Amorphous Alloy

Ni‐B and Ni‐B/CNTs amorphous alloy catalysts were prepared by chemical reduction and impregnation‐chemical reduction methods, respectively, and characterized by TEM, ICP, XPS, XRD, BET and CO chemisorption techniques. Their catalytic activities were evaluated in acetylene selective hydrogenation reaction. Based on characterizations, the effects of carbon nanotubes on Ni‐B amorphous alloy were attributed to both its structure effect, dispersing Ni‐B particles, leading to bigger surface area of active nickel and enhancing the thermal stability, and the electronic effect, resulting in electron‐rich nickel centers. Therefore, the superior thermal stability and acetylene selective hydrogenation activities of Ni‐B/CNTs to Ni‐B amorphous catalyst were obtained in the present study.     

乙炔与氢原子反应的IRC和反应速度常数的从头算研究

乙炔与氢原子反应:H+H—C≡C—H→ H—C≡C:+H_2在碳氢化合物的氧化、光解和热解中都具有重要意义。Dagaut等人做过动力学研究,但从理论角度研究其反应动力学尚未见报道。本文用量化方法在反应途径哈密顿基础上,求得了反应途径(IRC)上各点的IRC曲率(B_F)、IRC与其它各振动模式之间的耦合常数(B_(F,t))等,并计算出反应速度常数。 本文用HF/6-31G优化出了过渡态的几何构型(图1),并给出了过渡态的虚振动模式。     

镍钴双金属-卟啉有机框架复合纳米材料构建的无酶传感器检测多巴胺

以Ni、Co为金属节点,5,10,15,20-四（4-羧基苯基）卟啉（TCPP）为金属配体,合成了金属有机框架材料（MOFs）作催化材料,以还原氧化石墨烯（rGO）和乙炔黑（ACET）作信号放大材料,制备出一种灵敏度高、稳定性高、选择性好的无酶电化学传感器,用于检测多巴胺（DA）。通过一步水热法制成rGO-NiCoTCPP,再用滴涂法将其修饰在玻碳电极上,即得GCE/rGO-NiCoTCPP电极,最后将ACET滴涂在此电极上,得到GCE/rGO-NiCoTCPP/ACET电极。利用红外光谱、扫描电子显微镜和电化学阻抗对此电极进行了表征,并将不同修饰电极放在磷酸缓冲液中进行循环伏安表征。GCE/rGO-NiCoTCPP/ACET传感器对DA具有较宽线性范围（0.4 ~160 μmol/L）及较高的电流响应（检出限为0.198 μmol/L）,有望应用于实际样品中DA的检测。     

Ab initio calculations of minimum-energy pathways of the nucleophilic addition of the H anion, LiH molecule and Li/H ion pair to acetylene and methylacetylene

Ab initio calculations were performed for special points of the minimal energy pathways (MEP) of the nucleophilic addition reactions of the isolated H⁻ anion, LiH molecule and Li⁺/H⁻ ion pair to acetylene (A) and methylacetylene (MA) molecules, proceeding in accordance (M) and against (aM) the Markovnikov's rule. All structural parameters were optimized using the restricted Hartree–Fock (RHF) method. For the addition of H⁻, the 6-31++G^* basis set was used and for the reactions of LiH and Li⁺/H⁻ the 6-31G^* basis set with the subsequent recalculation of single point energies, taking into account of electron correlation energy by means of the second-order Möller–Plesset perturbation theory at the MP2/6-31++G^** level. The results of calculations demonstrate, that the energy characteristics of both M- and aM-additions with H⁻ do not differ sufficiently (0.1–1.2 kcal/mol for the activation energies (ΔE_a) and the reaction heats (ΔQ)). The substitution of the H atom by the CH₃ group in A molecule results in practically the same values of ΔQ and ΔE_a. On the contrary, for the LiH molecule and Li⁺/H⁻ ionic pair, the M-addition is favorable (charge control). It is found that the presence of electrophile decreases the activation energy by 3–5 kcal/mol as compared with the addition of the isolated hydride ion H⁻.     

Diacetylene's weak bonding to acetylene clusters

An interaction potential previously developed for the acetylene–polyyne dimer was used to explore the interaction potential surfaces for clusters containing a diacetylene molecule and two or more acetylene molecules. Ab initio calculations were performed on the smallest clusters in order to assess the energetic and structural features predicted by the model potential. The preferred arrangements of the monomers in the clusters maximize the favorable quadrupole–quadrupole interactions between the monomers.     

富氧空气-乙炔火焰原子吸收光谱法测定地质样品中的微量钼

本文首次提出富氧空气－乙炔火焰原子吸收光谱法测定地质样品中微量钼的方法,用正交实验方法对实验条件进行了优化选择,当观察高度为10mm、空气流量为6.0L/min、氧气流量为2.3L/min、乙炔流量为5.4L/min时,对钼的测定具有较高的灵敏度,本法中,大多数共存离子对钼的干扰较小,溶液中加入表面活性剂十二烷基硫酸钠时,具有最大的增感效应和抑制干扰的效应,方法的测定精密度为4.65%,检出限为0.039μg/mL。应用本法测定地质标准样品中的微量钼,结果令人满意。     

A short-cut from 1-acetyl adamantane to 2-(1-adamantyl)pyrroles

The oxime of 1-acetyl adamantane 2 is added to acetylene (KOH/DMSO, 70 °C, initial acetylene pressure 13 atm, 30 min) to afford the corresponding O-vinyl oxime 5 in 80% yield. The latter upon heating (DMSO, 120 °C, 1 h) gives 2-(1-adamantyl)pyrrole 3, 1-acetyl adamantane 1, and adamantane (6:3:1 mass ratio), the yield of the pyrrole 3 being 83% (based on 1-acetyl adamantane 1 consumed). Under harsher conditions (NaOH/DMSO, 130 °C, atmospheric pressure of acetylene, 4 h) oxime 2 reacts with acetylene to furnish pyrrole 3, 1-acetyl adamantane 1, 1-vinyl adamantane 9, and adamantane (6:7:3:1 mass ratio), with the isolated yield of pyrrole 3 reaching 34%. Under pressure (NaOH/DMSO, 120 °C, initial acetylene pressure 14 atm, 1 h) the same reaction leads to 2-(1-adamantyl)-1-vinylpyrrole 4 and ketone 1 in 48% (based on consumed ketone 1) and 24% yields, respectively. The pyrrole 4 is easily deprotected to the corresponding 1H-pyrrole 3 in 77% yield by treatment (aqueous MeCN) with Hg(OAc)₂ and NaBH₄.     

Effective dipole moment parameters of C2H2 for the 100, 7.7, 1.4, 1.3, 1.2 and 1.0 μm regions

Based on new line intensity measurements collected from the literature, the effective dipole moment parameters of acetylene have been found for the 100, 7.7, 1.4, 1.3, 1.2 and 1 μm spectral regions by least-squares fittings. On average, the experimental uncertainty was obtained in all fits. The new sets of the effective dipole moment parameters combined with those that were previously published allow for the calculation of the line intensities for the majority of the acetylene bands in the spectral range from 100 to 1 μm.     

Hydrochlorination of acetylene using expanded multilayered vermiculite (EML-VMT)-supported catalysts

Catalyst supports have very important effects on catalyst performance.A novel expanded multilayered vermiculite(EML-VMT) is successfully used as the catalyst support for the acetylene hydrochlorination.By mixing carbon on the surface of EML-VMT[i.e.,EML-VMT-C),the HgCl_2/EML-VMT-C achieved a high acetylene conversion of 97.3%,a vinyl chloride selectivity of 100%and a turn over frequency(TOF) value of 8.83 × 10~(-3)s~(-1) at a temperature of 140 C,an acetylene gas hourly space velocity(GHSV) of 108 h~(-1)',and a feed volume ratio V(HC1)/V(C_2H_2) of 1.15.Moreover,the HgCl_2/EML-VMT-C shows good stability.The EML-VMT also shows potential in the preparation of other EML-VMT-supported catalysts.