Characterization of nanoporous low-k thin films by small-angle neutron scattering contrast variation

Small-angle neutron scattering contrast variation is applied to characterization of nanoporous low-dielectric constant (low-k) thin films. Films are exposed to saturated solvent vapor in air, whereby the pores fill with liquid by capillary condensation. The pores are filled with mixtures of hydrogen- and deuterium-containing solvents to vary the neutron contrast with the matrix (wall). The composition of the solvent mixture is systematically varied to identify a composition that minimizes the scattered intensity (contrast match point). From the contrast match point composition, film characteristics including matrix density and homogeneity are assessed. Four spin-on low-k materials including a methylsilsesquioxane, an organic polymer, a xerogel, and a hydrogensilsesquioxane are characterized by the new technique. Calculated matrix mass densities are compared to independent density measurements obtained by an established specular X-ray reflectivity technique. We find no evidence of "closed pores", defined here as pores inaccessible to the probe solvent, in any of the materials studied.     

超临界流体色谱在生物工程中应用的新进展

超临界流体色谱（SFC）是高效液相色谱（HPLC）和气相色谱（GC）的重要补充技术。用SFC可以分离多数不能用GC分离的低挥发性物质。与传统的HPLC相比，SFC的分离速度更快、效率更高。本文综述了SFC在生物分子分离分析方面应用的新进展。引用文献74篇。     

几种褐煤的超临界萃取研究

用超临界萃取方法对褐煤进行萃取研究，在半连续实验装置上进行了８种中国褐 煤样萃取试验．用甲苯作溶剂非等温萃取，萃取压力为１０ＭＰａ．试验结果表明，萃 取转化率和萃取物产率与煤样挥发分呈线性关系，转化率介于３０％－５４５；萃取物 产率介于１９％一３２％．加入１０％四氢萘于甲苯溶剂中．转化率由３８％增至６２％， 萃取物产率由２０％增至４０％，对过程进行了动力学处理，动力学参数与煤的Ｈ／Ｃ 原子比有线性关系。     

Ni改性HZSM-5催化类煤模型化合物热解研究

以苯乙醚(PEE)和苯基苄基醚(BOB)为类煤模型化合物,在固定床反应器上研究了它们在镍改性HZSM-5催化剂存在下的催化热解行为.采用浸渍法将镍负载于HZSM-5沸石,对所得催化剂采用XRD、FT-IR、H2-TPR、NH3-TPD进行表征,还研究了还原预处理对催化剂性能的影响.研究表明,NiO/HZSM-5能显著提...     

煤热解与甲烷蒸汽重整耦合过程焦油在碳基镍催化剂上的原位催化提质（英文）

本研究采用Ni/KD-9催化剂，对CP-SRM过程焦油进行原位催化提质研究。结果表明，在650℃热解温度下，CPSRM在5Ni/KD-9催化作用下的焦油产率为24.4%，略低于不进行催化提质的焦油产率，而轻质焦油产率（18.9%）是未提质时的1.4倍。相比未提质焦油，用5Ni/KD-9提质后焦油中的C₂、C₃和C₄烷基取代苯含量分别增加0.5、0.6和4.0倍；酚和萘的含量也明显提高。采用同位素示踪方法结合典型组分质谱图，探究了催化提质过程的反应机理。结果表明，5Ni/KD-9可以同时催化焦油裂解和甲烷蒸汽重整（SRM）,SRM过程产生的小分子自由基，如·CH_x，·H和·OH可以与焦油裂解产生的自由基结合，从而避免焦油的过度裂解。     

东北两种泥炭超临界萃取物结构研究

对东北两种泥炭(桦甸草本泥炭、伊春藓类泥炭)超临界萃取物进行了元素分析、平均分子量测定、红外分析和~1HNMR分析,并对桦甸泥炭萃取物中正己烷可溶物进行了GC-MS分析。结果表明,萃取物中含有脂肪族结构、芳香结构、大量含氧基团,并含有脂环化合物。桦甸泥炭萃取物平均分子量为325,芳碳率为0.34,芳香结构以单环为主;伊春泥炭萃取物平均分子量为315,芳碳率为0.52。     

键解离焓的理论方法研究

The density functional theory (DFT) is the most popular method for evaluating bond dis-sociation enthalpies (BDEs) of most molecules. Thus, we are committed to looking for alternative methods that can balance the computational cost and higher precision to the best for large systems. The performance of DFT, double-hybrid DFT, and high-level com-posite methods are examined. The tested sets contain monocyclic and polycyclic aromatic molecules, branched hydrocarbons, small inorganic molecules, etc. The results show that the mPW2PLYP and G4MP2 methods achieve reasonable agreement with the benchmark values for most tested molecules, and the mean absolute deviations are 2.43 and 1.96 kcal/mol after excluding the BDEs of branched hydrocarbons. We recommend the G4MP2 is the most appropriate method for small systems (atoms number ≤20); the double-hybrid DFT methods are advised for large aromatic molecules in medium size (20 ≤atoms number ≤50), and the double-hybrid DFT methods with empirical dispersion correction are recommended for long-chain and branched hydrocarbons in the same size scope; the DFT methods are advised to apply for large systems (atoms number ≥50), and the M06-2X and B3P86 methods are also favorable. Moreover, the di erences of optimized geometry of different methods are discussed and the effects of basis sets for various methods are investigated.     

超临界甲苯萃取含重金属渣油回收有机质

在半连续萃取装置上 ,对 Veba联合裂解工艺中得到的渣油 VCC-R(含镍 393× 1 0 - 6 ,钒2 31 0× 1 0 - 6 )用甲苯进行萃取 ,以除去渣油中的重金属 .实验采用非等温技术 ,研究了温度、压力和溶剂类型等对萃取的影响 .结果表明 ,VCC-R的回收率在 64%～ 69% ( daf) ;萃取物主要在1 0 0～ 350℃得到 ,其中镍和钒的质量分数小于 6× 1 0 - 6 ,表明 98%和 99%的镍和钒已除去 .萃取残渣集中了 VCC-R中的重金属和灰分 ,有很低的氢含量、质量分数大于 1 0 0 0× 1 0 - 6 的镍和大于 60 0 0× 1 0 - 6的钒     

Cu/Ce负载对赤泥脱除中低温烟气中NO的促进作用

本研究对酸洗赤泥催化剂进行Cu、Ce、Cu/Ce浸渍负载,并研究了金属改性赤泥对烟气中NO_x的催化转化性能。研究结果表明,Cu负载催化剂中的Cu⁺与Cu²⁺,有效促进了赤泥对低温烟气(200–300℃)中的NO转化率,Cu的负载量达到6%时,赤泥的最高NO转化率达到了90.7%;而Ce负载催化剂中的Ce³⁺与Ce⁴⁺,有效促进了赤泥对中温烟气(200–400℃)中的NO转化率,Ce的负载量达到8%时,赤泥的最高NO转化率达到了94.0%;Cu/Ce负载催化剂表现出比单金属负载催化剂更好的低温NO转化率,最佳的负载Cu:Ce比例为1∶1,双金属负载催化剂表现出比Cu负载催化剂更好的中温(300–400℃)中的NO转化率,最高达到了95.5%。其原因是,在Cu/Ce协同作用下,Cu⁺以及Cu²⁺的还原过程分别从229、302℃降至201以及247℃,同时使发生Fe₂O₃→FeO的还原过程的温度降...