Low-temperature Denitration Mechanism of NH_(3)-SCR over Fe/AC Catalyst

To study the modification mechanism of activated carbon(AC)by Fe and the low-temperature NH_(3)-selective catalytic reduction(SCR)denitration mechanism of Fe/AC catalysts,Fe/AC catalysts were prepared using coconut shell AC activated by nitric acid as the support and iron oxide as the active component.The crystal structure,surface morphology,pore structure,functional groups and valence states of the active components of Fe/AC catalysts were characterised by X-ray diffraction,scanning electron microscopy,nitrogen adsorption and desorption,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,respectively.The effect of Fe loading and calcination temperature on the low-temperature denitration of NH_(3)-SCR over Fe/AC catalysts was studied using NH_(3)as the reducing gas at low temperature(150℃).The results show that the iron oxide on the Fe/AC catalyst is spherical and uniformly dispersed on the surface of AC,thereby improving the crystallisation performance and increasing the number of active sites and specific surface area on AC in contact with the reaction gas.Hence,a rapid NH_(3)-SCR reaction was realised.When the roasting temperature remains constant,the iron oxide crystals formed by increasing the amount of loading can enter the AC pore structure and accumulate to form more micropores.When the roasting temperature is raised from 400 to 500℃,the iron oxide is mainly transformed fromα-Fe_(2)O_(3)toγ-Fe_(2)O_(3),which improves the iron oxide dispersion and increases its denitration active site,allowing gas adsorption.When the Fe loading amount is 10%,and the roasting temperature is 500℃,the NO removal rate of the Fe/AC catalyst can reach 95%.According to the study,the low-temperature NH_(3)-SCR mechanism of Fe/AC catalyst is proposed,in which the redox reaction between Fe~(2+)and Fe~(3+)will facilitate the formation of reactive oxygen vacancies,which increases the amount of oxygen adsorption on the surface,especially the increase in surface acid sites,and promotes and adsorbs more reaction gases(NH_(3),O_(2),NO).The transformation from the standard SCR reaction to the fast SCR reaction is accelerated.

Theoretical Studies of PCl_3/H_2 Gas Chromatography Mechanism

Density functional theory B3LYP method was firstly applied to fully optimize the geometrical configuration of each stable point on PCl3/H2 gas chromatography reaction potential energy surface on the 6-311G＊＊ basis set, and single point energy was computed at the QCISD（T）/ 6-311G＊＊ level, then the transition state was validated by analyzing the unique imaginary vibration modes of each transition state and calculating intrinsic reaction coordinate （IRC）, and the major reaction and competing reaction paths of PCIs/H2 gas chromatography reaction were presented through comparing active energy barrier, and phosphor was finally gained from the reaction of PH and PCI.

Theoretical Study on the Isomerization Mechanism of Enol Ester from 2-Acyl-1,3-cyclohexanediones

The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step.

非晶态MnO_x/TiO_2催化剂的制备及其低温NH_3-SCR性能

采用自发沉积法、共沉淀法及浸渍法制备MnO_x/TiO_2催化剂,通过XRD、TEM、N2吸附-脱附、XPS、H_2-TPR、NH_3-TPD等一系列表征手段研究MnO_x/TiO_2催化剂的结构与性质,并考察MnO_x/TiO_2催化剂低温NH_3-SCR性能。结果表明,自发沉积法制备的MnO_x/Ti O2(s)催化剂具有完全非晶态结构,Mn和Ti之间存在强相互作用,较共沉淀法制备的MnO_x/TiO_2(c)及浸渍法制备的MnO_x/Ti O2(i)表现出更强的氧化还原能力。MnO_x/TiO_2(s)具有较高的比表面积、较多的表面酸量,有利于NH_3的吸附与活化。且表面高浓度的Mn4+离子及吸附氧,有利于将NO氧化为NO2,促进发生"fast-SCR"反应,进而使其表现出优异的低温脱硝性能。MnO_x/TiO_2(s)催化剂在150℃时NO的转化率高达92.8%,在150-350℃NO的转化率保持在90%以上,此外其还具备较强的抗H_2O和SO_2毒化能力。

K_(2)CO_(3)辅助钯催化C-H活化反应的理论研究

K_(2)CO_(3)是一种常见的碱金属碳酸盐,在有机合成中常被用作碱性添加剂,以加快过渡金属尤其是钯催化C-H活化反应的速率或提高反应产率。因此,研究K_(2)CO_(3)辅助的钯催化C-H活化反应成为近年来有机合成和理论计算领域的热点之一。本文对近十年来K_(2)CO_(3)辅助钯催化C-H活化反应的最新理论研究进展进行分类总结,重点对钯催化C-H活化反应的微观机理、K_(2)CO_(3)的作用机制等进行了深入探讨,并对该领域的发展前景进行展望。

Comprehensive understanding of the superior performance of Sm-modified Fe_(2)O_(3)catalysts with regard to NO conversion and H_(2)O/SO_(2)resistance in the NH_(3)-SCR reaction

Sm-doped Fe_(2)O_(3)catalysts,with a homogeneous distribution of Sm in Fe_(2)O_(3)nanoparticles,were synthesized using a citric acid-assisted sol-gel method.Kinetic studies show that the reaction rate for NO_(x)reduction using the optimal catalyst(0.06 mol%doping of Sm in Fe_(2)O_(3))was nearly 11 times higher than that for pure Fe_(2)O_(3),when calculated based on specific surface area.Furthermore,the Fe_(0.94)Sm_(0.06)O_(x)catalyst maintains>83%NO_(x)conversion for 168 h at a high space velocity in the presence of SO_(2)and H_(2)O at 250℃.A substantial amount of surface-adsorbed oxygen was generated on the surface of Fe_(0.94)Sm_(0.06)O_(x),which promoted NO oxidation and the subsequent fast reaction between NO_(x)and NH_(3).The adsorption and activation of NH_(3)was also enhanced by Sm doping.In addition,Sm doping facilitated the decomposition of NH_(4)HSO_(4)on the surface of Fe_(0.94)Sm_(0.06)O_(x),resulting in its high activity and stability in the presence of SO_(2)+H_(2)O.

C_3H^+与N反应的理论研究

用密度泛函方法在QCISD(T)/6 311++G //B3LYP/6311G 水平上研究了气相反应C3H++N的反应机理.得到了不同能量产物的可能的反应通道,获得反应势能面.整个反应为多通道反应,经过多个步骤完成,共找到9个中间体和11个过渡态,产物C3H++N(P2)为能量较低的产物,通道3:IM5→TS4→IM6→TS5→IM7→TS7→IM8→P2为较为可行的反应通道.

基于Isight平台NSGA-Ⅱ方法的3-PRS并联机构多目标优化

把Isight软件运用到3-PRS并联机构的多目标参数优化中,分析并建立3-PRS并联机构的工作空间、灵巧度、刚度和承载能力的指标。采用蒙特卡洛方法对多目标指标函数进行编程求解,以Isight软件为平台,集成Matlab软件,构建多目标优化基本流程,用Isight软件中封装的NSGA-Ⅱ方法对3-PRS并联机构的五个目标函数进行优化。得到分布性良好的Pareto解集及Pareto前沿,目标指标得以分析,并得出参数与目标之间变化规律。可根据优化信息,在Pareto解集中选取适合实际工况的最优解,最后给出优化算例。

H2TiO3新型锂离子筛研究进展

H2TiO3新型锂离子筛是近年来从盐湖卤水和海水中提锂的研究热点.详述了H2TiO3锂离子筛的结构,明确了H2TiO3的结构不同于前驱体Li2TiO3的结构,提出了H2TiO3是具有3R 1层序的层状双氢氧化物,可以被描述为电中性的金属氢氧化物的叠加[(OH)2OTi2O(OH)2].目前,H2TiO3前驱体的制备方法主要有固相反应法、溶胶-凝胶法和水热法.综述了三种制备方法对H2TiO3性能的影响,其中,水热法制备的Li2TiO3前驱体晶粒尺寸小、结构稳定、Li+提取率高,得到的H2TiO3锂离子筛饱和吸附容量高.因此,水热法具有广阔的应用前景.H2TiO3锂离子筛通常为粉体材料,在使用和转移中存在着流损大、回收再利用困难,造成动态应用较差等问题,限制其在实际工业中的应用.介绍了H2TiO3锂离子筛的掺杂和成形的研究进展,提出了相关建议.最后,对H2TiO3锂离子筛的吸附机理进行简要总结,主要有离子交换机制、化学吸附、单层吸附.

3-取代硫基-5-(2-羟基苯基)-4H-1,2,4-三唑类化合物抑菌活性的QSAR研究

采用MOPAC-AM1方法对13种3-取代硫基-5-(2-羟基苯基)-4H-1,2,4-三唑类化合物分子进行几何优化和计算EHOMO、ELUMO、QC1～QC8、QN1～QN3、QO及QS等量子化学描述符(Lt).通过最佳变量子集回归建立这些化合物对白色念珠菌、大肠杆菌、金黄色葡萄球菌等抑菌活性(IJ:IM,IE和IS)的QSAR模型.结果显示ELUMO和QS直接影响这些化合物的生物活性:硫原子上电荷量增大,其抑菌活性增强;ELUMO越高,IJ下降.对于白色念珠菌的IM模型的相关系数(R2)和逐一剔除法交叉验证系数(R2cv)依次为0.913和0.806,相应IE模型为0.907和0.838,相应IS模型为0.881和0.771.通过R2adj、F、R2cv、VIF、AIC、FIT等检验,上述模型具有令人满意的稳健性和预测能力.结果显示抑菌机理的重要信息,可用于新活性标题化合物的理论设计.

Low-temperature NH_(3)-SCR performance of a novel Chlorella@Mn composite denitrification catalyst

The synthesis process of conventional Mn-based denitrification catalysts is relatively complex and expensive.In this paper,a resource application of chlorella was proposed,and a Chlorella@Mn composite denitrification catalyst was innovatively synthesized by electrostatic interaction.The Chlorella@Mn composite denitrification catalyst prepared under the optimal conditions(0.54 g/L Mn^(2+)concentration,20 million chlorellas/mL concentration,450℃ calcination temperature)exhibited a well-developed pore structure and large specific surface area(122 m^(2)/g).Compared with MnOx alone,the Chlorella@Mn composite catalyst achieved superior performance,with~100%NH_(3)selective catalytic reduction(NH_(3)-SCR)denitrification activity at 100-225℃.The results of NH_(3)temperature-programmed desorption(NH_(3)-TPD)and H_(2)temperature-programmed reduction(H_(2)-TPR)showed that the catalyst had strong acid sites and good redox properties.Zeta potential testing showed that the electronegativity of the chlorella cell surface could be used to enrich with Mn^(2+).X-ray photoelectron spectroscopy(XPS)confirmed that Chlorella@Mn had a high content of Mn^(3+)and surface chemisorbed oxygen.In-situ diffuse refectance infrared Fourier transform spectroscopy(in-situ DRIFTS)experimental results showed that both Langmuir-Hinshelwood(L-H)and Eley-Rideal(E-R)mechanisms play a role in the denitrification process on the surface of the Chlorella@Mn catalyst,where the main intermediate nitrate species is monodentate nitrite.The presence of SO_(2)promoted the generation and strengthening of Bronsted acid sites,but also generated more sulfate species on the surface,thereby reducing the denitrification activity of the Chlorella@Mn catalyst.The Chlorella@Mn composite catalyst had the characteristics of short preparation time,simple process and low cost,making it promising for industrial application.

Promoted NH_(3)-SCR activity and hydrothermal stability of Cu-SSZ-50 catalyst synthesized by one-pot method

Nitrogen oxide(NO_(x))is one of the most critical contaminants in the air,and the control of NO_(x)emission from diesel vehicles is very important.Cu-based small-pore zeolites have already been applied for NO_(x)abatement on diesel vehicles.Among the small-pore zeolites,Cu-SSZ-50 catalysts with good NH_(3)-SCR catalytic activity were believed to have potential for application.In this study,a one-pot synthesis method for Cu-SSZ-50 catalysts was developed for the first time,using the co-templates of Cu-TEPA and 2,6-dimethyl-N-methylpyridinium hydroxide.In this synthesis method,Cu-SSZ-50 with various Cu contents can be obtained by adjusting the amount of Cu-TEPA without the need for a further after-treatment process.The addition of Cu-TEPA affected the framework atoms and Cu species,and a lower Si/Al ratio and more SCR active Cu species were obtained.The synthesized catalyst with a Cu/Al ratio of 0.40 exhibited over 90%NO_(x)conversion between 200℃and 450℃for the selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).Meanwhile,over 80%NO_(x)conversion could be obtained from 250℃to 450℃after hydrothermal aging at 750℃for 16 h.In addition,both L-H and E-R mechanisms were proven to exist for the one-pot-synthesized Cu-SSZ-50 by in situ DRIFTS experiments.The simple synthesis procedure,excellent catalytic activity and hydrothermal stability brighten the prospects for the application of Cu-SSZ-50.

Theoretical Study on the Reaction of PCl_3/H_2 on Silicon Substrate Surface

The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly undergoes dissociative adsorption, and then the adsorption product reacts with H2 via a four-step multi-channel mode to give the final product PSi4 cluster. The geometries at each stationary point were fully optimized. The possible transition states were determined by vibrational mode analysis and IRC verification. And finally, the main reaction channel was given.

通过醚的α-位C(sp^(3))—H键官能化合成醚类衍生物的研究进展

醚及其类衍生物是有机化合物中的重要组成部分,许多生物活性分子、药物和天然产物中也存在醚类结构。近年来通过醚类分子(包括环醚和非环醚)的α-位C(sp^(3))—H官能化来合成了多种不同类型的醚类衍生物已取得了令人瞩目的研究成果。本综述从醚α-位C(sp^(3))—H官能化所需的反应条件出发,对2017年到2020年来的研究成果进行了综述。

Synthesis of high purity Li2CO3 and MgCO3·3H2O in a homogeneous-like organic phase

Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3·3H2O rangi ng from nanosphere to nanorod. Compared with coupled reacti on and solve nt extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.

Synthesis and Crystal Structure of a New Quinazolinone Compound 2,3-Dihydro-2-(2-hydroxyphenyl)-3-phenyl-quinazolin-4(1H)-one

A new quinazolinone compound 2,3-dihydro-2-(2-hydroxyphenyl)-3-phenyl- quinazolin-4(1H)-one 3 ([C20H16O2N2]?C2H5OH, Mr = 362.42) and compound 2-(2-hydroxy- benzylidene-amino)-N-phenyl-benzamide 2 (C20H16O2N2, Mr = 316.34) were prepared from a precursor of 2-amino-N-phenyl-benzamide 1 (C13H12ON2, Mr = 212.25). Compound 3 was characterized by single-crystal X-ray diffraction analysis. The crystal belongs to orthorhombic, space group Pbca with a = 1.2889(11), b = 1.6170(14), c = 1.7729(15) nm, V = 3.695(6) nm3, Z = 8, F(000) = 1536, Mr = 362.42, Dc = 1.303 g/cm3, μ(MoKα) = 0.087 mm-1, R = 0.0447 and wR = 0.0879. The crystal structure analysis indicates that the title compound has a two-dimensional network structure formed by hydrogen bonds and electrostatic interactions.

一种3-PRS并联机构正向运动学求解方法

并联机构正向运动学求解复杂、存在多解,是研究的热点和难点。提出用D-H法和图形可视化相结合的方法对3-PRS并联机构进行正向运动学求解的方法。首先,对机构中的球铰做等效转换,运用D-H法对支链进行运动学分析,推导出3-PRS并联机构的正向运动学方程;然后,采用迭代法得到16组正向运动学方程的解,通过可视化编程,直观地得到3-PRS并联机构的位形,即得到并联机构的运动学正解。结果表明,所得到的一组运动学正解与实际结构的位形相符。该方法有效、正确,并适用于求解其他类型的并联机构正向运动学。

基于ANSYS的1-3型水泥基压电复合材料力电响应分析

运用ANSYS有限元方法,分别对PZT5H压电陶瓷和1-3型水泥基压电复合材料的力电响应进行了模拟分析。分析结果表明:在位移约束和面载荷下,PZT5H压电陶瓷和1-3型水泥基压电复合材料上的最大位移和最大电势均发生在压电陶瓷(柱)上表面,且产生的最大电压均发生在最大位移处,陶瓷在垂直方向上的电势与位移分层明显且一致。

丙烯氢原子[1,3]σ迁移的分子力学研究

在前人工作的基础上，用分子力学的方法进一步研究丙烯氢原子[1，3]σ异面迁移的反应机理．从分子的结构变化过程中整个分子的张力变化，具体分析出3个碳原子的键角减少而造成的张力增加并不是导致新键较迟形成的主要因素．

基于ADAMS的3-UPRP并联机构的运动学分析及仿真

目的对3-UPRP并联机构进行运动学分析和仿真,验证其是否具有良好的运动学性能。方法运用修正的G-K公式计算出该机构的自由度,并且利用D-H法计算3-UPRP并联机构的位置解,利用虚设机构法求出3-UPRP并联机构的一阶影响系数,利用ADAMS对机构进行位移、速度、加速度的分析。结果得到了机构的位置解以及仿真后的速度、加速度等图像,图像曲线都呈现周期性、有规律的运动,曲线未出现突变点和断点,变化范围稳定。结论该机构具有较好的运动学性能,在包装机械等领域有很好的应用前景。