多级孔氧化铝负载钯催化剂的制备及加氢性能研究

文章以聚甲基丙烯酸单酯(PMMA)微球为模板剂,采用三嵌段共聚物F127辅助胶体晶体模板的方法合成介-大孔复合孔道结构的Al_2O_3载体,通过浸渍还原法制备了Pd/3DOM Al_2O_3负载型催化剂,考察了其在苯乙烯加氢反应中的活性。采用氮气物理吸附-脱附(N_2-BET)、场发射扫描电子显微镜(field emission scanning electron microscope, FESEM)、高分辨率透射电子显微镜(high resolution transmission electron microscope, HRTEM)、X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)等分析方法对催化剂进行了表征。结果表明:活性物种主要以Pd~0的形式高度分散在3DOM Al_2O_3载体上;开放有序的多级孔结构有利于反应物和产物在孔道内的扩散,使其在苯乙烯加氢反应中的活性优于相同条件下γ-Al_2O_3负载的Pd催化剂,Pd/3DOM Al_2O_3的转换频率(turnover frequency, TOF)值可达0.56 s~(-1),高于Pd/γ-Al_2O_3的0.45 s~(-1)。     

Co掺入对CeMoO_x/Al_2O_3协同催化NO、CO和C_3H_8的影响

采用挤出成型法将Co掺入CeMo_(0.15)O_x/Al_2O_3制备系列催化剂CeMo_(0.15)Co_(0.15)O_x/Al_2O_3,研究Co掺入对协同催化脱除CO、NO和C_3H_8的影响。采用X线衍射仪(XRD)、N2吸附/脱附法、NH3程序升温脱附法(NH_3-TPD)、NO程序升温脱附法(NO-TPD)、H_2程序升温还原法(H_2-TPR)和X线光电子能谱(XPS)等手段对催化剂进行表征。结果表明:Co掺入有利于CeMo_(0.15)O_x/Al_2O_3氧化CO和C_3H_8,CeMo_(0.15)Co_(0.15)O_x/Al_2O_3在空速7 200 h~(-1)条件下,NO的转化率为98.85%,CO的转化率为79.41%,C_3H_8的转化率为81.33%。催化剂中Co的掺入会提高氧化-还原性能、酸量、NO吸附-脱附能力、Ce~(3+)浓度以及化学吸附氧浓度。这些结果均有利于提高协同催化脱除CO、NO和C_3H_8的活性。     

程序升温还原和定温吸附法研究负载钯催化剂中的金属—载体强相互作用

以不同载体的钯催化剂来研究金属——载体之间的强相互作用(SMSI)。利用程序升温还原法(TPR)和定温吸附(TRS)相结合的技术来研究这些催化剂的还原情况和对氢的吸附情况。发现钯在低于200℃时就被还原。在较高温度下氢从Pd到载体有溢流,高温氢处理也会导致SMSI和熔结现象。这些溢流、熔结和SMSI的程度决定于载体。而SMSI也抑制着Pd对氢的大量吸附。在相同还原条件下,负载Pd催化剂有下列熔结趋势:Pd/C>Pd>TiO_2>Pd/Al_2O_3>Pd/SiO_2。     

Pd-Ni/γ-Al_2O_3吸附剂的制备及其苯吸附脱硫性能研究

针对市售Pd吸附脱硫剂成本高、深度脱硫效果偏低的现状,本文以改性γ-Al_2O_3为载体,采用液相原位还原法制备出一种低成本、高脱硫能力的负载型三维纳米线网状结构的Pd-Ni吸附剂。利用XRD、TEM、SEM、BET等对样品的组成、结构和形貌进行表征,并利用催化剂评价装置和GC-MS考察了不同原子比的Pd-Ni/γ-Al_2O_3吸附剂对苯的脱硫效果。结果表明:Pd-Ni纳米线直径为4～5 nm,长达数微米,纳米线与Al_2O_3载体紧密结合,形成负载型三维网状结构吸附剂(活性组分质量分数为1%)。当Pd∶Ni原子比为1∶1时,经0.5 h吸附脱硫后可使苯原料中噻吩含量由300μg/L降至10μg/L以下,脱硫率达95%以上,是工业Pd/Al_2O_3(69.2%)的1.40倍,吸附剂中Pd的使用量约减少50%,极大降低了生产成本。本方法制备工艺简单,可控度高,为高效苯深度脱硫吸附剂的研发提供了理论依据和技术支持,具有重要的指导意义。     

CeO_2改性NiO/γ-Al_2O_3催化剂的苯胺焦油加氢轻质化

采用分步沉淀法制备CeO_2改性NiO/γ-Al_2O_3催化剂,通过比表面积分析(BET)、X线衍射(XRD)、H2程序升温还原(H2-TPR)、H2程序升温脱附(H2-TPD)对催化剂结构和物化性能进行表征,研究催化剂对苯胺焦油加氢裂化的反应活性。结果表明:适量加入CeO_2可提高NiO在载体γ-Al_2O_3表面的分散,提高NiO/CeO_2/γ-Al_2O_3催化剂的还原性及吸氢能力,进而提高催化剂的活性和稳定性。采用CeO_2质量分数15%的NiO/CeO_2/γ-Al_2O_3催化剂,在反应温度265℃、反应压力3.0 MPa、液时空速0.3 h-1和氢油体积比2 000的条件下,苯胺焦油裂解率为100%,胺类物质收率为58.54%。     

不同载体对Cu系催化剂催化醋酸异丙酯加氢工艺的影响

本文以醋酸异丙酯为原料催化加氢,同时制备乙醇和异丙醇。用共沉淀法制备SiO_2、Al_2O_3、ZrO_2和TiO_24种不同载体负载的Cu系催化剂,分别考察它们的催化反应性能;借助N2吸附-脱附仪、X线衍射仪(XRD)、H_2程序升温还原(H_2-TPR)、N_2O氧化滴定及NH3程序升温脱附(NH_3-TPD)等表征手段,分析对比4种载体对Cu的分散性、CuO-载体之间的协同作用、表面酸性等的影响及最终对反应结果的影响。结果表明:Cu/SiO_2表现出较好的催化活性且主产物的选择性最高;Cu/ZrO_2中因CuO与ZrO_2间的协同作用促进了Cu的高度分散,因而活性最高,但较强的酸性降低了主产物乙醇的选择性;Cu/TiO_2和Cu/Al_2O_3的催化活性以及主产物选择性都明显偏低。在Cu/SiO_2催化剂上进行了醋酸异丙酯加氢反应的工艺优化,筛选出了最佳工艺条件:温度290℃,反应压力6 MPa,氢酯进料摩尔比30,质量空时96 g·h/mol。在最佳条件下,醋酸异丙酯的转化率达96%,乙醇的选择性达94%,异丙醇的选择性达95%。     

CoMoNi/Al_2O_3-SiO_2催化剂用于掺炼焦化汽油扩大重整原料来源的研究

随着清洁油品标准的提高,人们对催化剂性能的要求也逐渐提高,传统Al_2O_3载体已不能满足人们的要求。通过对传统Al_2O_3载体加以改进,研制出一种适用于掺炼劣质加氢焦化汽油的重整预加氢催化剂CoMoNi/Al_2O_3-SiO_2。该剂具有较高的加氢脱硫、脱氮及烯烃饱和性能,在反应压力2.5 MPa、体积空速4.0 h~(-1)、氢油体积比200∶1的工艺条件下,进行了掺炼不同比例(0%、20%、50%)加氢焦化汽油原料的加氢性能评价,加氢产品均能达到重整原料的要求,并进行了催化剂1 500 h活性稳定性试验,试验结果表明催化剂具有良好的活性稳定性。     

载体对镍基催化剂在苯酚加氢反应中的影响

以Ni(NO3)2·6H2O为活性金属前驱物,采用过量浸渍法制备了Ni/HZSM-5、Ni/HY、Ni/Al_2O_3、Ni/TS-1、Ni/ZrO_2和Ni/CeO_2催化剂,Ni的质量分数由TPR结果计算可得分别为9.2%、9.1%、9.2%、9.5%、9.2%、9.3%.考察了催化剂对苯酚加氢反应的活性和产物选择性的影响.采用X射线衍射、N_2吸附、NH_3程序升温脱附、H_2程序升温脱附等手段对催化剂进行了表征.结果表明,载体的孔结构、酸度的强弱和酸中心数量与苯酚加氢活性具有紧密联系.在反应温度493 K,氢气压力5 MPa下反应180 min,Ni/Al_2O_3具有最高的苯酚转化率,达到85.63%,产物中环己酮选择性最高,达到79.2%;Ni/HZSM-5也有较高的苯酚转化率,而此时产物中环己烷的选择性最高,达到93.9%.     

不同分散剂对活性Al_2O_3性能的影响

采用共沉淀法分别制备添加淀粉、聚乙二醇(PEG)做分散剂和不添加任何分散剂的3种La-Al_2O_3材料,并利用低温氮气吸附-脱附、X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)对材料进行了表征。结果表明,添加分散剂能够有效提高材料的织构性能和抗高温老化性能,改善Al_2O_3材料表面的酸中心强度及酸量。3种材料中,添加PEG做分散剂制备的Al2O3材料经1 050℃焙烧10h后具有最大的比表面积(115.9m~2·g~(-1)),孔容为0.37mL·g~(-1)。XRD结果表明添加PEG能有效抑制在高温老化过程中材料晶型向α相转变。分别以经950℃处理后的3种材料为载体,采用浸渍法制备单Pd(Pd载量为0.83wt%)汽车尾气净化催化剂。催化活性测试结果表明,添加分散剂制备的材料能够提高催化活性,其中添加PEG做分散剂的材料制得的新鲜催化剂和老化催化剂均具有较低的起燃温度和完全转化温度。     

以Al_2O_3为黏结剂制备的Pt-WO_3/ZrO_2/Al_2O_3催化剂上的正庚烷异构化

采用挤条法制备了一系列以Al_2O_3为黏结剂的Pt-WO3/ZrO2/Al_2O_3(PtWZA)催化剂,在微型固定床装置上评价了正庚烷在PtWZA上的异构化性能。主要考察了黏结剂Al_2O_3质量分数、WO3质量分数和焙烧温度对PtWZA催化剂物化性质和异构化性能的影响,并采用XRD、氮气吸附-脱附、Py-FTIR等手段对催化剂的晶相结构、比表面积和酸性进行了表征。结果表明:Al_2O_3的引入明显影响催化剂的异构化活性,且对活性的影响不仅与Al_2O_3质量分数有关,而且与WO3质量分数也紧密相关。对于含较低WO3质量分数的Pt15WZA而言,添加少量Al_2O_3(质量分数为2%)导致催化活性大幅度提高;而WO3质量分数提高到20%时,添加质量分数为2%的Al_2O_3对Pt20WZA的活性影响不大。当Al_2O_3的质量分数提高到15%时,Pt15WZA与Pt20WZA的活性大大下降。提高WO3质量分数显著提高了PtWZ15A的异构化活性。升高焙烧温度有利于提高Pt20WZ10A催化剂活性,过高的焙烧温度导致催化剂活性大幅度下降,较为适宜的温度为800～850℃。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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