Mo/LaHY分子筛的热稳定性及酸性的研究

用浸渍法制备具有不同MoO3担载量的Mo/LaHY分子筛,在500℃温度下焙烧,并将质量分数wMo=2%担载量的Mo/LaHY分子筛样品在不同温度下焙烧.利用XRD,BET和NH3-TPD等表征手段考察了分子筛的热稳定性及酸性.结果表明,担载了Mo的Mo/LaHY分子筛仍保持了LaHY分子筛骨架的完整性,MoO3进入分子筛孔道内与LaHY分子筛的质子酸发生作用,且随着Mo担载量的增加,Mo/LaHY分子筛的总酸量逐步下降.在800℃以下温度焙烧,wMo=2%担载量的Mo/LaHY样品中LaHY的骨架结构基本保持完整,当焙烧温度升高至900℃时,分子筛骨架发生崩塌.     

用H—ZSM—5分子筛作催化剂合成乙酸丁酯

用Ｈ－ＺＳＭ－５沸石分子筛作催化剂，在釜式反应器内对丁醇和乙酸的酯化反应进行了研究，考察了分子筛的焙烧温度、硅铝化、催化剂用量、反应物摩尔比和反应温度等对酯化反应的影响。     

新型模板剂分子筛FeMCM-41的合成及催化活性

用松香为模板剂．采用水热合成法合成了FeMCM-41分子筛．研究了原料配比、pH、焙烧温度、晶化时间等因素对分子筛合成的影响；用合成的分子筛催化松香与正丁醇的酯化反应，研究了分子筛的催化活性．     

HZSM-5及改性HZSM-5上乙醇和乙酸的酯化反应

本文研究了不同焙烧温度及磷、镁改性HZSM-5沸石分子筛上乙醇和乙酸的酯化反应。实验结果表明:在适当焙烧温度或适当磷、镁含量的条件下,酯化反应选择性有明显提高,而乙醇转化率变化不大。酯化反应及副反应醚化反应均是在弱酸中心上进行的,但醚化反应所需的酸强度比酯化反应高。     

MoO3对HZSM-5分子筛酸性的影响

用浸渍法制备了不同MoO3担载量的Mo/ZSM-5分子筛催化剂,并利用XRD、BET和NH3-TPD及Py-IR等分析方法对催化剂进行表征.结果表明,担载了Mo后的Mo/ZSM-5分子筛在773K温度焙烧下,仍保持了ZSM-5分子筛骨架的完整性,Mo物种已进入分子筛孔道.随着Mo担载量的增加,Mo/ZSM-5分子筛的比表面和总酸量均下降.     

HZSM─5（55）对乙酸和异戊醇酯化反应催化活性的研究

以ＨＺＳＭ—５（５５）原粉为原料改性．６００℃焙烧的催化剂，对已酸异戊醇酯化反应有较好的催化活性和稳定性。其最佳反应条件为：温度：１３５～１４０℃；酸醇比：３；原料空速：２—３ｈ１－１．     

Beta和HZSM—5沸石上乙酸与正戊醇的催化酯化

在固定床反应器内，研究了乙酸和正戊醇在β和HZSM－5沸石上的酯化反应．实验表明，500℃焙烧的Hβ沸石对乙酸和正戊醇的酯化是最有效的催化剂．反应温度的最佳范围是140～150℃．更高的反应温度将导致催化剂活性和选择性的下降．酯化的选择性随酸／醇比（mol）及LHSV的增加而增加．对离子交换度及焙烧温度对沸石的表面性质及催化活性的影响进行了讨论．     

不同骨架硅铝比Y分子筛热改性过程的固体NMR表征

不同次邻近铝含量可导致改性后Y分子筛酸中心性质的较大差别，较高si／Al比Y分子筛焙烧脱羟时可能出现三配位铝．随骨架Si／Al比不同，Y型分子筛脱铝形成的非骨架铝性质也有所不同．以化学环境敏感的四极核Na一为探针，证实了改性产生的非骨架Al对骨架阳离子位的环境有较大影响，这可能是B，L酸协同作用后出现增强酸性的证据．     

ZSM-5型分子筛催化剂酸性质的研究

本文用Ｈａｍｍｅｔｔ指示剂法和吡啶中毒脉冲色谱法测定了ＺＳＭ－５型分子筛催化 剂的酸度和酸强度分布。选择了ＮＨ４离子最佳交换条件。考察了不同交换度、 ＮＨ４－型催化剂的焙烧温度和焙烧时间对山苯歧化反应性能的影响，并与酸度测定 结果相关联。 试验指出，随着ＮＨ４离子交换度的增加，酸性中心总数及强酸中心都增加， 反应活性不断提高，直至交换平衡。高温焙烧过程中有脱羟基和脱铝作用发生，致使 反应活性下降，对二甲苯选择性提高． 吡啶中毒试验证明了强酸中心有利于生成间二甲苯，弱酸中心有利于选择生成对 二甲苯。     

S2O8^2—／ZrO2固体超强酸催化剂上的正戊烷反应性能研究

考察了焙烧温度、活化温度等因素对S2O8^2-/ZrO2(PSZ)固体超强酸常温下催化正戊烷反应性能的影响，利用色谱－质谱（GC－MS）、傅里叶红外（FT－IR）、原位X－射线粉末衍射（XRD）、此表面测定（BET）、含硫量分析等手段研究了正戊烷反应产物、催化剂晶型变化及表面酸位类型等。结果表明，焙烧温度和活化温度是影响催反应活性的关键。焙烧温度在723－973K制备的PSZ固体超强酸催化剂，308K下对正戊烷均具有催化反应活性，823K焙烧样品活性最佳；对于最佳焙烧温度样品，活化温度在373－673K之间，均具有较高的反应活性，活化温度为523K时活性最佳。异构化表观活化能为41．7kJ/mol。整个反应大致可以分为3个阶段：反应初期，产物均为异戊烷，表明发生的是异构化反应；反应中期，异构化反应速率减低，产物中出现异丁烷，表明异构化反应和裂解反应同时发生；反应后期，异构化产物明显减少，异丁烷和己烷异构体明显增加，表明裂解反应已经取代异构化反应，成为反应的主流。适宜的焙烧温度使ZrO2晶化是形成超强酸的必要条件；合适的活化温度影响酸位类型，523K下活化的样品主要为强Bronsted酸位，同时有少量的强Lewis酸位存在。     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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