铜基催化剂催化合成气一步合成甲醇和甲酸甲酯IV.空速、反应时间、杂质和Cu-Cr摩尔比的影响(英文)

在低温低压和浆态反应条件下,考察了空速、反应时间、杂质及Ｃｕ－Ｃｒ摩尔比对铜基催化剂催化合成气一步合成甲醇和甲酸甲酯反应的影响。实验结果表明,空速对催化剂活性有较显著的影响;ＣＯ转化率与反应时间无关,但Ｈ２的转化率与反应时间有关。在１５小时之内Ｈ２的转化率随反应时间增加而缓慢增加,此后与反应时间无关。此外,高浓度的杂质使催化剂的活性和寿命下降,而且Ｃｕ／Ｃｒ摩尔比和热处理气氛对催化剂的物相和活性也有显著的影响。     

电子束在等离子体微波器件中的脉动

 对填充等离子体漂移空间小脉动电子束进行了近似分析,对大脉动电子束进行了较精确的计算,结果表明虽然α区和β区束的脉动性能各不相同,但幅度和波长均受限于电子入射的初始条件和等离子体参数,当其它条件给定后存在一最佳等离子体填充密度。     

合成气低温液相催化制甲醇和甲酸甲酯铜基催化剂体系研究 Ⅰ.氯化亚铜催化剂体系中各种因素的影响

合成气低温液相催化制甲醇和甲酸甲酯铜基催化剂体系研究 Ⅰ.氯化亚铜催化剂体系中各种因素的影响     

铜基催化剂催化合成气一步合成甲醇和甲酸甲酯 I.温度和压力的影响(英文)

考察了在低温、低压和浆态反应条件下,由合成气一步直接合成甲醇和甲酸甲酯（ＭＦ）的反应和催化剂。结果表明,不同方法制各的Ｃｕ基催化剂具有不同的催化活性和甲酸甲酯选择性。采用络合沉淀法（ＣＰ）制备的催化剂具有较高的催化活性和ＭＦ选择性。温度和压力对催化剂的活性和ＭＦ选择性具有明显的影响。Ｃｕ－Ｃｒ催化剂的活性随温度和压力的增加而增加,其选择性随温度的升高而降低,随压力的升高而增加。     

密度泛函方法研究HS2X的稳定构型

采用量子化学中的密度泛函理论(DFT),在B3LYP／6-311 G(3df,2p)水平上全优化得到了单卤代二硫烷HSSX(X-H,F,Cl,Br)链型和分叉型两种异构体的平衡结构。计算结果表明．在热力学上,所有链型的HSSX为稳定构型．其能量分别较分叉型构型低109．8、60．2、74．8和73．1kJ／mol。同时,采用统计热力学方法,研究了两种平衡结构之间相互转化的化学热力学性质,发现异构化反应的平衡常数很小。     

低压供热涂层材料制备及热性能研究

低压供热技术具有安全系数高和节能降耗等优势,因而成为石化稠油长输管线、风力发电叶片冬季防覆冰和室内供暖等领域的研究热点之一。本文制备了一系列低压供热涂层材料,研究不同碳功能填料对涂层发热速率、发热功率及最高发热温度的影响规律,并揭示石墨烯和碳纤维对提升涂层材料热性能的协同作用。其中石墨烯纳米片的还原程度对材料热性能具有重要影响,降低其表面官能团密度对提升涂层供热特性具有促进作用,但是官能团密度过低会导致石墨烯纳米片的聚团现象,引起涂层发热不均匀。加入适量碳纤维可以提高石墨烯的均匀分散性,提升发热速率。优化石墨烯纳米片和碳纤维的比例后,采用24V电压驱动时,涂层材料的发热速率达到7.1℃s-1,功率密度为800Wm-2,最高发热温度为124℃。     

The influence of unipolar axial magnetic field on the behavior of vacuum arcs

The behavior of vacuum arcs under the influence of unipolar axial magnetic field (AMF) has been investigated. In experimental investigations, the vacuum arc mode is studied at different arc currents by using high-speed charge-coupled device (CCD) video images. In spite of the AMF, first sign of arc constriction appears at relatively small currents of about 15 kA (RMS). Three different arc modes were found. Based on generalized Ohm's law, the current density distribution in the vacuum arc with unipolar axial magnetic field is computed using three-dimensional finite-element method (FEM) software. The calculated current distribution is confirmed by the vacuum arc appearance taken from CCD video film. The distribution of AMF can be optimized by such experiments and theoretical analysis.     

Aerogel nanoarchitectonics based on cellulose nanocrystals and nanofibers from eucalyptus pulp: preparation and comparative study

Cellulose - Nanocellulose-based materials have attracted significant attention because of their attractive advantages. Particularly, aerogel, a porous nanocellulose material, have been used in...     

Spontaneous initiation and development of hydrogen–oxygen detonation with ozone sensitization

This work studies numerically the spontaneous initiation and sustenance of a detonation wave from a hot spot with a nonuniform initial temperature embedded within an H₂O₂ mixture with and without O₃ addition. For the case with either no or just a small amount of O₃ addition, a weak reaction wave is auto-ignited at the hot spot, accelerates and then transitions to a pulsating detonation, which propagates along the temperature gradient and quenches as it runs into the cold fresh mixture. However, with increasing O₃ addition, the possibility of sustenance of a developing detonation within the gradient is significantly enhanced as it enters the cold mixture. Furthermore, the reduced induction time by O₃ addition leads to earlier appearance of the spontaneous reaction wave and detonation formation in the cold mixture, demonstrating that quenching of the detonation is largely related to the instability property of the mixture because the shortened induction time reduces substantially the instability. It is also noted that, for 5%O₃ addition, a low-temperature flame produced by the O₃ reactions is present in front of the spontaneous reaction wave, inducing a local pressure wave, which facilitates spontaneous initiation and sustains the detonation entering the cold mixture. Moreover, O₃ addition renders the critical temperature to induce the minimum spontaneous wave speed higher than the crossover temperature, while they are very close for the case without O₃.     

Particle-in-Cell Simulation of the Focusing Properties of High Energy Electron Beam in Plasma Ion Channel

The focusing properties of high energy electron beam in ion channel is investigated in the paper. The collisions of electrons with the neutral gas and the ionization resulted are considered to study the formation of ion channels with PIC method. The effects of various parameters on the beam focusing are analyzed.