催化剂颗粒撞击壁面的有限元分析

针对催化裂化过程中催化剂颗粒大量跑损的问题,采用有限元的方法建立了单颗催化剂颗粒撞击壁面的有限元模型,并运用Abaqus作为前处理器。催化剂颗粒是一种典型的脆性材料,在有限元模型中选取了相应的材料本构模型,模拟了不同参数(撞击形态、入射速度、入射角度)的催化剂颗粒撞击壁面的过程,建立了催化剂颗粒的质量损失与催化剂颗粒参数间的关系,并对模拟结果进行了分析。最后,根据数值模拟的结果,优化了催化剂颗粒的参数,提出了减少催化剂跑损的措施。研究结果表明,撞击过程中的不同催化剂颗粒参数对催化剂的磨损量会产生较大的影响,催化剂颗粒的磨损量随着入射速度和入射角度的增大而增大,当催化剂颗粒以45°的形态撞击壁面时,磨损量最小。     

High-throughput reactor system with individual temperature control for the investigation of monolith catalysts

A high-throughput parallel reactor system has been designed and constructed to improve the reliability of results from large diameter catalysts such as monoliths. The system, which is expandable, consists of eight quartz reactors, 23.5 mm in diameter. The eight reactors were designed with separate K type thermocouples and radiant heaters, allowing for the independent measurement and control of each reactor temperature. This design gives steady state temperature distributions over the eight reactors within 0.5 degrees C of a common setpoint from 50 to 700 degrees C. Analysis of the effluent from these reactors is performed using rapid-scan Fourier transform infrared (FTIR) spectroscopic imaging. The integration of this technique to the reactor system allows a chemically specific, truly parallel analysis of the reactor effluents with a time resolution of approximately 8 s. The capabilities of this system were demonstrated via investigation of catalyst preparation conditions on the direct epoxidation of ethylene, i.e., on the ethylene conversion and the ethylene oxide selectivity. The ethylene, ethylene oxide, and carbon dioxide concentrations were calibrated based on spectra from FTIR imaging using univariate and multivariate chemometric techniques. The results from this analysis showed that the calcination conditions significantly affect the ethylene conversion, with a threefold increase in the conversion when the catalyst was calcined for 3 h versus 12 h at 400 degrees C.     

In situ synthesis of carbon nanotubes on heated scanning probes using dip pen techniques

Carbon nanotubes (CNT) were synthesized on heated scanning probes and under ambient conditions without requiring Chemical vapor deposition (CVD) apparatus or process gases. In this study, dip pen nanolithography (DPN) techniques were utilized for deposition of catalyst precursors on the scanning probe tips in the form of aqueous solution of metal salts--prior to the synthesis of the CNT. A layer of fullerene (C(60)) of approximately 200 nm thickness was vapor deposited on the scanning probe tip prior to the deposition of the metal catalyst. During the in situ synthesis of the CNT on the scanning probes, the temperature of the heated scanning probes reached 350-400 degrees C. Hence the scanning probes were heated in an inert atmosphere to prevent potential oxidation of the deposited fullerene layer. The synthesized CNTs were subsequently characterized using SEM and Raman spectroscopy. The Raman spectroscopy showed peaks in the Radial breathing mode (RBM), as well as the defect (D) and graphitic (G) bands. The RBM peaks indicate that the single walled carbon nanotube (SWCNT) ranged in diameter from 0.9-1.5 nm. The peaks in the Raman spectra are indicative of SWCNT mixtures (metallic and semconducting) and possibly multiwalled carbon nanotube (MWCNT). Hence this process can be optimized to synthesize SWCNT of a specific chirality (metallic or semiconducting). This study differs from an earlier study reported in the literature involving synthesis of CNT on scanning probes where the process temperatures typically exceeded 700 degrees C, and resulted in synthesis of highly graphitic MWCNT (Sunden, et al., 2006).     

基于有限元法催化剂颗粒撞击壁面的数值模拟

为解决催化裂化装置中的许多构件因为催化剂颗粒长期不断冲击而导致失效等的问题,将有限元法应用到其模拟仿真中,分析了单颗催化剂颗粒参数(角度、速度、材料)对不同壁面材料的撞击而造成壁面磨损的影响,建立了催化剂颗粒撞击壁面的数值分析模型,研究了催化剂颗粒以不同的速度、撞击角度,以及不同的催化剂颗粒的材料撞击不同材料的壁面对壁面造成的影响,并分析了催化剂颗粒变形对壁面磨损的影响,根据计算的结果,对催化剂颗粒参数进行了优化控制,提出了减少催化剂颗粒变形和构件磨损的技术措施.研究结果表明,该方法能够使催化裂化装置长期安全稳定地运行.     

催化剂反应罐温度控制系统

针对催化剂反应罐温度控制的需要，研制了催化剂反应罐温度计算机控制系统。采用PC机、RS232／422通讯接口、SR53／SR73智能仪表，实现了对催化剂反应罐温度的实时检测、实时控制，为催化剂反应罐温度控制提供了一种有效、方便的自动化手段。     

Atomic-scale electron microscopy at ambient pressure

We demonstrate a novel nanoreactor for performing atomic-resolution environmental transmission electron microscopy (ETEM) of nanostructured materials during exposure to gases at ambient pressures and elevated temperatures. The nanoreactor is a microelectromechanical system (MEMS) and is functionalized with a micrometer-sized gas-flow channel, electron-transparent windows and a heating device. It fits into the tip of a dedicated sample holder that can be used in a normal CM microscope of Philips/FEI Company. The nanoreactor performance was demonstrated by ETEM imaging of a Cu/ZnO catalyst for methanol synthesis during exposure to hydrogen. Specifically, the nanoreactor facilitated the direct observation of Cu nanocrystal growth and mobility on a sub-second time scale during heating to 500 degrees C and exposure to 1.2 bar of H(2). For the same gas reaction environment, ETEM images show atomic lattice fringes in the Cu nanocrystals with spacing of 0.18 nm, attesting the spatial resolution limit of the system. The nanoreactor concept opens up new possibilities for in situ studies of nanomaterials and the ways they interact with their ambient working environment in diverse areas, such as heterogeneous catalysis, electrochemistry, nanofabrication, materials science and biology.     

ICP—OES方法测定RN型加氢催化剂中金属杂质含量

RN型加氢催化剂在石油化工领域有广泛应用,金属杂质含量的高低将直接影响催化剂的活性。本文建立了一种电感耦合等离子发射光谱法（ICP—OES）方法测定RN型加氢催化剂中Ca、Cu、Fe、Mg、Ti、Mn、K、Zn和Na金属杂质元素含量的分析方法。方法的测定范围在100mg／kg～10000mg／kg,加标回收率为90％～105％,相对标准偏差在10％以内。该方法操作简便,数据准确可靠,已应用于RN型加氢催化剂的日常分析中,精密度可满足对样品的分析要求。     

四丁基碘化胺相转移催化法合成苯甲酸苄酯

主要研究了由苯甲酸钠和氯化苄为原料,采用相转移催化法合成苯甲酸苄酯的酯化反应。通过几种催化剂的考察,筛选出合成苯甲酸苄酯反应性能较好的一种季铵盐类相转移催化剂为四丁基碘化铵((C4H9)4NI),同时考察了它的最佳反应条件。研究结果表明:在反应温度为110℃,苯甲酸钠与氯化苄摩尔比为1:1.3,反应时间2.5h～3.0h,催化剂用量为苯甲酸钠摩尔量的6%左右,pH为5～6的弱酸性时为最佳反应条件。四丁基碘化铵是季铵盐类相转移催化合成苯甲酸苄酯的较为理想的一种催化剂。     

利用全数字网络型热像仪对甲醇裂解器温度场的检测

本文用Research-N1型全数字网络型热像仪对裂解器内温度场进行检测研究。结果表明:由于裂解器催化室外壳阻挡废气的流动,使催化室后的温度和远离催化室底部处的温度较低,严重影响了甲醇的裂解效果。为裂解器的进一步改进提供实验依据。     

粉末X射线衍射法测定氢气还原的气相醛加氢催化剂

采用粉末X射线衍射鉴定氢气还原的气相醛加氢催化剂中晶体物相并应用Scherrer法定量测定铜的晶粒尺寸。其晶体物相鉴定结果为:石墨、氧化锌、铜。采用化学计量学峰形拟合的方法计算铜(111)晶面晶粒尺寸约为10.3 nm,测定数据能够满足气相醛加氢催化剂研发的要求。     

α-羟基丙酸乙酯的合成研究

以乳酸和乙醇为原料合成α-羟基丙酸乙酯。考察了几种催化剂对合成α-羟基丙酸乙酯的影响效果,同时对催化剂用量、原料配比、反应时间及温度对产品收率的影响进行考察。实验结果表明:以硫酸氢钠为催化剂,用量为3.0g,反应时间3h,反应温度120℃,物料比为1∶3,α-羟基丙酸乙酯的酯化率可达到86.6%,纯度为97.76%。说明该催化剂活性好,无污染,可作为催化合成α-羟基丙酸乙酯的良好的催化剂。     

Ethanolysis of soybean oil into biodiesel: process optimization via central composite design

A process for production of ethyl ester for use as biodiesel has been studied. The sodium hydroxide catalyzed transesterification of soybean oil with ethanol was carried out at different molar ratio of alcohol to oil, reaction temperature and catalyst amount for a constant agitation in two hours of reaction time. Central composite design and response surface methodology were used to determine optimum condition for producing biodiesel. It was found that ethanol to oil ratio and catalyst concentration have a positive influence on ester conversion as well as interaction effects between the three factors considered. An empirical model obtained was able to predict conversion as a function of ethanol to oil molar ratio, reaction temperature and catalyst concentration adequately. Optimum condition for soybean ethyl ester production was found to be moderate ethanol to oil ratio (10.5: l), mild temperature range (70°C) and high catalyst concentrations (l.0%wt), with corresponding ester conversion of 93.0%.     

催化用离心压缩机提高风量的改造

介绍了催化裂化用离心压缩机在主体不变的前提下，通过一系列改造实现加大风量和提高效益的情况。为催化裂化装置的改造提供了很好的借鉴。     

流动催化法制备碳纳米纤维工艺的研究进展

流动催化法是最有潜力实现碳纳米纤维工业化的生产方法。重点综述了在制备过程中温度、催化剂、载气及促进剂等因素对碳纳米纤维生长影响的研究进展,提出了综合优化各个反应参数的新思路以及该方法的未来发展方向。     

柴油机不同结构后处理系统试验研究

为了研究SCR催化剂载体之间的间隙和出口段的优化对整个催化器性能以及涡后参数的影响,进行了对比试验。结果表明:SCR催化剂载体之间的间隙对催化器的性能没有影响,出口端的优化可以降低SCR催化器压差约4.0kPa,但是对DOC压差和DPF压差影响不大;不同结构参数的催化器对废气量和涡后温度是没有影响的,但是催化器背压越大的涡后压力也较大。     

粉末X射线衍射法鉴定气相醛加氢催化剂中晶体化合物

采用粉末X射线衍射法鉴定了一种气相醛加氢催化剂中的晶体化合物,并应用化学计量学峰形拟合法和Scherrer法计算了其中氧化铜的晶粒尺寸。鉴定结果认为,气相醛加氢催化剂中的晶体为:石墨、氧化锌(PDF-#36-1451)、氧化铜(PDF-#45-0937或PDF-#48-1548)。氧化铜(111)晶面晶粒尺寸约为5.4nm。实验结果能够满足气相醛加氢工艺的要求。     

透射电子显微技术在RIPP炼油催化剂表征中的应用

利用透射电子显微技术对加氢催化剂以及积炭催化裂化催化剂进行了表征。扫描透射电子结合X射线能谱技术确定了氧化态加氢催化剂中的微粒为活性金属组分的适度聚集；能量过滤透射显微技术获得了积炭催化裂化催化剂的Al、C的元素分布像。     

Catalysts for the synthesis of alphaolefin oligomer

The polymerisation method in the production of alphaolefin oligomer rests on the catalyst selected, and certain conditions are given that the method should fulfil. After a brief examination of the results of three kinds of catalyst, the Friedels-Craft catalyst type is discussed in terms of production of medium, high and low viscosity alphaolefin oligomers.     

三元催化器损坏的批量分析

随着三元催化器在乘用车上的广泛使用,三元催化器引起的车辆后处理系统故障并不鲜见。本文通过与整车厂合作,批量分析了售后市场返回的135件三元催化器故障件,对故障类型进行分类后,有针对性的对部分故障零件进行了实验室分析。证明了三元催化器的损坏主要来自催化器封装缺陷、中毒和高温失火。其中催化器中毒和高温失火烧熔在前级催化剂较容易发生,而后级催化器的损坏大多来自封装缺陷造成的机械损坏。     

An investigation of reaction progression through the catalyst bed in methanol autothermal reformation

This study investigates autothermal reforming of fuel cell-grade methanol as a method for producing hydrogen for transportation applications. A previous study on the effects of oxygen-to-carbon ratio on ATR reactor performance showed that the optimum of O₂/CH₃OH=0.30 found in the experimental tests is 30% higher than the theoretical optimum of 0.23. In this study, the influence of catalyst bed length is investigated to give insight into the reaction progression through the catalyst bed in methanol autothermal reformation. The effect of reaction progression through the catalyst bed is experimentally investigated in relation to reactor output parameters of fuel conversion, temperature profile, and reactor efficiency. The results from this study serve as a baseline for future research of autothermal reforming of hydrocarbon fuels as a method for producing hydrogen.