Analysis and proposition of limiting current density measurement protocol

Limiting current density at different temperatures, backpressures, and balance gases can be used to separate molecular diffusion resistance, Knudsen diffusion resistance and local transport resistance of membrane electrode assembly (MEA). However, the measurement of limiting current density has no unified protocol. The diverse choices in the literature, either in the control of current or voltage or in the atmosphere like relative humidity and O₂ concentrations, make it difficult to compare the results and identify the true bottleneck hindering the mass transport. In this work, the current-voltage curves obtained by current scanning/stepping and voltage scanning/stepping methods under dilute O₂ of different concentrations and a wide range of relative humidity were measured and analyzed systematically. It is found that the voltage stepping method is superior to the other three ways of control for the reliable determination of the limiting current density. Aided with simultaneous electrochemical impedance spectroscopy measurement, the limiting current density can be determined with pinpoint accuracy. When the limiting current density is just used to qualitatively evaluate different MEA, the voltage scanning method can be used instead for its high time efficiency. The selection of the atmosphere also plays an important role in suppressing the distortion from excessive water and reducing the spurious contribution from proton conduction resistance. It is found that O₂ concentrations at 0.5 vol% and relative humidity at 90% can give the best estimation of O₂ transport resistance in membrane electrode assembly.     

KOAc/NaY催化合成邻甲基苯甲醚

以KOA c/NaY为催化剂,在连续流动固定床反应器内,邻甲基苯酚(OC)与碳酸二甲酯(DMC)经过气固相催化反应合成了邻甲基苯甲醚(OM)。考察了内、外扩散对KOA c/NaY催化剂活性的影响。实验结果表明,当气流线速度大于30cm/m in时可消除外扩散对合成反应的影响;当KOA c/NaY催化剂的平均粒径在0.30~0.75mm(20~80目的颗粒)时能消除内扩散对合成反应的影响。在消除内、外扩散效应后,还考察了反应温度、原料配比、空速对合成反应的影响,得到较佳的反应条件:催化剂5mL,反应温度548K,反应压力0.6M Pa,空速0.6h-1,n(DMC)∶n(OC)=1,在线评价时间7h。在此条件下,OC的转化率高达85.7%,OM的选择性大于99%。     

微波干燥在气相超稳Y型分子筛制备中的应用研究

研究了微波干燥在气相超稳Y型分子筛制备中的应用。结果表明，分子筛经微波干燥后，其理化性质有所改善，结晶度提高，经气相超稳化反应后其产品结构及物化性质与传统电加热干燥后的气相超稳产品基本一致，说明微波干燥可替代传统干燥方式。与传统电加热干燥方式相比，微波干燥能缩短干燥时间，有效降低能耗。     

改进尿素包装工艺 不断提高产品质量

通过对尿素包装工艺的不断改进，提高了尿素粒度、减少粉尘含量，效果明显。     

合成直链烷基苯的锆磷铝固体酸催化剂 I.催化剂合成及其影响因素

合成了一系列用于苯与直链烯烃烷基化反应的含有杂原子的磷铝分子筛固体酸催化剂 (MeZrAPO 5 ) ,同晶取代磷铝分子筛骨架中磷和铝的杂原子包括锆和至少一种选自硅、硼、镓、锗、铁、镁、锡等的元素。考察了晶化温度、晶化时间、杂原子种类、铝源等因素对催化剂合成的影响 ,探索了合成样品中模板剂脱除的最佳条件。结果表明 ,晶化温度高于 15 0℃、n(TEA) /n(Al2 O3 )≥ 1 5以及加入Zr原子都有利于直接生成MeZrAPO 5晶相 ;用小晶粒和高结晶度的铝源合成时 ,分子筛的结晶度高。     

择形催化合成2,6-DMN的研究进展

介绍了2,6-二甲基萘(2,6-DMN)的制备方法,详细论述了萘、甲基萘在分子筛催化剂上择形催化合成2,6-DMN的研究进展,提出了择形催化合成2,6-DMN的研究方向。     

矩形垂直筛板的流体力学性能研究

在600mm的有机玻璃冷模塔中,用水-空气体系测定矩形垂直筛板的塔板压降、漏液和雾沫夹带等流体力学性能,确定了合理的塔板结构,使其具有较高的气液通量和较宽的操作范围,空塔动能因子最大可达3.0kg1/2(m1/2.s)-1,液流强度可达21.6m3/(m.h)。并对不同气液流量下塔板的流体力学实验数据进行关联和分析,得出了矩形垂直筛板的干板压降计算关联式以及漏液率随液流强度和空塔动能因子的变化关系,为矩形垂直筛板的设计提供了依据。与新垂直筛板相比,矩形垂直筛板具有更低的塔板压降。     

Numerical Study of a Modified Time-Stepping θ-Scheme for Incompressible Flow Simulations

In [Turek (1996). Int. J. Numer. Meth. Fluids 22, 987–1011], we had performed numerical comparisons for different time stepping schemes for the incompressible Navier–Stokes equations. In this paper, we present the numerical analysis in the context of the Navier–Stokes equations for a modified time-stepping θ-scheme which has been recently proposed by Glowinski [Glowinski (2003). In: Ciarlet, P. G., and Lions, J. L. (eds.), Handbook of Numerical Analysis, Vol. IX, North-Holland, Amsterdam, pp. 3–1176]. Like the well-known classical Fractional-Step-θ-scheme which had been introduced by Glowinski [Glowinski (1985). In Murman, E. M. and Abarbanel, S. S. (eds.), Progress and Supercomputing in Computational Fluid Dynamics, Birkh?user, Boston MA; Bristeau et al. (1987). Comput. Phys. Rep. 6, 73–187], too, and which is still one of the most popular time stepping schemes, with or without operator splitting techniques, this new scheme consists of 3 substeps with nonequidistant substepping to build one macro time step. However, in contrast to the Fractional-Step-θ-scheme, the second substep can be formulated as an extrapolation step for previously computed data only, and the two remaining substeps look like a Backward Euler step so that no expensive operator evaluations for the right hand side vector with older solutions, as for instance in the Crank–Nicolson scheme, have to be performed. This modified scheme is implicit, strongly A-stable and second order accurate, too, which promises some advantageous behavior, particularly in implicit CFD simulations for the nonstationary Navier–Stokes equations. Representative numerical results, based on the software package FEATFLOW [Turek (2000). FEATFLOW Finite element software for the incompressible Navier–Stokes equations: User Manual, Release 1.2, University of Dortmund] are obtained for typical flow problems with benchmark character which provide a fair rating of the solution schemes, particularly in long time simulations.Dedicated to David Gottlieb on the occasion of his 60th anniversary     

泥浆制备中工艺改造的研究

根据室条件下粉磨试验结果，发现球磨过程中筛上料变化存在的突变范围，提出两次加料一次加水可改变泥浆颗粒分布，并找出适宜的加料种类与时间。另外给予测粒度分布提供了宝贵的试验基础数据。     

雅克拉凝析气田高压脱水工艺的成功应用

雅克拉凝析气田位于新疆阿克苏境内，2005年11月29日建成投运的260×10⁴m³/d雅克拉集气处理站是目前中石化最大的高压凝析气处理装置。该站的高压分子筛脱水工艺为两塔流程，采用差压再生（吸附压力5.9 MPa、再生压力2.8 MPa）、再生气自动回收工艺技术，并采用时序控制程序自动切换，具有工艺简单可靠、自动化程度高、热能利用率高、脱水露点深度高、操作维护简单、投资较少、运行成本低等优点，自建成投产以来运行稳定，效果十分显著。该工艺装置的成功应用，对类似脱水装置设计、操作具有一定参考价值。