铜基催化剂孔隙率对气体有效扩散系数的影响

研究了18种具有不同孔结构参数的粒状铜基甲醇合成催化剂孔隙率对有效扩散系数的影响。结果发现，催化剂微孔孔隙率增大，曲节因子亦增大，扩散阻力增加。将孔隙率与催化剂曲节因子关联，得到了半经验方程，用它可估算催化剂的曲节因子。     

拟稳态法测定气相扩散系数

根据拟稳态一维扩散原理,建立了气相扩散系数的测定装置。在该装置上,测定了8个体系的气相扩散系数,其中CH_2Cl_2-空气,CH_2Cl_2-H_2,CH_3CH_2Br-空气,CH_3Cl_2Br-H_2,CHCl_3-H_2等5个体系的气相扩散系数实验值,迄今尚未见文献报道。实验结果表明,本测试装置稳定性好,实验误差小,实验装置体积小,测试过程较为简便。     

甲醇制烯烃反应SAPO-34催化剂积炭行为的原位漫反射红外光谱分析

依据酸性催化剂表面吸附态物种分子产生红外信号的机理,采用原位漫反射红外光谱技术对甲醇制烯烃反应中不同反应时间与床层位置的SAPO-34催化剂积炭行为进行研究。结果表明,反应时间与床层位置的变化对SAPO-34催化剂积炭数量和物种有显著影响。反应时间延长导致SAPO-34催化剂积炭量增加,且积炭成分中重组分稠环芳烃比例上升,积炭速率逐渐加快。积炭量随床层位置自上而下逐渐减少,失活催化剂笼中烷基芳香烃类积炭通过环化和脱氢逐渐转变为多环芳香烃类。     

沸石催化剂内液相交互扩散系数的测定

采用简单实用的试验方法研究了苯和异丙苯在沸石内的交互扩散情况,通过测定不同时间点的扩散质的浓度,利用适宜的数学模型和最小二乘法关联出两种体系中各扩散质在沸石催化剂内的交互扩散系数。可以为苯烷基化反应的工业模拟提供重要的基础数据。     

大孔结构重油加氢脱金属催化剂的制备、表征及重油在催化剂中有效扩散系数的求解

以大孔拟薄水铝石为原料,沥青残渣为造孔剂,经超临界干燥和焙烧得到催化剂载体,通过浸渍活性组分得到重油加氢脱金属催化剂并进行扩散实验。结果表明,制备条件对重油加氢脱金属催化剂的物性影响较大,通过对各种制备因素进行优化并对催化剂进行表征和扩散实验,进一步表明制备的催化剂具有较大的比表面积、孔容、适宜的孔分布及大孔结构,适合加工金属含量较高的原油,重油分子在添加造孔剂催化剂中的有效扩散系数变大。     

亚微米ZSM-5催化剂预处理及其在乙醇脱水过程中的积炭行为

在固定床反应器中考察了乙醇脱水反应中亚微米ZSM-5分子筛催化剂的预处理及积炭行为,采用热重(TG)、低温氮吸附、X射线荧光光谱(XRF)、X射线衍射(XRD)和核磁共振(NMR)等方法对催化剂进行表征。结果表明,催化剂在使用前活化时的焙烧温度以550℃为宜。催化剂在水蒸气预处理后,初始活性升高。随着质量空速的升高,初始乙醇转化率和乙烯选择性以及积炭量均有所降低;但质量空速过低时,催化剂活性降低很明显。原料乙醇中的水能降低催化剂的积炭量和积炭的不饱和度,可使催化剂脱铝增加约5%。随着催化剂颗粒粒径的减小,催化剂的活性增高,在粒径约为0.4 mm时,积炭量较低。     

原位水热合成法制备ZSM-5/堇青石整体式催化剂

以蜂窝状堇青石为载体,采用原位水热合成法制备了ZSM-5/堇青石整体式催化剂。考察了四丙基氢氧化铵(TPAOH)含量、水硅摩尔比和晶化温度等对ZSM-5分子筛在堇青石载体上负载量的影响。结果表明:模板剂TPAOH的含量对负载量有显著影响,当摩尔比n(TPAOH)/n(SiO2)≤0.2时,改变晶化温度和水硅摩尔比均可获得较佳的分子筛负载量;当n(TPAOH)/n(Si O2)0.2时,较高的碱度导致前驱体溶胶的溶解,使分子筛多在溶液中晶化,显著减小分子筛在堇青石载体上的负载量。当n(TPAOH)/n(Si O2)≤0.2时,水硅比减小,ZSM-5分子筛负载量逐渐增大,最大负载量可达42.8%。晶化温度降低,分子筛的负载量和晶粒均减小。整体式催化剂用于NO的催化氧化活性研究表明,堇青石载体上分子筛的负载量越高,整体式催化剂的比表面积越大,催化活性越好。     

协同调节ZSM-5孔结构及酸性制备高性能MTP催化剂

以水热合成法制备了结晶度良好的硼硅MFI沸石,对其进行碱处理并在此过程中添加Al³⁺以达到脱硼补铝的目的,得到具有不同孔结构和酸性质的多级孔分子筛。采用X射线衍射(XRD)、扫描电镜(SEM)、物理吸附和氨气程序升温脱附(NH₃-TPD)等手段对合成的分子筛进行了表征,并在固定床反应器中考评了分子筛样品催化甲醇制丙烯(MTP)反应的性能。结合MTP反应评价和反应后分子筛样品的热重分析,发现碱处理过程中选择适宜的NaOH浓度有利于丙烯选择性提高,同时降低积炭速率。实验结果表明：在甲醇空速为3 h^-1的条件下稳定运行600 h,甲醇转化率大于99%,丙烯选择性保持稳定,失活催化剂积炭量约为40%(质量分数),催化剂容炭能力良好。     

HZSM-5催化剂气相沉积改性及催化甲苯歧化抗积炭性能

为使HZSM-5具有较高的甲苯歧化催化活性,提高对二甲苯的选择性以及催化剂的抗积炭稳定性,采用钛酸四丁酯、正硅酸乙酯和亚磷酸二乙酯对HZSM-5催化剂进行化学气相沉积改性。分别采用红外光谱和吡啶程序升温脱附(TPD)表征了改性前后催化剂表面酸中心性质。实验结果表明,HZSM-5沸石气相化学沉积覆Ti、Si和P的氧化物后,表面酸中心类型和弱酸中心密度没有改变,强酸中心密度有所下降,其中化学气相覆P的HZSM-5酸中心强度明显增强。改性后的HZSM-5沸石用于甲苯歧化反应催化剂时,经过气相化学沉积覆Si和P的HZSM-5催化剂不仅能提高甲苯歧化催化活性,而且能够大幅度提高催化剂的抗积炭能力。     

阶跃与方波示踪法测量气体的有效扩散系数

建立阶跃与方波示踪测量气体有效扩散系数的实验装置,并提出了扩散系数计算中所涉及的超越方程特征根的求解方法。采用稳态法,脉冲、方波和阶跃示踪动态法测量气体的有效扩散系数,对以扩散池为主体的各种实验方法进行评价。实验结果表明,当颗粒内的孔隙主要由大孔构成时,各种方法所得结果相近。阶跃与方波示踪法可以可靠地用来测量气体的有效扩散系数。     

反应条件下多孔催化剂上有效扩散系数及曲节因子的分析计算

采用CDS－810微反系统,在实验条件为：常压、氢苯比3.0-8.0、温度363.15K-453.15K时,进行了在四种不同粒度Ni/Al2O3催化剂上的气相苯加氢反应,利用实验数据计算了不同反应组成、不同反应速率时苯的有效扩散系数、反应死区及催化剂的曲节因子。计算结果表明：有效扩散系数不随反应速率改变,多孔催化剂的曲节因子可以看作多孔催化剂的结构参数,不随反应条件变化。     

多孔固体催化剂的有效导热系数

建立了测定多孔固体催化剂骨架导热系数的实验装置和由此计算催化剂有效导热系数的简化方法，测定并计算了若干工业过程催化剂的有效导热系数，同时，计算了甲烷蒸汽转化催化剂的非等温效率因子。     

THE DESIGN OF VANADIUM TRAPPING SYSTEM FOR FCC CATALYSTS

The addition of distillation residues to the FCC feedstock leads to increased vanadiumloading on catalyst and the problems in catalyst deactivation.The deactivation process is related tothe destructive attack on the zeolite crystallite by V_2O_5.Formation of low melting pointV_2O_5-USY-Na_2O phases accelerates the diffusion of vanadium through the catalyst.A proposedmechanism,based on accelerated dealumination,is shown in the paper.Comparative vanadiumtrapping performances have been tested for FCC catalysts and the crystalline ABO_3 as an effectivevanadium trap is demonstrated in laboratory tests.     

测定多孔性固体催化剂颗粒有效导热系数的新方法

提出了一种测定空气中催化剂有效导热系数的方法。该方法简便、易行,实验误差小于5％.在此基础之上用woodside随机分布模型计算了反应条件下催化剂有效导热系数。误差分析表明：该模型误差较小,完全可以用于工程计算。     

A SIMPLIFIED MODEL FOR DETERMINATION OF MOISTURE DIFFUSIVITY OF DATE FROM EXPERIMENTAL DRYING CURVES

ABSTRACT

Experimental drying curves for Tunisia Deglet Nour dates were obtained in a laboratory dryer under different drying conditions The air temperature was varied from 30 to 69^°C, relative humidity from 11.6 to 47.1 % and air velocity from 0.9 to 2.7 m/s. A numerical method to obtain a solution of a diffusion equation in which the diffusivity depends upon temperature and moisture content has been proposed to investigate the moisture movement in a date by assuming the sample to be a homogenous infinite cylinder. To rind the fitting moisture and temperature dependent diffusivity, the calculated drying curves are compared with the observed drying curves and an empirical equation for the moisture diffusivity of the date has presented as a function of temperature and moisture. It has been shown that the moisture distribution in the date during drying can be obtained by using the empirical equation presented.     

异丁醛的新合成法

氧化物混合载体上的Ｖ＿２Ｏ＿５催化剂有效地促进了甲醇与乙醇合成异丁醛的反应。这是崭新的工艺路线，与传统的丙烯氢甲酰化路线相比，很有特点，是开发甲醇下游产品的候选项目，对制备甲基丙烯酸甲酯（ＭＭＡ）尤为重要，但有关的催化剂特征及其基础研究尚待加强。     

COMPOSITION AND QUALITY OF THE GASOLINE OBTAINED FROM SYNGAS ON Cr2O3-ZnO/ZSM5 CATALYSTS

The kinetic equations for the formation of the lumps of the gasoline produced (C₅⁺ fraction), paraffins (C₅-C₈), xylenes (o-xylene, m-xylene and p-xylene) and aromatics (benzene, toluene, C₉-C₁₁) in the transformation of syngas on Cr₂O₃-ZnO/ZSM5 bifunctional catalyst have been established as a function of the concentration of both reactants (CO and H₂) and CO₂ byproduct. The effect of the operating conditions on the RON and on the molecular weight of the gasoline has been studied by experimentation in an integral fixed bed reactor in the range between 10 and 50atm and between 300 and 425°C. The octane index increases with Cr/Zn atomic ratio of the Cr₂O₃-ZnO metallic function, with Si/Al ratio of the HZSM5 zeolite, with space time and with the CO/H₂ molar ratio in the feed, in that order, whereas it passes through a maximum with pressure (at 20 atm) and with temperature (at 375°C). On the other hand, the molecular weight of the gasoline increases with the Cr/Zn atomic ratio, pressure, CO/H₂ molar ratio and space time, and decreases with the Si/Al ratio and temperature.     

MEASUREMENTS OF EFFECTIVE DIFFUSIVITY IN LARGE-PORE PERMEABLE PELLETS WITH VARIOUS GEOMETRIES USING THE CHROMATOGRAPHIC METHOD

Mathematical models for solid cylinder and hollow cylinder pellets, where intraparticle convection was considered, have been established and solutions in the Laplace domain have been obtained. Consequently, the equivalence between the hollow cylinder and the slab characteristic dimensions was presented for the first-order-reaction/diffusion/convection problem. A modified chromatographic method has been developed to measure the intraparticle diffusivity in solid cylinder pellets. The axial dispersion of the column packed with the hollow cylinder pellets was measured and a correlation for the Peclet number versus Reynolds number has been obtained. Intraparticle convection has been measured with large pore sphere pellets which present a “foam structure” by using the conventional chromatographic method. Intraparticle Peclet numbers and the permeability of this pellet were determined.