ADN在Pd-Zn体系中的催化分解研究

二硝酰胺铵(ADN)是一种无毒高比冲的单组元推进剂。实现ADN水溶液的高效催化分解对于推力器启动和产生稳定推力起着至关重要的作用。文中采用浸渍法制得不同质量比(10∶0.2,10∶1,10∶5)的Pd-Zn/Al_2O_3双金属催化剂。利用TGA-DTA和MS-online对相关的催化分解动力学和反应机理进行了研究,同时使用TEM等对催化剂形貌进行了表征。结果表明,Pd-Zn/Al_2O_3双金属催化剂能够实现ADN的一步分解,微量Zn的加入能起到稳定和分散金属Pd的作用。当Pd和Zn的质量比为10∶0.2时,催化剂具有良好催化活性和稳定性,并且使二硝酰胺铵(ADN)催化分解向生成较高N_2含量的方向进行。     

低温启动单组元凝胶LLG-1热危险性研究

为了研究运输、贮存过程中低温启动单组元凝胶LLG-1的热危险性,利用差示扫描量热仪DSC及高性能绝热量热仪PHI-TECⅠ对其进行测试。测试结果表明,低温启动单组元凝胶LLG-1的比放热量为2 288.10±53.44 J·g^-1,采用Ozawa法计算得到其活化能为49.05 kJ·mol^-1,利用DSC测试方法及理论计算,得到的热爆炸临界温度过低,有悖于现实,表明该测试方法不适用。后利用加速度绝热量热仪PHI-TECⅠ对该物质进行测试,得到了该物质在实际贮存容器中的活化能为162.67 kJ·mol^-1,长期贮存自加速分解温度SADT=365.4 K。并将其自加速分解温度与相同条件下测试得到的单推-3自加速分解温度进行了对比,结果表明其自加速分解温度高于单推-3自加速分解温度,LLG-1热安全性优于单推-3。     

甲醇催化分解反应的研究

应用气固催化反应装置，进行甲醇催化分解反应的研究。当使用Ｃｕ－Ｚｎ－Ｃｒ及Ｎｉ－Ｋ／Ａｌ２Ｏ３催化剂时，反应温度为３００℃，气体空速为４８９．２ｈ－１，催化剂粒度为１６目时，甲醇分解率分别为４８．２％和５０．９％。讨论了各种反应条件对活性的影响     

甲苯二氨基甲酸甲酯催化分解反应的研究

对甲苯二氨基甲酸甲酯（TDC）热分解制备甲苯二异氰酸酯（TDI）进行了研究,考察了溶剂、温度、压力、催化剂浓度及热载体和催化剂重复利用对TDC液相分解性能的影响。最佳反应条件为：邻苯二甲酸二辛酯（DOP）为溶剂,反应温度260℃,反应压力5.4 kPa,冷凝柱顶温度165℃,TDI的最高收率为99%;邻苯二甲酸二辛酯、...     

轻烃催化裂解制低碳烯烃反应规律与原料特征化

利用小型固定床实验装置对比研究了轻烃模型化合物的催化裂解性能,从优到劣的顺序依次是正构烯烃、正构烷烃、环烷烃、异构烷烃、芳香烃。正构烷烃、异构烷烃与环烷烃催化裂解的总低碳烯烃收率有较大差别,但是总低碳烯烃选择性却均在56.57%左右。研究了直馏石脑油的催化裂解性能,发现乙丙烯收率和总低碳烯烃收率随反应温度的升高及重时空速的降低而逐渐增大;在反应温度680℃、重时空速4.32 h^-1和水油稀释比0.35的条件下,乙丙烯收率35.87%（质量）,总低碳烯烃收率为41.94%（质量）。针对轻烃催化裂解提出了原料特征化参数KF,它是原料H/C原子比、相对密度与分子量的函数,能较好地表征轻烃原料的催化裂解性能。     

高温液态水中木糖无催化分解反应动力学

The kinetics of non-catalyzed decompositions of xylose and its decomposition product furfural in high temperature liquid water （HTLW） was studied for temperature from 180 to 220℃ and under pressure of 10MPa. The main products of xylose decomposition were furfural and formic acid, and furfural further degraded to formic acid under HTLW condition. With the assumption of first order kinetics e.quation, the evaluated activation energy of xylose and furfural decomposition was 123.27kJ·mol^-1 and 58.84kJ·mol^-1, respectively.     

Pd/AC催化剂催化分解甲酸反应条件的研究

采用水浴振荡法,研究了振荡速度、催化剂粒径、催化剂用量、反应温度、反应时间等因素对Pd/AC催化剂催化分解甲酸活性的影响,得出了Pd/AC催化剂催化分解甲酸的优化条件。结果表明,在振荡速度为200 r/min、内/外扩散影响消除的条件下,将1.0 g150~180μm的Pd/AC催化剂与100 mL浓度为0.1 mol/L的甲酸水溶液进行分解反应,发现最佳反应温度为80℃,反应时间为60 min,Pd/AC催化剂催化分解甲酸的分解率可达到95%,在此优化条件下,Pd/AC催化剂对含甲酸的工业废水的分解率达80%。     

Pd/AC催化剂催化分解甲酸反应条件的研究

采用水浴振荡法,研究了振荡速度、催化剂粒径、催化剂用量、反应温度、反应时间等因素对Pd/AC催化剂催化分解甲酸活性的影响,得出了Pd/AC催化剂催化分解甲酸的优化条件.结果表明,在振荡速度为200 r/min、内/外扩散影响消除的条件下,将1.0 g 150～180 μm的Pd/AC催化剂与100 mL浓度为0.1 mol/L的甲酸水溶液进行分解反应,发现最佳反应温度为80℃,反应时间为60 min,Pd/AC催化剂催化分解甲酸的分解率可达到95%,在此优化条件下,Pd/AC催化剂对含甲酸的工业废水的分解率达80%.     

Pd/C催化剂催化分解甲酸反应动力学研究

采用湿空气氧化法研究了常压下Pd/C催化剂催化分解甲酸的反应动力学。建立了甲酸催化分解反应速率经验方程,Pd/C催化分解甲酸在323～363K范围内表观活化能为22.1kJ·mol-1。     

AgCl/H-ZSM-5催化分解NO反应及失活机理

采用水热分散法制备了AgCl/H-ZSM-5催化剂，并对其催化分解NO的反应进行了研究。运用X-射线衍射（XRD）、固体魔角旋转核磁共振（MASNMR）和能量色散X-射线微区分析（EDAX）对Ag-Cl/H-ZSM-5催化剂进行表征，着重阐明AgCl/H-ZSM-5催化剂在NO分解反应过程中活性相、载体的结构变化与催化分解NO反应活性的关系。     

Transport phenomena in packed bed reactor technology for chemical looping combustion

Chemical looping combustion (CLC) is potentially the technology best suited for capturing CO₂ at low cost and efficiently providing a low energy option for the separation of CO₂ from flue gases. The process consists in the cyclic reduction and oxidation of metal oxide particles, which act as oxygen carriers. The particles are exchanged between two reactors, usually a circulating fluidised bed and a bubbling bed reactor, where the oxidation and reduction reactions occur, respectively. Noorman et al. (2007) explored a dynamically operated packed bed for CLC technology. Successive work undertaken by the same group (Noorman et al., 2009) has shown the feasibility of the concept, and expressions for the mass and heat front velocities were determined. In this work, the oxidation of the packed bed reactor is analysed as a problem presenting discontinuities which are sustained by transport processes and are indistinguishable from phase interfaces. Travelling mass and heat fronts arise as a consequence of the reaction kinetics; a specific problem is analysed, where the oxidation is modelled similarly to an adsorption problem and the mass front velocity is calculated for some limiting transport conditions. It is shown that the mass front velocity arises naturally when the Kotchine's procedure (Astarita and Ocone, 2002) is applied to the system. An interesting feature of the analysis presented here is that some general results can be obtained without making any specific assumption about the kinetics. The results obtained are indeed amenable to be extended to other processes where the reacting material is a bed of solid particles. The treatment presented can be implemented when small perturbations occur in the bed, thus giving useful information on predicting whether the unwanted changes in the process conditions are sustained or die out.     

Chemical reaction engineering in the chemical processing of metals and inorganic materials

The advances made in the field of chemical engineering as applied to the processing of metals and other inorganic materials are reviewed. The reactions involved in this field are heterogeneous in nature, the fluid-solid noncatalytic reactions being the most important group of examples. In these heterogeneous reactions, interfacial chemical reactions are always accompanied by the transfer of mass and heat between the reaction interface and the bulk fluid. The interplay of these steps determines the overall characteristics and analysis of the reaction rate. The review examines the developments in the quantitative rate analysis of various fluid-solid reaction systems. Examples are largely drawn from the work of the author and coworkers, which has led to the formulation of the Law of Additive Reaction Times and its application to a wide range of fluid-solid reactions. The serious effects of thermodynamics on fluid-solid reaction with small equilibrium constants, in terms of the overall rate and the falsification of activation energy, have been examined based on a careful quantitative analysis.     

CFD modeling of the effect of absorbent size on absorption performance of a packed bed column

This paper reports a study on the ability of the computational fluid dynamics (CFD) modeling for analyzing the fluid flow hydrodynamics and absorption in a packed bed column. The water absorption by silica gel absorbents in an experimental packed bed was investigated, and the absorption performance of two different sizes of absorbent was studied. A series of experiments were carried out for five setups which are different in the weight ratio of the employed big to small absorbents. The CFD modeling was carried out for all five experimental setups. The predicted results show that by more replacing of the big absorbents with the small ones the water absorption increased. On the other hand, a greater pressure drop was observed as more small absorbents were used. The predicted absorption rates were compared with the measured values and on average a consistency within 11.6% was observed.     

Modelling of packed bed membrane reactors for autothermal production of ultrapure hydrogen

The conceptual feasibility of a packed bed membrane reactor for the autothermal reforming (ATR) of methane for the production of ultrapure hydrogen was investigated. By integrating H₂ permselective Pd-based membranes under autothermal conditions, a high degree of process integration and intensification can be accomplished which is particularly interesting for small scale H₂ production units. A two-dimensional pseudo-homogeneous packed bed membrane reactor model was developed that solves the continuity and momentum equations and the component mass and energy balances. In adiabatic operation, autothermal operation can be achieved; however, large axial temperature excursions were seen at the reactor inlet, which are disadvantageous for membrane life and catalyst performance. Different operation modes, such as cooling the reactor wall with sweep gas or distributive feeding of O₂ along the reactor length to moderate the temperature profile, are evaluated. The concentration polarisation because of the selective hydrogen removal along the membrane length was found to become significant with increasing membrane permeability thereby constraining the reactor design. To decrease the negative effects of mass transfer limitations to the membrane wall, a small membrane tube diameter needs to be selected. For a relatively small ratio of the membrane tube diameter to the particle diameter, the porosity profile needs to be taken into account to prevent overestimation of the H₂ removal rate. It is concluded that autothermal production of H₂ in a PBMR is feasible, provided that the membranes are positioned outside the inlet region with large temperature gradients.     

Visualization of water vapour flow in a packed bed adsorber by near-infrared diffused transmittance tomography

This work presents a procedure based on spatially-resolved near-infrared imaging, in order to observe temperature and composition maps in gas–solid packed beds subjected to effects of aspect ratio and non-isothermal conditions. The technique was applied to the water vapour flow in a packed bed adsorber of low aspect ratio, filled with silica gel, using a tuneable diode laser, focal planar array detector and tomographic reconstruction. The 2D projected images from parallel scanning permitted data to be retrieved from the packing and above the packing sections of 12.0×12.0×18.2 mm³ at a volume-resolution of 0.15×0.15×0.026 mm³ and a time-resolution of less than 3 min. The technique revealed uneven temperature and composition maps in the core packed bed and in the vicinity of the wall due to flow maldistribution. In addition, the heat uptake from the packed bed and local cross-mixing were experimentally ascertained by local profiles of the water vapour composition and temperature under various aspect ratios and feed flow rates. The relative deviations in temperature and compositions were 11.1% and 9.3%, respectively. The deviation in composition, which covers the packing and above the packing sections, was slightly higher than the deviation of 8% obtained up-to-date but was limited to the exit of a packed bed adsorber.     

Anaerobic catalytic oxidation of hydrocarbons in moving heat waves. Case simulation: Propane oxidative dehydrogenation in a packed adiabatic V-Ti oxide catalyst bed

The model simulation study has shown that the anaerobic process of oxidative dehydrogenation of propane under periodic alteration of feeding between propane and air may be realized in adiabatic catalyst beds in a stable continuous cyclic mode in a two-reactor scheme. In the case of an appropriate choice of process parameters (cycle duration and feeding flow rates) the process appears to be autothermal, i.e. it does not require any inlet gas preheating for stable operation. Compared with a similar steady-state adiabatic process, the proposed process is characterized with much lower maximum catalyst temperatures, giving the way to process pure propane without diluting it with inert gases, thus simplifying the downstream procedure of product separation. Predicted propylene yield is competitive with the one for the steady-state adiabatic process, while sufficient technological benefits of the new technology are expected (decrease in energy consumption and minimization of heat-exchange environment, process safety improvement, suppression of coke formation and efficient coke incineration).     

旋转填充床内微观混合化学反应计算数学模型

在层状扩散模型的基础上, 以1-萘酚与对氨基苯磺酸重氮盐在旋转填充床内发生的竞争串联偶氮化合反应为例，探讨了填充床内的微观混合情况.引进了两个调整反应物与生成物关系的参数，对整个反应过程建立了一个计算数学模型;并进行了计算，计算预测的结果与实验数据在规律上和数值上都较好符合.     

石灰石分解反应的等温热重法研究

利用等温热重法结合多因素方差分析,研究温度、CO2浓度、升温速率、颗粒尺寸四种因素对石灰石分解的影响.研究表明,温度和环境中的CO2浓度是影响石灰石分解反应时间的主要因素,与其二者相比,升温速率和颗粒尺寸的影响则可忽略不计;随着温度的升高,CO2对反应时间的延长效应逐渐减弱,950℃时,20％浓度外输CO2气氛下石灰石的分解反应时间与0％浓度外输CO2气氛下几乎相等;升温速率和颗粒尺寸的影响作用主要表现在对分解前诱导时间的影响.     

Stability analysis of structured chemical engineering systems via decomposition

The stability properties of highly dimensional chemical engineering systems are investigated using a decomposition method and vector Lyapunov functions. Finite stability regions are found for sequences of three and sixteen stirred tank reactors within which a first order exothermic reaction occurs. The stabilty region is of a shape one would expect intuitively on the basis of the sequential structure of the system and of a much larger size than was previously reported in the literature. The computational effort involved is negligible. In addition bounds on the input fluctuations are developed for which the system is stable. These input-output stability criteria can generally not be obtained from a direct application of Lyapunov's theory and appear to be of practical interest.