DIRECT OXIDATION OF ETHYLENE TO ACETALDEHYDE IN A HOLLOW FIBER MEMBRANE REACTOR†

A hollow fiber membrane reactor, which resembles a tube-and-shell heat exchanger, was developed for homogeneous catalytic reactions with gas reactants and products. The gas stream flows through the tube side while the reaction takes place in the catalyst solution which fills the shell side. The separation load of product from the catalyst solution can be reduced by using a hollow fiber membrane reactor instead of a conventional bubble column reactor. The reactor operates in a plug-flow pattern with a large mass transfer area per unit volume of catalyst solution

This concept was investigated experimentally using the direct oxidation of ethylene to acetaldehyde reaction in an aqueous solution of palladium (H) chloride-cupric chloride with a silicone rubber membrane reactor and a polypropylene membrane reactor. It was experimentally demonstrated that membrane reactors could achieve higher production rates per unit volume of catalyst than the conventional sparged reactor. The experimental data were in good agreement with the predictions by the mathematical model. The conditions under which the membrane reactor will be more advantageous than the conventional sparged reactors can be readily ascertained with the analytical solution of the simplified membrane reactor model.     

微孔无机膜反应器研究

主要介绍了无机膜在化学反应中的应用－－膜反应器研究，对膜反应器的特点、类型、应用、影响因素以及与其它反应器的比较进行了评述，并对其应用前景进行了展望。     

空心玻璃微珠复合聚氨酯泡沫的模塑成型收缩率

研究了用空心玻璃微珠复合聚氨酯泡沫塑料制成厚度不同、形状不同、结构不同的制品时模型成型的收缩率，以及在模塑成型过程中，熟化温度、熟化时间和熟化后在模具内保持的时间对模塑成型收缩率的影响。结果表明，制品模塑成型收缩率随着厚度的增加而增大；加入金属嵌件后可较大程度地限制制品收缩；当熟化温度高于100℃时，随着熟化温度的升高，制品收缩率增大。     

Preparation of a tubular palladium membrane by photocatalytic deposition

A novel photocatalytic deposition method for the preparation of a thin tubular palladium membrane is presented in this paper. The membrane is prepared on a porous asymmetric TiO₂ support by photocatalytic reaction of palladium ion, followed by electroless plating. Gas permeation results show that the membrane exhibits increased hydrogen permeance with the increase of temperature. The hydrogen permeance and selectivity to nitrogen at 773 K are about 1.43×l0⁻⁶ mol m⁻² s⁻¹ Pa⁻¹ and 17, respectively, when the pressure in the feed side is 0.1 MPa. The activation energy of hydrogen permeation is 11.06 kJ/mol at the temperature range of 573–773 K.     

Hollow fiber membrane contactor as a gas-liquid model contactor

Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfacial area. These features of the hollow fiber membrane contactor make it very suitable as a gas-liquid model contactor and offer numerous advantages over the conventional model contactors. The applicability and the limitations of this novel model contactor for the determination of physico-chemical properties of non-reactive and reactive gas-liquid systems are investigated in the present work. Absorption of CO₂ into water and into aqueous NaOH solutions are chosen as model systems to determine the physico-chemical properties for non-reactive and reactive conditions, respectively. The experimental findings for these systems show that a hollow fiber membrane contactor can be used successfully as a model contactor for the determination of various gas-liquid physico-chemical properties. Moreover, since the membrane contactor facilitates indirect contact between the two phases, the application of hollow fiber model contactor can possibly be extended to liquid-liquid systems and/or heterogeneous catalyzed gas-liquid systems.     

用于甲烷选择性氧化反应制甲醇的膜催化技术

研究了将甲烷选择性地一次氧化制取甲醇的膜催化技术。采用ZrO2－Y2O3陶瓷膜，在较温和的反应条件下（常压，460℃左右），可以将甲烷选择性地一次氧化成为甲醇。     

A paraffin-fueled SOFC system design and integration

This paper addresses an integrated design of paraffin-reformer, gas separations and the electricity production with a solid oxide fuel cell (SOFC). The overall design consists of three modules. First module is a system of paraffin reformer. In this module, the paraffin feed stream is to send to a steam-reformer. In the second module, the gas separations method illustrated is the combination of a methane-permeable membrane with a pressure-swing adsorption (PSA). In the third module, the purified hydrogen is fed to the SOFC unit. To be energy efficient, this paraffin-fueled SOFC system is designed with the consideration of heat integration. The intent of this paper is to provide a possible, alternative way of cogeneration systems for refinery and petrochemical plants.     

Mechanical properties of hybrid fiber-reinforced concrete at low fiber volume fraction

Concretes containing different types of hybrid fibers at the same volume fraction (0.5%) were compared in terms of compressive, splitting tensile, and flexural properties. Three types of hybrid composites were constructed using fiber combinations of polypropylene (PP) and carbon, carbon and steel, and steel and PP fibers. Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber-reinforced concretes. Among the three types of hybrids, the carbon-steel combination gave concrete of the highest strength and flexural toughness because of the similar modulus and the synergistic interaction between the two reinforcing fibers.     

催化-分离脱氢膜反应器的透氢性能研究

1 前言在化学化工领域中利用膜材料的选择性渗透和催化作用来改善反应性能正越来越受到人们的重视。与传统的颗粒状催化剂-固定床反应器体系相比较,膜催化反应器在质量传递、热量传递和活化反应物方面有较大的差异。例如,用传统的固定床反应器由于受热力     

高效快速纤维球过滤器的应用

介绍了纤维球过滤器的特点、工作原理及其在脱盐水装置中的应用效果。