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    Home > Chemicals Industry > New Chemical Materials > Transition metal oxide molecular sieve achieves effective separation at higher temperature

    Transition metal oxide molecular sieve achieves effective separation at higher temperature

    • Last Update: 2021-06-28
    • Source: Internet
    • Author: User
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      High-purity C 2 H 4 and C 2 H 2 are the most commonly used basic raw materials for synthetic chemicals in industry
    In the process of industrial production of ethylene, acetylene by-products will inevitably be produced.
    Even a small amount of acetylene can cause poisoning of the ethylene polymerization catalyst, and explosions in severe cases

    At the same time, ethane is also an unavoidable by-product in the process of industrial ethylene production.
    The relative volatility and boiling point of the two are also very close, and the traditional low-temperature rectification energy consumption is large

    Therefore, the separation of C 2 hydrocarbon gas mixtures such as C
    2 H 6 , C 2 H 4 and C 2 H 2 has always been a major challenge facing the chemical industry .
    Therefore, choosing an appropriate method to effectively separate the two is also a process worth exploring .


      Adsorption-based separation methods, such as adsorption separation and membrane separation, are effective methods to solve this problem because of their high efficiency and low cost
    In recent years, many researchers have developed different types of microporous materials such as metal organic framework materials (MOFs), zeolites and activated carbons for the separation of C
    2 hydrocarbons, and have achieved good separation performance at low temperatures
    However, the C
    2 H 4 production process requires high temperature, and the separation process at low temperature causes a lot of energy waste
    So far, there have been few attempts to separate C
    2 hydrocarbons at high temperatures
    And most of the separation temperature is not high enough

    Therefore, the development of porous materials for high-temperature separation of C
    2 hydrocarbons is very important

      Recently, the team of Professor Zhang Zhenxin and Li Yanshuo of Ningbo University reported that a kind of transition metal oxide molecular sieves (ZOMOs) based on ε-Keggin units, namely sodium cobalt molybdate (Na-CM), can be realized at higher temperatures.
    Effective separation of C
    2 hydrocarbons


      Figure 1.
    POM structure model based on ε-Keggin unit


      The material cavity (7.
    4 Å) is formed by connecting ten POM units, and the opening is only 3.
    4 Å, which
    is close to the size of C
    2 hydrocarbon gas
    This material has different adsorption properties for C
    2 H 6 , C 2 H 4 and C 2 H 2 , and has strong interaction with C 2 H 4 and C 2 H 2 , and has a high ideal solution adsorption theory ( IAST) selectivity


      Figure 2.
    Na-CM at 85℃, 100kPa, (a) C
    2 H 4 /C 2 H 6 , (b) C 2 H 2 /C 2 H 6 , (c) C 2 H 2 /C 2 H The breakthrough curve of 4 and (d) the corresponding gas breakthrough selectivity

      The material shows good performance in terms of repeatability, stability and separation performance.
    Dynamic competitive adsorption experiments show that the material can effectively separate C
    2 binary mixtures and even ternary mixtures, and has high selectivity
    When the temperature is increased to 85 ℃, the material can still maintain good separation performance


      This result was recently published on Angewandte Chemie International Edition.
    The first author of the article is Wang Jie, a master's student at Ningbo University


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