【Haichuan Chemical Industry Insights】Zhejiang University has developed microporous polymer materials for separating acetylene and ethylene ions
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This post was last edited by Desert Fish on 2020-6-24 at 19:32. The research team led by Professor Xing Huabin from Zhejiang University has developed a series of high-performance ion-exchange microporous polymer materials for the separation of acetylene and ethylene. Recently, the research team led by Professor Xing Huabin from Zhejiang University created a series of high-performance ion-exchange microporous polymer materials intended for the separation of acetylene and ethylene. The micropores in these polymer materials are larger than acetylene molecules but smaller than ethylene molecules. Therefore, acetylene can be adsorbed. Furthermore, the anions in polymers can interact strongly with the more acidic acetylene molecules, while having weaker interactions with the more basic ethylene molecules. These two factors result in an acetylene-ethylene selectivity of up to 474.4 for the ionic microporous polymer material, which is the highest value to date. The relevant results have been published in Advanced Materials.
Ethylene is an important petrochemical product, with global annual production exceeding 170 million tons in 2016. Ethylene produced by the cracking of hydrocarbons inevitably contains a small amount of acetylene. However, these acetylenes cause problems in the subsequent production of polyethylene by deactivating the polymerization catalyst and reducing the quality of polyethylene. Therefore, it is of great significance for chemical production to develop efficient and stable materials capable of separating acetylene from ethylene. However, separating ethylene from acetylene is not an easy task. This is because ethylene and acetylene have similar molecular structures and physical and chemical properties. However, the kinetic diameter of ethylene is 0.863 ? larger than that of acetylene, and it has greater basicity. These two differences in properties make it possible to separate them.
Taking the polymer P(Ph-3MVIm-Br) as an example, these microporous polymers exhibit excellent gas adsorption selectivity. The authors confirmed the monomer structure using solid-state 13C NMR (Figure 2a). After the polymerization reaction, P(Ph-3MVIm-Br) formed a spherical powder morphology with a diameter of several hundred nanometers (Figure 2b). Physical adsorption experiments of CO2 showed that P(Ph-3MVIm-Br) is rich in micropores, with pore sizes concentrated between 3.24 Å and 7.60 Å (Figure 2c). These micropores allow CO2 molecules to enter, but N2 molecules with a larger kinetic radius are difficult to adsorb in large quantities (Figure 2d). The selectivity of gas adsorption lays the foundation for separating acetylene and ethylene.
Molecular simulations have also confirmed the selectivity of polymer materials for gases. After exploring the pores of P(Ph-3MVIm-Br) using molecules with a molecular size of 1.20 ?, it was found that most of the pores were interconnected (Figure 3a). The pores of P(Ph-3MVIm-Br) are completely impermeable to molecules with a size of 1.55 Å (Figure 3b), indicating that such molecules cannot pass through the channels between the pores. The simulation results further indicate that pores are present in the polymer due to intermolecular and intramolecular cross-linking, forming charged ion cages for anions and polymer chains (Figure 3c). These pores allow acetylene to enter, and the ion cage interacts strongly with acetylene, thereby increasing its adsorption capacity.
It is not yet clear what applications this research has in practice
Zhejiang University is quite strong in this area
In the future, industrialization could replace C2 hydrogenation reactors.
If this is such a remarkable breakthrough, I look forward to its practical application