Chinanews.com, Hangzhou, December 12 (Tong Xiaoyu, Ke Yineng, Wu Yalan) On December 15, the reporter learned from Zhejiang University that the school's scientific research team has developed a new anionic functionalized porous material ZU-12, which realizes the accurate screening of propylene and propane and the high propylene diffusion rate by adjusting the orifice size and pore cavity size.
Diagram of the local sieving pore structure, propylene diffusion coefficient and energy consumption of propylene separation of molecular sieve material ZU-609 (from pressure swing adsorption simulation calculation). Courtesy of Zhejiang University
It is reported that the relevant paper was published online in the form of "First Release" on December 2023, 12, Beijing time.
Propylene is one of the world's largest chemical products and an important basic chemical raw material. However, in industrial production, propylene and propane are only two hydrogen atoms apart, and the size is very similar, so it is difficult to separate them simply. The journal Nature has pointed out that the development of energy-efficient olefin/alkane separation technology has been hailed as one of the seven chemical separation processes that can change the world.
Based on this, the team of Professor Xing Huabin and Yang Lifeng of the School of Chemical Engineering and Biological Engineering of Zhejiang University and Hangzhou International Science and Technology Innovation Center began to tackle technical problems.
Molecular sieve is a key mechanism to achieve high selectivity for the identification of substances similar in size. The basic principle is that only molecules smaller than the sorbent orifice are allowed to enter the pore, and larger molecules are blocked.
The theory is perfect, the reality is cruel. Because the narrow pores will limit the diffusion of molecules in the interior, molecular sieve materials have long faced problems such as poor diffusion mass transfer, low adsorption capacity, and difficult desorption, which seriously affect the separation efficiency.
"In order to increase the passage rate of olefins, high temperatures are often used in industry to 'drive' the gas and 'run' faster." Xing Huabin said, but this method reduces the working capacity of the adsorbent and increases the energy consumption of the separation process, which is not conducive to the large-scale promotion of industry.
How to achieve rapid material transfer in a limited space, that is, the problem of "limited diffusion and mass transfer" in chemical engineering, has always been a cutting-edge research field. Xing Huabin said that the precise separation of olefins/alkanes in small bottles and tanks in the laboratory may not be effective when placed in the equipment of hundreds of square meters and thousands of square meters in the factory, so making the separation process "faster" is a key technical challenge to improve the efficiency of the chemical process, which is of great significance for industrial applications.
As a result, researchers from Zhejiang University have developed a fast, efficient and low-carbon molecular sieve material ZU-609 under precise control. Through the precise control of the orifice, this new molecular sieve material only allows propylene molecules to enter, blocking the passage of propane molecules, so as to achieve fast and accurate identification.
In order to make the separation process faster, the researchers of Zhejiang University adopted a "small at both ends and a large middle" screening channel, with "isolation piers" at the inlet and outlet of the channel to block propane molecules, and after propylene entered, it could quickly pass through the "middle wide" pores, and the diffusion coefficient was increased by 1-2 orders of magnitude compared with the previous molecular sieve materials.
"The new molecular sieve we developed can not only quickly pull the propylene molecules passing through it, but also quickly let go, which lays the foundation for efficient and low-carbon separation of propylene." Yang Lifeng said.
The results of pressure swing adsorption calculations show that the energy consumption of ZU-609 propylene separation is reduced by 2 times and the propylene production efficiency is increased by 2 times compared with the previously reported screening material. "Our research provides a new idea for the core problem of chemical engineering, which is enhanced by microporous diffusion and mass transfer, and lays a foundation for the development of low-carbon separation technology." Xing Huabin introduced that this is also conducive to the localization of ultra-high purity electronic chemicals.
It is reported that Cui Jiyu, a 2019 doctoral student in the School of Chemical Engineering and Biological Engineering of Zhejiang University, is the first author of the paper, and Xing Huabin and Yang Lifeng are the corresponding authors of the paper. The research was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Zhejiang Province. (ENDS)