New progress has been made in the research of catalytic removal of cold chain ethylene

Recently, the team of Professor Mitsuki Xiu of the School of Resources and Environmental Engineering of East China University of Science and Technology and the team of Professor Toru Murayama of Tokyo Metropolitan University in Japan have made a breakthrough in the field of long-term catalytic removal of cold chain ethylene, and the relevant research has been published online in Nature-Communications.

Selective oxidation of ethylene to acetic acid on the catalyst surface. Photo courtesy of East China Institute of Technology

China is a big country in fruit and vegetable production and logistics and transportation. After picking fruits and vegetables, ethylene ripening agents will be continuously released to accelerate their ripening aging and quality deterioration. Studies have shown that trace amounts of ethylene ripen and age fresh vegetables and fruits, even under cold chain system conditions (0°C to -4°C). Therefore, efficient and long-lasting cold chain environmental trace ethylene removal studies are very important.

Researchers who remove ethylene efficiently at room temperature or even lower have received widespread attention, but it has been reported that the catalyst has a very short single effective working time (less than 3 hours) under cold chain conditions, which cannot meet the transportation of fruit and vegetable products between regions in China.

Through rational analysis of the low-temperature catalytic oxidation process of ethylene, the research team found that ethylene is difficult to efficiently and deeply oxidize into the final product carbon dioxide, and is mainly converted into ethanol, acetaldehyde, acetic acid and other intermediate forms deposited on the surface of the catalyst. Combined with the state properties of each intermediate under cold chain conditions, the researchers concluded that if ethylene can be selectively oxidized to a solid intermediate such as acetic acid, it will be conducive to long-term exposure of catalytic active sites, thereby greatly improving the stability of catalytic ethylene oxide under cold chain conditions.

Based on this, the research team developed an AuPt alloy nanocluster highly dispersed deposition acid-containing site ZHM20 catalyst that can selectively oxidize ethylene to acetic acid, and online mass spectrometry confirmed that the catalyst can generate acetic acid products. The ethylene removal experiment showed that the ethylene removal rate of the catalyst was as high as 80% and stable for more than 40 hours at 0 °C, far exceeding the best report in the literature, and the catalyst could work for up to 15 days at a time, and the performance of the catalyst could be fully restored by heat treatment. More importantly, the research team proposed a new strategy for the design of high-efficiency ethylene removal catalysts, that is, to use the physical properties of ethylene transformation species at specific operating temperatures, such as the formation of solid-like acetic acid species at 0 °C, so as to improve the long-term stability of the catalyst. (Source: China Science News, Zhang Shuanghu, Li Chenyang)

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