Professor Chen received PhD degree in Chemical Engineering from University of Leeds (UK) in 1998 supported by full Scholarship of British Council, Master in Chemical Engineering from Zhejiang University in 1990, and Bachelor in Chemical Engineering from Huaqiao University in 1984. Currently, he is a full professor of College of Chemistry and Chemical Engineering, and also the head of the Department of Chemical & Biochemical Engineering at Xiamen University. He has won several awards including the National Academic and Innovation Award in 1997 and the SinoPec Science and Technology Progresses Award (1996 and 1997). In his early career, he held several research positions in the UK including Loughborough University (1998-2000.1), University College London (2000.2-2000.12), Imperial College London (2001.1-2004.12) and Research Fellow at the Department of Biochemical Engineering of University College London (2005.1-2008.2).
Catalytic wet air oxidation (CWAO) is considered to be a promising process used in the sewage disposal for its high efficiency, low cost and general applicability. However, the deactivation and low activity of catalysts extremely limit the utilization of this process, especially for wastewater containing ammonia.
From the reported literature for CWAO of ammonia, two reaction mechanisms were found and then used to design efficient and stable catalysts for this reaction. However, when reaction temperature is lower than 150℃, the situation (mechanism) will change. The presentation will talk about the findings in our research group about these changes, and how to make use of the changes to enhance the ammonia removal from waste water.
Then the research extends to CWAO of the N,N-dimethylformamide (DMF). For this reaction, catalysts often suffer from metal leaching due to the lone pair electrons in the intermediate compounds as the lone pair electrons can generate strong chemical bonds with metals on the catalysts.
Basically, the Pd/CeO2-C was used as catalyst to oxidize the DMF in waste water. Based on our experimental results, oxygen transfer which has been observed between noble metals and cerium oxide through TPR-MASS, can dramatically increase the activity of DMF oxidation. Meanwhile, electrons supply from carbon to metal oxide has been proved and makes the catalysts extraordinary stable. However, catalysts using cerium oxide and carbon as support inevitably suffer metal leaching and low activity respectively. Therefore, we combine carbon and cerium oxide together to make a new kind of support that is CeO2/C. Then Pd atoms was put on the surface of CeO2 to make a triple-layer Pd/CeO2/C, which can take both advantages of oxygen and electron transfer and obtain high activity and stability.
Audience Take away:
• The issue to use metal catalysts in CWAO of ammonia is the stability as the existing lone pair on ammonia will cause metals leaching from catalysts.
• The changes of pH and temperature in reaction will change the reaction mechanism.
• Electron transfer may be much more important than oxygen transfer in CWAO of ammonia.
• The above findings help to design a better catalyst with triple-layer Pd/CeO2/C for CWAO of DMF.
• The triple-layer Pd/CeO2/C was well characterized.