New progress has been made in the study of methane activation at Dalian Institute of Chemical Research. After the construction of multiple pairs of electron recycling systems, the successful implementation of selective oxidation of methane to methanol under low temperature (80 ℃) conditions (J. Am. Chem. Soc., 128 (2006) 16028) The "Interface and Nanocatalysis" research group led by Bao Xinhe, a researcher at Dalian Chemical Research Institute, has made new progress in the basic research of direct methane activation. Through cooperation with the US West Pacific National Laboratory, using high-field solid-state nuclear magnetic technology, the real catalyst was directly studied, and the complete solid catalyst active center structure information was obtained. The relevant results were published in the latest issue of the Journal of the American Chemical Society (J. Am. Chem. Soc., 130 (2008) 3722). The "Chemical and Engineering News" in the United States has paid close attention to this work, and it was reposted in the latest issue of C & E News, Science & Technology Concentrates, and given a high evaluation. Methane is the main component of natural gas, and its efficient activation and selective conversion is a major problem in the field of catalysis and even chemistry. It has been widely concerned and valued by researchers for a long time. In 1993, scientists from the Dalian Institute of Chemical Physics first reported the methane aromatization process in which methane was directly activated and converted under the anaerobic conditions under the action of a metal-supported molecular sieve catalyst to prepare basic chemical raw materials aromatic hydrocarbons and simultaneously obtain hydrogen. attention. Over the years, researchers at Dalian Institute of Chemical Research have conducted extensive and in-depth research in many aspects of theory and application, and have achieved outstanding research results. Related achievements won the second prize of National Natural Science Award in 2005. In recent years, the research team led by Bao Xin and researchers has carried out a lot of detailed and in-depth research on catalyst structure, reaction mechanism and research and development of new catalysts. Recently, classmates Zheng Heng and Dr. Martin of the research team collaborated with the Western Pacific National Laboratory in the United States for the first time to directly observe the Mo species on the catalyst surface using 95Mo NMR technology under high-field solid-state nuclear magnetic (900 MHz). The results show that during the preparation of the Mo / ZSM-5 catalyst, the Mo species will strongly interact with the acid center of the molecular sieve to form a Mo-O-Al species with strong interaction. This species is in weak interaction with The state of molybdenum oxide microcrystals has an equilibrium relationship. When the Mo content of the catalyst is low, the Mo-O-Al species dominate the catalyst surface, and when the Mo content of the catalyst is high, the molybdenum oxide microcrystals become the dominant species. Through the correlation with the catalytic activity, it is concluded that the Mo-O-Al species in the exchange position is the active center of the direct conversion reaction of methane. This result has an important guiding role in understanding and understanding the structure and catalytic mechanism of the active center of the catalytic reaction, as well as the development of highly efficient catalysts. This study is the first successful example of using high-field 95Mo NMR to study a real catalyst system, and demonstrates that high-field nuclear magnetism solves the chemical problems of traditionally difficult to observe atomic nuclei (such as Mo, Ag, Ti, etc.), especially involving The tremendous power of related scientific problems in the real catalytic system.
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