저작권자 © Korea IT Times 무단전재 및 재배포 금지
Environment Technology / Interview Remarkably enhanced catalytic functions, lifetimes Prof. Ryoo Ryong, KAIST (Korea Advanced Institute of Science and Technology) who received the Top Scientist Award by Korean government last year, is being watched keenly as he is introduced in the Cover Story of "Nature Materials" recently. The following article is an interview with prof. Ryoo Ryong, Department of Chemistry, Director, Center for Functional Nanomaterials, KAIST, carried out by The Korea IT Times as part of ET (environment technology) .Ed. Q: First off, please explain 'Zeolite', a catalyst stuff which is used in all sorts of petrochemistry industry A: Zeolites are the crystalline aluminosilicate minerals containing regular arrangement of the small nanopores (diameter < 10-9 m). The zeolite nanopores allow incorporation of the small organic molecules and these zeolite nanopores can chemically transform those organic molecules into more useful molecules. Therefore, the zeolites have been widely used as important catalysts in petrochemical and fine chemical industries. The importance of zeolite catalysts can be clearly noted by the fact that the majority of the world's gasoline is currently produced by the cracking of petroleum using the zeolite catalyst. It is also noteworthy that zeolites have also played key role in the development of environmentally benign processes in the chemical industries. For instance, zeolites with strong acidity can replace the sulfuric acid catalysts in many chemical processes. This significantly reduces the production of environmentally toxic wastes. Due to the scientific and technological importance, many scientists, both in the academia and industry, are paying enormous efforts in order to improve the properties of zeolites. Q: What is a momentum of the research to supplement shortcomings such as low catalyst activity because Zeolite's reaction object molecule's speed is slow A: Zeolites contain regular arrangement of the small nanopores, in which molecules can be catalytically transformed to the desired products. Typically, the nanopore diameter of conventional zeolite is less than 1 nm (10-9 m). Due to the small pore diameter, the large molecules cannot go through the zeolite pore structures. Even the small molecules can exhibit very limited diffusion speed within the zeolite pore structures. In many applications, the slow diffusion speed into the nanoporous structures act as a bottleneck, which limits the efficiency of zeolite catalytic performances. The diffusion limitation also accelerates the undesirable formation of the side products at the pore entrances, which significantly reduces the catalytic activity and reusability of zeolite catalysts. To solve these problems, our research center tried to develop a synthesis methodology that can generate the additional large nanopores (5-10 nm) within the zeolite crystals containing small nanopores (<1 nm). It was expected that such large nanopores could act as a 'highway' for 'molecular traffic', allowing dramatically improved molecular diffusion into the zeolite structures. To achieve this goal, we rationally designed the organic additive molecules that can induce the formation of large nanopores within the zeolite crystals. We confirmed that the resultant zeolites containing both large and small nanopores ('hierarchically nanoporous') could exhibit remarkably enhanced catalytic functions and life times. Q: What's your opinion regarding the outlook that 'Zeolite' will be utilized to the future environment process whose value-added is high such as high value-added process to divert waste plastics analysis as well as intermediate into gasoline A: The new zeolite containing the large nanopores allows fast diffusion of the large molecules into the zeolite structures. Consequently, zeolites are highly promising for the catalytic conversion of the large molecules such as decomposition reaction of waste plastics and cracking reaction of heavy oils. The amount of discarded waste plastic is constantly increasing each year and it is causing serious pollution problems. If waste plastic can be chemically recycled, than these will certainly become the cheap and abundant source for the useful chemicals and energy. Heavy oil is formed after distillation of more precious fractions such as gasoline from the crude oil; it is the leftover of distillation process. The new zeolite catalysts are very promising material to catalyze the valueless heavy oil into the more value-added products such as gasoline. Q: What is the part that you prepare for application to domestic industry through superior catalyst activity A: After the development of new zeolite materials, we are trying to actively collaborate with many chemical industries both in Korea and foreign countries. The collaboration is aimed to develop the new core technologies for the petrochemical and fine chemical processes using the newly developed zeolites as a catalyst.