|SEM micrograph showing the uniform formation of mesoporous MFI zeolites.|
Korean researchers have developed a new type of zeolite that could serve as an efficient catalyst in refining applications.
In a paper published online in Nature Materials, the team led by Prof. Ryoo Ryong at the Korea Advanced Institute of Science and Technology (KAIST), describes the development of a direct synthesis route to tunable and highly mesoporous zeolites.
Zeolite is the most widely-used catalyst now in the petrochemical industry. It has many outstanding advantages but the hitch is that its efficiency was mediocre due to its slow reaction rate. In comparison, our new-fangled zeolite shows a substantially advanced reaction rate, at 1.5 times to dozens of times better than the one currently available.—Prof. Ryoo Ryong in an interview in the Korea Times
Zeolites are porous, sieve-like minerals that have been used for decades in purifiers, filters and other devices. They make extremely active catalysts by confining molecules in small spaces with its crystalline pores.
Having the ability to produce cost-effective, targeted zeolites on an industrial scale could replace energy-inefficient separations (such as in fuel refining) with membrane separations. In other words, instead of heating the feedstock liquid and distilling the desired chemicals, the new membrane sieves could achieve the same goal when the fluid simply passes through.
Accordingly, understanding the mechanism for zeolite formation—the better to be able to design the appropriate zeolites and manage their production—has been an area of intense research focus. (Earlier post.)
Ryoo and his team synthesized their zeolites by adding a rationally designed amphiphilic organosilane surfactant to conventional alkaline zeolite synthesis mixtures. The resulting mesopore diameters could be uniformly tailored, similar to ordered mesoporous silica with amorphous frameworks.
The KAIST zeolites feature pores that are 10nm in diameter on top of more conventional smaller pores of 0.3 to 1.5 nm. The larger pore size allows for the diffusion of larger gas and oil molecules into the center of the zeolite.
We synthesized zeolite with pores that are 10 nanometers in diameters on top of conventional small ones. It is like cutting through a 10-lane expressway in addition to existing small roads to weed off traffic jams.—Prof. Ryoo Ryong
“Amphiphilic organosilane-directed synthesis of crystalline zeolite with tunable mesoporosity”; MinKee Choi, Hae Sung Cho, Rajendra Srivastava, Chithravel Venkatesan, Dae-Heung Choi and Ryong Ryoo; Nature Materials AOP; 6 August 2006 | doi:10.1038/nmat1705