CAS Researchers Develop Ionothermal Procedure for Mg-Containing Zeolite Fabrication; Good for Hydroisomerization

24 December 2008

A research team headed by Prof. Tian Zhi-jian with the Chinese Academy of Sciences (CAS) Dalian Institute of Chemical Physics has developed an ionothermal procedure for the synthesis of a magnesium-containing zeolite (MAPO-11) that, with platinum supported onto the structure, shows excellent reactivities in the hydroisomerization of hydrocarbons. Hydroisomerization is widely used in oil refining, and in processes such as UOP’s production of renewable jet fuel from vegetable oils.

A paper on their work was published in a recent issue of the journal Chemistry-A European Journal.

The use of ionothermal procedures for zeolite fabrication—as opposed to the conventional hydrothermal procedure—has been developed and pursued by Dr. Russel Morris and his team at the University of St. Andrews in the UK. Morris and his team published an initial paper on the topic in the journal Nature in 2004.

Ionothermal synthesis uses ionic liquids or eutectic mixtures as both solvent and template in the preparation of zeolites. The overall idea, as explained by the Morris Group, is to replace water as the solvent so that the surface of a growing zeolite crystallite is always (or almost always) interacting with the organic template cation and not with a molecular solvent.

With ionothermal synthesis, preparations can take place at ambient pressure (heating up the ionic liquids produces no vapor pressure). This is in contrast to traditional hydrothermal synthesis where the pressure produced is significant and requires extra safety precautions.

Zeolites are widely used as ion-exchange beds in domestic and commercial water purification, softening, and other applications. In chemistry, zeolites are used to separate molecules (only molecules of certain sizes and shapes can pass through), and as traps for molecules so they can be analyzed.

Zeolites have the potential of providing precise and specific separation of gases including the removal of H₂O, CO₂ and SO₂ from low-grade natural gas streams. Other separations include noble gases, N₂, O₂, freon and formaldehyde. However, at present, the true potential to improve the handling of such gases in this manner remains unknown.

The CAS research project was supported by the National Natural Science Foundation of China.

Resources

• Lei Wang, Yun-Peng Xu, Bing-Chun Wang, Shao-Jun Wang, Jia-You Yu, Zhi-Jian Tian, Li-Wu Lin (2008) Ionothermal Synthesis of Magnesium-Containing Aluminophosphate Molecular Sieves and their Catalytic Performance. Chemistry - A European Journal 14 (34) pp 10551-10555 doi: 10.1002/chem.200801383

• Emily R. Cooper, Christopher D. Andrews, Paul S. Wheatley, Paul B. Webb, Philip Wormald and Russell E. Morris (2004) Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues. Nature 430, 1012-1016 doi: 10.1038/nature02860