Large zeolites: why and how to grow in space

Zeolite crystals are one of the Chemical Process Industry's most valuable catalytic and adsorbent materials. Large, essentially defect-free zeolite crystals could be used to better understand zeolite catalysis mechanisms, and could help in designing better zeolite adsorption systems. In addition, if zeolites could be made large enough, they could be used to make zeolite membranes; these could be used as reactors/separators, resulting in highly improved efficiency. Space provides a unique environment to grow large zeolites by allowing them to continue to grow suspended in their nutrient field. In order to better utilize this microgravity environment, it is necessary to control the nucleation event. Triethanolamine (TEA) can be used to control the time release of aluminum in a zeolite A solution. In a 1 g environment, the use of TEA resulted in a 25 - 50× increase in average and maximum crystal size. It is proposed that if fluid motion can be controlled and the rate of nutrient transport increased, substantially larger zeolite crystals can be formed in microgravity, using such nucleation control agents.