운송 수단을 비롯한 여러가지 에너지 소스를 대체할 수단으로 각광 받는 수소를 우리가 직접적으로 쓸 수 있는 날도 얼마 남지 않은듯 하다. 미시간대학의 연구원들에 따르면 Microporous 물질이 많은 양의 수소를 낮은 압력과 보통 온도로도 저장 할 수 있다고 전한다.

여러 국가들의 연구원들은 그 동안 수소의 연료에 대한 장점에 대한 많은 연구가 이루어 졌다. 석탄에너지와 비교해 보면 물을 사용하는 수소에너지에는 엄청나게 커다란 에너지와, 공해를 유발 시키지 않는다는 점을 장점으로 꼽을수 있다.

하지만 수소를 안전하게 저장하는데 있어서는 아직도 어려움을 겪고 있다. 그 예로 수소 연료를 이용한 자동차의 개발등이 쉽지 않다고 한다.


MATERIALS SCIENCE
POROUS CRYSTALS SOAK UP HYDROGEN
Molecular design leads to materials with large H2 storage capacity

http://pubs.acs.org/cen/topstory/8120/8120notw1.html

MITCH JACOBY

A key obstacle to using hydrogen as a fuel for transportation and other applications may soon be overcome, thanks to an advance in hydrogen-storage materials. Microporous materials designed by researchers at the University of Michigan, Ann Arbor, can be used to reversibly adsorb large quantities of hydrogen (a few percent by weight) at room temperature and low pressure. The family of metal-organic framework materials and the methods used to synthesize them may lead to even higher storage capacities, abating the hazards of storing hydrogen at high pressure.

Researchers in many countries have focused their efforts in recent years on methods for exploiting hydrogen's fuel benefits. Compared to hydrocarbons, its advantages include higher energy density and no pollution, because the sole by-product of combustion or electrochemical oxidation of hydrogen is water. In addition, the lightweight element is plentiful--although most is tied up as H2O.

Capitalizing on hydrogen's qualities--for example, in fuel cells for automotive applications--remains challenging, however. Among other reasons, there is no convenient way for the public to store and transport large quantities of hydrogen safely. Some advances in storage materials have been reported in connection with metal-hydride systems and carbon-based adsorbents, but both types of materials suffer from various shortcomings. And although safety certifications recently have been awarded in Europe for gas cylinders designed to hold 10,000 psi of hydrogen, safety concerns aren't expected to disappear anytime soon.

But now, Michigan graduate student Nathaniel L. Rosi and chemistry professor Omar M. Yaghi and their coworkers at Michigan, Los Alamos National Laboratory, and Arizona State University have designed and constructed promising storage compounds. Their crystalline materials, composed of metal-organic frameworks with a cubic three-dimensional extended porous structure, can adsorb up to 2% by weight of hydrogen at room temperature and about 10 atm of pressure [Science, 300, 1127 (2003)]. At lower temperatures, hydrogen uptake as high as 4.5% has been achieved, the group reports.

The materials, which remain stable even after solvent molecules are removed, are made up of cubes in which each corner is occupied by an OZn4(CO2)6 cluster that is bridged by six carboxylates of an organic linker. The group prepared crystals using various linkers including 1,4-benzenedicarboxylate, cyclobutylbenzene, and naphthalene.

The work is "an important advance toward safe hydrogen storage," notes Michael D. Ward, a crystal expert and professor of chemical engineering and materials science at the University of Minnesota, Twin Cities. The new materials fall short of the Department of Energy's target hydrogen-storage capacity of 6.5 wt %, Ward notes, but their architecture offers a rare opportunity to select solid-state properties through molecular design. The crystals can be manipulated through straightforward organic synthesis, Ward adds, "promising tailor-made hydrogen-storage materials."

미네소타 대학의 화학공학 교수이자, 결정체 전문가인 Michael D. Ward 씨는 이 물질이 앞으로 수소를 조금더 안전하게 저장 하는데 있어서 중요하다고 설명했다. 이 새로운 물질은 에너지국의 목표에 6.5 wt % 정도 모자라지만, 이 연구가 주는 의미는 커다랗다고 할 수 있다.

LOTS O' SPACE Metal-organic framework crystals composed of OZn4(CO2)6 clusters (blue) and naphthalene linkers (gray) can adsorb several weight % of hydrogen (orange).