Carbon Dioxide Molecule

University of Toronto chemists envision new fuel economy

TORONTO, ON -- Imagine pulling up to the pump and filling your tank with fuel derived from greenhouse gas emissions. This vision of a new fuel economy is taking shape as University of Toronto researchers put novel chemical reactions to work in order to develop a carbon-neutral system to recycle carbon dioxide, or CO2, into liquid fuel.

The innovative research project is fueled by a $268,000 grant from Carbon Management Canada (CMC-NCE), a Network of Centres of Excellence that supports research to eliminate carbon emissions from the fossil energy industry.

In the 2011 round of CMC-NCE funding, $10 million was awarded to Canadian researchers working on 18 projects. The recently announced decision to fund the projects was made after a rigorous, international peer-review process. The University of Toronto project is one of three that focus on enabling and emerging technologies.

U of T chemists Douglas Stephan and Eugenia Kumacheva are laying the foundation for an efficient and cost-effective method to transform CO2 and hydrogen into water and methanol, a liquid fuel. The ultimate goal is an energy-generation system that would be carbon neutral, with every CO2 molecule released from fuel consumption being converted back into methanol.

"The CMC funding is giving us an opportunity to explore chemistry that relates to one of the biggest problems facing humankind," said Stephan.

Methanol, or methyl hydrate, is the same clean-burning fuel that's used to heat a fondue pot. A liquid, methanol is relatively easy to store and transport, even with existing delivery systems—gas station pumps, for example.

"The big problem with new possible fuels is the infrastructure for transportation," commented Stephan.

The unprecedented approach to CO2 capture and reuse builds on his group's breakthrough discovery of a new way to capture and use CO2, research that has been supported in part by NSERC and the green chemistry commercialization body, GreenCentre Canada

"It's really incredibly simple chemistry that we've discovered," said Stephan. "We generate this new reactivity that we've been able to observe with CO2 and a variety of other small molecules."

To carry out the process, chemical reagents dubbed "frustrated Lewis pairs" are used to effect these new chemical reactions. Extremely effective and versatile, the frustrated Lewis pairs are also nontoxic—unlike conventional catalysts employed to convert CO2 to methanol.

Applications (Optical Properties of Materials) Part 5

Helium-Neon Laser

A cavity about 2 mm in diameter is filled with 0.1 Torr Ne and 1 Torr He (Fig. 13.36(a)). A current that passes through the gas produces free electrons (and ions). The electrons are accelerated by the electric field and excite the helium gas by electron-atom collisions. Some of the helium levels are resonant with neon levels so that the neon gas also becomes excited by resonant energy transfer (Fig. 13.36(b)). This constitutes a very efficient pumping into the neon 2s- and 3s-levels. (Direct electron-neon

Figure 13.36. Helium-neon laser. (a) Schematic diagram of the laser cavity with Littrow prism to obtain preferred oscillation at one wavelength. (The end windows are inclined at the Brewster angle for which plane-polarized light suffers no reflection losses.) (b) Energy level diagram for helium and neon. The decay time for the p-states is ~10 ns; that of the s-states 100 ns. The letters on the energy levels represent the angular momentum quantum number; the number in front of the letters gives the value for the principal quantum number; and the superscripts represent the multiplicity (singlet, doublet, etc.), see topic 3.

Lasing occurs between the neon s- and p-levels and produces three characteristic wavelengths. Suppression of two of the wavelengths is accomplished by multilayer dielectric mirrors, which provide a maximum reflectivity at the desired wavelength, or by a Littrow prism, as shown in Fig. 13.36(a).

The carbon dioxide laser is one of the most efficient and powerful lasers which is used in industry for cutting and welding. The active ingredients contained in a CO2 laser tube consist of 10-20% carbon dioxide, 10-20% nitrogen, and a few percent hydrogen. The remainder is helium. Pumping is accomplished by electron-atom collisions (see above) setting the nitrogen molecules into vibrational motions. This vibrational energy is then transferred to the carbon dioxide molecules by resonant energy transfer. The CO2 molecule possesses three fundamental modes of vibration, as shown in Fig. 13.37(a). The lasing occurs between these levels as shown in Fig. 13.37(b). The energy output, that is, the population inversion is greatly improved by reversion of the vibrational modes to the ground state of cold helium atoms (similar to Fig.13.35(b), see also Fig. 13.37(b)). This is accomplished by water cooling the walls of the laser tube.

The carbon dioxide molecule, its infrared spectrum and mechanical structure ...

Food microbiology, an introduction

Greenhouse gas carbon dioxide mitigation, science and technology

Physical review

J.C.S. Dalton