Plenary Lecture, ENERGY & ENVIRONMENT (EE'09), Cambridge, UK, February 21-23, 2009

Plenary Lecture

Dimethyl Ether (DME): A Clean Fuel of the 21st Century and Catalysts for It

Assistant Professor Kaoru Takeishi
Department of Materials Science and Chemical Engineering,
Faculty of Engineering
Shizuoka University

Dimethyl ether (DME) is the smallest ether, and its chemical formula is CH3OCH3. DME usually exists as gas, but it is easy to liquefy by cooling at -25oC at atmospheric pressure and by pressurizing under 5 atm at room temperature. Therefore, DME is easy to handle like liquefied petroleum gas (LPG). DME will be used as fuel of substitute of LPG. In China, DME is mixed into LPG and used as a domestic fuel. Cetane number of DME is 55-60, so DME will be used as a diesel fuel. In Japan, China, Sweden and so on, DME buses and trucks are testing on public roads. DME does not contain poisonous substances, and it burns with no particulate matters (PM), no sulphur oxides (SOx), and less nitrogen oxides (NOx). Therefore, DME is expected as a clean fuel of the 21st century. DME is able to replace light oil and LPG, and its physical properties are similar to those of LPG. It is possible that DME infrastructures will be settled more rapidly than hydrogen, because existing LPG infrastructures can be used for DME.
On the other hand, it is expected that fuel cell is one of the methods to restrain the global green effect. Steam reforming of methane, LPG, gasoline, and methanol is actively researched and developed as hydrogen supply methods for the fuel cells. Methanol steam reforming is easy to perform at around 250-300oC. However, the toxicity of methanol is high, and its infrastructure is not well developed. The infrastructures for natural gas, LPG, and gasoline are well established, but those steam reforming are difficult even at high temperatures around 800oC, and they contain sulphur resulting in catalyst poisoning. DME is expected as excellent hydrogen carrier and hydrogen storage, because DME will be easy to reform into hydrogen if there will be excellent catalysts of DME steam reforming. Therefore, I have been studying on DME steam reforming for hydrogen production, and researching on catalysts for DME steam reforming and DME synthesis.
The results of steam reforming of DME over several catalysts suggested the following facts: H2 production with steam reforming of DME consists of two steps. The first step is hydrolysis of DME into methanol. The second step is steam reforming of methanol that produces H2 and CO2. The rate determining step is hydrolysis of DME into methanol. The copper alumina catalysts prepared by the sol-gel method are excellent for H2 production by steam reforming of DME. The reason is that gamma-Al2O3 for the hydrolysis and Cu for methanol-steam reforming are co-existing closely on the catalyst surface. The consecutive reactions smoothly occur. Addition of Zn, Mn, or Fe into Cu(30wt.%)/Al2O3 activates steam reforming of DME. The Cu-Zn(29-1wt.%)/Al2O3 catalyst shows the excellent activity of DME steam reforming; the DME conversion is 95%, H2 yield is 95%, and CO concentration was 0.8 mol.%. I have developed a new catalyst for H2 production from DME, and the catalyst give us a great potential for H2 supply from DME. Also I have developed catalysts for direct DME synthesis from syngas (mixture of hydrogen and carbon monoxide). The catalysts are prepared by the sol-gel method, and the surface of the catalysts is optimum for direct DME synthesis. Copper sites for methanol synthesis from syngas,
gamma-Al2O3 sites for dehydration of methanol into DME, and copper sites for water-gas shift reaction from H2O & CO into H2 & CO2, are co-existing closely on the catalyst surface. The consecutive reactions (methanol synthesis, methanol dehydration, and water-gas shift reaction) smoothly occur, and DME is produced fast. Therefore, these catalysts will be very effective for new energy system of DME and hydrogen.

Brief biography of the speaker:
Oct 1994 Present: Assistant Professor, Faculty of Engineering, Shizuoka University
Mar. 2005: Doctor of Engineering, Tokyo Institute of Technology
Apr. 1989 Sep. 1994: Assistant Professor, Junior College of Engineering, Shizuoka University
Apr. 1987 Mar. 1989: Researcher, Gotemba R&D Laboratory, Dow Chemical Japan
Apr. 1985 Mar. 1987: Master Course of Electronic Chemistry, Tokyo Institute of Technology (Master of Science)
Apr. 1981 Mar. 1985: Undergraduate Course of Chemistry, Science University of Tokyo (Bachelor of Science)
My main research field is catalysis chemistry. Now, I have specially been working for catalyst development for new fuels such as dimethyl ether (DME) and hydrogen.


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