Microreactors could redefine chemistry, nanodrip by drop

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Dec. 8, 2003 — Move over, lab-on-a-chip. Those microdevices from firms such as Affymetrix Inc. and Caliper Technologies Corp. are advancing life sciences, but a lesser-known tributary of microfluidics is working toward one-upping them with a “chemical-plant-in-a-box.”

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Just last week, Global Hydrogen Inc. — a joint venture between Velocys Inc., a startup based in Plain City, Ohio, and ConocoPhillips — revealed plans to apply microchemical processing to convert natural gas into pure hydrogen or synthetic diesel fuel.

Like labs-on-a-chip, these microchemical reaction systems are composed of tiny channels, mixing chambers, heaters, reactors and other components. But rather than manipulating or analyzing biomolecules and DNA, microreaction technology is designed to conduct chemistry that is possible only with extremely small quantities of fluids in small spaces.

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Potential applications are as diverse as there are chemical processes, so device dimensions are not really confined to the “box” metaphor. Researchers at Pacific Northwest National Laboratory (PNNL) in Richland, Wash., have built what they believe to be the world’s smallest fuel processor, about the size of a pencil eraser, for use in hand-held wireless equipment and sensors by the U.S. military.

Some of the other key organizations working on microchem technology include the IMM in Germany and Stevens Institute of Technology in Hoboken, N.J. Other commercial companies include Ehrfeld Mikrotechnik AG outside Frankfurt, Germany, and GTL Microsystems, a joint venture of FMC Technologies Inc. in Houston and U.K.-based Accentus plc.

Microchem prototypes run the gamut from a standalone apparatus — like the six-pound cooling system PNNL is working on for U.S. soldiers to wear — to multiple machines networked together for higher-volume industrial applications.

A single small device, for example, could process liquid methanol into hydrogen gas inside a micro fuel cell. Hundreds of micro reactors could run in a massively parallel fashion for large-scale production of materials such as hydrogen peroxide, or for the kind of specialized chemical engineering needed in making pharmaceuticals.

The New Jersey Center for MicroChemical Systems at Stevens Institute is working on all these areas.

Ronald Besser, who co-leads Stevens’ microchem center, explains that chemical reactions in extremely small volumes of fluids inside microchannels have a number of advantages over traditional chemistry.

Heat from such reactions dissipates very rapidly, allowing ingredients to be combined at temperatures, pressures or concentrations that on a larger scale would be explosive.

Chemicals blended by the microdrop also mix extremely fast (hence Velocys’ name), which could create new categories of compounds. Surface-to-volume ratio of liquids in a microreactor or channel also interact more rapidly with catalytic particles or thin films, increasing efficiency and reducing cost.

Clyde Payne, chief executive of chemical industry consulting firm The Catalyst Group, sees the early promise for microchemical systems in low-volume, high-value applications such as specialty chemicals and pharmaceuticals. But he cautioned that most prototype systems are essentially expensive, handmade projects today. He estimated it would take several years to make the equipment affordable for commercial production.

What makes the effort worthwhile is that “reactions in very small spaces simply gives you access to chemistry you can’t do at larger scales,” said Besser. That’s why Stevens Institute, with funding from the Department of Energy and the state of New Jersey, is working on micro chemical pilot projects with pharmaceutical giant Bristol-Myers Squibb Co. and FMC Inc., one of the world’s largest producers of hydrogen peroxide. Lucent’s New Jersey Nanotechnology Consortium is also a partner in the project.

Through Velocys, ConocoPhillips and other partners have invested more than $70 million to develop industrial applications for microchannel technology. Two promising areas are producing hydrogen and converting “stranded” natural gas into a synthetic liquid diesel fuel in the field. Gas reserves in places like Alaska are large but uneconomical to develop if they can’t be transported. The challenge for Velocys is making the gas-to-liquid conversion cheap enough to produce liquid fuel at prices competitive with conventional oil.

On Dec. 4, Velocys revealed plans for a full-scale demonstration module in 2005 and hopes for an industrial rollout in 2006.

Wolfgang Ehrfeld, who helped pioneer microreaction technology in the early 1990s, started Ehrfeld Mikrotechnik AG in 2000 after leaving the IMM. Ehrfeld, who helped found the IMM in 1991 with his wife Ursula, also co-authored a seminal book on microreactors in 2002.

Ehrfeld said he left IMM to start his own company because he wanted to spur the commercialization of microchemical systems. While he declined to specify customers, Ehrfeld said the company has developed a modular microreaction system with broad and flexible application. He added that Merck &Co. has used microchemical systems to produce the liquid crystals for LCD screens.

But Ehrfeld noted that wider implementation of microchemical processes in industry will require a shift in thinking. Conventional chemical plants built to last thirty years lock manufacturers into technology and processes that can become outdated.

He contends that the chemical industry, or at least a sector of it, must become more like the consumer electronics and computer industries where products are constantly upgraded and have shorter lives in the market.

A modular microchemical infrastructure would, he believes, cost less and take up less space than conventional capital equipment. It could be reconfigured more easily to keep pace with a faster development cycle.


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