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16 Chemical Micro Process Devices Amy E. Smithson Changes are afoot in the chemical and related industries. In addition to their drive for efficiency and flexibility, chemical companies have more recently sought to reduce their environmental footprint and achieve greater process safety. Chemical micro process technology, initially developed in the 1980s, is proving that it can respond to the industry’s needs. Compared to standard chemical reactors, miniaturized devices are safer, faster, more selective, and more energy efficient. Moreover, micro process devices produce higher and more uniform product yields, have greatly reduced waste streams, and are more cost-effective. These advantages explain why the chemical industry has investigated multiple applications of this technology and begun to adopt it for research and development (R&D), process development, product scale-up, and actual commercial production. Although legitimate companies are embracing micro process technology, there is a risk that state and substate actors could divert it for harmful purposes. The hijacking of a civilian technology is hardly a new phenomenon. World War I ushered in the militarization of chemistry, and the use of poison gas was a hallmark of that conflict. Although the entry into force of the Chemical Weapons Convention in 1997 has eased concerns about the state-level pursuit of chemical weapons, Aum Shinrikyo’s infamous attack in March 1995 on the Tokyo subway with the nerve agent sarin, and the use of chlorine-spiked bombs by Islamic fundamentalists in Iraq in 2007, have shown that crude forms of chemical warfare are within the reach of terrorists. Amid this mixture of positive and negative proliferation trends, the coming-of-age of chemical micro process technology portends additional uncertainty. Such devices are ideal for the sustained processing of corrosive chemicals, a characteristic of poison gas production. Moreover, a micro plant could manufacture substantial quantities of chemical warfare (CW) agents with few of the telltale indicators commonly associated with chemical weapons factories, such as pollution abatement equipment. Thus the handful of states with ongoing CW programs could exploit micro production devices to advance and conceal these activities. Some states might 236 A. E. Smithson even consider reentering the chemical weapons business if they were confident that an illicit weapons program would go undetected. For terrorists, micro process devices could ease the technical obstacles involved in scaling up the production of CW agents. The challenge for the international community is to find a way to allow micro process technology to flourish for legitimate commercial and scientific purposes while preventing its acquisition by those with intent to harm. Overview of the Technology Chemical micro process devices can be strikingly compact, and some are as small as credit cards, dice, or coins. Made of materials such as ceramic, stainless steel, glass, silicon, or the nickel-steel alloy known as Hastelloy, they are well suited for highly exothermic reactions and the long-term processing of highly corrosive chemicals . With inner channels ranging from submicrometer to submillimeter in size, chemical micro devices have a high ratio of reactor surface to reactant volume that promotes efficient surface catalysis and heat exchange. These characteristics in turn allow the precise regulation of chemical reactions and reduce the formation of unwanted by-products. Chemical micro devices also operate continuously, using miniature sensors and computers to maintain tight control over mixing, temperature , pH, flow rate, and other reaction conditions.1 Precision injection of chemicals into the channels of a micro device allows tiny drops to merge and react, often within seconds. To further enhance reaction efficiency , the channel walls can be seeded with catalysts, constructed in various shapes, and internally structured with etched patterns to enhance mixing. A variety of chemical micro process devices have been developed, including several different types of reactors, heat exchangers, and mixers. Such devices have successfully performed inorganic, biochemical, and organic chemical reactions and have been applied to the combinatorial production of molecular structures for high-throughput screening. Microreactors also have the potential to use chemistries that are not possible in standard industrial equipment, such as the high-yield production of hydrogen cyanide from formamide.2 History of the Technology Scientists discussed the possibility of chemical nanoprocessing for over seventy years before the development of the requisite manufacturing technologies made it possible to turn theory into reality. Another significant factor that led to the emergence of the technology was the German government’s response during the 1980s to the green movement’s demand for policies and technologies to reduce environmental pollution . Although Germany’s large chemical industry was already subject...

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