Characterization and systems integration of microreactors

Abstract

Microfabrication technology presents the opportunity to create highly instrumented, micro-scale chemical reactors that bring with them the potential for new analytical capabilities, point-of-use synthesis, and highly parallel screening methods. However, the use of integrated circuit-like reaction devices, such as the MIT thin-film microreactor, also gives rise to a spectrum of new engineering challenges with respect to reactor system integration and scale-up schemes. This work demonstrates the integration of multiple microreactors operating in parallel within a system that includes gas flow control components and the associated electronic circuitry. The system built is equivalent to a conventional laboratory reactor system but in 1/10th of the space. Fluidic and electronic interfaces, thermal management, and operational safety are all considerations in microreactor packaging. A standard microchip socket from Texas Instruments was selected as the first level packaging. The sockets have mechanical attributes that lend them to, with minor reworking, simultaneous fluidic and electronic connection. This selection makes PC board mounting of the reactor devices straightforward. Shut-off microvalves and proportional microvalves from Redwood Microsystems, with their control electronics, have also been mounted on PC boards to control the gas flow in the system. This allows the entire system: reactors, device electronics, and gas distribution manifold to be mounted on standard CompactPCI cards and housed in a commercially available chassis. A Kaparel CompactPCI chassis is used to house the microreactor system.

Electrical connections between the boards are achieved through a standard backplane and custom-built rear I/O PC boards. The system is comprised of a temperature controller card that regulates temperature for auxiliary heaters in the system; a gas mixing board that mixes the feed gas for the microreactors; two microreactor boards that each contain two microreactors with their feed flow controllers; and two heater circuit boards that provide power to the microreactor heaters. A National Instruments embedded real time processor is used to provide closed-loop control and monitor system alarms. A host PC, running LabVIEW 6, is used as the human machine interface for operator interaction and historical data logging.