Externally Controlled Chemical Microreactor For Reaction Investigations Under Supercritical And Subcritical Conditions

In the study of chemical reactions for research and chemical plant engineering, external pressure and activity control has not been available in the past. Although internal pressure control has been used, it has been found to be difficult to incorporate, and inaccurate at best. Researchers at Arizona State University have designed and built a new reaction cell for in situ investigations of commercially and fundamentally important reaction processes. The unique characteristic of this invention is that the pressure and temperature can be fully controlled during in situ reaction investigations from ambient conditions to 250C and 3,000 PSI. This is facilitated by integrating external communication with the gas or fluid of interest, with full pressure and activity control. The micro-reactor allows direct probe beam (light, X-rays, etc.) interaction with a sample during a reaction to investigate in situ reaction processes. This system is also suitable for investigating a variety of materials under controlled temperature and pressure conditions. The device permits sequential simultaneous microscopic observation of the sample before, during and after the reaction as well as continuous visual access to the cell interior.This design has the inherent advantages of (i) precise control of the pressure and activity of the gas or fluid of interest and (ii) allowing reactions to be observed under constant reactant gas or fluid activity (pressure). Previously, since external pressure/activity control and monitoring was unavailable, reactant pressure/activity would inherently decrease as a reaction progressed and the reactant gas/fluid was consumed. This effect was particularly limiting, as reaction conditions could not be well controlled during observation.Potential commercial applications are broad in scope. The microreactor can be used to explore in situ a variety of important chemical and materials processing applications involving supercritical or subcritical fluids. These include organic and organometallic reactions, pharmaceutical materials processing, organic waste decomposition, geochemical and mineralogical reactions, and solvothermal materials synthesis reactions. For example, ammonolysis and hydrogenation reactions in supercritical fluids provide a useful alternative to standard synthesis methods. In addition, organic synthetic reactions using supercritical (CO2) fluids can eliminate the organic waste solvents that are used in traditional methods. Similar applications extend to commercially important solvent extraction processes, such as the decaffeination of coffee. There are also important advantages in the preparation of drug delivery systems using supercritical fluids rather than standard organic solvents.