{"id":1710,"date":"2010-07-12T14:18:58","date_gmt":"2010-07-12T18:18:58","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1710"},"modified":"2010-07-23T10:08:16","modified_gmt":"2010-07-23T14:08:16","slug":"characterizing-immobilized-catalysts-using-packed-bed-microreactors","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/characterizing-immobilized-catalysts-using-packed-bed-microreactors\/","title":{"rendered":"Characterizing Immobilized Catalysts Using Packed-Bed Microreactors"},"content":{"rendered":"

Catalyst immobilization on heterogeneous supports affords several advantages over homogeneous catalysts for chemical synthesis in continuous flow processes.\u00a0 The use of packed beds in flow systems offers built-in catalyst separation from the effluent while allowing for high catalyst loadings.\u00a0 However, heterogeneous catalysts typically suffer from two problems: 1) reduced activity compared to the homogeneous analogue and 2) loss of activity over time due to deactivation or leaching.\u00a0 A requirement for using immobilized catalysts in continuous processes is an understanding of the activity and stability of the catalyst over long periods.<\/p>\n

Towards this end, we have developed a platform for characterizing immobilized catalysts using silicon microreactors.\u00a0 These devices have void volumes of 28-140 \u00b5L, which allow complete characterization using milligram quantities of material.\u00a0 The devices are fabricated using deep reactive-ion-etching (DRIE), coated with silicon nitride to enhance chemical compatibility, and capped with pyrex to allow visual access.\u00a0 The microfabricated weir has 25 \u00b5m wide channels (Figure 1); thus, particles larger than 25 \u00b5m can be retained.\u00a0 Fluidic connections are made using a compression packaging scheme that was recently developed in our group [1<\/a>]<\/sup> (Figure 2).\u00a0 Both polymer beads and silica gel have been loaded and retained, though polymer beads offer challenges due to their tendency to swell in organic solvents.\u00a0 Application of this system to studying covalently bound catalysts and physisorbed catalysts [2<\/a>]<\/sup> is ongoing.
\n\n\t\t