Microchannel reactors for fast periodic operation: the catalytic dehydration of isopropanol

Abstract

A microchannel reactor specially designed for periodic operation and a process to deposit a catalyst, -alumina, inside the reactor channels were developed. The hydrodynamics of the reactor was characterised. Although the #ow in the microchannels is laminar, a uniform radial concentration pro"le and consequently a narrow residence time distribution were obtained. Depending on the manufacturing method the Bodenstein number was found to be Bo"ud/D K 70. The catalytic coating had no in#uence on this distribution indicating a uniform deposition of the catalyst within the microchannels. As the inlet function was only slightly modi"ed in the reactors, frequencies of up to 1 Hz could be imposed for periodic operation. The dehydration of isopropanol to propene was chosen as model reaction to study the dynamic behaviour of a microreactor under periodic concentration variations. The kinetics was "rstly studied in a conventional "xed-bed reactor with the catalyst developed for the microreactor. Experimental results con"rmed the theoretically predicted increase of the reactor performance under periodic operation exceeding the maximum obtainable performance under steady-state conditions.

Hydrogen production for fuel cell application in an autothermal micro-channel reactor

“…This allows optimizing the contact time of the reactants avoiding the formation of unwanted by-products. Moreover, the short residence time (<0.1 s) allows a quick response to dynamic changes in the inlet conditions [1,2]. For non-stationary operations of the reactor, this feature is essential.…”

Pulsed activation in heterogeneous catalysis

“…Specifically, Rouge and coworkers [122], Brandner and coworkers [64,94,95] and Jensen and coworkers [65] have published results on temperature cycling in the order of 10 1 − 10 2 K at frequencies in the order of 10 −1 − 10 0 Hz by using microstructured reactor designs. Sotowa and coworkers [67] achieved temperature cycling with an amplitude in the order of 10 2 − 10 3 K with a period in the order of 10 0 Hz by using a free floating heated wire.…”

Micro-structured string-reactor for autothermal production of hydrogen

“…Due to the small diameters of the micro-channels, the radial diffusion time is small compared to the mean residence time in the reactor and axial dispersion can be efficiently suppressed [20,21].…”