Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

Abstract

SummaryIn this contribution we present for the first time a continuous process for the production of highly active Pt catalysts supported by carbon nanotubes by use of an electrically heated tubular reactor. The synthesized catalysts show a high degree of dispersion and narrow distributions of cluster sizes. In comparison to catalysts synthesized by the conventional oil-bath method a significantly higher electrocatalytic activity was reached, which can be attributed to the higher metal loading and smaller and more uniformly distributed Pt particles on the carbon support. Our approach introduces a simple, time-saving and cost-efficient method for fuel cell catalyst preparation in a flow reactor which could be used at a large scale.

Continuous Fuel Cell Catalyst Preparation in a Directly Electrically Heated Tubular Reactor

“…As follows from the presented results, a tube with an inner diameter of 2.06 mm, which had been used in earlier activities to perform heating-up times down to 50 s [2][3][4], was suitable for this function, but obviously is not appropriate for performing much shorter heating-up times.…”

“…A directly electrically heated tube is an easy-to-install apparatus and will perform a linear fluid temperature evolution along the tube, because the heat evolution in each volume element of the tube is controlled by the ohmic losses in the metallic tube through which the electric current travels. This linear temperature ramp will indeed develop between the electrical contacts at the tube, which has been examined in previous works [2,4].…”

“…According to the results of previous works [1][2][3] which suggest a few minutes retention time as sufficient for widely finishing the reduction and nucleation reaction, two different reaction tubes of stainless steel 1.4301 with an inner diameter of 2.0 mm and a wall thickness of 0.3 mm were designed to obtain average retention times of some minutes at a volumetric flow rate of 1.5 mL min -1 . These tubes were bendable by means of a special tool.…”

“…Previous experimental results suggest rapid heating for a polyol reaction, either by microwave heating [1] or by use of a directly electrically heated and continuously operated tubular reactor [2,3]. The main advantages of the last-mentioned method are a much easier to perform temperature control and a great potential for an uncomplicated realization of highly reproducible operation conditions in a steadystate continuous process.…”

Continuous flow chemistry: a discovery tool for new chemical reactivity patterns

“…The positive impact of continuous flow chemistry on chemical processes is well studied and has been covered by many review articles. 1 The main benefits which are frequently cited are the improved heat and mass transfer, [2][3][4] greater reaction control, 5 the ease of heating solvents above their boiling point, 6 higher safety when dealing with reactive and hazardous intermediates 7 and relative simplicity of their automation and telescoping of multistep reactions. 8,9 Together these lead to overall process intensification.…”