Silicone microreactors for the photocatalytic generation of hydrogen

Abstract

A silicone microreactor with 500 mu m-width microchannels coated with a Au/TiO2 photocatalyst was manufactured and tested for the photocatalytic generation of hydrogen from gaseous water-ethanol mixtures under dynamic conditions. The manufacture of the microreactor included the fabrication of a polylactic acid (PLA) mold with a 3D printer and casting with polydimethylsiloxane (PDMS) prepolymer. After curing, the silicone microreactor was peeled off and the microchannels were coated with a Au/TiO2 photocatalyst prepared by impregnation of preformed Au nanoparticles over TiO2, and sealed with a thin silicone cover. The microreactor was tested at room temperature and atmospheric pressure under different operational conditions (photon irradiance, residence time, photocatalyst loading, and water ethanol ratio). Hydrogen production rates of 5.4 NmL W-1 h(-1) were measured at a residence time of 0.35 s using a H2O:C2H5OH molar ratio of 9:1, a photocatalyst load of 1.2 mg cm(-2) and a UV irradiance (365 nm) of 1.5 mW cm(-2) achieving an apparent quantum efficiency of 9.2%. The photogeneration of hydrogen with commercial bioethanol was also tested. A long-term photocatalytic test of two days revealed a stable hydrogen photoproduction rate. The use of silicone microreactors represents an attractive and customizable solution for conducting photochemical reactions for producing hydrogen at low cost. (C) 2016 Elsevier B.V. All rights reserved.Postprint (published version

Fast and Simple Microwave Synthesis of TiO2/Au Nanoparticles for Gas-Phase Photocatalytic Hydrogen Generation

“…The amount of deposited photocatalyst was set to 4 mg, in order to achieve an optimal photocatalyst loading value of ca. 1.2 mg/cm 2 previously reported by Castedo et al ( 2016 ). The insets in Figure 5 show the materials corresponding to the as-synthesized samples A and B.…”

Kinetic analysis and CFD simulations of the photocatalytic production of hydrogen in silicone microreactors from water-ethanol mixtures

“…This process can be intensified by using suitable photocatalytic microreactors that allow an efficient use of the photons through a good contact between the photocatalyst and the reactants and a good exposure to the light. The recently reported effectivity of these microdevices for hydrogen production through the photocatalytic dehydrogenation of bioethanol [13] is promising to develop future power applications. This work is a contribution to this approach in which silicone The symbols correspond to the experimental results and the lines to the CFD simulations.…”

“…The microchannels and the deposition of the Au/TiO 2 catalyst on their walls were studied by scanning electron microscopy (SEM) with a Zeiss Neon40Crossbeam Station equipped with a field emission electron source. As reported previously, the photocatalyst was also characterized by X-ray diffraction (XRD), UV-vis reflectance spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) [13].…”

“…More recently, we have manufactured a silicone microreactor with microchannels using a simple, versatile and cheap technology based on 3D printing and polydimethylsiloxane (PDMS) polymerization. The main advantage of the latter is that it allows the use of sunlight directly, which obviously reduces the hydrogen production costs [13].…”

“…Figure 1 shows the devices manufactured in this work to carry out the photocatalytic production of hydrogen and the physical models of the fluidic domains developed to conduct the CFD simulations. The single silicone microreactor and the scheme of its fabrication has been reported previously [13]. Briefly, the PDMS microreactor shown in Figure 1A consisted on nine microchannels of 500 μm (width) x 1 mm (depth) x 47 mm (length), with a total volume of 0.21 cm 3 , and two headers to facilitate gas distribution.…”