Preparation of thick mesoporous silica coating by electrophoretic deposition with binder addition and its water vapor adsorption–desorption properties

• Electrophoretic deposition (EPD) of mesoporous silica (MPS) was successfully demonstrated.
• The strength of the MPS coating improved by the EPD with TEOS binder.
• 100 μm-thick MPS coating showed excellent H2O adsorption–desorption property.
• It also showed sufficient stability for more than 250 cycles of H2O-adsorption.
• The dehumidification amount per hour was 6.9 g-H2O/g-MPS.

Ordered mesoporous silica (MPS) is expected to provide an adsorbent for energy-efficient air-conditioning systems, such as desiccant cooling systems, humidity control systems, and adsorption heat pumps, which can contribute to the reduction of CO2 emissions because they offer the possibility of recovery at temperatures as low as 50 °C. For these applications, it is crucial to establish a method for fixing MPS on substrates with high thermal conductivity. We have already studied the technological feasibility of using the electrophoretic deposition (EPD) process to prepare a thick coating of MPS powder on a metal substrate. In this study, we investigated EPD with the addition of a small amount of binder and succeeded in increasing the mechanical strength and thermal stability of the thick MPS coating. The approximately 100 μm-thick MPS coating showed excellent water vapor adsorption–desorption properties and sufficient stability for more than 250 adsorption–desorption cycles, without any reduction in the adsorption amount. The dehumidification amount per cycle was 0.23 g-H2O/g-MPS, which correspond to 6.9 g-H2O/g-MPS/h.

Figure optionsDownload as PowerPoint slide