Synthesis and Characterization of MIL-101 (Cr) Adsorbent Coating on Microchannel Walls for Water Adsorption Heat Pumps

A novel approach is developed for washcoating metal-organic framework MIL-101 (Cr), a high-performance water adsorbent, uniformly on a cordierite honeycomb microchannel monolith. The methodology relies upon the characterization of the slurry, which consists of MIL-101 (Cr), SiO2 nanoparticle binder, and a distilled water base and the adsorbent loading as its function. The adsorbent layer thickness is experimentally characterized as a function of viscosity and binder and MIL-101 (Cr) mass fraction. The highest normalized loading of 10%, at the optimized solid fraction of 6%, is identified, for which the layer thickness is remarkably high at 106 mu m. The coated layers are analyzed for homogeneity, porosity, durability, and adsorbent property variations before and after coating through scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and ultrasonic vibration tests. While the adsorbent properties were retained after the washcoating process, the adsorbent layer showed excellent adhesion and durability after ultrasonic vibrations for 4800 h. The channels fabricated using this method can be readily scaled up in separation and heat pump systems.