Experimental investigations for various types of adsorption isotherms

• Main Author: Tan, Jarrell Jun Hao
• Other Authors: Anutosh Chakraborty
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/78585
• Institution: Nanyang Technological University

Global warming has led to a greater demand for environmentally friendly machines, as many current heavy machinery and processes such as the industrial water chiller still emit greenhouse gases. The refrigerant used in industrial water chillers contains greenhouse gases which can contribute to global warming potentials. Therefore, industries are moving toward greener alternatives, one of which is the adsorption technology which uses functional Metal-Organic Frameworks (MOF) as porous materials to store environmentally unfriendly refrigerants or greenhouse gases. MOFs are large porous 3-dimensional organic compounds consisting of metal ion and organic linkers. MOFs can be used as water adsorbents due to their high micro porosity properties. The focus of this study will be on the modification of MOF material MIL- 101(Cr), a crystalline mesoporous adsorbent that has excellent water adsorbent properties due to its large surface area and porous volume. A total of four different adsorbents of MIL-101 (Cr) were modified by adding organic side groups of [-(NH2)], [-(CH3)], [-(CH3)2] and [-(CH3)2 + -(NH2)] to improve the water adsorption uptake and kinetics of adsorption. The various isotherm curves of the adsorbents were also obtained. The MIL-101-based adsorbents were synthesized and then analyzed with Scanning Electron Micrography (SEM) and X-Ray Diffraction (XRD) to investigate the microstructures of these modified adsorbents. Next, Thermogravimetric Analysis (TGA) was carried out to test the thermal stability of the adsorbents. Subsequently, an experimental investigation was conducted to determine the water adsorption uptakes of the adsorbents and the adsorption kinetics in comparison to the parent adsorbent of MIL-101(Cr). The four modified adsorbents were successfully synthesized, and it was discovered that all the modified adsorbents displayed shorter hydrophobic length and quicker kinetics compared to the parent adsorbent. Therefore, the modified adsorbents’ gravimetric water adsorption uptake at low pressure region between 0 to 0.42 P/Ps were greater than the parent MIL-101(Cr). NH2-MIL-101(Cr) exhibited superior water adsorption properties compared to the other three modified adsorbents and parent MIL-101(Cr).