Synthesis of Pillar-layered Metal Organic Frameworks for Carbon Dioxide Adsorption Applications /

Abstract

Over the past century, the dependency of humans on fossil fuels has increased dramatically. Fossil Fuels have become the main source of energy production because of their low cost and easy availability but they have their own drawbacks. The biggest disadvantage of using Fossil Fuels is that they produce gasses that are harmful for the environment. The gasses that harm the environment are called Green House Gasses (GHGs) and Carbon dioxide is the biggest contributor of all GHGs present in the environment. For the past two decades a lot of work has been done to study GHGs and methods have been developed to capture, store or convert environmental and/or exhaust CO2. One of the more advanced method for CO2 capture is physical adsorption which has been accomplished using different materials by different researchers. Recently, Metal Organic Frameworks (MOFs) have come up as one of the more efficient adsorption materials for CO2 capture or as catalysts to enhance CO2 capture. MOFs are materials that contain a 2-D lattice that contains a network of Metal ions and Organic Linkers combining to produce a structure that can trap gaseous molecules. These MOFs are functionalized to produce enhanced adsorption results and better properties like improved surface area or affinity to CO2 molecules. There are two types of functionalization used in MOFs i) Pre synthetic Functionalization ii) Post synthetic Functionalization. In this research the method of Pre-synthetic Functionalization is used to turn the 2-D structure of the MOF into a 3-D structure to enhance its surface area and pore volume. These types of MOFs are called Pillared-Layer MOFs as they have a pillar material that combines multiple layers of the 2-D lattice and results in producing a 3-D MOF. In this study, we synthesize, characterize and test two Pilared-Layer MOFs for CO2 capture. The MOFs are Zn-BDC-Dabco and Co-BDC-Dabco in which Zinc and Cobalt are the metal ions, BDC or Terephthalic Acid acts as the organic linker and Dabco acts as the pillar. These samples showed improved CO2 adsorption compared to the same MOFs without Dabco and showed better results than a lot of other similar MOFs. The Cobalt and the Zinc based MOFs showed a CO2 adsorption capacity of 4.4 mol/kg and 6.3 mol/kg respectively and showed good thermal stability up to 300 degrees Celsius.