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Investigation of Performance and Improvement of the Activity of MOF-based Catalysts in CO Oxidation Reaction

Abbasi, Fatemeh | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54671 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Cyrus; Karimi Sabet, Javad
  7. Abstract:
  8. Different catalysts have been proposed for CO oxidation reaction and still many researches are performed to obtain a catalyst with high activity and stability. In this study, MOFs of CuBTC, MIL-101(Cr), and NH2-MIL-101(Cr) and active metal of Pd have been selected and their performances have been investigated in CO oxidation reaction. MOFs have been synthesized by hydrothermal method. Pd loading has been performed by impregnation method in various pH and in aqeous palladium nitrate solution and palladium nitrate solution in nitric acid. To reveal the effect of the nature of noble metal, activity of 1% Pt/MIL has been investigated. Amine-functionalized MIL-101(Cr) has been synthesized by hydrothermal (MNH2) and post-synthetic modification (MNH2-p) approaches. The performance of Pd/MNH2, Pd/MNH2-p, Pd/CuBTC, and Pd/MIL catalysts in the CO oxidation reaction is investigated and the effect of concentration and flow of hydrogen, calcination of them under pure oxygen, and different order of calcination and reduction procesess are evaluated. The results show that Pd/MNH2 has the highest activity but low temperature stability in oxygen. Pd/MIL has good activity and stability. Therefore, in order to improve the activity of Pd/MIL, Ni, alkali and alkaline earth metals as promoters and phosphotangenic acid (PTA) are applied. PTA is loaded into MIL cavities by impregration and incapsulation methods. A simple and new approach to incorporate PTA within MIL cavities is presented, which results in a PTA-MIL with a surface area higher than the MIL. The results show that higher activity of Pd/PTA-MIL and PdMg/MIL than other catalysts studied. The feed including istopes of oxygen has been prepared by electrolysis and setup of isotopic exchane under the atmospheric condition has been prepared. The catalytic activity of Pd/MIL, Pd/PTA-MIL, PdMg/MIL, Ag/MIL, AgO/MIL, 3% Rh/PTA-MIL and 3% Ru/PTA-MIL catalysts have been investigated in isotopic exchange reaction. No activity have been observed. Pd/CuO catalyst has been tested in the reaction to show that there are no problem under the reaction and analysis system and the exchange starts at 435 ℃. This result indicates that there is no problem ib the setup of the reaction, but higher temperatures are required to observe the reaction on MOF-based catalysts, which cannot be provided on MOFs
  9. Keywords:
  10. Catalyst ; Promoter ; Metal-Organic Framework ; Isotopic Exchange ; Phosphotungstic Acid ; Carbon Monoxide Oxidation

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