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Improvement of Mechanical Properties of Nickel Nanocatalyst with Application in Methane Reforming

Zafar Doagoo, Masoomeh | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: English
  3. Document No: 56916 (57)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Sadrnezhad, Khatiboleslam
  7. Abstract:
  8. This research aims to introduce a nanocatalyst based on open-cell nickel foam (NiFm) with 40 pore per inch(ppi) to save energy during methane steam reforming (MSR), an endothermic reaction, by increasing catalyst thermal properties with improved progressive compression strength. The nanocatalyst is synthesized with a chemical stepwise synthesis approach, thermal-chemical pretreatment, pulsed electrocodeposition of Ni-Al2O3 (γ) nanoparticles, and calcination. Herein, a polyurethane (PU) nonconductive substrate is transformed to nickel foam by using replication sponge method. The purchased PU became conductive by nickel electroless bath using sodium hypophosphite with 5-15 (µm) thickness nickel layer. Then deposition is continued by nickel bath electrodeposition technique to increase nickel thickness up to 50-80 (µm) for strengthening. Afterwards, the polymeric substrate is removed by pyrolysis with a thermal controlled procedure in a tube furnace with purging 99.999% argon gas flow. In continue, to increase roughness the NiFm is pretreated to coat nickel/alumina(γ) nanoparticles (NPs) with pulse electrocodeposition (PED) method then calcination to synthesize the nanocatalyst. Measurements of thermal diffusivity(α) with flash xenon technique gained 4.41×10-6 m2s-1 and values of specific heat capacity (Cp) by differential scanning calorimetry (DSC) and thermal conductivity(λ) enhanced by 65% with temperature rise in 150 to 550◦C for Ni-alumina(γ) foam nanocatalyst. Furthermore, hardness and compression tests for comparing pure NiFm, Ni-alumina(γ) foams and the common pellet catalyst used in MSR are measured. Results indicated that the foams’ hardness improved from 145 Vickers hardness (HV) to 547 HV and the progressive compression strength increased from 1.1 MPa to 5MPa, while for pellet is 3 MPa with a brittle failure. Specific surface area (SBET) of foams enhances from 1.48 m2g-1 to 48 m2g-1 and for the pellet is 35 m2g-1. Roughness is measured at 409(µm) for the PED foam and 105 (µm) for the pellet. The SEM and optical microscopy images are used for morphological analysis and the pores size is measured by ImageJ. Characterization of synthesized specimens is performed with XRD, TGA, laser profilometer, FESEM, EDS, and H2-TPR. XRD (x-ray diffraction) analysis showed NiO and NiAl2O4 in the structure. The interface between the catalytic component (NiAl2O4), and nickel affected the catalytic ability for MSR. However, in the catalytic test by online GC set at temperature of 500 ◦C the reported outlet composition of H2 is 64.3% after 2.5(hour) which is comparable to the similar reactions reported at 720 ◦C by other investigations
  9. Keywords:
  10. Nickel Foam ; Open-Cell Foam ; Pulse Elctrodeposition ; Nano Catalyst ; Methane Steam Reforming (MSR) ; Gama-Alumina ; Pulse Electrocodeposotion

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