Synthesis, Characterization, and Reactivity Studies of Nickel-Gallium Bimetallic Catalysts for Partial Acetylene Hydrogenation

Open Access
Author:
Jones, Michael Joseph
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Robert Martin Rioux Jr., Thesis Supervisor
  • Themis Matsoukas, Honors Advisor
Keywords:
  • Chemical Engineering
  • Catalysis
  • Hydrogenation
  • Reaction
  • Acetylene
  • Ethylene
  • Nickel
  • Gallium
Abstract:
An important reaction in the industrial production of polyethylene is the removal of acetylene impurities from concentrated ethylene streams by catalytic hydrogenation. This reaction is currently conducted over palladium-based catalysts, with the most common being palladium-silver alloys. However, the palladium needed for industrial reactors is quite expensive. There has been recent interest in using earth-abundant metals to develop cheaper bimetallic catalysts that are active and selective toward ethylene production. Nickel-gallium compounds were selected as the catalysts of interest in this study. The catalysts were synthesized by annealing bulk nickel and gallium at varying molar ratios and grinding the resulting ingots into powders. Characterization of the catalysts was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). A batch reactor system was used to hydrogenate 13C acetylene, and the reaction pathways were monitored with gas chromatography-mass spectrometry. The results of this study show that increasing gallium content increases selectivity toward ethylene production but decreases overall activity. Further studies will need to be conducted to determine whether nickel is the proper active metal for this reaction and whether a different bimetallic compound could provide higher absolute ethylene selectivity.