Eunkyung Cho

The upgrading of waste plastic pyrolysis oil (WPPO) through hydrotreating (HDT) is crucial for transforming plastic waste into chemical feedstock. The catalytic role of HDT is of paramount importance for this conversion procedure. In this study, bimetallic catalysts based on Ni and Mo were prepared using the surfactant-assisted melt-infiltration (SAMI) method, completely omitting the use of liquid solutions. Thorough analysis via X-ray diffraction, transmission electron microscopy, and hydrogen temperature-programmed reduction confirmed that the addition of Span60 surfactant effectively prevented the aggregation of Ni and Mo components, reduced the size of metal particles, and improved the dispersion of active sites on the zeolite supports. Consequently, NiMo-based catalysts incorporating Span60, synthesized using the SAMI method, exhibited a superior catalytic performance in the removal of nitrogen, sulfur, and chloride impurities from WPPO during HDT compared to those without surfactant. Specifically, the catalyst prepared with Span60 exhibited 15% higher nitrogen conversion compared to the catalyst prepared without Span60.

A pellet catalyst was prepared to be used in a large-scale steam methane reformer. Hydrotalcite powder (MG30) was used as a precursor to prepare MgAl₂O₄ pellet supports at different calcination temperatures. Ni-supported catalysts with egg-shell-type distribution were prepared on these pellet supports: Ni/sup-x (where x is the calcination temperature of the support with x = 1273, 1373, and 1473 K). Among them, Ni/sup-1473, which experienced the highest calcination temperature (1473 K), showed the highest methane conversion and lowest weight loss owing to carbon deposition. As a result, when the calcination temperature increased, the egg-shell thickness decreased, and the reducibility of the catalyst was enhanced. Although a small amount of Ni (3.5 wt%) was used, the egg-shell-type catalyst had superior catalytic activity and coke resistance. Therefore, the egg-shell-type catalyst using Ni as the active material and MgAl₂O₄ calcined at high temperature as the support is expected to be appropriate for large-scale industrial steam methane reforming reactions.