Research Projects

This project aims to develop a practically workable process for recycling mixed plastic waste into aviation fuel-range hydrocarbons using novel heterogeneous nanoalloy catalysts. Plastic is an important commodity for modern society, but it generates a vast amount of waste with about 12 billion metric tons of garbage by 2050. Thus, there is an increasing demand for recycling plastic waste into chemicals and fuels, which will reduce plastic pollution and the plastic industry's dependency on fossil feedstock. In particular, recycling mixed plastic waste represents a potential approach to enhance the economic viability of plastic recycling technology. Poly(ethylene terephthalate) (PET), poly(carbonate) (PC), and poly(urethane) (PU) are widely used plastic materials, with a major contribution to plastic waste, which can be converted into aviation fuels under hydroprocessing conditions using hydrogen gas in the presence of alcohols (methanol or ethanol). The development of an efficient heterogeneous catalyst with tunable acid-redox properties is essential for recycling mixed plastic waste into aviation fuels. This project proposes a potential strategy to develop multifunctional heterogeneous catalysts, consisting of encapsulated nanoalloys (Pd-Ni and Ru-Ni) in a doped porous SiO2. The proposed catalyst design is novel and shows various benefits: (1) doping of Al3+ or Ti4+ into porous SiO2 can provide abundant acid sites that can accelerate the cleavage of plastic polymers into monomers in the presence of alcohols. 2) Alloying a noble metal (e.g., Pd or Ru) with a base metal (e.g., Ni) can not only reduce the overall cost of the catalyst but also provide selective redox sites for the hydrodeoxygenation of monomers into aviation fuel-grade hydrocarbons. (3) The hierarchical porous structure of SiO2 can inhibit the catalyst deactivation by encapsulating nanoalloys and enhance the diffusion of reagents/intermediates to achieve optimum results in the mixed plastic waste-to-fuel process. The project's primary goals are the precise control of the porous structure of SiO2, doping of Al3+ or TI4+, and nanoalloy (Pd-Ni and Ru-Ni) dispersion into the porous structure of SiO2 to obtain optimum acid-redox sites for the mixed plastic waste-to-fuel process. The challenge of optimizing the porosity and the acid-redox sites can be overcome by controlling the materials’ synthesis conditions. A thorough study of the acid-redox, porosity, nanoalloy dispersion, and particle size will be conducted using various analytical techniques. The catalysts screening for the liquid-phase recycling of mixed plastic waste will be done under a hydrogen atmosphere, followed by reaction conditions’ optimization, catalyst stability/reusability, and kinetic/mechanistic studies to achieve higher yields of aviation fuel-range hydrocarbons. A fundamental understanding of these approaches will aid in a better rational design of the multifunctional catalysts for various applications.