(227e) Efficient Polystyrene Depolymerization Enabled By Inorganic Nano-Sheet Catalyst

The applications of plastics are diverse and widespread, spanning from industrial to domestic utilities. However, global annual plastic production surpassed 760 billion pounds per year in 2019, leading to a rapid buildup of waste and putting immense pressure on waste management systems. The negative implications of plastics on the environment and their inadequate recyclability have resulted in anti-plastic sentiments. It is alarming that approximately 85% of produced plastic is dumped in landfills or incinerators, posing a significant threat to ecosystems due to the release of microplastics and hazardous materials.

The United States is actively promoting plastic recycling due to various reasons, including the implementation of China's National Sword policy, brand owner commitments, and anti-plastic sentiments.

Polystyrene, a widely used polymer, had global production of about 15.6 million metric tons in 2019. PS caters to a vast range of industrial and domestic applications. PS stands out as the only commodity polymer that exhibits the potential for depolymerization into its styrene monomer. Catalytic pyrolysis and solvent-assisted pyrolysis have also been employed to overcome some of the challenges associated with PS depolymerization. Other methods, like microwave-assisted pyrolysis, vacuum conditions, and high pressure, have also been investigated as strategies to achieve PS degradation. However, these methods carry their own set of challenges, such as lower % styrene yields, the formation of a large number of byproducts, the requirement for high temperatures to achieve pyrolysis, and longer reaction times.

In this work, we present catalytic pyrolysis of PS using an inorganic nanomaterial as a catalyst. The depolymerization reactions were carried out under a vacuum with s few weight percent of the recyclable catalyst. The abstract shows preliminary results, as shown figures. Detailed experimental results referring to catalyst characterization and the product analysis through NMR and GC-MS will be presented at the conference.

The salient features of the catalyst based on the preliminary results were as follows

1. High monomer product recovered
2. High percentage of styrene monomer in the product
3. Low coke formation during recycles
4. High reaction rate
5. Easy catalyst separation
6. Easy catalyst regeneration
7. Low-cost catalyst