Carbon Dioxide-based Plastic Pyrolysis for Hydrogen Production Process: Sustainable Recycling of Waste Fishing Nets

초록

Fishing net waste (FNW) constitutes over half of all marine plastic waste and is a major contributor to the degradation of marine ecosystems. While current treatment options for FNW include incineration, landfilling, and mechanical recycling, these methods often result in low-value products and pollutant emissions. Importantly, FNWs, comprised of plastic polymers, can be converted into valuable resources like syngas and pyrolysis oil through pyrolysis. Thus, this study presents a process for generating high-purity hydrogen (H-2) by catalytically pyrolyzing FNW in a CO2 environment. The proposed process comprises of three stages: First, the pretreated FNW undergoes Ni/SiO2 catalytic pyrolysis under CO2 conditions to produce syngas and pyrolysis oil. Second, the produced pyrolysis oil is incinerated and repurposed as an energy source for the pyrolysis reaction. Lastly, the syngas is transformed into high-purity H-2 via the Water-Gas-Shift (WGS) reaction and Pressure Swing Adsorption (PSA). This study compares the results of the proposed process with those of traditional pyrolysis conducted under N-2 conditions. Simulation results show that pyrolyzing 500 kg/h of FNW produced 2.933 kmol/h of high-purity H-2 under N-2 conditions and 3.605 kmol/h of high-purity H-2 under CO2 conditions. Furthermore, pyrolysis under CO2 conditions improved CO production, increasing H-2 output. Additionally, the CO2 emissions were reduced by 89.8% compared to N-2 conditions due to the capture and utilization of CO2 released during the process. Therefore, the proposed process under CO2 conditions can efficiently recycle FNW and generate eco-friendly hydrogen product.

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