Catalytical thermal conversion of waste fishing nets for a higher added value energy products generation and caprolactam recovery

Abstract

The ongoing eutrophication processes and water pollution caused by marine plastic waste are relevant ecological problem. Collected wastes are possible alternative feedstock for additional higher added value energy product generation. Moreover, caprolactamis the main compound of nylon-6 waste fishing nets and its recovery conserves natural resources, maximizes waste economic performance, and closes the circular economy loop of the fishing net industry. In order to contribute to the creation of circular economy, investigation of pyrolysis process and the effect of catalyst synergy with different temperatures on the formulated products has been performed. This work aims to analyse the used fishing nets (FN), using TGA-DTG-FTIR systems and mini pyrolysis plant. Experiments were conducted with Y-type zeolite and ZSM-5 as catalysts with a ratio of 1 by 3 and 1 by 8, respectively. Micro-thermal analysis using the TGA-DTG-FTIR system was processed for feedstock characterization purposes, which showed that the fishing gear has one minor decomposition peak around 200 °C, and the major one around 450 °C, with a total weight loss of 88 wt%. Pyro-oils analysis showed that the main fractions could be assigned to aromatic and aliphatic hydrocarbons, such as naphthalene, styrene, and toluene. Moreover, the recovery of caprolactam shows a possibility to obtain not only energy products, but also higher added value chemical derivatives. Temperature and catalyst synergetic approach influence for the recovered products investigation showed the optimum conditions as 700 °C for the highest purity and quality products generation. Based on the results, catalytic thermal treatment at 700 °C with Y-Type could be adapted as a promising technique for extracting of caprolactam with a high yield (96 %).