Hydrogen Production Promotion from Nonrecyclable Plastic Waste via a Single-Step Catalytic Thermal Cracking/Steam Reforming Scheme

Abstract

A complete analysis of a catalytic pyrolysis scheme, evolved to a combined in situ thermal cracking/steam reforming scheme, to valorize nonrecyclable plastic waste is presented. The study aims to analyze the three fractions obtained, focusing on the production of a hydrogen-rich gaseous fraction with industrial interest. The optimization in terms of hydrogen generation is carried out using various ruthenium-containing catalytic systems prepared by a facile preparation method. Several catalytic systems were tested, all ruthenium-containing materials interacting with g-C₃N₄, ZSM5, high-surface-area carbon, and TiO₂ as active supports. In the combined reaction scheme defined by catalytic cracking/steam reforming reactions at 550 °C of the pyrolysis gases using a RuO₂/TiO₂ composite system in a one-step reaction system, 270.7 mmol of hydrogen (13.5 mmol g^–1 of plastic waste) were obtained, representing an increase of 227.6 mmol in comparison with the traditional thermochemical process. The contribution is completed with a characterization scheme of the obtained product fractions and composite catalysts, including a postreaction analysis, which allowed the identification of the main properties (catalysts) and operating conditions (setup) to optimize the process.