The end-of-life management of plastic represents a significant environmental challenge, largely due to its limited use, low biodegradability, and high volume of disposed material, in the order of 400 million tonnes by 2019. Several types of polymers can be recycled by mechanical means, but some others, like plastics, sometimes require chemical methods for their reuse. In this context, gasification is one of the most promising chemical recycling techniques. Gasification is a thermochemical process performed at moderate temperatures of work (800–1100 °C) that converts carbonaceous materials into rich hydrogen gas, which can be used for energy obtention or the Fisher–Tropsch process. However, this procedure can also produce undesirable by-products like tar and char. The products’ composition and relative quantities are highly dependent on the overall process configuration and the input fuel. The current study evaluates the catalytic gasification of the most common plastic waste, seeking to obtain higher gas yields and syngas with high energy. The text focuses on the current state of development and recent advances in various publications over the last fifteen years, with emphasis on thermoplastics and thermosets. The search showed that temperatures, the type of fluidizing gas, and the catalyst have a major influence on the quality of the obtained gas. Optimal gasification conditions, such as temperatures between 600 and 900 °C, depending on the plastic feedstock, steam-to-feedstock ratios > 1, the appropriate selection of a gasifying agent according to gas requirements and energy optimization, and the composition and location of the catalyst in the system (in situ, in the reactor, or ex situ), are identified as critical for maximizing H₂ and CO production and minimizing tar. Finally, we provide summaries of the last advanced patent in the field, where the main focus appears to be feedstock pretreatment intended to ensure handling feasibility due to the variety of plastic wastes.

The management of solid waste and the supply of energy are two of the most important environmental problems of our time. Projections indicate that by 2050, the global demand for electrical energy is expected to increase by 35% and the amount of solid waste generated to increase by 45%. In this context, polymeric waste materials such as biomass and plastics can be valorised through thermochemical processes for the generation of energy. Gasification, which converts carbonaceous materials into syngas, tar, and char, is one of the most promising recycling technologies. The composition and relative quantities of the products are influenced by the process configuration, operating parameters, and the type of fuel used. Tar removal is facilitated by adding specific catalysts to the process. The co-processing of biomass and plastics in the gasification process, called co-gasification, improves the gas yield and reduces solid residues. This review evaluates catalytic and non-catalytic co-gasification of biomass waste and non-biodegradable plastics, with a focus on syngas production and its energy potential.