← Back to Publications

Catalytic Technologies for Waste Recycling and Conversion: Driving Sustainable Innovation

Author: Dr. Ahmad Saylam

Document type: Open technical preprint

Version: v1

Publication date:

Technical status: Narrative technical review and development overview. It supports technology orientation, comparison of catalytic routes and development-question formulation, but it is not a systematic review, a validated catalyst-selection model, a final process design, environmental certification or an industrial performance guarantee.

DOI: 10.5281/zenodo.19769294

Zenodo record: https://zenodo.org/records/19769295

Abstract

Catalysis can play an important role in waste conversion and recycling by altering reaction pathways, selectivity, operating severity and product distribution. This review examines catalytic approaches relevant to organic-waste conversion, biomass utilization and chemical recycling of plastics.

Depending on feedstock, catalyst, reactor configuration and process conditions, catalytic systems such as metal oxides, zeolites and nickel-based materials may improve selectivity, conversion or product quality and support the production of fuels, monomers, syngas and other products. Any reduction in energy use or environmental burden must be evaluated against an explicit reference process and complete system boundary.

The paper reviews catalytic technologies associated with hydrothermal liquefaction, pyrolysis, gasification, depolymerization and bio-oil upgrading. It also discusses practical limitations, including catalyst deactivation and poisoning, feedstock heterogeneity, contamination, heat and mass-transfer limitations, cost, catalyst recovery and regeneration, product upgrading, downstream separation, scalability and environmental management.

Emerging directions include nanostructured catalysts, biocatalysts, photocatalysts, electrocatalysts and hybrid systems. Their industrial relevance depends on matching catalyst chemistry and reactor conditions to the actual feedstock, product objective, contaminant tolerance, separation train, catalyst lifetime, safety constraints and operating envelope. Novel catalyst activity alone is therefore not sufficient evidence of process-level advantage.

Processes covered

  • catalytic and biocatalytic conversion of organic waste;
  • hydrothermal liquefaction of wet biomass and organic residues;
  • catalytic pyrolysis and gasification of biomass and plastics;
  • catalytic depolymerization and monomer recovery;
  • syngas conditioning, reforming and catalytic upgrading;
  • catalytic upgrading of bio-oils and pyrolysis vapours;
  • catalytic treatment of industrial wastewater and gaseous emissions.

Scope and evidence boundary

The review supports technology orientation, identification of relevant catalytic routes, preliminary comparison of benefits and limitations, formulation of development questions and planning of more focused literature, laboratory or pilot studies. It does not establish a ranked catalyst or technology recommendation for a specific waste stream.

Application to a specific waste stream requires verified feedstock composition and variability, catalyst and support selection, kinetic and equilibrium data, transport and hydrodynamic analysis, catalyst deactivation, poisoning and regeneration studies, product and contaminant analysis, closed material and energy balances, downstream upgrading and separation design, process-safety review, durability evidence and representative pilot validation.

Claims concerning lower emissions, reduced energy demand, circularity, resource efficiency or economic viability should be evaluated against a clearly defined reference process, functional basis and complete system boundary. Catalyst activity, conversion or selectivity alone does not establish lifecycle or economic superiority.

Full text

A lawful local copy of the open technical preprint is available for direct browser reading: View PDF .

The canonical deposited record, metadata and deposited files remain available through Zenodo: open the Zenodo record .

License

The deposited work is identified as available under the Creative Commons Attribution 4.0 International licence .

Recommended citation

Saylam, A. (2025). Catalytic Technologies for Waste Recycling and Conversion: Driving Sustainable Innovation. Version v1. Zenodo. https://doi.org/10.5281/zenodo.19769294

Development and validation interpretation

This review is best used as an orientation layer within a broader process-development workflow. Candidate catalytic routes should move forward only when the governing chemistry, transport limitations, catalyst lifetime, product-quality requirements and separation burden are sufficiently understood for the next decision.

Laboratory catalytic activity, short-duration conversion tests and software calculations are different evidence types. None of them alone establishes long-term catalyst durability, scale-up behaviour, product purification performance or industrial economics.