Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - FLEXI-PYROCAT (Development of flexible pyrolysis-catalysis processing of waste plastics for selective production of high value products through research and innovation)

Teaser

Each year approximately 27 million tonnes of waste plastics are generated in the European Union, the majority of which is recycled or used in energy recovery processes but more than 30% is landfilled representing a waste of resource. There is also significant export of waste...

Summary

Each year approximately 27 million tonnes of waste plastics are generated in the European Union, the majority of which is recycled or used in energy recovery processes but more than 30% is landfilled representing a waste of resource. There is also significant export of waste plastics out of the EU each year.
This project aims to develop and maintain long term collaborations between Universities in the EU with China and Australia with a common goal to advance waste pyrolysis technology by introduction of novel catalysts to produce an innovative two-stage pyrolysis-catalytic process. The technology allows flexible processing of waste plastics to selectively target and produce high value products - (i) hydrogen, (ii) carbon nanotubes, (iii) chemicals or (iv) gasoline.
The research aims to develop optimised catalysts that deliver high quality yields of the targeted high value products. Thereby, process integration of the pyrolysis technology with catalysis aims to deliver an innovative technology with full flexibility to alter process conditions and/or catalytic reactions to deliver the targeted high value products. The project also aims to extend the research and innovation to understand the range of biomass waste feedstocks suitable for co-processing with waste plastics.

Work performed

The most promising technology for the production of high value products based on previous FLEXI-PYROCAT work has found that the two-stage pyrolysis-catalysis of the feedstock has the most potential in terms of flexibility.
Scale-up of the pyrolysis-catalysis process was undertaken in order to understand the implications in process development by moving from experimental bench scale reactors to larger quantities of feedstock, larger scale and further to continuous processing. Process modeling of the scale-up plastic waste pyrolysis catalysis system was undertaken. A process flow diagram of the industrial scale plastic waste catalysis pyrolysis process was developed using Aspen Plus®. A techno-economic assessment was produced based on a mass and energy balance of the process and estimated cost data.
Co-processing of waste plastics and biomass was successfully performed in a two-stage reactor with different plastics for the production of hydrogen. Adding polystyrene significantly improves the quality of bio-oil from biomass due to co-processing and improving the aromatic content and gasoline range hydrocarbons in the oil. Co-processing biomass and waste plastics however has a detrimental effect on the quality of product carbon nanotubes.
Standards and specifications of commercially carbon nanotubes, hydrogen, petroleum derived fuels (gasoline, diesel), and aromatic chemicals have been compared with the target end-products produced from the FLEXI-PYROCAT project. Carbon nanotubes produced from plastics showed the most promise in matching to commercial standards.
A WEB based learning resource related to the pyrolysis and gasification of wastes plastics for the recovery of high value products has been prepared and presented aimed at high school children and teachers and the informed general public. The three packaged learning resources contain a wealth of easily accessible information and references and are presented as ‘Open Access’ on the FLEXI-PYROCAT WEB SITE;
Articles published in high impact international journals are a highlight of the FLEXI-PYROCAT project, resulting in currently 23 papers published as OPEN ACCESS. Several of the papers are amongst the top ‘most downloaded articles’ of the journals (e.g. Journal of the Energy Institute (Impact Factor 4.2) and Journal of Analytical & Applied Pyrolysis (Impact Factor 3.4). In addition, one paper reported on work by the consortium members that has produced carbon nanotubes from waste plastics and then incorporated the collected carbon nanotubes into composite material which was tested and shown to deliver superior strength characteristics. The research was published in the journal Process, Safety & Environmental Protection (103 (2016): 107-114) which is the Official Journal of the European Federation of Chemical Engineering. The work was featured by the Institution of Chemical Engineers monthly magazine ‘The Chemical Engineer’ (November 2016, pp21) with a circulation in excess of 40,000 copies per issue.

Final results

There have been significant scientific advances in the project including advances beyond the current state-of-the-art;
• New research beyond the state-of-the-art has been carried out by developing a range of catalysts. Work has shown that type of catalyst metal promoter, the location and particle size of the nano-metal particles in the catalyst, the type of catalyst support material and method of catalyst preparation all influence the conversion of waste plastics to hydrogen and carbon nanotubes.
• The project has developed an innovative process to use stainless steel mesh which is impregnated with nickel to produce a nickel-mesh catalyst. This development is for easy collection of the carbon nanotubes in the combined two-stage combined pyrolysis-catalysis reactor system.
• Carbon nanotubes produced from waste plastics have been incorporated into composite material which was tested and shown to deliver superior strength characteristics. The tensile and flexural strength and the tensile and flexural modulus of the CNT composite material were significantly improved by the addition of the recovered CNTs.
• The research has been extended by using carbon dioxide as a process gas for the pyrolysis process, known as \'dry reforming\'. This uses a \'greenhouse gas\' to increase the amount of product syngas (combined hydrogen and carbon monoxide). The work has identified the best catalyst for the process as Ni-Co-Al2O3. In addition, processing waste plastics with both carbon dioxide and steam was able to manipulate the H2:CO ratio to optimise for a range of end-product uses e.g. for Fischer Tropsch production of gasoline.
• The work has also emphasised the impact of contamination of waste plastics for the production of chemicals, liquid fuels such as gasoline and carbon nanotubes. Volatile contaminants such as chlorine and sulphur significantly affect the performance of the catalyst and can result in contamination of the product liquid fuels and chemicals. Volatile metal contaminants can result in carry-over of the metals into the product liquid fuels and chemicals. In the case of carbon nanotubes, the presence of chlorinated plastic (PVC) impacts on the quality of the product carbon nanotubes.
• Process modeling of the scale-up plastic waste pyrolysis catalysis system.using Aspen Plus® produced a process flow sheet with 6 functional units. A techno-economic assessment was produced based on a mass and energy balance of the process and estimated cost data.
• Co-processing waste plastics with biomass in the pyrolysis-catalysis process has been shown to improve the quality of bio-oil, particularly addition of polystyrene which increases the yield of gasoline range hydrocarbons and increases aromatic content of the product oil. The influence of co-processing on carbon nanotube production indicates that the presence of biomass has a detrimental effect on the quality of the product carbon nanotubes. Addition of plastics to biomass also suggest hydrogen yield can be increased.

Website & more info

More info: https://flexi-pyrocat.com/.