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Advances in Catalysis for Plastic Conversion to Hydrocarbons

A recently issued technical investigation commissioned by the members of the Catalytic Advances Program (CAP) details recent advancements in catalysis for plastic conversion to hydrocarbons

See PPT Deck here (as PDF) | See Report TofC here (as PDF)

This TCGR report analyzes the role, gaps and prospects for using catalysis and related technologies and materials to convert plastics to hydrocarbons. The worldwide production of plastic products has been increasing rapidly over the last few decades. A continuous rise in plastic demand has led an increase in the generation of plastic waste. Around 60% of plastics enter the environment as plastic waste. 

Among the options for plastics recycling, catalytic pyrolysis is getting increased attention. This is due to the possibility of processing gasoline range hydrocarbons from plastic waste that could directly be used as a fuel. Although hydrocracking is an advantageous process with respect to the quality of hydrocarbon product obtained, the requirement of hydrogen (which is of high cost) increases the operational cost of this process. Metal-containing ionic liquids are also effective and green catalysts have been developed to replace toxic heavy metal catalysts. It is worth mentioning that polymers/waste plastics display a wide range of chemical structures which makes the depolymerization technically difficult and the task gets even more complicated due to presence of mixed streams in wastes.

Figure 1: a) Proportion of demand of various plastic types b) Major composition of plastic packaging wastes.
Sources: PlasticsEurope, 2019; Colantonio et al., 2019

Among the critical scope items included in this CAP report are:

  • Recent developments in catalytic processes for the conversion of plastic into hydrocarbons.
  • Catalytic pyrolysis process, which involves conversion of long chain polymeric molecules into small molecular weight hydrocarbons, in the presence of catalyst, under inert atmosphere.
  • Hydrocracking of plastic, that involves cleavage of carbon-carbon bond of heavy plastic molecules (high boiling) into lighter molecules (low boiling) in the presence of hydrogen with successive or simultaneous hydrogenation of unsaturated molecules.
  • Recent advancement in catalyst development for hydrocracking, such as zeolites, sulfated zircona, mesoporous catalyst, aluminosilicates, and bifunctional catalysts.
  • Recent trends regarding composite catalyst synthesis for getting required product selectivity, that not only improves the product selectivity but also effectively increases the conversion of plastic at comparatively lower reaction temperatures.
  • The metathesis reaction, which is a bimolecular double displacement reaction involving the exchange of bonds between the two reacting chemical species and its applications in depolymerization of polymers/plastics.
  • The recent literature for depolymerization, mainly used when macromolecules are reduced to monomer units without major changes in chemical compositions or petrochemical materials which can later be used for production of chemicals.
  • Various other approaches used for degradation/depolymerization of plastic wastes such as bioprocesses, reductive depolymerization and co-processing techniques.

TCGR’s report, Advances in Catalysis for Plastic Conversion to Hydrocarbons, summarizes the driving forces in tertiary recycling and degradation techniques for plastic in detail, including; pyrolysis, hydrocracking; alkane metathesis; and depolymerization. Recent developments in catalysts, suitable plastic types, and product distribution corresponding to each catalytic process are the focus of this report and are discussed in detail. Physical recycling techniques, such as primary recycling and secondary recycling are not addressed, as they are deemed out of the scope for this report, as is the quaternary recycling technique for energy recovery.

The PPT Deck, as well as a PDF containing the complete TofC, List of Figures and Tables, are available for download below:

See PPT Deck here (as PDF) | See Report TofC here (as PDF)

More information about this report and other services of CAP can be seen at
https://www.catalystgrp.com/tcg-resources/member-programs/catalytic-advances-program/ .
Call +1-215-628-4447 or e-mail Chris Dziedziak at cdziedziak@catalystgrp.com,
and we’ll be happy to discuss these and other interesting membership benefits.