PTQ Q3 2023 Issue

Olefins production pathways with reduced CO2 emissions

Regulations call for use of renewable feedstocks and electrification via unconventional, sustainable, and circular routes to ethylene, propylene, and other petrochemicals

Christopher R Dziedziak and John J Murphy The Catalyst Group (TCG)

T he focus of recent R&D and commercial develop- ments for novel processes and catalysts for olefins production goes well beyond traditional thermal steam cracking, fluid catalytic cracking (FCC), and propane dehydrogenation (PDH) routes, to include ‘green’ and cir - cular approaches. These routes include, but are not limited to, the utilisation of biomass or waste plastic, renewably produced methane and syngas, direct CO2 conversion, and the electrification of reactors. All of these approaches must address certain critical factors affecting technology viabil- ity, notably the CO2 footprint, lifecycle analysis, and overall sustainability in a move towards ‘Net Zero 2050’ for the chemical and polymer industries. The ‘energy transition’ is impacting and changing the priorities and thinking on conventional olefins production, compelling a closer examination of the shifts toward:  Biomass and recycled waste feedstocks to the cracker and FCC units, trending toward the higher production of bioethylene and biopropylene for bio-PE and bio-PP  The significant investment and progress toward electrifi - cation, highlighted by The Cracker of the Future Consortium  The emphasis on ESG, CO₂ emissions reduction, and improved energy efficiency. Historical context and drivers Refiners and petrochemical companies have seen demand for fuels, petrochemical intermediates, plastics/rubbers, and other products change, with calls for increased circularity and environmental consideration increasing. While they contain favourable demand growth projections above GDP levels, when combined, ethylene and propylene account for the second highest greenhouse gas (GHG) emissions (~250 Mt CO₂e). For decades, steam cracking has been the dominant method to make olefins. However, the same pitfalls that existed in the past will continue going forward, such as high energy requirements, large quantities of produced GHG emissions (mainly in the form of CO₂), the ethylene/ propylene ratio and propylene deficit, and feedstock inflex - ibility. This has led to a flurry of R&D interest in developing novel processes and catalysts that go beyond traditional thermal steam cracking, FCC, and PDH. Over the last several years, nations and oil/petrochemical

companies have been increasing their pledges towards lowering GHG emissions, in some cases to zero. Consumer goods companies are ramping up efforts to produce less, reuse more waste, and lower their carbon footprints, while consumers and investors are demanding that companies do more to address these environmental issues. How pro - ducers and process licensors respond to these changes moving forward will largely determine which chemical and plastics producers will remain leaders. CO₂ reduction pathways In 2021, TCGR completed a multi-client study on the topic of unconventional catalytic olefins technologies, address - ing topics like the propylene deficit, feedstock availability and flexibility, world-scale production vs stranded facili - ties, modular or small-scale production, and environmental issues pertaining to resource utilisation, life cycle analysis, and GHG emissions.¹ Highlighting the study’s findings, focusing on pathways towards reduced CO₂ emissions in olefins production, should provide the readers with a better understanding of where their own technology fits in this landscape or pos - sibly which solutions are right for their own operations. They can identify technological gaps and hurdles to over- come and how to plan their strategic and/or commercial objectives in the coming years. Lastly, they should also comprehend the important role that catalysis will play in addressing the challenges for olefins production and, more broadly, the petrochemical/chemical industry. Fluid catalytic cracking Recovery of ethylene and propylene from FCC off-gas has gained importance. FCC units have long been a source of propylene as a valued by-product of gasoline produc- tion. Specialised process designs and catalysts have been developed to increase FCC-derived propylene production. Technology licensors have developed and offer FCC tech - nologies that span the propylene production range from 8 to 20+ wt% propylene yield on fresh feed. Several new catalysts with substantially larger propylene yields have been invented, as demonstrated in a recent review on light olefins production via FCC.² The selective production of light olefins from waste

PTQ Q3 2023