For mixed plastic wastes, the tolerance of the FCC unit to lower hydrogen content and higher concarbon feedstocks may offer an advantage. BASF has partnered with Neoliquid to explore the upg- radability of mixed plastic waste using catalytic cracking. Neoliquid operates commercial-scale pyrolysis units in Spain, preparing oils from a variety of renewable and recy- cled wastes. ACE evaluation was performed using an oil prepared from a residential mixed plastic waste stream char- acterised by an effective hydrogen index of 1.5 and a concar- bon of 1.0 consistent with a mild conventional resid oil. The composition of the oil measured using simulated distillation via gas chromatography (GC) compared to that associated with polyolefin pyrolysis oil and conventional gasoil is illus- trated in Figure 5 . A more detailed analysis of the oil using GC combined with mass spectroscopy revealed evidence of several plas- tics, including polyethylene, polypropylene, polystyrene, and polyethylene terephthalate (see Figure 6 ). In the ACE reactor, the pyrolysis oil was fed undiluted using the com- mercial BASF max naphtha catalyst, resulting in the yields illustrated in Figure 7 . Consistent with the design of the catalyst used in this experiment, the pyrolysis oil was con- verted into a largely naphtha product mix but also con- tained a significant fraction of olefinic LPG. The coke yield of roughly 4% is in line with conventional mild resid and consistent with the concarbon of 3.9%. Compared to the cracking of pure polyolefin pyrolysis oil, there is a decrease in LPG/gasoline, which is consistent with the higher aro- matic content of the mixed plastic waste oil accumulating in the gasoline product fraction. Producing green fuels using FCC Deriving fuels from biomass replaces fossil carbon with renewable carbon that will not add to the issue of atmos- pheric carbon accumulation and climate change. Biomass is a broad term referring to a wide variety of plant-derived mate- rials. However, for this discussion, we can narrow our focus
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it may be possible to apply a fixed bed catalytic process, which has the potential to significantly simplify the process, allowing integration into the pyrolysis process itself (ex-situ catalytic pyrolysis). While polyolefins are the most straightforward plastic waste, they only represent 45% of the total available plastic waste generated each year. Further, it will not be practical to completely sort polyolefins from other plastics. Pyrolysis and further upgrading of mixed plastics will be more challeng- ing than polyolefin-based wastes.2 For example, polystyrene will undergo non-random scission during pyrolysis, largely yielding only alkylbenzenes, increasing the aromatic content of the oil. As another example, pyrolysis of polyethylene terephtha- late (PET) results in relatively low liquid yields that largely contain benzoic acid, introducing both oxygenates and aro- matics into the pyrolysis oil. In practice, streams of plastic waste will be made up of a mixture of materials. Even if polyolefins are desired, complete sorting will not be practi- cal, and some level of other plastics will always be present. Figure 5 Composition of pyrolysis oils derived from pure LDPE and actual urban mixed plastic waste compared to conventional gasoil
Examples of dominant hydrocarbon species in oil
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Figure 6 Composition of pyrolysis oil derived from mixed plastic waste with illustrations of dominant species identified using GC-MS
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PTQ Q4 2023
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