PTQ Q1 2023 Issue

Q Do you see growing investor interest in process- ing plastic waste-derived pyrolysis oil through refinery assets, such as hydrocrackers? Against this backdrop, how prepared are refiners to invest in contaminants removal systems (for pretreatment of the pyrolysis oils)? A Michael Allegro, Technical Services Specialist, BASF, Advanced plastic recycling is becoming an important part of many long-term refinery strategies. One key consider - ation is how the legislation will pan out. Will plastics-to- fuel be an economical route, or is full plastics circularity the end goal? With many refineries configured to maximise transporta - tion fuel products, the yield of plastic precursors on a lb- per-lb basis of waste plastics may not be high enough to meet the circularity targets likely to be mandated. However, if fuels produced from waste plastic oils can qualify for renewable credit, the conversation about utilising refinery assets becomes much more attractive. Contaminant removal is a major challenge for refiners considering processing plastic pyrolysis oils (pyoils). Aside from the associated Capex, these systems may come with unique maintenance requirements, large plot spaces, high Opex, and new environmental impacts that refineries are not prepared to bring inside their battery limits. Additionally, there is uncertainty about waste availabil- ity, which could require refiners to purchase from multiple sources. This can lead to increased variability in pyoil qual - ity, which could make investing in the appropriate contami - nant removal systems more complicated. A Fu-Ming Lee, Maw-Tien Lee, and Tzong-Bin Lin, all Senior Consultants, Shin-Chuang Technology, and Ricky Hsu, Founder, International Innotech, Inc., ricky_hsu@ Interest is growing in converting waste plastics, including PE, PP, PS, PET, ABS, and PVC, into pyrolysis oil through steam cracking, cat cracking, or hydrocracking. However, several problems are encountered:  Lack of pretreatment systems for removing heavy metal contaminants from the feed, such as lead, nickel, zinc, cop - per, chromium, antimony, and barium (from additives to the plastics), to protect cat cracking or hydrocracking catalysts.  Reactor plugging problems (we observed a commercial demo plant shut down in 30 days due to plugging).  Pyrolysis oil rich in aromatics or olefins is low in cetane number and unsuitable for diesel fuel (but for lower-grade fuel oils). The magnetically induced Universal Filter (developed and commercially demonstrated by Shin-Chuang Technology in Taiwan) may remove heavy metals and solid particles (down to nanometer sizes) in the feed stream to protect the reactor catalysts. (Refer to US patent 9,352,331). Alternatively, instead of converting waste plastics into pyrolysis oil, Shin-Chuang Technology has commercially incorporated waste tyre rubber and waste plastics into the huge worldwide specialty cement and concrete mar- kets with very low processing costs (no chemical reactor,

no heating, no pressurising, no cooling, and no CO2 or gas emissions). Plastics, including PE, PP, PS, as well as butyl rubber (tyres) are hydrophobic, so mixing them with hydrophilic cementitious materials forms a loose mixture with very weak strength. The strength of the cement matrix required as the construction material is from the hydrates produced through hydration of cement and water. However, typical cementitious material cannot stop water from damaging its internal structures. Over the years, people have tried all kinds of methods to incorporate polar plastics such as PVA or non-polar plastics such as PP fibre into the cement- matrix composite (CMC) to improve the hydrophobic capa - bility of cement and concrete without satisfactory results. The novel method disclosed in US patent 10,882,785B1 issued to Shin-Chuang Technology is to disperse the hydrophobic waste plastic or rubber particles as carriers of the hydrophobic agent uniformly throughout the cement matrix by improving the surface property of the particles. Hydration occurs in the cement matrix without disturbance. After hydration, the CMC becomes hydrophobic with mini - mal strength loss. For example, after hydration, the ‘hydro - phobic’ cement mortar containing 4 wt% waste tyre rubber exhibits higher than 95% compression strength compared to that of ‘hydrophilic’ mortar containing no rubber. An SEM image of the hydrate of the CMC showed tight and uniform C-S-H bonding to confirm the high compression strength. Also, gaps in the CMC are hydrophobic, and the water contact angle in the gaps is too large to allow film flow of the water, so water cannot pass through. However, mois - ture can get through freely, making this CMC a hydro - phobic but breathable construction material. The product is successfully commercialised with references available. Furthermore, the CMC provides a much-improved sound (noise) barrier and heat insulation than regular cement or concrete. A Joris Mertens, Principal Consultant, KBC (A Yokogawa Company), joris.mertens@kbcglobal Yes, we see a growing interest in waste plastic pyrolysis and, consequently, in processing technology for the waste plastic pyrolysis oil (WPPO) product. Refiners are better prepared to handle WPPO in that they are familiar with hydrotreating technology, which is central to WPPO clean - ing technology. Besides knowing how to start, run, and shut down these units, refiners are familiar with handling catalysts and have the necessary hydrogen to run them. On the other hand, treating WPPO requires consideration of other factors. First is unit size. Both the treating technology and pyroly - sis represent emerging technologies. The first industrial units coming online are tiny by refinery standards, with feed rates lower than 10 m3/h (below 1.5 kBPD). Sizes of the treating units are set primarily by availability of the WPPO feed rather than by technical constraints. Therefore, hydrogen availability is unlikely to be a major constraint despite the high specific hydrogen consumption. Although a simplified block flow diagram will look similar to that of a hydrocracker, KBC expects most of these units will be


PTQ Q1 2023

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