Scrap tires pyrolysis oil as a co-feeding stream on the catalytic cracking of vacuum gasoil under fluid catalytic cracking conditions Elena Rodríguez, Roberto Palos, Alazne Gutiérrez ⇑ , José M. Arandes, Javier Bilbao Department of Chemical Engineering, University of the Basque Country UPV/EHU, PO Box 644, 48080 Bilbao, Spain article info Article history: Received 22 July 2019 Revised 15 January 2020 Accepted 18 January 2020 Keywords: Tires Pyrolysis oil Cracking Fluid catalytic cracking Fuel production Waste refinery abstract The co-feeding of scrap tires pyrolysis oil (STPO) on the catalytic cracking of vacuum gasoil (VGO) has been investigated with the aim of exploring the capacity of the refinery fluid catalytic cracking (FCC) unit to upgrade discarded tires at large-scale. The runs have been carried out in a CREC (Chemical Reactor Engineering Centre) riser simulator reactor that mimics the behavior of the industrial unit at the follow- ing conditions: 500–560 °C; catalyst/oil ratio, 3–7 g cat g oil À1 ; contact time, 6 s. Obtained results with the blend of 20 wt% STPO in VGO have been compared with those obtained in the cracking of the pure streams, i.e., STPO and VGO, to get a proper idea of the synergetic effects that could be involved in the co-feeding. This way, when the STPO is co-fed with the VGO the production of naphtha (C 5 –C 12 ) and light cycle oil (C 13 –C 20 ) lumps are maximized, as the over-cracking reactions that convert them into gaseous products (C 1 –C 4 ) are mitigated. Consequently, the co-feeding promotes the production of high-interest hydrocarbons for refineries. Additionally, the naphtha obtained in the cracking of the blend shows a lower content of paraffins and naphthenes than that obtained with the VGO, and higher of olefins and aromatics. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction Today, there is a pressing need to find large-scale solutions to avoid the environmental impacts derived from the inappropriate managing of discarded tires (Hita et al., 2016a). According to the European Tyre & Rubber Manufacturers Association and the US Tire Manufacturers Association, the current generation of dis- carded tires was of 3.9 Mt in the EU and 4 Mt in the US in 2017, respectively (Zang et al., 2019). Even though scrap tires can pro- duce heat energy by their incineration, this thermal process is harmful both for humans and for the environment. Consequently, the thermochemical processes of gasification (Blanco Machin et al., 2017; Zang et al., 2019) and pyrolysis (Parthasarathy et al., 2016; Tan et al., 2018) are being extensively studied to spread the energy coverage of discarded tires to electric industry and automotive sector. Indeed, fast pyrolysis is attracting the greater attention (Lewandowski et al., 2019; Lopez et al., 2017, 2010), given the high liquid product (scrap tires pyrolysis oil, STPO) yield obtained. Also promising prospects for upgrading the solid product (recycled carbon black, rCB) are obtained, as the rCB can be dem- ineralized and reused as commercial carbon black (Martínez et al., 2019; Sagar et al., 2018). The large-scale valorization of the STPO depends on its use as a fuel. However, the STPO cannot be directly used as automotive fuel due to some drawbacks (Rowhani and Rainey, 2016; Umeki et al., 2016): (i) high content of heavy molecules; (ii) high content of aro- matics; and (iii) high content of heteroatoms (N, S and O). To increase the value of the STPO, the catalytic pyrolysis of discarded tires has been investigated reaching lower amounts of aromatics together with less products in the heavy cycle oil boiling range (boiling point > 343 °C) (Miandad et al., 2016, 2018). Moreover, with the aim of reducing the content of N, S and poly-aromatics in the STPO, Wang et al. (2019) have investigated the hydropyrol- ysis of scrap tires by using noble metal-based catalysts. In spite of the upgrade reached in the quality of the STPO with these catalytic pyrolysis processes, further cleaning and post-treatments are required. In this context is where the possibility of using already depreci- ated refinery units (including the reaction, separation and reform- ing stages) to adapt the composition of the STPO to the regulatory restrictions in the fuels market gains relevance. Moreover, the fast pyrolysis of scrap tires could be performed in a delocalized way nearby the collection points of discarded tires and, afterwards, pro- duced STPO could be transported to refineries for its normalized conversion into fuels and commodities. Following this strategy, a single refinery could treat the tires discarded in an extensive geo- graphical area. https://doi.org/10.1016/j.wasman.2020.01.026 0956-053X/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: alazne.gutierrez@ehu.eus (A. Gutiérrez). Waste Management 105 (2020) 18–26 Contents lists available at ScienceDirect Waste Management journal homepage: www.elsevier.com/locate/wasman