Scrap tires pyrolysis oil as a co-feeding stream on the catalytic cracking of vacuum gasoil under fluid catalytic cracking conditions

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 following conditions: 500-560 °C; catalyst/oil ratio, 3-7 g_cat g_oil^-1; 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 (C₅-C₁₂) and light cycle oil (C₁₃-C₂₀) lumps are maximized, as the over-cracking reactions that convert them into gaseous products (C₁-C₄) 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.

Keywords: Cracking; Fluid catalytic cracking; Fuel production; Pyrolysis oil; Tires; Waste refinery.