Quality and sustainability comparison of one- vs. two-step catalytic hydroprocessing of waste cooking oil

A quality and sustainability comparison of the catalytic hydroprocessing of waste cooking oil (WCO) using a single-step (hydrotreatment) vs. a two-steps (hydrotreatment + isomerization) approach was conducted. The product fuel properties from both approaches were excellent, abiding by the newly established CEN TS 15940:2012 standard for Hydrotreated Vegetable Oil (HVO) fuels. The only consideration of the single-step product regarding its increased cold flow properties was addressed by the second isomerization step or by blending with fossil diesel (<10% v/v). Furthermore, the environmental impact of the examined one- and two-step WCO catalytic hydroprocessing was evaluated via Life Cycle Assessment (LCA), quantifying the associated greenhouse gas (GHG) emissions. LCA indicated a reduced sustainability of the two-step product as compared to the one-step product, due to the additional energy and hydrogen requirements of the second isomerization step.