• sulfur removal
• bio oil
• biomass fast pyrolysis liquids
• Ni based catalyst
• sulfur catalytic adsorption
• desulfurization
• rimozione zolfo
• bio olio
• liquidi da pirolisi di biomassa

In the global green-energy scenario, sulfur species inside pyrolysis bio-oils are gaining concern for their polluting effects on the environment and for the poisoning and deactivation issues of certain hydrotreatment catalysts used for bio oil upgrading. In this work, a literature review was made to understand the nature of sulfur inside bio-oils, but the route from biomass to bio oil is still object of research. As such, total sulfur content in pyrolysis liquids was investigated with inductively coupled plasma (ICP-OES) technique and types of S-compounds were detected using comprehensive two-dimensional gas chromatography (GCxGC) equipped with sulfur chemiluminescence detector (SCD). Results show that low sulfur level is present inside softwood derived pyrolysis oil (90 ppm by ICP) and most of it is represented by sulphides; thiophenic compounds (T, BT, DBT etc.) are also present, but their ratio is very low compared to the total amount of S-compounds measured by GCxGC-SCD. Stabilized pyrolysis oil (SPO) was also analysed by means of GCxGC-SCD: sulfur compounds content was found to be lowered and no trace of sulphides or disulphides was detected, meaning that upgrading catalyst was poisoned.
Furthermore, current S-removal technologies were taken into account and the most suitable one was adopted: an attempt to remove such poisoning compounds from feedstock was carried out using a commercial nickel based catalyst tailored for refinery streams S-cleaning.
Such sulfur trap was used in two fixed-bed continuous set-ups with different operational conditions: one lab set-up was run in absence of hydrogen at three different temperatures (40, 80 and 120°C), the other was processed by BTG Biomass Technology Group BV (Enschede, Netherlands) at 120°C using a higher pressure in presence of hydrogen. Tests on both systems proved sulfur removal occurrence. Although Ni-sorbent was difficult to recover due to catalyst dissolution and nickel leaching issues, further experimentation can lead to promising results.