Extended Catalyst Lifetime Testing for HTL Biocrude Hydrotreating to Produce Fuel Blendstocks from Wet Wastes
Senthil Subramaniam, Daniel M. Santosa, Casper Brady, Marie Swita, Karthikeyan K. Ramasamy, Michael R. Thorson
Abstract
This paper reports on the catalyst stability of the hydrotreatment of HTL (Hydrothermal Liquefaction) biocrudes to produce finished liquid transportation fuel blendstocks. We report the stable hydrotreating of HTL biocrude derived from sewage sludge and food waste over industrially relevant hydrotreating CoMo and NiMo catalysts at relevant catalyst activities. The use of wet-waste-derived HTL biocrudes derived from both food waste and sewage sludge in the hydrotreater campaign strengthens the case that HTL biocrudes derived from a variety of wet-waste feedstocks can be upgraded without significant catalyst instability over industrially relevant hydrotreater time-periods. Stable hydrotreating performance was obtained with each feedstock. The overall yield was approximately 85% with all HTL biocrudes. Over 1500 h of steady-state operation, minimal deactivation was observed. These results indicate that a hydrotreatment process to upgrade can be stable for industrially relevant times, a critical roadblock to derisking commercialization. The upgraded product produces a diesel-rich (∼70% in the 150–350 °C range) fuel blendstock, with high cetane due to the high fraction of alkanes. Further, we report the impact of process levers on hydrotreating performance on a fully broken-in catalyst (following 1500 h of steady-state operation). The long-term catalyst stability presented here is an important demonstration to derisk HTL commercialization.