Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

Abstract

Coprocessing of biocrudes from hydrothermal liquefaction (HTL) of biomass and wastes with petroleum streams in refinery hydroprocessing has significant potential to accelerate the production of renewable transportation fuels in the near term. However, HTL biocrudes with some problematic characteristics can potentially cause faster deactivation of the catalysts, which is one of the biggest barriers to the adoption of biocrude in the current refinery process. In this work, we investigated the deactivation modes of a sulfide NiMo/Al2O3 hydrotreating catalyst used for coprocessing HTL biocrude (from wastewater sludge) with straight-run diesel. Spent catalysts were collected after coprocessing diesel with different biocrudes after >300 h time on stream and characterized by various techniques. Their catalytic activities were evaluated by model compound testing. Loss of catalyst activity was observed after coprocessing biocrudes. No structural change of the catalyst after coprocessing biocrudes was observed, and catalyst deactivation was largely due to catalyst fouling by carbonaceous species and metal contaminants (such as Fe and K) from biocrudes. Inorganic contaminant deposition leads to the external coating of the catalyst pellets on the top of the reactor, whereas the carbonaceous species potentially bind near the sulfide active phase, thereby blocking access to the active edge sites. Pretreatment of the HTL biocrude can reduce problematic species and alleviate catalyst deactivation during coprocessing.

Coprocessing Partially Hydrodeoxygenated Hydrothermal Liquefaction Biocrude from Forest Residue in the Vacuum Gas Oil Hydrocracking Process

“…13,28 The hydrodeoxygenated HTL biocrude was also shown to have better cohydrotreating performance with VGO than the untreated biocrude. A similar conclusion was reached in a study 40 where raw and hydrodeoxygenated HTL biocrudes were tested for coprocessing with straight-run diesel in a hydrotreating unit. Hydrotreating the biocrude was noted to relieve catalyst deactivation during coprocessing by removing coke-forming species and metals like Fe and K. Pyrolysis bio-oils are much harder to process than HTL biocrudes because of their extreme oxygen content (up to 40 wt %) and low chemical stability.…”

“…Emulsification has been reported to tackle the miscibility problem without mass rejection, ,, yet the effects of coprocessing emulsified biocrude blends are unknown to the best of our knowledge. It is important to highlight that the miscibility barrier to coprocessing can be overcome without upgrading by directly introducing the raw biocrude and petroleum feed via separate lines into refinery reactors. , Nevertheless, this strategy does not mitigate the adverse effects of oxygen and nitrogen compounds on catalyst activity and product distribution.…”

Lignite and Biomass Waste Hydrothermal Liquefaction Crude Upgrading by Hydrotreatment

“…Consequently, the solid product corresponds to matter deposited on the catalysts, for example, coke or minerals. Zhu et al studied the impact of co-processing HTL crude oil from sewage sludge with diesel during hydrotreatment, observing increased carbon content on the spent catalyst and the presence of K, Ca, and Fe on the catalyst . The semi-quantitive analysis of the inorganic elements in the crude oil is shown in Table S12, showing the presence of Si, Fe, and other trace elements, such as Ca, Zn, and P, in all crude oils.…”

“…Zhu et al studied the impact of co-processing HTL crude oil from sewage sludge with diesel during hydrotreatment, observing increased carbon content on the spent catalyst and the presence of K, Ca, and Fe on the catalyst. 34 The semi-quantitive analysis of the inorganic elements in the crude oil is shown in Table S12, showing the presence of Si, Fe, and other trace elements, such as Ca, Zn, and P, in all crude oils. Therefore, it is not surprising that significant amounts of Fe (0.2−1.0 wt %) and Si (0.2−0.7 wt %) were observed on all spent catalysts (Table S13).…”

Virtual Special Issue of Recent Advances in Biofuel Production via Co-refining Route

“…Sharma et al 15 studied miscibility of HTL biocrudes in refinery streams co-processing and concluded the usefulness of theoretical predictions made by Hansen solubility parameters. Zhu et al 16 investigated the deactivation modes of a hydrotreating catalyst used for co-processing HTL biocrude (from wastewater sludge) with straight-run diesel. They highlighted the need of pretreatment of the HTL biocrude to diminish catalyst deactivation.…”