Scaleable Hydrotreating of HTL Biocrude to Produce Fuel Blendstocks

Abstract

Hydrothermal liquefaction (HTL) offers an attractive route to produce fuel blendstocks from wet wastes. Scaleable hydrotreating data for the conversion of HTL biocrude to fuels is critical to the commercialization of HTL. Herein, we simulate the pore diffusion of hydrogen into the catalyst pores for the hydrotreating of HTL biocrudes and conclude that standard hydrotreating catalysts will be pore diffusion limited regarding hydrogen diffusion for HTL biocrude upgrading. By changing the catalyst size (crushed vs extrudate catalysts), we confirm an impact of pore diffusion on the overall hydrogenation rate of HTL biocrudes. When using whole pill extrudates, likely with pore diffusion limitations, we provide scale-able hydrotreating data for the stand-alone hydrotreating of a HTL biocrude (derived from sewage sludge). By running the reactor at two different hydrotreater scales (25x scale-up), we confirm the data quality.

Understanding the Upgrading of Sewage Sludge-Derived Hydrothermal Liquefaction Biocrude via Advanced Characterization

“…It was recently highlighted that catalyst crushing can change the pore diffusion properties, as well as the wetting and channeling properties, thus affecting product yields. 14 Investigation of the hydrotreating of HTL oil in continuous flow reactors with the use of catalyst extrudates is currently on-going to establish industrially relevant catalyst performance and operating conditions.…”

Sustainable Aviation Fuel from Hydrothermal Liquefaction of Wet Wastes

“…The WWHTLB samples were upgraded via hydrotreatment in a continuous tricklebed reactor, described [39] and utilized [20,21,[40][41][42] in previous studies. On the basis of previous HTL biocrude upgrading work conducted at PNNL, CoMo and NiMo catalysts were applied in the hydrotreatment process [20,21,40,41,43].…”

“…The WWHTLB samples were upgraded via hydrotreatment in a continuous tricklebed reactor, described [39] and utilized [20,21,[40][41][42] in previous studies. On the basis of previous HTL biocrude upgrading work conducted at PNNL, CoMo and NiMo catalysts were applied in the hydrotreatment process [20,21,40,41,43]. The upgraded WWHTLB material was distilled into 3 fractions (gasoline: 0-150 • C, jet: 150-250 • C, and heavier than jet: >250 • C) via vacuum distillation.…”

“…The results of this testing indicate that approximately 15% of the upgraded biocrude lies within the desired JFC range of 150-250 • C (see Figure 5). However, this fraction generally accounts for only 15-25% of upgraded WWHTLB [20,21]. Ideally, the majority of the sample would fall in this range to increase the SAF cut, and hence the attractiveness of HTL for SAF.…”

“…Several groups have demonstrated the efficacy of hydrotreating HTL biocrude at moderate pressure (~30-170 bar) and temperature (~350-450 • C) in a trickle bed reactor with traditional hydrotreating catalysts (sulfided CoMo and NiMo bimetal catalysts) [16][17][18][19][20][21]. Within the field of sustainable drop-in fuels development, the area that presents both the greatest challenges and possibly the biggest opportunities is that of sustainable aviation fuel (SAF).…”