Hydrocarbon Fuels from Sequential Hydrothermal Liquefaction (HTL) of Lignite and Catalytic Upgrading of Crude Oil

Abstract

Lignite from Belchatów in Poland was converted to hydrocarbon fuels, particularly in the kerosene and diesel ranges, through sequential hydrothermal liquefaction (HTL) and hydrotreatment (HDT) of the obtained crude oil. Different HDT temperatures were investigated (from 350 °C up to 390 °C). Despite the highly aromatic nature and high heteroatom content, the HTL lignite crude oil could undergo deep hydrodesulfurization (HDS = 99%) and hydrodeoxygenation (HDO = 98%) in a single HDT treatment stage, yielding a liquid product rich in aliphatic and aromatic, particularly monoaromatic, hydrocarbons. The hydrotreatment and hydrogenating capacity of the lignite crude oil was linked to the low concentration of compounds resistant to hydrotreatment in lignite and, consequently, lignite’s crude oil, permitting the easy transformation of the crude oil into hydrocarbon fuel. Still, the significant concentration of aromatic compounds, particularly monoaromatic and diaromatic, in the liquid product (≈45% of fuel range products) suggests that further upgrading, blending, or harsher HDT conditions might be necessary to improve the fuel quality. In addition to the crude oil, the HTL of lignite yielded a stream of char, which displayed a higher calorific value and lower heteroatom content than the original lignite feedstock, thus having a high potential for electricity production, which is the common use of lignite. Thus, introducing an HTL stage to extract crude oil before lignite use in electricity production could provide an alternative fuel source used as a strategy to increase multiple countries’ energetic independence.

Hydrotreatment of Sewage Sludge-Derived Hydrothermal Liquefaction Biocrude. Part I: Experimental

“…The formation of light hydrocarbons can be attributed to the cleavage of larger molecules in the biocrude during the HDT reaction. It is worth mentioning that C–C bound cleavage caused by hydrogenolysis or β-scission is unlikely to occur under the reaction conditions on NiMoS/Al 2 O 3 catalysts, as discussed in our previous work …”

“…Understanding the molecular composition of SS HTL oil and its evolution on upgrading is of primary importance for further industrial developments and kinetic modeling. The range products fuel, i.e., bp <520 °C, can be identified and quantified at the molecular stage by comprehensive GCxGC, , while the description of the heaviest fraction composed of heterocyclic molecules of the SS HTL oil and upgraded products is achieved by using FTICR -MS. , Nonetheless, characterization techniques, such as SEC and NMR, can be used as an alternative to providing a global image of the biocrude and upgrade products, helping to quantitatively follow the global composition of biocrude and subsequent upgrade products as demonstrated recently by Batalha et al…”