One-Pot Conversion of Bio-oil to Diesel- and Jet-Fuel-Range Hydrocarbons in Supercritical Cyclohexane

Abstract

This study demonstrates a new route for converting bio-oil, prepared from the hydrothermal liquefaction of cornstalks, to diesel- and jet-fuel-range hydrocarbons over Ni/ZrO2 in supercritical cyclohexane. Under relatively mild conditions (573 K, 5 MPa H2), we obtained a high yield (81.6 C%) of hydrocarbons with an excellent quality (90% of diesel- and jet-fuel-range hydrocarbons and 7% of gasoline-range hydrocarbons). Ni/ZrO2 efficiently and stably catalyzed all types of compounds in the bio-oil to the corresponding alkanes via hydrogenation, dehydration, hydrogenolysis, decarbonylation, and isomerization, without polymerizations among the different reactive compounds in bio-oil. The activity and selectivity for diesel- and jet-fuel-range hydrocarbons of Ni/ZrO2 showed no obvious changes after three cycles. Ni/ZrO2 was fairly stable in supercritical cyclohexane after 72 h of reaction time. This strategy provides a novel high-efficiency pathway for the preparation of high-quality hydrocarbons from bio-oil.

A Review of Hydrothermal Liquefaction Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels

“…Another "one-pot" conversion process using Ni/ZrO2 in supercritical cyclohexane at 300 °C was conducted by Shi et al [116] to upgrade cornstalk HTL bio-crude, obtaining 81.6% carbon yield with 90% diesel and jet fuel hydrocarbons. The upgraded oil had 0.75% oxygen, from 26.79% in the feed bio-crude, and a HHV of 46.86 MJ/kg.…”

“…Taking into account the advantages of liquefaction over pyrolysis, there is adequate imperative to advance research in upgrading HTL bio-crude to transportation fuels. However, there are still major hurdles in development of a commercially-competitive integrated process, starting from the significant capital needed for the HTL process alone [116]. Challenges in upgrading HTL bio-crude can be translated to opportunities for researchers to develop cost-efficient and sustainable technologies.…”

Upgrading of palmitic acid over MOF catalysts in supercritical fluid of n-hexane

“…[10][11][12][13] SCFs had been utilized as reaction medium for the hydrogenation upgrading of model compounds recently. [14][15][16][17][18] Supercritical methanol technology has proved to be effective for the upgrading of low-boiling fraction of bio-oil. 14 The upgrading of crude bio-oil was conducted in supercritical ethanol by Dang et al 15 Hydroprocessing of model bio-oil compound p-cresol in both water and supercritical n-heptane indicated that the reaction were mass-transfer controlled in water while in supercritical n-heptane the mass-transfer limitations were eliminated due to the complete H 2 miscibility and enhanced pore diffusivities.…”

“…17 The upgrading of bio-oil prepared from hydrothermal liquefaction of cornstalks over Ni/ZrO 2 in supercritical cyclohexane under 573 K and 5 MPa H 2 obtained 81.6% yield of hydrocarbons with an excellent quality. 18 The studies above are based on the model compounds in bio-oil comes from terrestrial biomass. The catalytic HDO of model compounds in algal-based bio-oil like palmitic acid in SCF media has not yet been reported.…”

A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

“…Nickel based catalysts are one of the most commonly used non-precious metal catalysts in the bio-oil upgrading studies reviewed in this report. Shi et al investigated biooil upgrading over Ni/ZrO 2 in supercritical cyclohexane and reported its stability and effectiveness in catalysing several reactions including hydrogenation, and decarbonylation [35]. Similarly, Zhang et al utilised Ni/SiO 2 -ZrO 2 catalyst and supercritical ethanol to upgrade bio-oil and reported the catalysts ability to facilitate complete removal of acids and aldehydes and increase the esters, higher heating value, and pH value [32].…”