Catalytic Upgrading of Switchgrass-Derived Pyrolysis Oil Using Supported Ruthenium and Rhodium Catalysts

Abstract

Upgrading of fast pyrolysis oils produced from swtichgrass was carried out using 5 wt % Ru and 5 wt % Rh on a carbon support as catalysts slurried in a polyethylene glycol solvent in a 300 mL Parr batch reactor in the presence of hydrogen. A hydrodeoxygenation (HDO) reaction was evaluated in the temperature range of 200−280 °C under hydrogen pressure of 300−1000 psig. The raw pyrolysis oil and the upgraded products were characterized by gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), and Fourier transform infrared spectroscopy (FTIR) techniques to establish the effectiveness of the hydrogenation process. With Ru/C at 280 °C and 1000 psig, the GC/MS data showed the absence of acetic acid and the principal liquid product slate included alcohols, hydrocarbons, cyclic compounds, and phenolics at a relative concentration of 5.2, 21.2, 3.8, and 35.7%, respectively.

Revealing the pathways of catalyst deactivation by coke during the hydrodeoxygenation of raw bio-oil

“…4. On the other hand, the formation of cyclohexane from phenol is commonly reported to follow a mechanism in which cyclohexanone, cyclohexanol and cyclohexene are intermediates [17,[52][53][54]76]. Moreover, methylcyclopentane, which is other naphthenic compound observed (aNP), could be obtained from the recombination of cyclohexane molecules [76].…”

“…The HDO of bio-oil is commonly carried out over Ni, Mo or W supported catalysts [7][8][9][10][11][12][13]. However, noble metal-based catalysts (Pt, Pd, Rh or Ru) [14][15][16][17][18][19][20], as well as supported bimetallic catalysts [21,22], show higher activity for HDO and allow for using less severe operational conditions. In these works in the literature, the use of both neutral (α-alumina) and acid (activated carbon, γ-alumina, silica-alumina) supports (thus forming metallic or bifunctional catalysts) have been reported for the preparation of the catalysts.…”

“…Moreover, the possibility for tailoring their porous texture [39,40] and modifying their surface functional groups [41,42] allows for controlling some catalytic properties such as the dispersion of the metallic particles [43]. Some functionalized ACs present a well-developed mesoporosity that favors the swept of both water and coke precursors outside of the catalyst particle, and therefore their use has been broadly studied as one of the most attractive supports for the HDO of bio-oil [2,12,[14][15][16][17][18]44,45]. Nevertheless, the intrisic nature of carbonbased catalysts hinders the characterization of the carbonaceous deposits and their regeneration through combustion.…”

Ketonization of hexanoic acid to diesel-blendable 6-undecanone on the stable zirconia aerogel catalyst

“…Abundant amounts of carboxylic acids are produced during the thermolysis of biomass [1][2][3] and the anaerobic fermentation of sugars [4,5] for the preparation of drop-in fuels. Although the carboxylic acid contains only two oxygen atoms in each molecule allowing to be converted to paraffins and olefins, its acidity must be reduced to produce petroleum-blendable hydrocarbons.…”

Role of Anhydride in the Ketonization of Carboxylic Acid: Kinetic Study on Dimerization of Hexanoic Acid

“…Among the fuel candidates obtained from biomass, there has been interest in using carboxylic acids for the production of n -alkane hydrocarbons. Carboxylic acids and their derivatives including acetic acid, propionic acid, butyric acid, hexanoic acid, − and methyl ketones can be synthesized during biological processes while acetic acid is found in pyrolysis oils, − and high carbon-number fatty acids (C16 and larger) are observed in biodiesel. ,, Although the content of oxygen atoms in these carboxylic acids is not very high, deoxygenation to obtain deoxygenated hydrocarbons and the condensation of small molecules to improve the fuel properties are required before using these biofuels as petroleum-like fuels. Hydrodeoxygenation, decarboxylation, decarbonylation, and ketonization have been suggested for producing deoxygenated hydrocarbons from biomass-derived feedstocks. , Among these processes, ketonization is selected in this study because it can produce high carbon-number hydrocarbons from smaller molecules using mild reaction conditions.…”