Catalytic Hydrotreatment of Biomass-Derived Fast Pyrolysis Liquids Using Ni and Cu-Based PRICAT Catalysts

Biomass-derived fast pyrolysis liquids (PLs) are not directly applicable as transportation fuels due to their high oxygen content and limited storage stability. Catalytic hydrotreatment is an efficient technology to convert such PLs to finished fuels or intermediates that can be used as a co-feed for existing oil refinery units. In this paper, we report catalyst screening studies for the mild hydrotreatment of PLs using commercially available Ni and Cu-based PRICAT catalysts at rather mild conditions (200 °C, initial 140 bar H2pressure) in a batch setup for 4 h. Among all catalysts, PRICAT NI 62/15 showed the best performance for mild catalytic hydrotreatment in terms of product properties (highest H/C ratio and lowest TG residue). The best catalysts were also tested for deep hydrotreatment at more severe conditions (350 °C, initial 100 bar H2pressure). Here, the PRICAT NI catalysts showed better performance than the benchmark Picula Ni-Mo catalyst when considering oil yield and H/C ratio. Advantageously, the hydrogen consumption during deep hydrotreatment is also reduced, rationalized by a lower methanation activity

Valorization of Pyrolysis Liquids:Ozonation of the Pyrolytic Lignin Fraction and Model Components

Pyrolytic lignin is the collective name of the lignin-derived fraction of pyrolysis liquids. Conversion of this fraction to biobased chemicals is considered an attractive valorization route. Here we report experimental studies on the ozonation of a pine-derived pyrolytic lignin dissolved in methanol (33 wt %). Results show a high reactivity of ozone, and a molecular weight reduction of up to 40% was obtained under mild conditions (0 °C, atmospheric pressure) without the need for catalysts. Detailed analysis of the product mixtures (GC/MS-FID, HPLC, GPC, NMR) showed the presence of low molecular weight (di)acids and esters, along with larger highly oxygenated aliphatics. A reaction network is proposed including the heterolytic cleavage of aromatic rings, followed by secondary reactions. The observations were supported by experimental studies using representative pyrolytic lignin model compounds and a biosynthetic lignin oligomer, which aided further elucidation on the reactivity trends for different chemical functionalities. Accordingly, the presence of hydroxy and methoxy substituents on the aromatic rings is shown to be the main reason for the high reactivity of pyrolytic lignin upon ozone exposure

Novel Route to Produce Hydrocarbons from Woody Biomass Using Molten Salts

[Image: see text] The thermochemical decomposition of woody biomass has been widely identified as a promising route to produce renewable biofuels. More recently, the use of molten salts in combination with pyrolysis has gathered increased interest. The molten salts may act as a solvent, a heat transfer medium, and possibly also a catalyst. In this study, we report experimental studies on a process to convert woody biomass to a liquid hydrocarbon product with a very low oxygen content using molten salt pyrolysis (350–450 °C and atmospheric pressure) followed by subsequent catalytic conversions of the liquids obtained by pyrolysis. Pyrolysis of woody biomass in molten salt (ZnCl(2)/NaCl/KCl with a molar composition of 60:20:20) resulted in a liquid yield of 46 wt % at a temperature of 450 °C and a molten salt/biomass ratio of 10:1 (mass). The liquids are highly enriched in furfural (13 wt %) and acetic acid (14 wt %). To reduce complexity and experimental issues related to the production of sufficient amounts of pyrolysis oils for further catalytic upgrading, model studies were performed to convert both compounds to hydrocarbons using a three-step catalytic approach, viz., (i) ketonization of acetic acid to acetone, (ii) cross-aldol condensation between acetone and furfural to C(8)–C(13) products, followed by (iii) a two-stage catalytic hydrotreatment of the latter to liquid hydrocarbons. Ketonization of acetic acid to acetone was studied in a continuous setup over a ceria–zirconia-based catalyst at 250 °C. The catalyst showed no signs of deactivation over a period of 230 h while also achieving high selectivity toward acetone. Furfural was shown to have a negative effect on the catalyst performance, and as such, a separation step is required after pyrolysis to obtain an acetic-acid-enriched fraction. The cross-aldol condensation reaction between acetone and furfural was studied in a batch using a commercial Mg/Al hydrotalcite as the catalyst. Furfural was quantitatively converted with over 90% molar selectivity toward condensed products with a carbon number between C(8) and C(13). The two-stage hydrotreatment of the condensed product consisted of a stabilization step using a Ni-based Picula catalyst and a further deep hydrotreatment over a NiMo catalyst, in both batch setups. The final product with a residual 1.5 wt % O is rich in (cyclo)alkanes and aromatic hydrocarbons. The overall carbon yield for the four-step approach, from pinewood biomass to middle distillates, is 21%, assuming that separation of furfural and acetic acid after the pyrolysis step can be performed without losses

Mono-, bi-, and tri-metallic Ni-based catalysts for the catalytic hydrotreatment of pyrolysis liquids

Catalytic hydrotreatment is a promising technology to convert pyrolysis liquids into intermediates with improved properties. Here, we report a catalyst screening study on the catalytic hydrotreatment of pyrolysis liquids using bi- and tri-metallic nickel-based catalysts in a batch autoclave (initial hydrogen pressure of 140 bar, 350 A degrees C, 4 h). The catalysts are characterized by a high nickel metal loading (41 to 57 wt%), promoted by Cu, Pd, Mo, and/or combination thereof, in a SiO2, SiO2-ZrO2, or SiO2-Al2O3 matrix. The hydrotreatment results were compared with a benchmark Ru/C catalyst. The results revealed that the monometallic Ni catalyst is the least active and that particularly the use of Mo as the promoter is favored when considering activity and product properties. For Mo promotion, a product oil with improved properties viz. the highest H/C molar ratio and the lowest coking tendency was obtained. A drawback when using Mo as the promoter is the relatively high methane yield, which is close to that for Ru/C. H-1, C-13-NMR, heteronuclear single quantum coherence (HSQC), and two-dimensional gas chromatography (GC x GC) of the product oils reveal that representative component classes of the sugar fraction of pyrolysis liquids like carbonyl compounds (aldehydes and ketones and carbohydrates) are converted to a large extent. The pyrolytic lignin fraction is less reactive, though some degree of hydrocracking is observed

Hydrotreatment of Fast Pyrolysis Oil Using Heterogeneous Noble-Metal Catalysts

Fast pyrolysis oils from lignocellulosic biomass are promising second-generation biofuels. Unfortunately, the application range for such oils is limited because of the high acidity (pH~2.5) and the presence of oxygen in a variety of chemical functionalities, and upgrading of the oils is required for most applications. Herein, we report an experimental study on the upgrading of fast pyrolysis oil by catalytic hydrotreatment. A variety of heterogeneous noble-metal catalysts were tested for this purpose (Ru/C, Ru/TiO2, Ru/Al2O3, Pt/C, and Pd/C), and the results were compared to those obtained with typical hydrotreatment catalysts (sulfided NiMo/Al2O3 and CoMo/Al2O3). The reactions were carried out at temperatures of 250 and 350 °C and pressures of 100 and 200 bar. The Ru/C catalyst was found to be superior to the classical hydrotreating catalysts with respect to oil yield (up to 60 wt %) and deoxygenation level (up to 90 wt %). The upgraded products were less acidic and contained less water than the original fast pyrolysis oil. The HHV was about 40 MJ/kg, which is about twice the value of pyrolysis oil. Analyses of the products by 1H NMR spectroscopy and 2D GC showed that the upgraded pyrolysis oil had lower contents of organic acids, aldehydes, ketones, and ethers than the feed, whereas the amounts of phenolics, aromatics, and alkanes were considerably higher.

Catalytic Hydrotreatment of Biomass-Derived Fast Pyrolysis Liquids Using Ni and Cu-Based PRICAT Catalysts

Biomass-derived fast pyrolysis liquids (PLs) are not directly applicable as transportation fuels due to their high oxygen content and limited storage stability. Catalytic hydrotreatment is an efficient technology to convert such PLs to finished fuels or intermediates that can be used as a co-feed for existing oil refinery units. In this paper, we report catalyst screening studies for the mild hydrotreatment of PLs using commercially available Ni and Cu-based PRICAT catalysts at rather mild conditions (200 °C, initial 140 bar H2pressure) in a batch setup for 4 h. Among all catalysts, PRICAT NI 62/15 showed the best performance for mild catalytic hydrotreatment in terms of product properties (highest H/C ratio and lowest TG residue). The best catalysts were also tested for deep hydrotreatment at more severe conditions (350 °C, initial 100 bar H2pressure). Here, the PRICAT NI catalysts showed better performance than the benchmark Picula Ni-Mo catalyst when considering oil yield and H/C ratio. Advantageously, the hydrogen consumption during deep hydrotreatment is also reduced, rationalized by a lower methanation activity

Novel Route to Produce Hydrocarbons from Woody Biomass Using Molten Salts

The thermochemical decomposition of woody biomass has been widely identified as a promising route to produce renewable biofuels. More recently, the use of molten salts in combination with pyrolysis has gathered increased interest. The molten salts may act as a solvent, a heat transfer medium, and possibly also a catalyst. In this study, we report experimental studies on a process to convert woody biomass to a liquid hydrocarbon product with a very low oxygen content using molten salt pyrolysis (350-450 °C and atmospheric pressure) followed by subsequent catalytic conversions of the liquids obtained by pyrolysis. Pyrolysis of woody biomass in molten salt (ZnCl2/NaCl/KCl with a molar composition of 60:20:20) resulted in a liquid yield of 46 wt % at a temperature of 450 °C and a molten salt/biomass ratio of 10:1 (mass). The liquids are highly enriched in furfural (13 wt %) and acetic acid (14 wt %). To reduce complexity and experimental issues related to the production of sufficient amounts of pyrolysis oils for further catalytic upgrading, model studies were performed to convert both compounds to hydrocarbons using a three-step catalytic approach, viz., (i) ketonization of acetic acid to acetone, (ii) cross-aldol condensation between acetone and furfural to C8-C13products, followed by (iii) a two-stage catalytic hydrotreatment of the latter to liquid hydrocarbons. Ketonization of acetic acid to acetone was studied in a continuous setup over a ceria-zirconia-based catalyst at 250 °C. The catalyst showed no signs of deactivation over a period of 230 h while also achieving high selectivity toward acetone. Furfural was shown to have a negative effect on the catalyst performance, and as such, a separation step is required after pyrolysis to obtain an acetic-acid-enriched fraction. The cross-aldol condensation reaction between acetone and furfural was studied in a batch using a commercial Mg/Al hydrotalcite as the catalyst. Furfural was quantitatively converted with over 90% molar selectivity toward condensed products with a carbon number between C8and C13. The two-stage hydrotreatment of the condensed product consisted of a stabilization step using a Ni-based Picula catalyst and a further deep hydrotreatment over a NiMo catalyst, in both batch setups. The final product with a residual 1.5 wt % O is rich in (cyclo)alkanes and aromatic hydrocarbons. The overall carbon yield for the four-step approach, from pinewood biomass to middle distillates, is 21%, assuming that separation of furfural and acetic acid after the pyrolysis step can be performed without losses