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The catalytic hydrotreatment of fast pyrolysis liquids (PL) from lignocellulosic biomass is a promising technology to improve the properties of PL. Mild hydrotreatment (< 250 °C) using a suitable catalyst allows the production of stabilized oils that have for instance potential for co-processing in existing oil refinery units. Here, we report a catalyst screening study to stabilize PL by a mild hydrotreatment using five Raney nickel “type” catalysts (Ra-Ni), more specifically a benchmark Ra-Ni, two types of Fe/Cr promoted, and two Mo-promoted ones. Experiments were performed at relatively mild hydrotreatment conditions (200 °C, initial 140 bar H2 pressure, 4 h) in a batch autoclave. Among all the Ra-Ni catalysts, the Mo promoted (A-7063) showed the highest hydro-(deoxy)genation activity, a lower extent of repolymerization (GPC), and lower charring tendency of the product oil (TGA) compared to the promoter-free and Fe/Cr promoted Ra-Ni catalysts. Analyses of the product oils showed that the oils contain a significant amount of phenolics (7.4–15.4 wt% on oil, GC x GC-FID). These findings indicate that commercially available Raney nickel “type” catalysts, and particularly the Mo promoted ones, are attractive to be used for the mild hydrotreatment of pyrolysis liquids.

The main reasons of catalysts deactivation in hydro-processing pyrolysis liquids are by coke deposition, poisoning by bio-oil impurities (S, N, K, Cl, etc.), leaching of catalyst components, structural degradation in the presence of H2O, and sintering. The deactivation of catalysts by the acidity of the pyrolysis liquid is a specific concern, and this deactivation mechanism was studied by treating newly developed NiCuMo-SiO2 catalysts in 1 M acetic acid water solution (pH = 2–3). The activity of the acid-treated catalysts was subsequently investigated in the hydrodeoxygenation of gaseous propionic acid, in a tubular reactor at 225 °C with n-hexane and n-octane serving as diluent and internal standard, respectively. The samples treated by acid at different times (15–360 min) were characterized by X-ray diffraction (XRD), high resolution transition electron microscopy (HRTEM), X-ray fluorescence (XRF), CO chemisorption, N2 physical adsorption, and X-ray photoelectron spectroscopy (XPS). XRF and HRTEM studies together with the residual mass of catalyst pointed out at gradual leaching of catalyst components. Among the catalyst components, dissolution of nickel was the most pronounced, while molybdenum content decreased to a lesser extent. This is due to the formation of more acid stable molybdenum blues. The amount of copper decreased only slightly, due its higher electrochemical potential. Oxidation of metalliс species Cu and Ni is shown to obtain Cu2O, NiO and Ni(OH)2-like phases. Interestingly, the acidic treatment resulted in increasing active surface of the catalyst, nevertheless, the catalyst activity in propionic acid conversion irreversibly decreased in time by the acetic acid treatment due to loss of the active components (substantially nickel).

Pyrolytic lignin (PL) is the collective name of the water-insoluble fraction of pyrolysis oils produced from the fast pyrolysis of lignocellulosic biomass. As the name suggests, PL is composed by fragments derived from lignin, which is the largest natural source of aromatic carbon. Its valorization is of major importance for the realization of economically competitive biorefineries. Nonetheless, the valorization of PL is hindered by its complex structure, which makes the development of tailored strategies for its deconstruction into valuable compounds challenging. In this work, we provide an in-depth analysis of the structural composition of PL obtained from a commercially available pine-derived pyrolysis oil obtained at 500 °C (Empyro B.V., the Netherlands). Molecular weight distribution and thermal stability were accessed by GPC and TGA, respectively, and the monomers present in the PL (≈ 15 wt%) were identified and quantified by chromatographic analyses (GCxGC–FID, GCxGC/TOF–MS, GC–MS and HPLC). Together with FTIR, Py-GC–MS, TAN, elemental analysis and various advanced NMR techniques (13C NMR, 31P NMR, 19F NMR, HSQC NMR, HMBC NMR), structural features of the PL oligomers were elucidated, revealing a guaiacyl backbone linked by alkyl, ether, ester and carbonyl groups, with none of the typical native lignin linkages (i.e. β–O–4, β–β, β–5) present. Furthermore, 72.3 % of the oxygen content in PL could be assigned to specific motifs by the quantitative analyses performed, and oligomeric models were proposed based on the obtained information. We expect that this characterization work can support future research on the development of valorization pathways for PL, allowing the feasible conversion of this promising feedstock into valuable biobased products with a wide range of possible applications, e.g. fuels, materials and specialty chemicals.

The pyrolysis liquid biorefinery concept involves separation of pyrolysis liquids in various fractions followed by conversion of the fractions to value-added products. Pyrolytic lignins (PLs), the water-insoluble fractions of pyrolysis liquids, are heterogeneous, cross linked oligomers composed of substituted phenolics whose structure and physicochemical properties vary significantly depending on the biomass source. The catalytic hydrotreatment of six PLs from different biomass sources (pine, prunings, verge grass, miscanthus and sunflower seed peel) was investigated to determine the effect of different feedstocks on the final product composition and particularly the amount of alkylphenolics and aromatics, the latter being important building blocks for the chemical industry. Hydrotreatment was performed with Pd/C, 100 bar of hydrogen pressure and temperatures in the range of 350–435 °C, resulting in depolymerized product mixtures with monomer yields up to 39.1 wt% (based on PL intake). The molecular composition of the hydrotreated oils was shown to be a strong function of the PL feed and reaction conditions. Statistical analyses provided the identification of specific structural drivers on the formation of aromatics and phenolics, and a simple model able to accurately predict the yields of such monomers after catalytic hydrotreatment was obtained (R2 = 0.9944) and cross-validated (R2 = 0.9326). These feed-product relations will support future selections of PL feeds to obtain the highest amounts of valuable biobased chemicals.

Catalytic hydrotreatment is recognized as an efficient method to improve the properties of pyrolysis liquids (PO) to allow co-feeding with fossil fuels in conventional refinery units. The promising catalyst recipes identified so far are catalysts with high nickel contents (38 to 57 wt.%), promoted by Cu, Pd, Mo and/or a combination, and supported by SiO2, SiO2-ZrO2, SiO2-ZrO2-La2O3 or SiO2-Al2O3. To gain insights into the reactivity of the pyrolytic sugar (PS) and pyrolytic lignin (PL) fraction of PO, hydrotreatment studies (350 °C, 120 bar H2 pressure (RT) for 4 h) were performed in a batch autoclave. Catalyst performance was evaluated by considering the product properties (H/C ratio, the charring tendency (TGA) and molecular weight distribution (GPC)) and the results were compared with a benchmark Ru/C catalyst. All Ni based catalysts gave products oils with a higher H/C compared to Ru/C. The Mo promoted catalyst performed best, giving a product with the highest H/C ratio (1.54) and the lowest TG residue (0.8 wt.% compared to 12 wt.% for the fresh PS). The results further revealed that the PS fraction is highly reactive and full conversion was achieved at 350 °C. In contrast, the PL fraction was rather inert, and only part of the PL fraction was converted. The fresh and spent catalysts after the hydrotreatment of the PS and PL fractions were characterized by elemental analysis, powder X-Ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM-EDX). The results revealed that the use of PS as the feed leads to higher amounts of coke deposits on the catalysts, and higher levels of Ni agglomeration when compared to experiments with PL and pure PO. This proofs that proper catalyst selection for the PS fraction is of higher importance than for the PL fraction. The Mo promoted Ni catalysts showed the lowest amount of coke and the lowest tendency for Ni nanoparticle agglomeration compared to the monometallic Ni and bimetallic Ni-Cu catalysts.

Lignin is a promising feedstock for the replacement of conventional carbon sources for the production of chemicals and fuels. In this paper, results are reported for the depolymerization of various residual lignins in the absence of a catalyst by utilizing ozone. Reactions were performed in a microreactor setup ensuring high gas-liquid mass transfer rates, a low inventory of ozone, and straightforward scale-up possibilities. The ozonation is demonstrated using a representative model compound (vanillin) and various lignins (pyrolytic and organosolv) dissolved in methanol (2.5 wt %). Experiments were performed under ambient conditions, at gas-liquid flow ratios ranging from 30 to 90 and short residence times on the order of 12-24 s. Analyses of the products after methanol removal revealed the presence of (di)carboxylic acids, methyl esters, and acetals. Extensive depolymerization was achieved (i.e., up to 30% for pyrolytic lignin and 70% for organosolv lignins). Furthermore, a two-step approach in which the ozonated lignin is further hydrotreated (350-400 degrees C, 100 bar H-2, 4 h, Pd/C as catalyst) showed a substantial increase in depolymerization efficiency, yielding a 2.5-fold increased monomer yield in the product oil compared to a hydrotreatment step only.

The use of novel nickel based catalysts for the catalytic hydrotreatment of pyrolytic sugars, the carbohydrate rich fraction of pine derived pyrolysis liquids, is reported. The catalysts are characterized by a high nickel loading (38 to 57 wt%), promoted by Cu, Pd, and/or Mo and a SiO2 based inorganic matrix. Experiments were carried out at 180 degrees C and 120 bar initial hydrogen pressure (room temperature) in a batch reactor set-up to gain insight in catalyst activity and product properties as a function of the catalyst composition. The most promising catalyst in terms of activity, as measured by the hydrogen uptake during reaction, was the Ni-Mo/SiO2-Al2O3 catalyst whereas the performance of the monometallic Ni/SiO2-Al2O3 catalyst was the lowest. As a result, the product oil obtained by the bimetallic Ni-Mo catalyst showed the highest H/C ratio and the lowest molecular weight of all catalysts tested. A detailed catalyst characterization study revealed that addition of Mo to the Ni catalyst suppresses the agglomeration of nickel nanoparticles during the catalytic hydrotreatment reaction.

The pyrolysis of lignocellulosic biomass generates a liquid product, known as pyrolysis oil, that can be further processed into biofuels and value-added chemicals. During pyrolysis, cellulose and hemicelulose fractions are converted into a range of water-soluble sugar derivatives, for which several valorisation strategies exist. On the other hand, lignin is broken down into so-called pyrolytic lignin, a water-insoluble complex mixture of aromatic oligomers that requires different upgrading strategies than the sugar rich fraction. Here, we report an experimental study on the valorisation of pyrolytic lignin via catalytic hydrotreatment in the absence of an external solvent. A variety of carbon-supported noble-metal heterogeneous catalysts were tested (Ru/C, Pd/C, Pt/C and Rh/C), as well as conventional hydrotreatment catalysts (sulphided NiMo/Al 2 O 3 and CoMo/Al 2 O 3 ) to obtain valuable low molecular weight aromatic and phenolic compounds. Overall, depolymerized liquids were obtained with organic yields of up to 63 wt%. Pd/C was shown to be the best catalyst, yielding 59 wt% of monomers based on the organic product (i.e. 33 wt% based on pyrolytic lignin intake). While noble metal catalysts favored higher monomer yields, though with some over-reduction of aromatic rings to saturated hydrocarbons, sulphided catalysts were more efficient in deoxygenation and aromatization reactions, but yielded less monomers. The hydrocracking efficiency was shown to be strongly dependent on the reaction temperature. Based on the experimental data, a global reaction network is proposed. The high monomer yields reveal the potential of catalytic hydrotreatment for the upgrading of pyrolytic lignin into valuable phenolics and aromatics.

High metal loading NiCu-based catalyst of Picula™ series produced by sol–gel technique was applied to furfural hydrogenation in the presence of hydrogen. This reaction represents the stabilization of pyrolysis oil that involves the selective reduction of aldehydes and ketones to alcohols and unsaturated C–C double bonds of pyrolysis oils components. The catalysts were pre-reduced at 250 and 300 °C. According to XRD analysis results, copper is mainly in the metallic state, and Ni is mostly in the form of oxide and silicate. XPS measurements reveal that hydrogen treatment at 250 °C leads to the partial reduction of Ni to the metallic state (6 %) while further reduction at 300 °C leads to an increase in this proportion up to 39 %. A 100 % selectivity towards furfuryl alcohol was achieved at 130 °C and 5 MPa of hydrogen in a batch reactor using decyl alcohol as a solvent. In the experiments with i-propanol as a solvent at 110–170 °C the main product was furfuryl alcohol, but minor components traced back were tetrahydrofurfuryl alcohol, 2-methylfuran and isopropyl furfuryl ether. The lower catalyst reduction temperature promotes the formation of isopropyl ester, while a higher reduction temperature favors further furfuryl alcohol hydrogenation.

Catalytic hydrotreatment is an attractive technology to convert fast pyrolysis oil to stabilized oil products for co processing in conventional crude oil refinery units. We report here the use of novel bimetallic NiCu- and NiPd-based (Picula) catalysts characterized by a high Ni content (29-58 wt %) and prepared using a sol gel method with SiO2, La2O3, kaolin, ZrO2, and combinations thereof as the support, for the catalytic hydrotreatment of fast pyrolysis oil. The experiments were performed in a batch autoclave (1 h at 150 degrees C, 3 h at 350 degrees C, and 200 bar initial pressure at 350 degrees C). The catalyst with the highest nickel loading (58 wt % Ni) promoted with Pd (0.7 wt %) was the most active, yielding oil products with improved properties compared to the crude pyrolysis oil (lower oxygen content, higher solubility in hydrocarbons, and less tendency for coke formation). For all Picula catalysts, except the ZrO2-based catalysts, methane formation was considerably lower than for Ru/C, the benchmark catalyst in catalytic hydrotreatment of fast pyrolysis oil. To anticipate possible catalyst deactivation at very long times on stream, catalyst regeneration studies were performed using thermogravimetric analysis. Analyses of the regenerated catalysts (X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer Emmett Teller surface area) showed the occurrence of active metal agglomeration.

In this paper, an experimental study on the hydrotreatment of fast pyrolysis liquids is reported in both batch and continuous set-ups using a novel bimetallic Ni–Cu based catalyst with high Ni loading (up to 50%) prepared by a sol–gel method. The experiments were carried out in a wide temperature range (80–410 °C) and at a hydrogen pressure between 100–200 bar to determine product properties and catalyst performance as a function of process conditions. To gain insight into the molecular transformations, the product oils were analysed by GC × GC, 1H-NMR and GPC and reveal that the sugar fraction is reactive in the low temperature range ( 300 °C). In addition, the organic acids are very persistent and reactivity was only observed above 350 °C. The results are rationalized using a reaction network involving competitive hydrogenation of reactive aldehydes and ketones of the sugar fraction of fast pyrolysis liquids and thermal polymerisation. In addition, relevant macro-properties of the product oils including flash point (30 to 80 °C), viscosity (0.06 to 0.93 Pa s) and TG residue (

Lignocellulose is a widely available carbon source and a promising feedstock for the production of advanced second‐generation biofuels. Nonetheless, lignin, one of its major components, is largely underutilized and only considered an undesired byproduct. Through catalytic hydrotreatment, the highly condensed lignin can be partially depolymerized into a range of monomers. However, its recalcitrance and the presence of aromatic fragments linked by C-C bonds require extensive cracking, which is challenging to achieve. Here, a two‐step strategy is reported in which an initial pretreatment step with ozone is used prior to catalytic hydrotreatment to boost lignin depolymerization. Three types of lignin (Kraft, pyrolytic, and Fabiola organosolv) are used as feedstocks and the ozonation step is performed under ambient conditions with either methanol or ethanol as the solvent. The pretreatment is shown to have a positive effect on the subsequent hydrotreatment reaction (Pd/C, 350 °C, 100 bar H2) and gives product oils with significantly lower Mw (up to 43% lower), higher volatility, and improved calorific values (up to 45.3 MJ kg−1) compared to a direct hydrotreatment.

A solution method was developed to calculate the simultaneous phase and chemical equilibria in high-pressure methanol synthesis (P = 20 MPa, 463

Fast pyrolysis oil from lignocellulosic biomass is an attractive energy carrier. However, to improve the product characteristics such as a reduced polarity and higher thermal stability, upgrading is required. We here report activities on the catalytic hydrotreatment of fast pyrolysis oil using bimetallic NiCu/delta-Al(2)o(3) catalysts with various Ni/Cu ratios (0.32 to 8.1 w/w) at a fixed total metal intake of about 20 wt% with the objective to improve product properties for co-feeding applications in conventional oil refineries. Hydrotreatment reactions were initially carried out for a model compound (anisole, continuous set-up, 300 degrees C, 10 bar) and subsequently for fast pyrolysis oil (batch autoclave, 1 h at 150 degrees C followed by 3h at 350 degrees C, at 100 bar initial pressure). Best results, i.e. the highest hydrodeoxygenation yield for experiments with anisole (75 mol%), and an upgraded oil with the most favorable properties for fast pyrolysis oil (high H/C ratio, low M-W of 500 g/mol, low thermogravimetric residue of 6.8 wt%), were obtained for a catalyst with a Ni to Cu wt% ratio of eight (16Ni2Cu). For this catalyst, hydrogen consumption was the highest (146 NL/kg(PO)). The findings were rationalized using a reaction network model earlier developed for Ru/C. Analysis of catalyst (ICP, HRTEM, XRD and TGA) before and after reaction showed the occurrence of leaching of both active metals (Ni and Cu) and support, as well as coke deposition on the support. The most active catalyst in the series (16Ni2Cu) also gave lowest leaching and coking levels in the series. (C) 2012 Elsevier B.V. All rights reserved.

Fast pyrolysis of biomass is an attractive approach for the densification of its energy content. Through this approach, biomass is transformed into liquids (bio-oils or pyrolysis oils) having a considerable oxygen content. Therefore, upgrading is required to convert oxygenates into hydrocarbons, improving the oil properties and broadening the application range. In this instance, catalytic hydrotreatment was demonstrated to be an attractive technology for the upgrading of fast pyrolysis oil into stabilized products. This chapter presents an overview on the typical features of the hydrotreatment process (e.g. reaction conditions, catalysts, product yields, deoxygenation levels, product properties, analytical methods, and reaction pathways). Finally, recent results for a catalytic hydrotreatment process in the presence of a novel Ni–Cu catalyst supported on SiO2 will be discussed. Regarding catalyst performance and properties of the product oil, this catalyst shows considerable advantages over the benchmark Ru/C catalyst.

Methanol is an important bulk chemical in the chemical industry. The global methanol de‐ mand was approximately 32 million metric tons in 2004 and is expected to grow [1]. Metha‐ nol is used mainly for the production of formaldehyde, acetic acid, and application products including polymers and paints. Furthermore, methanol can be used as a clean and renewa‐ ble energy carrier [1]. Methanol is mainly produced from syngas, a mixture of H2, CO, and minor quantities of CO2 and CH4. Syngas is commonly produced from fossil resources like natural gas or coal. Biomass, however, can also be used as resource for syngas and allows the synthesis of green methanol. Green methanol not only has environmental benefits, but may also lead to considerable variable cost reductions if the biomass resource has a low or even negative value.