Valorization of humin type byproducts from pyrolytic sugar conversions to biobased chemicals

The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such humin byproducts to biobased chemicals. Experiments were carried out with a model humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the humins are oligomeric in nature (M-w of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC-MS, 550 degrees C) with HZSM-5 50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on humin intake. Liquefaction experiments (batch reactor, 350 degrees C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting humin type byproducts to high value, low molecular weight biobased chemicals

Identification and classification of components in flash pyrolysis oil and hydrodeoxygenated oils by two-dimensional gas chromatography and time-of-flight mass spectrometry

Hydrodeoxygenated pyrolysis oils (HDO) are considered promising renewable liquid energy carriers. To gain insights in the various reaction pathways taking place during the hydrodeoxygenation reaction of pyrolysis oil, two-dimensional gas chromatography with time-of-flight mass spectrometric analyses (2D-GC-TOF-MS) was applied on the feedstock and product oil. Chromatographic parameters like injection temperature and column choice of the D-1-D-2 ensemble are discussed. Fractionation of the oils by hexane extraction was applied to show the distribution of analytes over the phases. Some 1000 and 2000 components in the pyrolysis and HDO oil, respectively could be identified and classified. The TOF-MS detection considerably improved the understanding of the molecular distribution over the D-1-D-2 retention time fields in the contour plot, in order to classify the analytes in functional groups. By group-type classification of the main components (>0.3% relative area), it was possible to characterize the oils by 250 and 350 analytes, respectively pyrolysis oil and HDO oil, describing 75% of the chromatographable fraction. The 2D-GC-TOF-MS method showed to be a useful and fast technique to determine the composition of (upgraded) pyrolysis oil and is potentially a very useful tool for exploratory catalyst research and kinetic studies. The 2D-GC-TOF-MS technique is not only useful for the chemical study as such, but also provides the basic knowledge for method transfer to a 2D-GC-FID (flame ionization detector) application. (C) 2008 Elsevier B.V. All rights reserved

Ozone mediated depolymerization and solvolysis of technical lignins under ambient conditions in ethanol

Technical lignins are highly available and inexpensive feedstocks derived from current large scale biomass utilizing industries. Their valorization represents a bottleneck in the development of biorefineries, as the inherently complex lignin structure often suffers severe condensation during isolation, leading to their current application as low value fuel. Processes able to depolymerize technical lignins into value-added (intermediate) molecules are of great interest for the development of integrated, viable routes aiming at the full valorization of lignocellulosic biomass. Here, we report an effective ozone mediated depolymerization of four technical lignins (Indulin-AT Kraft, ball-milled Indulin-AT Kraft, Alcell organosolv and Fabiola organosolv) in ethanol under ambient conditions without the need for catalysts. 52–87 wt% of these nearly ethanol insoluble lignins was broken down into soluble fragments upon ozone exposure. The average molecular weight of the soluble fragments was shown to have decreased by 40–75% compared to the parent materials. A range of (di)carboxylic acids and (di)ethyl esters was identified, accounting for up to 40 wt% of the ozonated lignin oils. These products are the result of phenol ring-opening reactions as well as oxidative cleavage of unsaturated linking motifs followed by partial esterification. Reactivity varied substantially among the lignin feedstocks. For instance, lower particle sizes and higher degradation of the native lignin structure were shown to be beneficial for the effective action of the ozone. Our results show that a straightforward ozonation process under ambient conditions can depolymerize recalcitrant lignins into oxygenated fragments and low molecular weight products soluble in ethanol. These can potentially be used for the synthesis of high-value drop-in chemicals

Catalytic hydrotreatment of pyrolytic lignins from different sources to biobased chemicals:Identification of feed-product relations

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

Biomethanol from Glycerol

Medical bioinformatic

Pyrolytic lignin:A promising biorefinery feedstock for the production of fuels and valuable chemicals

Lignocellulosic biomass is a key feedstock for the sustainable production of biofuels, biobased chemicals and performance materials. Biomass can be efficiently converted into pyrolysis liquids (also known as bio-oils) by the well-established fast pyrolysis technology. Currently, there is significant interest in the application of fast pyrolysis technology as principle biomass conversion technology due to its feedstock flexibility, low cost and high energy conversion efficiency, with many emerging commercial enterprises being established around the globe. Upgrading of the bio-oils is a requisite, and is complicated by its complex and heterogeneous organic nature. Pyrolysis liquids may be further separated by a simple water fractionation, yielding an aqueous sugar-rich phase and a water-insoluble pyrolytic lignin (PL) fraction. This separation step allows the use of dedicated conversion strategies for each fraction, which can be highly advantageous due to their differences in composition and reactivity. For example, the sugar-rich fractions can be used for fermentation, while the phenolic-rich PL is a particularly promising feedstock for the production of a wide range of platform chemicals and energy-dense streams upon depolymerization. To aid the emerging use of PL, novel characterization techniques and valorization strategies are being explored. In this review, the fast pyrolysis process and PL characterization efforts are discussed in detail, followed by the state-of-the-art regarding PL processing using both oxidative and reductive (catalytic) strategies, as well as a combination thereof. Possible applications are discussed and recommendations for future research are provided

Hydrothermal liquefaction versus catalytic hydrodeoxygenation of a bioethanol production stillage residue to platform chemicals:A comparative study

Biobased chemicals like phenols and aromatics are preferably produced from cheap biomass waste streams. In this work, we have explored the potential of a eucalyptus-derived second generation bioethanol production stillage (BPS) residue for this purpose. A comparative study between a hydrothermal liquefaction (HTL) and a catalytic hydrodeoxygenation (HDO) step, as well as a 2-step HTL-HDO approach is reported, targeting at value-added low molecular weight platform chemicals (mainly alkylphenols and aromatics). HDO was observed to be a more suitable strategy than HTL for the production of organic oils enriched in valuable monomers. The direct HDO of the BPS using a commercial Ru/C catalyst at 450 degrees C and 100 bar H-2 pressure led to an organic product oil (30.7 wt%) with a total monomer yield of 25.2 wt% (13.2 wt% of alkylphenolic+aromatics), compared to a 53.2 wt% of a product oil with 10.0 wt% monomers for the HTL step (305 degrees C). A 2-step HTL-HDO strategy was compared with the direct HDO approach. Comparable alkylphenolic+aromatic yields were obtained through this approach based on initial BPS intake (13.2 wt% vs 12.3 wt% for the direct HDO and HTL-HDO approach, respectively). Lower HTL temperatures (305 degrees C) for the first step are preferred to prevent over hydrogenation in the subsequent HDO step. As such, HTL appears a suitable pre-treatment for BPS and can (i) solve the issues related to the feeding of solids in pressurized continuous reactors for HDO and (ii) prevent coke formation during the HDO step, thus improving catalyst stability and durability

Torque measurement as a tool to monitor the breakdown of cassava starch gels, by the effect of Fenton's initiator for graft copolymerization

The use of a combined stirrer-torque meter allows for monitoring viscosity during polymerizations and other reactions, much faster and more continuous than off-line viscosity measurements. This method was applied in previous research about the grafting of acrylic acid onto cassava starch using Fenton's initiator. In this article the method is used to assess the effect of Fenton's initiator on gels of cassava starch in the absence of the monomer. The intention here is to activate the starch selectively first, which could improve graft selectivity. The interaction of a redox graft copolymerization initiator with starch gels when there is no monomer in the system yet, is hardly ever addressed in grafting literature. Remarkably, the present experimental study shows a rapid viscosity decrease of the starch gel, in the order of 70% in less than 2 min, at conditions reflecting graft copolymerization. This result must be considered a major setback for the application of pre-initiation. Torque measurement also allows to identify the important steps in the reaction of Fenton's reagent with starch without the need to do other, more intensive analyses on the chemistry. For example, it could be concluded that the second stage of Fenton's reaction, the slower decomposition of hydrogen peroxide by Fe3+ ions, accounts for another 20% loss of the original gel viscosity but over a longer period, some 30–60 min. Possible further decrease over a longer period is too slow or small relative to the measuring accuracy of the torque meter. FTIR analyses show the occurrence of peaks at 1730–1740 cm−1 in starch which has been subjected to reaction with Fenton's. These peaks are in the range of the vibrational frequencies associated to C[dbnd]O bonds, that are not present in the original starch. This provides at least a strong indication for oxidative degradation of the starch chains

Deterministic nano-assembly of a coupled quantum emitter - photonic crystal cavity system

The interaction of a single quantum emitter with its environment is a central theme in quantum optics. When placed in highly confined optical fields, such as those created in optical cavities or plasmonic structures, the optical properties of the emitter can change drastically. In particular, photonic crystal (PC) cavities show high quality factors combined with an extremely small mode volume. Efficiently coupling a single quantum emitter to a PC cavity is challenging because of the required positioning accuracy. Here, we demonstrate deterministic coupling of single Nitrogen-Vacancy (NV) centers to high-quality gallium phosphide PC cavities, by deterministically positioning their 50 nm-sized host nanocrystals into the cavity mode maximum with few-nanometer accuracy. The coupling results in a 25-fold enhancement of NV center emission at the cavity wavelength. With this technique, the NV center photoluminescence spectrum can be reshaped allowing for efficient generation of coherent photons, providing new opportunities for quantum science.Comment: 13 pages, 4 figure