Characterization of fast pyrolysis bio-oil from hardwood and softwood lignin

© 2020 by the authors. The depletion of fossil fuel reserves and the increase of greenhouse gases (GHG) emission have led to moving towards alternative, renewable, and sustainable energy sources. Lignin is one of the significant, renewable and sustainable energy sources of biomass and pyrolysis is one of the most promising technologies that can convert lignocellulosic biomass to bio-oil. This study focuses on the production and characterization of bio-oil from hardwood and softwood lignin via pyrolysis process using a bench-scale batch reactor. In this study, a mixed solvent extraction method with different polarities was developed to fractionate different components of bio-crude oil into three fractions. The obtained fractions were characterized by using gas chromatography and mass spectrometry (GCMS). The calculated bio-oil yields from Sigma Kraft lignin and Chouka Kraft lignin were about 30.2% and 24.4%, respectively. The organic solvents, e.g., toluene, methanol, and water were evaluated for chemical extraction from bio-oil, and it was found that the efficiency of solvents is as follows: water < methanol < toluene. In both types of the bio-oil samples, phenolic compounds were found to be the most abundant chemical groups which include phenol, 2-methoxy, 2-methoxy-6-methylphenol and phenol, 4-ethyl-2-methoxy that is due to the structure and the originality of lignin, which is composed of phenyl propane units with one or two methoxy groups (O-CH3) on the aromatic ring

Recent Insights into Lignocellulosic Biomass Pyrolysis: A Critical Review on Pretreatment, Characterization, and Products Upgrading

Pyrolysis process has been considered to be an efficient approach for valorization of lignocellulosic biomass into bio-oil and value-added chemicals. Bio-oil refers to biomass pyrolysis liquid, which contains alkanes, aromatic compounds, phenol derivatives, and small amounts of ketone, ester, ether, amine, and alcohol. Lignocellulosic biomass is a renewable and sustainable energy resource for carbon that is readily available in the environment. This review article provides an outline of the pyrolysis process including pretreatment of biomass, pyrolysis mechanism, and process products upgrading. The pretreatment processes for biomass are reviewed including physical and chemical processes. In addition, the gaps in research and recommendations for improving the pretreatment processes are highlighted. Furthermore, the effect of feedstock characterization, operating parameters, and types of biomass on the performance of the pyrolysis process are explained. Recent progress in the identification of the mechanism of the pyrolysis process is addressed with some recommendations for future work. In addition, the article critically provides insight into process upgrading via several approaches specifically using catalytic upgrading. In spite of the current catalytic achievements of catalytic pyrolysis for providing high-quality bio-oil, the production yield has simultaneously dropped. This article explains the current drawbacks of catalytic approaches while suggesting alternative methodologies that could possibly improve the deoxygenation of bio-oil while maintaining high production yield

A comparative structural characterisation of different lignin biomass

This study focuses on the structural characterisation techniques of lignin, which is the most abundant component in biomass and commonly produced as residual product in pulp mills industry. It is inexpensive, non-toxic and biodegradable. Four different lignins have been selected for this study including Alcell lignin, Kraft lignin and two milled wood lignins (MWL) derived from coniferous trees (softwoods) and deciduous trees (hardwood). Fourier transform infrared (FTIR) spectroscopy analysis has been performed on all four types of lignin to identify the functional groups present in the lignin structure. The results have indicated that Alcell lignin consists of more desirable functional groups than Kraft lignin with higher phenolic, carbonyl and aromatic groups. Elemental analysis has been performed to examine the carbon and hydrogen content. The elemental analysis results indicates that MWL contain more hydrogen and carbon in comparison to other two commercial lignins. Heating values have been investigated in terms of higher heating value (HHV) and lower heating value (LHV). The lowest values of HHV and LHV have been reported for Kraft lignin due to its condensed structure. The differential thermogravimetry (DTG) analysis have been performed, which determines the maximum degradation temperature of the lignins. The start and maximum degradation temperature for each lignin help to set the pyrolysis temperature of the lignin for bio-oil production. Components that have been observed via Py-GC-MS analysis have indicated that degradation of bonds has led to the formation of three main structural units of lignin known as guaiacyl (G), syringyl (S) and p-hydroxyphenyl propane (p-H)–type. The results indicate that the Py-GC-MS analysis of MWL have higher aromatic components in comparison to the commercially available lignins

Comparative Production of Bio-Oil from In Situ Catalytic Upgrading of Fast Pyrolysis of Lignocellulosic Biomass

Catalytic upgrading of fast pyrolysis bio-oil from two different types of lignocellulosic biomass was conducted using an H-ZSM-5 catalyst at different temperatures. A fixed-bed pyrolysis reactor has been used to perform in situ catalytic pyrolysis experiments at temperatures of 673, 773, and 873 K, where the catalyst (H-ZSM-5) has been mixed with wood chips or lignin, and the pyrolysis and upgrading processes have been performed simultaneously. The fractionation method has been employed to determine the chemical composition of bio-oil samples after catalytic pyrolysis experiments by gas chromatography with mass spectroscopy (GCMS). Other characterization techniques, e.g., water content, viscosity, elemental analysis, pH, and bomb calorimetry have been used, and the obtained results have been compared with the non-catalytic pyrolysis method. The highest bio-oil yield has been reported for bio-oil obtained from softwood at 873 K for both non-catalytic and catalytic bio-oil samples. The results indicate that the main effect of H-ZSM-5 has been observed on the amount of water and oxygen for all bio-oil samples at three different temperatures, where a significant reduction has been achieved compared to non-catalytic bio-oil samples. In addition, a significant viscosity reduction has been reported compared to non-catalytic bio-oil samples, and less viscous bio-oil samples have been produced by catalytic pyrolysis. Furthermore, the obtained results show that the heating values have been increased for upgraded bio-oil samples compared to non-catalytic bio-oil samples. The GCMS analysis of the catalytic bio-oil samples (H-ZSM-5) indicates that toluene and methanol have shown very similar behavior in extracting bio-oil samples in contrast to non-catalytic experiments. However, methanol performed better for extracting chemicals at a higher temperature

Biodegradable starch-based composites: effect of micro and nanoreinforcements on composite properties

Thermoplastic starch (TPS) matrix was reinforced with various kenaf bast cellulose nanofiber loadings (0–10 wt%). Thin films were prepared by casting and evaporating the mixture of aqueous suspension of nanofibers (NFs), starch, and glycerol which underwent gelatinization process at the same time. Moreover, raw fibers (RFs) reinforced TPS films were prepared with the same contents and conditions. The effects of filler type and loading on different characteristics of prepared materials were studied using transmission and scanning electron microscopies, X-ray diffractometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and moisture absorption analysis. Obtained results showed a homogeneous dispersion of NFs within the TPS matrix and strong association between the filler and matrix. Moreover, addition of nanoreinforcements decreased the moisture sensitivity of the TPS film significantly. About 20 % decrease in moisture content at equilibrium was observed with addition of 10 wt% NFs while this value was only 5.7 % for the respective RFs reinforced film

Facile preparation of a cellulose microfibers–exfoliated graphite composite: a robust sensor for determining dopamine in biological samples

© 2017, Springer Science+Business Media B.V. A simple and robust dopamine (DA) sensor was developed using a cellulose microfibers (CMF)–exfoliated graphite composite-modified screen-printed carbon electrode (SPCE) for the first time. The graphite-CMF composite was prepared by sonication of pristine graphite in CMF solution and was characterized by high-resolution scanning electron microscopy, Fourier transform, infrared, and Raman spectroscopy. The cyclic voltammetry results reveal that the graphite-CMF composite modified SPCE has superior electrocatalytic activity against oxidation of dopamine than SPCE modified with pristine graphite and CMF. The presence of large edge plane defects on exfoliated graphite and abundant oxygen functional groups of CMF enhance electrocatalytic activity and decrease potential to oxidize DA. Differential pulse voltammetry was used to quantify DA using the graphite-CMF composite-modified SPCE and demonstrated a linear response for DA detection in the range of 0.06–134.5 µM. The sensor shows a detection limit at 10 nM with an appropriate sensitivity and displays appropriate recovery of DA in human serum samples with good repeatability. Sensor selectivity is demonstrated in the presence of 50-fold concentrations of potentially active interfering compounds including ascorbic acid, uric acid, and dihydroxybenzene isomers

Analytical pyrolysis study of different lignin biomass

Lignin represents about 20–30 wt% of the wood content and it is an aromatic polymer composed of phenyl propane units that are connected through ether and condensed (C-C) linkages. It is the major by-product of second-generation bioethanol production. Lignin is a main impurity in the separation of cellulose from wood for pulp and paper. Four different lignins have been selected for this study including Alcell lignin, Kraft lignin and two milled wood lignins (MWL) derived from coniferous trees (softwoods) and deciduous trees (hardwood). Pyrolysis gas chromatography (Py-GC-MS) tests were performed on each sample using CDS 5200 pyrolyser connected to a gas chromatograph with mass spectra Shimadzu GCMS. The pyrolysis products with a phenolic nature obtained by pyrolysis of all four types of lignin has reflected the nature of different lignin origins. The results have shown that more components identified by pyrolysis of MWL (hardwood and softwood) in comparison with commercial lignins (Alcell and Kraft). Components that have been observed via Py-GC-MS analysis indicating that degradation of all four bonds and lead to formation of three main structural units of lignin. The structural analysis of the commercial lignins revealed the partial similarity to the commercially available lignin that means raw materials contains the sufficient aromatics to be used for bio-oil production

A comparative production and characterisation of fast pyrolysis bio-oil from Populus and Spruce woods

This study focuses on the production and characterisation of fast pyrolysis bio-oil from hardwood (Populus) and softwood (Spruce) using a bench-scale pyrolysis reactor at two different temperatures. In this study, a mixed solvent extraction method with different polarities was developed to extract different components of bio-crude oil into three fractions. The obtained fractions were characterized by using gas chromatography and mass spectrometry (GC-MS). The effect of temperature on the production of bio-oil and on the chemical distribution in bio-oil was examined. The maximum bio-oil yield (71.20%) was obtained at 873 K for bio-oil produced from softwood (Spruce). In contrast, at a temperature of 773 K, the bio-oil yields were 62.50% and 65.40% for bio-oil obtained from hardwood (Populus) and softwood (Spruce) respectively. More phenolic compounds were extracted at a temperature of 773 K for bio-oil derived from softwood (Spruce) whereas the bio-oil obtained from hardwood (Populus) produced mostly furans, acids and sugar compounds at this temperature. For both types of bio-oil, a wide variety of chemical groups were identified at a temperature of 873 K in comparison to 773 K

Analytical pyrolysis study of different lignin biomass

Lignin represents about 20–30 wt% of the wood content and it is an aromatic polymer composed of phenyl propane units that are connected through ether and condensed (C-C) linkages. It is the major by-product of second-generation bioethanol production. Lignin is a main impurity in the separation of cellulose from wood for pulp and paper. Four different lignins have been selected for this study including Alcell lignin, Kraft lignin and two milled wood lignins (MWL) derived from coniferous trees (softwoods) and deciduous trees (hardwood). Pyrolysis gas chromatography (Py-GC-MS) tests were performed on each sample using CDS 5200 pyrolyser connected to a gas chromatograph with mass spectra Shimadzu GCMS. The pyrolysis products with a phenolic nature obtained by pyrolysis of all four types of lignin has reflected the nature of different lignin origins. The results have shown that more components identified by pyrolysis of MWL (hardwood and softwood) in comparison with commercial lignins (Alcell and Kraft). Components that have been observed via Py-GC-MS analysis indicating that degradation of all four bonds and lead to formation of three main structural units of lignin. The structural analysis of the commercial lignins revealed the partial similarity to the commercially available lignin that means raw materials contains the sufficient aromatics to be used for bio-oil production

A comparative production and characterisation of fast pyrolysis bio-oil from Populus and Spruce woods

This study focuses on the production and characterisation of fast pyrolysis bio-oil from hardwood (Populus) and softwood (Spruce) using a bench-scale pyrolysis reactor at two different temperatures. In this study, a mixed solvent extraction method with different polarities was developed to extract different components of bio-crude oil into three fractions. The obtained fractions were characterized by using gas chromatography and mass spectrometry (GC-MS). The effect of temperature on the production of bio-oil and on the chemical distribution in bio-oil was examined. The maximum bio-oil yield (71.20%) was obtained at 873 K for bio-oil produced from softwood (Spruce). In contrast, at a temperature of 773 K, the bio-oil yields were 62.50% and 65.40% for bio-oil obtained from hardwood (Populus) and softwood (Spruce) respectively. More phenolic compounds were extracted at a temperature of 773 K for bio-oil derived from softwood (Spruce) whereas the bio-oil obtained from hardwood (Populus) produced mostly furans, acids and sugar compounds at this temperature. For both types of bio-oil, a wide variety of chemical groups were identified at a temperature of 873 K in comparison to 773 K