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The conversion of biomass into bio-oil through the pyrolysis process offers numerous benefits, such as bio-fuel and bio-resin synthesis. However, for bio-oil usage for any application, understanding its composition is vital. Therefore, this study investigated the effects of different commonly available woody biomass (Douglas fir, eucalyptus, and poplar) on bio-oil composition. The bio-oil was produced through fast pyrolysis at 500 °C in a fluidized bed reactor and collected using an electrostatic precipitator. The chemical composition was analyzed using gas chromatography–mass spectroscopy, and the hydroxyl groups were quantified using phosphorous-31 nuclear magnetic resonance. The poplar bio-oil had the most significant proportion (67 area%) of lignin-derived compounds and the highest OH concentration (6 mmol g−1). However, the proportion of carbohydrate-derived compounds was the largest (44 area %) in bio-oil produced from Douglas fir. Based on the OH concentration, poplar would be the most suitable feedstock for resin synthesis among the three feedstocks tested. [ABSTRACT FROM AUTHOR]

Different solid base catalysts such as CaO/CeO 2 , CaO/Al 2 O 3, and CaO/ZrO 2 were used for the depolymerization of alkali lignin. Various reaction parameters including reaction solvents (ethanol and methanol), time (30, 60, 90 and 120 min) and catalyst amounts have been screened at reaction temperature of 180 °C. Catalytic liquefaction produced higher bio-oil yield and maximum bio-oil yield (50.0 wt%) was obtained with ethanol and methanol solvent using different catalysts (CaO/ZrO 2 , and CaO/CeO 2). Non-catalytic reaction and support catalysts produced lower bio-oil yield (42.0–46.0 wt%). The bio-oil was analyzed using GC-MS, 1H NMR, TOC, CHNS and FT-IR. It has been seen from the bio-oil analysis that vanillin was the main product with about 41.8–62.2 area%. This is due to solid base catalyst significantly enhancing the β-O-4 cleavage which increased the bio-oil yield as well as the selectivity of compound. The fundamental vibrations band at 2943 and 2978 cm−1 were observed for methoxy proton in catalytic bio-oil with higher intensity compared to the non-catalytic bio-oil. Maximum higher heating value (HHV) of bio-oil was observed with CaO/CeO 2 catalyst with methanol solvent (27.6 MJ/kg). It is suggested that the energy of the bio-oil can be enhanced by CaO/CeO 2 catalyst using methanol solvent for liquefaction reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present study, pyrolysis–gas chromatography and mass spectrometry (Py–GC/MS) analysis were employed to characterize the structure and composition of evolving gas while using prot lignin as feedstock. Non-catalytic and catalytic (Co/TiO 2 , Co/CeO 2 and Co/ZrO 2) pyrolysis were performed at 300, 400, 500 and 600 °C. The pyrolysis products were grouped as phenolics (S, G and H-type), heterocyclic, other type, aromatic hydrocarbon and aliphatic hydrocarbon. Among all the catalysts, Co/CeO 2 effectively promoted the formation of S-type phenolics (30.8%) at 300 °C from the depolymerization of lignin, and showed maximum selectivity towards ethanone, 1-(2-hydroxy-5-methylphenyl) (26.3%) and acetosyringone (13.5%) at 300 °C. Maximum amount of H-type phenolics (49.7%) was observed in the presence of Co/TiO 2 catalyst at 600 °C. In another set of experiments, non-catalytic and catalytic (Co/CeO 2) hydropyrolysis of lignin were also investigated using 1, 5, 10 and 15 bar pressure of hydrogen at 300 °C. At 1 bar H 2 pressure, Co/CeO 2 catalyst effectively led to the production of maximum amount of aromatic hydrocarbon (46.8%) from the hydropyrolysis of lignin, while, 23.9% of aromatic hydrocarbon was obtained from the non-catalytic hydropyrolysis of lignin. [Display omitted] • The catalytic pyrolysis and hydropyrolysis study of prot lignin were carried out. • Higher % of Ethanone,1-(2-hydroxy-5-methylphenyl) (26.3%) was found with Co/CeO 2. • High yield of aromatic hydrocarbon (58.6%) was obtained with Co/CeO 2 at 1 bar H 2. • The formation pathway of aromatic and aliphatic hydrocarbon is discussed. [ABSTRACT FROM AUTHOR]

Photo-electrochemical properties of fluorine-doped tin oxide (FTO)/nickel oxide-nickel (Ni0.98Si0.02O2-Ni) with isolated Si sites are discussed. The Ni0.98Si0.02O2-Ni photo-electrocatalyst without any noble metal was prepared using a one-step chemical reduction precipitation method. Photo-electrochemical properties were investigated by cyclic voltammetry and chronoamperometry techniques in aqueous alkaline solution at pH 8.0. The photo-electrochemical response of the catalyst showed sensitivity to visible and UV light. The catalyst produced hydrogen from water at a rate of 0.5 mmol g−1 h−1 with the reduction of CO2 into CO under visible light in the absence of any light sensitizer or a noble metal. The metallic Ni amount in the catalyst system was optimized to obtain the best photo-electrocatalyst. The first principle DFT study showed that the incorporation of Si sites allowed absorbance of visible light. The catalyst was characterized by powder x-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma- atomic emission spectroscopy (ICP-AES), Brunauer–Emmett–Teller (BET), cyclic voltammetry, and chronoamperometry. The products were analyzed by gas chromatography- thermal conductivity detector (GC-TCD). [ABSTRACT FROM AUTHOR]

Background: The quest for sustainable production of renewable and cheap biofuels has triggered an intensive search for domestication of the next generation of bioenergy crops. Aquatic plants which can rapidly colonize wetlands are attracting attention because of their ability to grow in wastewaters and produce large amounts of biomass. Representatives of Azolla species are some of the fastest growing plants, producing substantial biomass when growing in contaminated water and natural ecosystems. Together with their evolutional symbiont, the cyanobacterium Anabaena azollae, Azolla biomass has a unique chemical composition accumulating in each leaf including three major types of bioenergy molecules: cellulose/hemicellulose, starch and lipids, resembling combinations of terrestrial bioenergy crops and microalgae. Results: The growth of Azolla filiculoides in synthetic wastewater led up to 25, 69, 24 and 40 % reduction of NH4-N, NO3-N, PO4-P and selenium, respectively, after 5 days of treatment. This led to a 2.6-fold reduction in toxicity of the treated wastewater to shrimps, common inhabitants of wetlands. Two Azolla species, Azolla filiculoides and Azolla pinnata, were used as feedstock for the production of a range of functional hydrocarbons through hydrothermal liquefaction, bio-hydrogen and bio-ethanol. Given the high annual productivity of Azolla, hydrothermal liquefaction can lead to the theoretical production of 20.2 t/ha-year of bio-oil and 48 t/ha-year of bio-char. The ethanol production from Azolla filiculoides, 11.7 ? 10³ L/ha-year, is close to that from corn stover (13.3 ? 10³ L/ha-year), but higher than from miscanthus (2.3 ? 10³ L/ha-year) and woody plants, such as willow (0.3 ? 10³ L/ha-year) and poplar (1.3 ? 10³ L/ ha-year). With a high C/N ratio, fermentation of Azolla biomass generates 2.2 mol/mol glucose/xylose of hydrogen, making this species a competitive feedstock for hydrogen production compared with other bioenergy crops. Conclusions: The high productivity, the ability to grow on wastewaters and unique chemical composition make Azolla species the most attractive, sustainable and universal feedstock for low cost, low energy demanding, near zero maintenance system for the production of a wide spectrum of renewable biofuels. [ABSTRACT FROM AUTHOR]

• Depolymerization of prot lignin was investigated using different amounts of H 2 O 2. • Maximum bio-oil (80 wt.%) was observed with 1 ml H 2 O 2. • Maximum acetosyringone (59.3 %) was obtained with 0.5 ml H 2 O 2. • GC–MS, FT-IR and 1H-NMR techniques were used for characterization of bio-oil Lignin is an aromatic renewable polymer of lignocellulosic biomass, due to which it can be considered as a source for various chemical, bio-materials, polymers production. The complex structure of lignin is a big challenge for its valorization. Here, we have investigated the depolymerization of prot lignin into valuable compounds using ethanol and water (1:1) solvent mixture at various temperatures (100, 120, 140, 160 and 180 °C), residence time (15, 30, 60 and 120 min) in the presence of different amounts (0.25, 0.5, 1.0, 1.5, 3.0 and 5.0 ml) of 30 % H 2 O 2 , 5 bar molecular oxygen and 1 bar N 2. Maximum bio-oil of 80.0 wt.% was obtained in the presence of 1.0 ml H 2 O 2 at 120 °C for 30 min residence time. The characterization of bio-oil was carried out using various techniques such as 1H-NMR, FT-IR, and GC–MS. The char residue has been characterized using total organic carbon (TOC) analyser. The GC–MS compounds of bio-oil has been divided into four categories namely G, H, S type phenolics, and other type compounds. Among these GC–MS compounds (G, H, S, and other type compounds), S-type phenolics (66.7 wt.%) were observed to be the most abundant component of bio-oil in the presence of 0.5 ml H 2 O 2. Maximum GC–MS area percentage of acetosyringone (59.3 %) was obtained as the major S-type phenolics at 120 °C temperature and 30 min residence time in the presence of 0.5 ml H 2 O 2. [ABSTRACT FROM AUTHOR]

• Reported the catalytic hydrothermal liquefaction of castor residue. • Factorial design was used to understand the effect of reaction parameters on product yield. • Maximum total bio-oil yield of 21.20 wt. % was obtained at 300 °C, 60 min and 0.5 M K 2 CO 3. • Marginal difference between predicted and actual values confirms the accuracy of model. Castor (Ricinus communis) is an evergreen, self- pollinating, perennial shrub that grows easily upto 10 m height. India ranks first in the world for the production of castor seed. Per ton of castor plant generates more than 50 % of residue in the form of its leaves and stems. Catalytic hydrothermal liquefaction of castor residue was performed at 260−300 °C for 60 min in the presence of alkali catalysts (KOH and K 2 CO 3). The factorial design of experiments was used to understand the effect of process parameters (temperature and catalysts) on total bio-oil yield and conversion. ANOVA was used to analyze the main and interaction effects, while p-values were used to rank the process variables on product yield. It was observed that the use of catalyst enhances the total bio-oil yield and the maximum total bio-oil yield of ca. 21.20 wt. % was found at 300 °C in the presence of 0.5 M K 2 CO 3. The experimental values are in good agreement with predicted values, indicating the accuracy of model for optimization of catalytic HTL of castor residue. Phenols and its derivatives, aromatics, N-contained compounds, acids were observed in bio-oil using GC–MS. An increase in the carbon and decrease in oxygen content leads to enhance the heating value of the product. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Coir pith waste is massively generated from coir fiber processing industries. • It can be pyrolyzed to obtained bio-oil rich in phenolic compounds. • Up to 88.14% phenolics were obtained in the organic fraction of bio-oil. • A parallel kinetic analysis can help in process optimization. Abstract The present study illustrates the production of phenolic compounds via slow pyrolysis of coir pith biomass in a bench-scale reactor. The primary objective of the study is to optimize the pyrolysis conditions to maximize the yield of bio-oil and phenolic compounds. Up to 88.14% phenolic compounds were obtained in the organic fraction of the bio-oil obtained at 350 °C. The phenolic compounds thus extracted can be used for the production of phenol-formaldehyde resins, which reduces the dependence on petroleum-based phenols for the manufacturing of resin. An independent kinetic analysis of the apparent pyrolysis reaction was also performed using thermogravimetry and isoconversional methodology. The calculated values of activation energy showed a variation from 28.41 to 200.09 kJ/mol, with the mean value being 140 kJ/mol. The thermodynamic parameters (ΔS, ΔH, and ΔG) were subsequently evaluated at different conversions using the activation energy values obtained from the kinetic analysis. [ABSTRACT FROM AUTHOR]