Fast hydropyrolysis of biomass Conversion: A comparative review.

Recent studies show that fast hydropyrolysis (i.e., pyrolysis under hydrogen atmosphere operating at a rapid heating rate) is a promising technology for the conversion of biomass into liquid fuels (e.g., bio-oil and C4+ hydrocarbons). This pyrolysis approach is reported to be more effective than conventional fast pyrolysis in producing aromatic hydrocarbons and also lowering the oxygen content of the bio-oil obtained compared to hydrodeoxygenation (a common bio-oil upgrading method). Based on current literature, various non-catalytic and catalytic fast hydropyrolysis processes are reviewed and discussed. Efforts to combine fast hydropyrolysis and hydrotreatment process are also highlighted. Points to be considered for future research into fast hydropyrolysis and pending challenges are also discussed.

Pith-specific lignification in Nicotiana attenuata as a defense against a stem-boring herbivore.

Plants have developed tissue-specific defense strategies in response to various herbivores with different feeding habits. Although defense responses to leaf-chewing insects have been well studied, little is known about stem-specific responses, particularly in the pith, to stem-boring herbivores. To understand the stem-specific defense, we first conducted a comparative transcriptomic analysis of the wild tobacco Nicotiana attenuata before and after attack by the leaf-chewing herbivore Manduca sexta and the stem borer Trichobaris mucorea. When the stem-boring herbivore attacked, lignin-associated genes were upregulated specifically in the inner parenchymal cells of the stem, the pith; lignin also accumulated highly in the attacked pith. Silencing the lignin biosynthetic gene cinnamyl alcohol dehydrogenase enhanced the performance of the stem-boring herbivore but had no effect on the growth of the leaf-chewing herbivore. Two-dimensional nuclear magnetic resonance results revealed that lignified pith contains feruloyltyramine as an unusual lignin component in the cell wall, as a response against stem-boring herbivore attack. Pith-specific lignification induced by the stem-boring herbivore was modulated by both jasmonate and ethylene signaling. These results suggest that lignin provides a stem-specific inducible barrier, protecting plants against stem-boring insects.

Pretreatment of bio-oil with ion exchange resin to improve fuel quality and reduce char during hydrodeoxygenation upgrading with Pt/C.

To obtain high-quality biofuel, bio-oil obtained from fast pyrolysis of woody biomass was pretreated with ion exchange resin (amberlyst 36) at 50°C, 100°C, and 150°C, and then the recovered liquid product was upgraded using hydrodeoxygenation (HDO) with Pt/C at 300°C. After the two-stage upgrading, 4 types of products (gas, light oil, heavy oil, and char) were obtained. Two-immiscible liquid products were consisted of organic heavy oil, derived from bio-oil, and aqueous light oil, based on the ethanol. The mass balances of the HDO products were influenced by the pretreatment temperature. Ion exchange pretreatment of bio-oil was effective in reducing the char formation during the hydrodeoxygenation (HDO) process. The pretreatment also improved the following heavy oil properties: the water content, heating value, viscosity, acidity, and oxygen level. As a parameter used to indicate the biofuel acidity, the total acid number (TAN) value, was clearly reduced from 114.5 (bio-oil) to 34.1-78.2 (heavy oils). Furthermore, the water and oxygen contents of bio-oil (21.1 and 52.6 wt%, respectively) declined after the pretreatment followed by HDO (ranged 5.1-6.9 and 19.0-25.5 wt%, respectively), thereby improving its higher heating value (HHV) from 17.2 MJ/kg (bio-oil) to 26.2-28.1 MJ/kg (heavy oils). The degree of deoxygenation (DOD) increased as the pretreatment temperature decreased, and the highest energy efficiency (79.8%) was observed after pretreatment at 100°C. In terms of catalyst deactivation during the reaction, both carbon deposition and surface cracking intensified with increasing pretreatment temperatures.

Overview of biochar production from preservative-treated wood with detailed analysis of biochar characteristics, heavy metals behaviors, and their ecotoxicity.

Concerns over the disposal of preservative-treated wood waste and its related environmental problems are the main driving forces of research into the recycling of preservative-treated wood. Preservative-treated wood waste composed of cellulose, hemicellulose, and lignin with several types of heavy metals can be recycled in various ways, such as wood-based composites, heavy metal extraction, energy recovery, etc. In particular, thermochemical conversion has attracted considerable attention recently because energy can be recovered from biomass as liquid fuel and bio-oil, as well as produce bio-char with a high carbon content, which can be applied to valuable products, such as soil amendment, adsorbents, solid fuels, and catalyst supports. On the other hand, environmental issues, such as heavy metal volatilization and heavy metal leaching, are still a challenge. This review reports the state-of-the-art knowledge of biochar production from preservative-treated wood with the main focus on the feedstock, process technology, biochar characteristics, application, and environmental issues. This review provides important information for future studies into the recycling of preservative-treated woods into biochar.

Safety and Tolerability of the Dual 5-Alpha Reductase Inhibitor Dutasteride in the Treatment of Androgenetic Alopecia.

BACKGROUND: After the approval of dutastride for androgenic alopecia (AGA) in 2009, Korean authority required a post-marketing surveillance to obtain further data on its safety profile. OBJECTIVE: The objective was to monitor adverse events (AEs) of dutasteride 0.5 mg in Korean AGA male patients in a clinical practice environment. METHODS: Open label, multi-center, non-interventional observational study was done from July 2009 to July 2013. AGA subjects (18~41 years of age) with no experience of dutasteride were enrolled. Dosage regimen was recommended according to the prescribing information. The incidences of any AEs, serious adverse events (SAEs), and adverse drug reactions (ADRs) were evaluated. Multiple logistic regression method was used to identify risk factors related to ADRs. Effectiveness was generally evaluated by physicians. RESULTS: During study period, 712 subjects were enrolled. The subjects of 29.3±6.0 years old exposed to dutasteride for 204.7±161.5 days. One hundred and ten (15.4%) of subjects reported 138 AEs. Four subjects (0.6%) reported 5 SAEs (right radius fracture, 2 events of chronic follicular tonsillitis, influenza infection, and acute appendicitis). Sixty-six subjects (9.3%) reported 80 ADRs. Most frequent ADRs were libido decreased (9 subjects, 1.3%), dyspepsia (8 subjects, 1.1%), impotence (7 subjects, 1.0%), and fatigue (5 subjects, 0.7%). Other interested ADRs were sexual function abnormality (4 subjects, 0.6%), gynecomastia (2 subjects, 0.3%), and ejaculation disorder (1 subject, 0.1%). Most subjects (78.6%) showed overall improvement after treatment of dutasteride in the effectiveness. CONCLUSION: Dutasteride 0.5 mg is to be well-tolerated in 18 to 41 years old AGA patients in a clinical practice environment.

Investigation of chemical modifications of micro- and macromolecules in bio-oil during hydrodeoxygenation with Pd/C catalyst in supercritical ethanol.

Miscanthus bio-oil was subjected to hydrodeoxygenation (HDO) with Pd/C at different temperatures (250, 300 and 350°C) and times (30, 45 and 60 min) to investigate the chemical modification of micro- and macromolecules in bio-oil. Four main products - char, gas and two immiscible oils (light and heavy oil) - were obtained from the HDO reaction. Yields of heavy oil as a targeting product of HDO varied from 60% to 13%, whereas those of gas and char were ranged from 7% to 36% and 6% to 17%, respectively. Water content was estimated to<1% and heating value was 26-31 MJ kg(-1). Reduction of unstable oxygen-containing compounds such as acids (2-hydroxy-butanoic acid), aldehydes (furfural), alcohols (butanedial) and sugars (levoglucosan) were characteristic in heavey oil. Apart from hydrogenation and deoxygenation, micromolecules in bio-oil were plausibly modified to stable ketones, esters and saturated components via demethoxylation, dealkylation, decarbonylation, dehydroxylation and ring opening. Macromolecular lignin fragments (referred to as pyrolytic lignins in bio-oil and phenol polymers in heavy oil) were extracted and subjected to several analyses. Approximately 60% of the pyrolytic lignins were decomposed into low molecular weight compounds during HDO reaction. Moreover, essential functional groups, OCH3 and phen-OH groups attached to pyrolytic lignin, were severely modified during HDO reaction.

Investigation of structural modification and thermal characteristics of lignin after heat treatment.

Milled wood lignin was subjected to heat treatment between 150 and 300°C to understand the pattern of its structural modification and thermal properties. When the temperature was elevated with interval of 50°C, the color of the lignin became dark brown and the lignin released various forms of phenols from terminal phenolic groups in the lignin, leading to two physical phenomena: (1) gradual weight loss of the lignin, up to 19% based on dry weight and (2) increase in the carbon content and decrease in the oxygen content. Nitrobenzene oxidation and (13)C NMR analyses confirmed a cleavage of ß-O-4 linkage (depolymerization) and reduction of methoxyl as well as phenolic hydroxyl group were also characteristic in the lignin structure during heat treatment. Simultaneously with lignin depolymerization, GPC analysis provided a possibility that condensation between lignin fragments could also occur during heat treatment. TGA/DTG/DSC data revealed that thermal stability of lignin obviously increased after heat treatment, implicating the structural rearrangement of lignin to reduction of ß-O-4 linkage as well as accumulation of CC bonds.

Fast pyrolysis of potassium impregnated poplar wood and characterization of its influence on the formation as well as properties of pyrolytic products.

TGA results indicated that the maximum decomposition temperature of the biomass decreased from 373.9 to 359.0°C with increasing potassium concentration. For fast pyrolysis, char yield of potassium impregnated biomass doubled regardless of pyrolysis temperature compared to demineralized one. The presence of potassium also affected bio-oil properties. Water content increased from 14.4 to 19.7 wt% and viscosity decreased from 34 to 16.2 cSt, but the pH value of the bio-oil remained stable. Gas chromatography/mass spectroscopy (GC/MS) analysis revealed that potassium promoted thermochemical reactions, thus causing a decrease of levoglucosan and an increase of small molecules and lignin-derived phenols in bio-oil. Additionally, various forms of aromatic hydrocarbons, probably derived from lignins, were detected in non-condensed pyrolytic gas fractions.

Effects of various reaction parameters on solvolytical depolymerization of lignin in sub- and supercritical ethanol.

Organosolv lignin was treated with ethanol at sub/supercritical temperatures (200, 275, and 350 °C) for conversion to low molecular phenols under different reaction times (20, 40, and 60 min), solvent-to-lignin ratios (50, 100, and 150 mL g(-1)), and initial hydrogen gas pressures (2 and 3 MPa). Essential lignin-degraded products, oil (liquid), char (solid), and gas were obtained, and their yields were directly influenced by reaction conditions. In particular, concurrent reactions involving depolymerization and recondensation as well as further (secondary) decomposition were significantly accelerated with increasing temperature, leading to both lignin-derived phenols in the oil fraction and undesirable products (char and gas). As the main components in the oil fraction, oxygenated phenols, guaiacol, and syringol as well as their alkylated forms were detected. The yield of alkylated phenols showed a drastic increase at 350 °C in the presence of initial hydrogen gas due to prevailing hydrodeoxygenation and hydrogenation reactions of the vinyl/allyl/oxygenated phenols. These reactions were also demonstrated indirectly from the results of atomic H/C and O/C of the oils. The highest amount of monomeric phenols released from lignin (1.0 g) was measured as ca. 96.7 mg at 350 °C, 40 min, 100 mL g(-1), and 3 MPa of H2. In addition, GPC analysis suggested a possibility of condensation between lignin-degraded fragments during the solvolysis reaction.