Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
1.
Bioresour Technol ; 399: 130557, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38460561

RESUMO

A novel cascade pyrolysis upgrading process for acid hydrolysis lignin (AHL), consisting of pyrolysis, catalytic upgrading of pyrolysis vapors, and pyrolysis char, was developed to improve the yield of value-added products (monophenolic chemicals and carbon materials). Pyrolysis of AHL at 450 °C and subsequent catalytic upgrading of pyrolysis vapors over Ni/H-ZSM-5 boosted the concentration of monophenolic chemicals in pyrolysis liquids by 58%. The carbon material prepared from pyrolysis char using KOH as activating agent exhibited a large specific surface area of 2902.5 m2/g and a large total pore volume of 1.45 cm3/g, thus affording good adsorption capacity for methylene blue (824.87 mg/g) and iodine (2333.17 mg/g). Moreover, the cascade pyrolysis upgrading of AHL achieved a yield of 68.52% desired products, which was much higher than the reported results (single production of monophenols and pyrolysis char). In summary, this work provides a potential reference for efficient utilization of lignin in large-scale applications.


Assuntos
Carbono , Lignina , Pirólise , Adsorção , Hidrólise , Gases , Ácidos
2.
J Pers ; 92(1): 130-146, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37041673

RESUMO

OBJECTIVE: Personality changes across the life span. Life events, such as marriage, becoming a parent, and retirement, have been proposed as facilitating personality growth via the adoption of novel social roles. However, empirical evidence linking life events with personality development is sparse. Most studies have relied on few assessments separated by long time intervals and have focused on a single life event. In contrast, the content of life is composed of small, recurrent experiences (e.g., getting sick or practicing a hobby), with relatively few major events (e.g., childbirth). Small, frequently experienced life events may play an important and overlooked role in personality development. METHOD: The present study examined the extent to which 25 major and minor life events alter the trajectory of personality development in a large, frequently assessed sample (Nsample = 4904, Nassessments = 47,814, median retest interval = 35 days). RESULTS: Using a flexible analytic strategy to accommodate the repeated occurrence of life events, we found that the trajectory of personality development shifted in response to a single occurrence of some major life events (e.g., divorce), and recurrent, "minor" life experiences (e.g., one's partner doing something special). CONCLUSION: Both stark role changes and frequently reinforced minor experiences can lead to personality change.


Assuntos
Desenvolvimento da Personalidade , Personalidade , Humanos , Estudos Longitudinais , Personalidade/fisiologia , Transtornos da Personalidade , Acontecimentos que Mudam a Vida
3.
J Pers ; 92(1): 298-315, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37072929

RESUMO

OBJECTIVE: Personality changes are related to successfully performing adult occupational roles which require teamwork, duty, and managing stress. However, it is unclear how personality development relates to specific job characteristics that vary across occupations. METHOD: We investigated whether 151 objective job characteristics, derived from the Occupational Information Network (O*NET), were associated with personality levels and changes in a 12-year longitudinal sample followed over the school to work transition. Using cross-validated regularized modeling, we combined two Icelandic longitudinal datasets (total N = 1054) and constructed an individual-level, aggregated job characteristics score that maximized prediction of personality levels at baseline and change over time. RESULTS: The strongest association was found for level of openness (0.25), followed by conscientiousness (0.16) and extraversion (0.14). Overall, aggregated job characteristics had a stronger prediction for personality intercepts (0.14) than slopes (0.10). These results were subsequently replicated in a U.S. sample using levels of the Big Five as the dependent variable. This indicates that associations between job characteristics and personality are generalizable across life stages and nations. CONCLUSIONS: Our findings suggest that job titles are a valuable resource that can be linked to personality to better understand factors that influence psychological development. Further work is needed to document the prospective validity of job characteristics across a wider range of occupations and age.


Assuntos
Desenvolvimento da Personalidade , Personalidade , Adulto , Humanos , Adulto Jovem , Estudos Longitudinais , Estudos Prospectivos , Transtornos da Personalidade
4.
Nat Commun ; 14(1): 7749, 2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-38012194

RESUMO

The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li2CO3-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C2+ yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li2CO3 shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li2CO3 coating. Furthermore, we establish a generalized correlation between Pr4+ content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts.

5.
Psychol Bull ; 148(7-8): 588-619, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35834197

RESUMO

Past research syntheses provided evidence that personality traits are both stable and changeable throughout the life span. However, early meta-analytic estimates were constrained by a relatively small universe of longitudinal studies, many of which tracked personality traits in small samples over moderate time periods using measures that were only loosely related to contemporary trait models such as the Big Five. Since then, hundreds of new studies have emerged allowing for more precise estimates of personality trait stability and change across the life span. Here, we updated and extended previous research syntheses on personality trait development by synthesizing novel longitudinal data on rank-order stability (total k = 189, total N = 178,503) and mean-level change (total k = 276, N = 242,542) from studies published after January 1, 2005. Consistent with earlier meta-analytic findings, the rank-order stability of personality traits increased significantly throughout early life before reaching a plateau in young adulthood. These increases in stability coincide with mean-level changes in the direction of greater maturity. In contrast to previous findings, we found little evidence for increasing rank-order stabilities after Age 25. Moreover, cumulative mean-level trait changes across the life span were slightly smaller than previously estimated. Emotional stability, however, increased consistently and more substantially across the life span than previously found. Moderator analyses indicated that narrow facet-level and maladaptive trait measures were less stable than broader domain and adaptive trait measures. Overall, the present findings draw a more precise picture of the life span development of personality traits and highlight important gaps in the personality development literature. (PsycInfo Database Record (c) 2023 APA, all rights reserved).


Assuntos
Transtornos da Personalidade , Personalidade , Humanos , Adulto Jovem , Adulto , Desenvolvimento da Personalidade , Emoções , Estudos Longitudinais
6.
Sci Rep ; 11(1): 3205, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547339

RESUMO

Using a genetically informative design (about 2000 twin pairs), we investigated the phenotypic and genetic and environmental architecture of a broad construct of conscientiousness (including conscientiousness per se, effortful control, self-control, and grit). These four different measures were substantially correlated; the coefficients ranged from 0.74 (0.72-0.76) to 0.79 (0.76-0.80). Univariate genetic analyses revealed that individual differences in conscientiousness measures were moderately attributable to additive genetic factors, to an extent ranging from 62 (58-65) to 64% (61-67%); we obtained no evidence that shared environmental influences were observed. Multivariate genetic analyses showed that for the four measures used to assess conscientiousness, genetic correlations were stronger than the corresponding non-shared environmental correlations, and that a latent common factor accounted for over 84% of the genetic variance. Our findings suggest that individual differences in the four measures of conscientiousness are not distinguishable at both the phenotypic and behavioural genetic levels, and that the overlap was substantially attributable to genetic factors.


Assuntos
Personalidade , Autocontrole , Gêmeos/genética , Adolescente , Criança , Feminino , Interação Gene-Ambiente , Estudos de Associação Genética , Humanos , Masculino , Análise Multivariada , Fenótipo , Gêmeos/psicologia
7.
iScience ; 23(1): 100814, 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31954322

RESUMO

Selectively breaking the C-O bonds within biomass during catalytic fast pyrolysis (CFP) is desired, but extremely challenging. Herein, we develop a series of metal-oxide nanocomposites composed of W, Mo, Zr, Ti, or Al. It is demonstrated that the nanocomposites of WO3-TiO2-Al2O3 exhibit the highest deoxygenation ability during CFP of lignin, which can compete with the commercial HZSM-5 catalyst. The nanocomposites can selectively cleave the C-O bonds within lignin-derived phenols to form aromatics by direct demethoxylation and subsequent dehydration. Moreover, the nanocomposites can also achieve the selective breaking of the C-O bonds within xylan and cellulose to form furans by dehydration. The Brønsted and Lewis acid sites on the nanocomposites can be responsible for the deoxygenation of lignin and polysaccharides, respectively. This study provides new insights for the rational design of multifunctional catalysts that are capable of simultaneously breaking the C-O bonds within lignin and polysaccharides.

8.
Psychol Sci ; 30(5): 776-788, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30990767

RESUMO

We replicated the study by Tucker-Drob, Cheung, and Briley (2014), who found that the association between science interest and science knowledge depended on economic resources at the family, school, and national levels, using data from the 2006 Programme for International Student Assessment (PISA). In more economically prosperous families, schools, and nations, student interest was more strongly correlated with actual knowledge. Here, we investigated whether these results still held despite substantial changes to educational and economic systems over roughly a decade. Using similar data from PISA 2015 ( N = 537,170), we found largely consistent results. Students from more economically advantaged homes, schools, and nations exhibited a stronger link between interests and knowledge. However, these moderation effects were substantially reduced, and the main effect of science interest increased by nearly 25%, driven almost entirely by families of low socioeconomic status and nations with low gross domestic product. The interdependence of interests and resources is robust but perhaps weakening with educational progress.


Assuntos
Produto Interno Bruto/tendências , Instituições Acadêmicas/economia , Ciência/educação , Estudantes/psicologia , Logro , Adolescente , Produto Interno Bruto/estatística & dados numéricos , Humanos , Conhecimento , Instituições Acadêmicas/estatística & dados numéricos , Ciência/economia , Fatores Socioeconômicos
9.
J Pers Soc Psychol ; 117(3): 635-658, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30920282

RESUMO

Recent work in personality development has indicated that the magnitude of individual differences in personality increases over child development. Do such patterns reflect the differentiation of individuals by genotype, an increasing influence of environmental factors, or some (interactive) combination of the two? Using a population-based sample of over 2,500 twins and multiples from the Texas Twin Project, we estimated age trends in the variances in self- and parent-reported measures of the Big Five personality traits between Ages 8 and 18 years. We then estimated age trends in the genetic and environmental components of variance in each measure. Individual differences in personality increased in magnitude from childhood through mid-adolescence. This pattern emerged using both children's self-reports and ratings provided by their parents, and was primarily attributable to increases in the magnitude of genetic influences. Most of the increasing genetic variance appeared nonadditive, pointing to the possibility that developmental processes tend to make genetically similar individuals disproportionately more alike in their personality traits over time. These findings could reflect increasing or accumulating effects of trait-by-trait interactions; person-by-environment transactions, whereby genetically similar people are disproportionally likely to experience similar environments; the activation of dominant genes across developmental transitions (e.g., puberty); or some combination of these three processes, among other factors. Theories of personality development will need to accommodate these descriptive findings, and longitudinal, genetically informed designs are needed to test some of the specific hypotheses springing from this study. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Desenvolvimento do Adolescente/fisiologia , Desenvolvimento Infantil/fisiologia , Genética Comportamental , Personalidade/fisiologia , Adolescente , Criança , Feminino , Humanos , Individualidade , Masculino , Personalidade/genética , Desenvolvimento da Personalidade
10.
Bioresour Technol ; 274: 281-286, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30529333

RESUMO

In this study, ball milling and ionic liquid pretreatments were utilized to alter cellulose structure prior to fast pyrolysis and enzymatic hydrolysis. The variations in the products distribution of cellulose fast pyrolysis, and their dependence on the structure of cellulose, and the temperature of fast pyrolysis were illustrated. Fast pyrolysis of pretreated cellulose yielded more levoglucosan than crystalline cellulose (14.7%) at 300 °C. Nevertheless, the levoglucosan achieved higher yield (64.3%) from crystalline cellulose at 400 °C. At last, a comparison between fast pyrolysis and enzymatic hydrolysis for cellulose saccharifaction was made. Fast pyrolysis was a promising alternative to liberate levoglucosan from cellulose. Further investigation and development were required to maximize the levoglucosan production.


Assuntos
Celulose/metabolismo , Glucose/análogos & derivados , Biomassa , Fermentação , Glucose/biossíntese , Hidrólise , Pirólise , Temperatura , Fatores de Tempo
11.
Eur J Pers ; 33(3): 317-336, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-34083874

RESUMO

Students engage in learning activities with different achievement goal orientations. Some students pursue learning for learning sake (i.e. mastery goal orientation), some are driven by gaining favorable judgement of their performance (i.e. performance approach goal orientation), and others focus on avoiding negative judgement (i.e. performance avoidance goal orientation). These goal orientations are linked with academic achievement, and troublingly, students report decreasing levels of goal orientations across the school years. However, little is known concerning the mechanisms that drive this decline. In a large (N = 891 twin pairs) cross-sectional genetically informative sample (age = 8 to 22 years), we found that older students reported lower goal orientations. Then, we identified shifts in the magnitude of genetic and environmental variance in each goal orientation. For example, variance in mastery goal orientation was primarily associated with environmental factors during the elementary school years. As students entered high school, genetic influences increased, replacing shared environmental influences. Finally, we situated these findings in the larger nomological network by testing associations with psychological constructs (e.g. personality and cognitive ability) and contextual variables (e.g. parents, schools, and peers). The development of academic motivation is complex with many interconnecting factors that appear to shift with age.

12.
Bioresour Technol ; 268: 212-220, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30077882

RESUMO

Olivine synthesized by wetness impregnation (WI) and thermal fusion (TF) methods were investigated as in-situ catalysts to reduce the tar content during air-blown biomass gasification in a circulating fluidized bed (CFB). The results showed that the tar content decreases with the increase of reaction temperature. Raw-olivine reduced tar content by 40.6% compared to non-active bed material (silica sand) experiments; after calcination, the catalytic activities of olivine catalysts were further improved due to the migration of Fe from olivine grain to the surface. 1100-WI-olivine could reduce the tar content by up to 81.5% compared with that of raw-olivine because of the existence of Fe2O3, NiO and NiO-MgO. For 1400-TF-olivine, due to the formation of NiFe2O4, the tar content decreased to 0.77 g/Nm3, an 82.9% reduction compared to raw-olivine. Moreover, the TF-olivine had a stronger anti-attrition performance and was more suitable for using in a circulating fluidized bed.


Assuntos
Compostos de Ferro , Compostos de Magnésio , Silicatos , Biomassa , Compostos Férricos , Gases
13.
Polymers (Basel) ; 9(11)2017 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-30965903

RESUMO

In this manuscript, glycerol was used in corncobs' pretreatment to promote levoglucosan production by fast pyrolysis first and then was further utilized as raw material for chemicals production by microbial fermentation. The effects of glycerol pretreatment temperatures (220⁻240 °C), time (0.5⁻3 h) and solid-to-liquid ratios (5⁻20%) were investigated. Due to the accumulation of crystalline cellulose and the removal of minerals, the levoglucosan yield was as high as 35.8% from corncobs pretreated by glycerol at 240 for 3 h with a 5% solid-to-liquid ratio, which was obviously higher than that of the control (2.2%). After glycerol pretreatment, the fermentability of the recovered glycerol remaining in the liquid stream from glycerol pretreatment was evaluated by Klebsiella pneumoniae. The results showed that the recovered glycerol had no inhibitory effect on the growth and metabolism of the microbe, which was a promising substrate for fermentation. The value-added applications of glycerol could reduce the cost of biomass pretreatment. Correspondingly, this manuscript offers a green, sustainable, efficient and economic strategy for an integrated biorefinery process.

14.
Biotechnol Biofuels ; 9(1): 196, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27651831

RESUMO

BACKGROUND: Fermentable sugars are important intermediates in the biological conversion of biomass. Hemicellulose and amorphous cellulose are easily hydrolyzed to fermentable sugars in dilute acid, whereas crystalline cellulose is more difficult to be hydrolyzed. Cellulose fast pyrolysis is an alternative method to liberate valuable fermentable sugars from biomass. The amount of levoglucosan generated from lignocellulose by fast pyrolysis is usually lower than the theoretical yield based on the cellulose fraction. Pretreatment is a promising route to improve the yield of levoglucosan from lignocellulose. RESULTS: The integration of dilute sulfuric acid hydrolysis and fast pyrolysis to obtain fermentable sugars was evaluated in this study. Dilute sulfuric acid hydrolysis could remove more than 95.1 and 93.4 % of xylan (the main component of hemicellulose) from sugarcane bagasse and corncob with high yield of xylose. On the other hand, dilute sulfuric acid hydrolysis was also an effective pretreatment to enhance levoglucosan yield from lignocellulose. Dilute acid hydrolysis could accumulate glucan (the component of cellulose) and remove most of the alkali and alkaline earth metals which were powerful catalysts during fast pyrolysis. Further increase in dilute acid concentration (from 0 to 2 %) in pretreatment could promote the yield of levoglucosan in fast pyrolysis. The acid pretreated sugarcane bagasse and corncob gave levoglucosan yields of 43.8 and 35.2 % which were obvious higher than those of raw sugarcane bagasse (12.0 %) and corncob (7.0 %). CONCLUSIONS: Obtaining fermentable sugars by combination dilute acid hydrolysis of xylan and fast pyrolysis of glucan could make full utilization of biomass, and get fermentable sugars economically from biomass for bio-refinery.

15.
Bioresour Technol ; 200: 8-13, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26476158

RESUMO

Sugars are one of intermediates in the biological and chemical conversion of biomass. The objective of this study was to make comparison of obtaining fermentable sugars by enzymatic hydrolysis and fast pyrolysis of ball milling pretreated cellulose. After ball milling pretreatment for 0-18h, with the accumulation of alkali and alkali earth metals (from 50.8 to 276.4ppm) and decrease of the crystalline structure (from 89.8% to 10.1%), the hydrolysis yields increased from 23.6% to 56.0% in enzymatic saccharification, while the yields of levoglucosan diminished from 61.5% to 45.6% gradually in fast pyrolysis. Both enzymatic saccharification and fast pyrolysis had unique attractive features and unfavorable limitations. The present research provided a concept for considering choices among the technologies and feedstocks currently available.


Assuntos
Biotecnologia/métodos , Celulose/química , Glucose/análogos & derivados , Biomassa , Celulases/química , Celulases/metabolismo , Celulose/metabolismo , Fermentação , Glucose/química , Glucose/metabolismo , Hidrólise , Metais/análise
16.
Bioresour Technol ; 196: 194-9, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26241838

RESUMO

In this study, the effects of glycerol pretreatment on subsequent glycerol fermentation and biomass fast pyrolysis were investigated. The liquid fraction from the pretreatment process was evaluated to be feasible for fermentation by Paenibacillus polymyxa and could be an economic substrate. The pretreated biomass was further utilized to obtain levoglucosan by fast pyrolysis. The pretreated sugarcane bagasse exhibited significantly higher levoglucosan yield (47.70%) than that of un-pretreated sample (11.25%). The promotion could likely be attributed to the effective removal of alkali and alkaline earth metals by glycerol pretreatment. This research developed an economically viable manufacturing paradigm to utilize glycerol comprehensively and enhance the formation of levoglucosan effectively from lignocellulose.


Assuntos
Celulose/metabolismo , Fermentação , Glucose/análogos & derivados , Glicerol/metabolismo , Paenibacillus polymyxa/metabolismo , Álcalis/isolamento & purificação , Biomassa , Glucose/metabolismo , Hidrólise , Lignina , Saccharum
17.
Bioresour Technol ; 182: 364-367, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25690683

RESUMO

The objective of this study was to get fermentable sugars by dilute acid hydrolysis of hemicellulose and fast pyrolysis of cellulose from sugarcane bagasse. Hemicellulose could be easily hydrolyzed by dilute acid as sugars. The remained solid residue of acid hydrolysis was utilized to get levoglucosan by fast pyrolysis economically. Levoglucosan yield from crystalline cellulose could be as high as 61.47%. Dilute acid hydrolysis was also a promising pretreatment for levoglucosan production from lignocellulose. The dilute acid pretreated sugarcane bagasse resulted in higher levoglucosan yield (40.50%) in fast pyrolysis by micropyrolyzer, which was more effective than water washed (29.10%) and un-pretreated (12.84%). It was mainly ascribed to the effective removal of alkali and alkaline earth metals and the accumulation of crystalline cellulose. This strategy seems a promising route to achieve inexpensive fermentable sugars from lignocellulose for biorefinery.


Assuntos
Biotecnologia/métodos , Carboidratos/química , Celulose/química , Glucose/análogos & derivados , Polissacarídeos/química , Álcalis/química , Metabolismo dos Carboidratos , Celulose/metabolismo , Fermentação , Glucose/química , Hidrólise , Polissacarídeos/metabolismo
18.
Bioresour Technol ; 176: 15-22, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25460979

RESUMO

Wet and dry torrefaction of corncobs was conducted in high-pressure reactor and tube-type reactor, respectively. Effect of wet and dry torrefaction on chemical structure and pyrolysis behavior of corncobs was compared. The results showed that hemicellulose could be effectively removed from corncobs by torrefaction. However, dry torrefaction caused severe degradation of cellulose and the cross-linking and charring of corncobs. X-ray diffraction analysis revealed that crystallinity degree of corncobs was evidently enhanced during wet torrefaction, but reduced during dry torrefaction as raising treatment temperature. In thermogravimetric analysis, wet torrefied corncobs produced less carbonaceous residues than raw corncobs, while dry torrefied corncobs gave much more residues owing to increased content of acid insoluble lignin. Pyrolysis-gas chromatography/mass spectroscopy analysis indicated that wet torrefaction significantly promoted levoglucosan yield owing to the removal of alkali metals. Therefore, wet torrefaction can be considered as a more effective pretreatment method for fast pyrolysis of biomass.


Assuntos
Biocombustíveis , Biotecnologia/métodos , Glucose/análogos & derivados , Temperatura Alta , Componentes Aéreos da Planta/química , Polissacarídeos/isolamento & purificação , Zea mays/química , Biomassa , Cromatografia Gasosa-Espectrometria de Massas , Glucose/isolamento & purificação , Pressão , Termogravimetria , Água/química , Difração de Raios X
19.
Bioresour Technol ; 140: 138-45, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23707909

RESUMO

Biomass direct chemical looping (BDCL) conversion with natural hematite as an oxygen carrier was conducted in a fluidized bed reactor under argon atmosphere focusing on investigation the cyclic performance of oxygen carrier. The presence of oxygen carrier can evidently promote the biomass conversion. The gas yield and carbon conversion increased from 0.75 Nm(3)/kg and 62.23% of biomass pyrolysis to 1.06 Nm(3)/kg and 87.63% of BDCL, respectively. The components of the gas product in BDCL were close to those in biomass pyrolysis as the cyclic number increased. The gas yield and carbon conversion decreased from 1.06 Nm(3)/kg and 87.63% at 1st cycle to 0.93 Nm(3)/kg and 77.18% at 20th cycle, respectively, due to the attrition and structural changes of oxygen carrier. X-ray diffraction (XRD) analysis showed that the reduction extent of oxygen carrier increased with the cycles. Scanning electron microscope (SEM) and pore structural analysis displayed that agglomeration was observed with the cycles.


Assuntos
Biomassa , Biotecnologia/métodos , Compostos Férricos/farmacologia , Gases/metabolismo , Oxigênio/farmacologia , Microscopia Eletrônica de Varredura , Porosidade , Temperatura , Difração de Raios X
20.
Bioresour Technol ; 138: 321-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23624050

RESUMO

Eucalyptus wood powder was first subjected to hydrothermal pretreatment in a high-pressure reactor at 160-190°C, and subsequently fast pyrolyzed in a fluidized bed reactor at 500°C to obtain high quality bio-oil. This study focused on investigating effect of hydrothermal pretreatment on bio-oil properties. Hemicellulose and some metals were effectively removed from eucalyptus wood, while cellulose content was enhanced. No significant charring and carbonization of constituents was observed during hydrothermal pretreatment. Thus pretreated eucalyptus wood gave higher bio-oil yield than original eucalyptus wood. Chemical composition of bio-oil was examined by GC/MS and (13)C NMR analyses. Bio-oil produced from pretreated eucalyptus wood exhibited lower contents of ketones and acids, while much higher levoglucosan content than bio-oil produced from original eucalyptus wood, which would help to improve thermal stability of bio-oil and extract levoglucosan from bio-oil. Hydrothermal pretreatment also improved bio-oil fuel quality through lowering water content and enhancing heating value.


Assuntos
Reatores Biológicos , Biotecnologia/métodos , Eucalyptus/efeitos dos fármacos , Temperatura Alta , Óleos de Plantas/química , Água/farmacologia , Madeira/efeitos dos fármacos , Técnicas de Cultura Celular por Lotes , Biocombustíveis , Biomassa , Biotecnologia/instrumentação , Cromatografia Gasosa-Espectrometria de Massas , Espectroscopia de Ressonância Magnética , Metais/análise , Madeira/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA