Impact of Simulated Warming on Growthand Floral Characteristics of Two Varieties of Medicinal Epimedium

ABSTRACT An open top chamber (OTC) warming system was established in natural field conditions to study the impact of simulated warming on growth and floral characteristics of E. wushanense and E. acuminatum. Results: plant height and leaf growth were affected significantly.In +2°C warming condition, increment of plant height, leaf length and width and daily mean incrementof the two varieties were significantly greater than those of the control group; however, in warming +5°C condition, the increments were significantly lower than those of the control group. Floral differentiation was presented when different treatment was adopted. Floral quantitative character of E. acuminatum increased markedly after +2°C warming, but declined markedly after +5°C warming; however, floral quantitative characters of E. wushanense declined after +2°C and +5°C warming. The results can be used as a reference for cultivation and introduction of the two varieties

Selectively biorefining levoglucosan from NaOH pretreated corncobs via fast pyrolysis

Fast pyrolysis is a comparable technology with enzyme or acid hydrolysis for saccharification of biomass. The low yield of levoglucosan and the formation of inhibitors to biocatalysts from lignocellulose hamper the fermentable utilization of pyrolysate. In this study, aiming to enhance the production of levoglucosan, dilute alkali pretreatment was performed prior to fast pyrolysis of corncobs. The yield of levoglucsoan from pretreated corncobs was significantly improved (34.8%) as compared to that from un-treated corncobs (3.0%), which was mainly attributed to the removal of alkaline and alkaline earth metals as well as lignin fraction by NaOH pretreatment. Conversely, NaOH pretreatment suppressed the formation of acids (from 11.1 to 2.2%), furans (from 2.5 to 2.0%), ketones (from 15.7 to 9.8%) and phenols (from 4.8 to 1.3%), which were common inhibitors to the biocatalysts. Accordingly, NaOH pretreatment facilitated further selective conversion of biomass in fast pyrolysis and made the pyrolysate more fermentable. [GRAPHICS]

Selective production of anhydrosugars and furfural from fast pyrolysis of corncobs using sulfuric acid as an inhibitor and catalyst

The objective of this study was to selectively coproduce anhydrosugars and furfural from the fast pyrolysis of biomass by H2SO4 impregnation. The pyrolysis behaviors of raw and H2SO4-impregnated corncobs, cellulose and xylan were systematically studied by a thermogravimetric analyzer (TGA) and commercial pyroprobe reactor. The results demonstrate that H2SO4 impregnation can reduce the formation of char and drastically improve the yield of anhydrosugars and furfural. The maximum yields of levoglucosan (38.45 wt% based on cellulose), furfural (19.18 wt% based on hemicellulose) and xylosan (9.49 wt% based on hemicellulose) were obtained by fast pyrolysis of corncobs impregnated with 2.75 wt% H2SO4. By comparing the product distributions from fast Pyrolysis of H2SO4-impregnated cellulose, xylan, and raw and demineralized corncobs, it is concluded that H2SO4 can act as an inhibitor to suppress the catalytic functions of structural alkali and alkaline earth metals (AAEM) to improve the yield of anhydrosugars, and H2SO4 can also act as a catalyst to accelerate the dehydration of hemicellulose to form more furfural. It is speculated that H2SO4 could first react with structural AAEM in lignin to form lignosulfonates (e.g., potassium lignosulfonate), thus reducing the catalytic functions of structural AAEM during fast pyrolysis of corncobs. These findings provide a simple and efficient method for the selective coproduction of anhydrosugars and furfural from waste biomass

Maximizing Anhydrosugar Production from Fast Pyrolysis of Eucalyptus Using Sulfuric Acid as an Ash Catalyst Inhibitor

Anhydrosugars, such as levoglucosan (LG), are high value-added chemicals which are mainly derived from fast pyrolysis of pure cellulose. However, fast pyrolysis of raw lignocellulosic biomass usually produces a very low amount of levoglucosan, since alkali and alkaline earth metals (AAEM) present in the ash can serve as the catalysts to inhibit the formation of levoglucosan through accelerating the pyranose ring-opening reactions. In this study, eucalyptus was impregnated with H2SO4 solutions with varying concentrations (0.25⁻1.25%). The characteristics of ash derived from raw and H2SO4-impregnated eucalyptus were characterized by X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). The pyrolysis behaviors of raw and H2SO4-impregnated eucalyptus were performed on the thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TG analysis demonstrated that the H2SO4-impregnated eucalyptus produced less char than raw eucalyptus. Py-GC/MS analysis showed that even small amounts of H2SO4 can obviously improve the production of anhydrosugars and phenols and suppressed the formation of carboxylic acids, aldehydes, and ketones from fast pyrolysis of eucalyptus. The rank order of levoglucosan yield from raw and impregnated eucalyptus was raw < 1.25% H2SO4 < 1% H2SO4 < 0.75% H2SO4 < 0.25% H2SO4 < 0.5% H2SO4. The maximum yield of levoglucosan (21.3%) was obtained by fast pyrolysis of eucalyptus impregnated with 0.5% H2SO4, which was close to its theoretical yield based on the cellulose content. The results could be ascribed to that H2SO4 can react with AAEM (e.g., Na, K, Ca, and Mg) and lignin to form lignosulfonate, thus acting as an inhibitor to suppress the catalytic effects of AAEM during fast pyrolysis of eucalyptus

Chemical Looping Gasification of Torrefied Biomass Using NiFe2O4 as an Oxygen Carrier for Syngas Production and Tar Removal

The aim of this study was to investigate the effect of torrefaction severity and ratio of the oxygen carrier to feedstock on syngas production and tar removal during chemical looping gasification of eucalyptus using NiFe(2)O(4)as an oxygen carrier. Torrefaction of eucalyptus was conducted in a fixed bed reactor with varying torrefaction temperatures and residence times. The chemical looping gasification of torrefied eucalyptus and its derived char using NiFe2O4 as an oxygen carrier was systematically investigated by thermogravimetric analysis-mass spectrometry and analytical pyrolysis-gas chromatography/mass spectrometry. The results showed that torrefaction of eucalyptus can improve its char reactivity and reduce tar formation during chemical looping gasification. In addition, the optimal torrefaction severity of eucalyptus for chemical looping gasification was 280 degrees C with a residence time of 40 min. Furthermore, the chemical looping gasification of eucalyptus torrefied at 280 degrees C with a varying mass ratio of NiFe2O4 to feedstock was carried out in a fixed bed reactor to verify the possibility of obtaining clean syngas. The results demonstrated that the optimal mass ratio of NiFe2O4 to feedstock for chemical looping gasification of torrefied eucalyptus was 1.25. Chemical looping gasification of torrefied eucalyptus at this condition can achieve the highest total gas yield of 1.05 Nm(3)/kg and the lowest tar content of 3.5 g/Nm(3). These findings provide a novel and efficient method to obtain clean syngas production with low tar content from biomass

Comprehensive Utilization of Hemicellulose and Cellulose To Release Fermentable Sugars from Corncobs via Acid Hydrolysis and Fast Pyrolysis

Conversion of lignocellulose to sugars suitable for microbial fermentation is an outstanding obstacle in developing biorefinery. Both hemicellulose and cellulose fractions are polymers of sugars and thereby primary candidates for fermentable sugars production. In this study, the flexibility of an integrated biomass conversion process was offered. The hemicellulose of corncobs was utilized to release fermentable sugars by sulfuric acid hydrolysis first. The remaining solid residue from acid hydrolysis, containing a lot of cellulose, was further used to produce levoglucosan by fast pyrolysis. This process appeared to present several advantages: (i) Almost all of hemicellulose (99.7%) was hydrolyzed, and the yield of xylan was achieved 86.1%. (ii) The alkali and alkaline earth metals, which had negative catalytic influence on levoglucosan formation, were nearly and completely (93.7%) removed by acid pretreatment. (iii) A preferential degradation of hemicellulose and amorphous cellulose during acid hydrolysis resulted in accumulation of crystalline cellulose of acid-pretreated biomass, which was favorable for levoglucosan production. (iv) The yield of levoglucosan increased by 450.0% for acid-pretreated corncobs (37.4%) compared with that of raw material (6.8%). The effectiveness to enhance levoglucosan yields ranged as high as 63.4%. Further increase in sulfuric acid concentration (0-10%) and temperature (30-120 degrees C) in acid pretreatment prior to fast pyrolysis could enhance levoglucosan formation. Consequently, this strategy, which utilized simple chemical regents to overcome biomass recalcitrance and liberate fermentable sugars while also remaining cost-effective, has the potential to underlie a biorefinery

Quantitative structure-reactivity relationships for pyrolysis and gasification of torrefied xylan

Hemicellulose is the most reactive component of biomass during torrefaction. Torrefied hemicellulose will be one of the most significant factors determining the reactivity of torrefied biomass during subsequent pyrolysis and CO2 gasification. Xylan, as the representative for hemicellulose, was torrefied in a bench scale tubular reactor with varying torrefaction temperature and residence time. The results demonstrated that the pyrolysis and CO2 gasification reactivity of xylan and its derived char was evidently reduced by torrefaction. As torrefaction temperature increased from 200 to 280 degrees C, the comprehensive pyrolysis index (CPI) of xylan decreased evidently from 16.14 to 2.72 10(-4)%/(min.degrees C-2), while the average CO2 gasification reactivity of biochar derived from xylan decreased from 9.11 to 7.33 min(-1). These results could be attributed to that xylan proceeded devolatilization, polycondensation and carbonization reactions during torrefaction to form torrefied xylan with a condensed aromatic structure. The FIX or O/C ratio of torrefied xylan can be used as a structural indicator for quantitative evaluation of its torrefaction severity and resulting reactivity during pyrolysis and CO2 gasification. These findings can provide useful information for identifying the effect of torrefaction on structure alterations of hemicellulose and resulting reactivity during pyrolysis and CO2 gasification. (C) 2019 Elsevier Ltd. All rights reserved