Aqueous phase reforming (APR) of biomass derived feedstock producing hydrogen was reviewed. The APR process was discussed based on different feedstock categories such as sugars, polyols and ethanol. The mechanism of A...Aqueous phase reforming (APR) of biomass derived feedstock producing hydrogen was reviewed. The APR process was discussed based on different feedstock categories such as sugars, polyols and ethanol. The mechanism of APR was analyzed referring to different structures of feedstock. The reaction pathways of APR were investigated. The usage of catalysts should be judged by feedstock on the requirement including C-C bond cleavage, water-gas shift (WGS) reaction, and catalyst maintenance. The prospects were concluded based on the recent works from bimetallic catalysts and high efficient supports. Examples of significant challenges of reducing catalyst cost and increasing catalyst stability have been discussed. The modification and utilization of alkane selectivity of APR processes for liquid fuel production was also investigated.展开更多
The study focus was an examination of the hydrothermal pretreatment method applied to the lignocellulosic substrate, represented by the prairie cord grass, and comparison between different conditions based on the yiel...The study focus was an examination of the hydrothermal pretreatment method applied to the lignocellulosic substrate, represented by the prairie cord grass, and comparison between different conditions based on the yield of glucose after enzymatic hydrolysis. The treatment did not involve any chemicals usage. Enzymatic hydrolysis was performed in order to examine the amount of glucose which was released from pretreated materials. The most efficient pretreatment conditions were at high temperature and relatively short reaction time (210°C and 10 min), after which the lignocellulose structure was the most available for enzymes actions which resulted in a pretreatment conversion rate of 97%. Temperature had a significant influence on glucose release during the hydrolysis, which was confirmed by the Michaelis-Menten and kinetic models. Kinetic models were used to fit the inhibitors and their conversion rates were related to temperature.展开更多
The effect of catalysts on the microwave pyrolysis of aspen pellets was studied.A range of chlorides,nitrates and metal-oxides were added at 2%of the aspen mass(air dry aspen pellet weight basis).Chlorides in particul...The effect of catalysts on the microwave pyrolysis of aspen pellets was studied.A range of chlorides,nitrates and metal-oxides were added at 2%of the aspen mass(air dry aspen pellet weight basis).Chlorides in particular were found to favor liquid yield,especially the yield of water phase residue.Average liquid yield with added chlorides was 41%mass of the total biomass input,compared to 35%mass without catalyst.Metal-oxides were found to favor pyrolysis heavy oil,and thus total oil yield,since the yield of light oils seemed to be fairly constant.Nitrates were found to favor pyrolysis gas production.Pure light oils and light oils blended with diesel were found to be a potential diesel fuel substitute.展开更多
This study investigated microwave pyrolysis of switchgrass with particle sizes from 0.5 mm to 4 mm and determined the effects of reaction temperature and time on the yields of bio-oil,syngas,and bio-char.A prediction ...This study investigated microwave pyrolysis of switchgrass with particle sizes from 0.5 mm to 4 mm and determined the effects of reaction temperature and time on the yields of bio-oil,syngas,and bio-char.A prediction model was satisfactorily developed to describe the bio-oil conversion yield as a function of reaction temperature and time.Second-order reaction kinetics was also developed to model the switchgrass pyrolysis.Switchgrass with different particle sizes was found to be similarly pyrolyzed by microwave heating.The research results indicated that thermochemical conversion reactions can take place rapidly in large-sized switchgrass by using microwave pyrolysis.GC-MS analysis indicates that the bio-oil contained a series of important and useful chemical compounds:phenols,aliphatic hydrocarbons,aromatic hydrocarbons,and furan derivatives.These chemical compounds evolved were related to the pyrolysis conditions.展开更多
Bio-oil from thermochemical conversion of biomass is a complex mixture of polar and non-polar compounds,and cannot be used directly as a combustion engine fuel due to its low heating value,high viscosity,chemical inst...Bio-oil from thermochemical conversion of biomass is a complex mixture of polar and non-polar compounds,and cannot be used directly as a combustion engine fuel due to its low heating value,high viscosity,chemical instability,and incomplete volatility.Mixed-solvent extraction was developed to fractionate bio-oils from microwave-assisted pyrolysis of corn stover to produce light oil(a mixture of light and inflammable fuel oil components from bio-oil)with low viscosity and low combustion residue,and high value chemicals.Different fractions from bio-oil were characterized using GC/MS and TG,and a major chemical(hydroxy-butanedioic acid diethyl ester)was separated.展开更多
Rice-glucose-lysine blend was extruded using a co-rotating twin-screw extruder.The effects of different extrusion conditions on the browning properties of extrudates were analyzed and compared using the CIE Lab system...Rice-glucose-lysine blend was extruded using a co-rotating twin-screw extruder.The effects of different extrusion conditions on the browning properties of extrudates were analyzed and compared using the CIE Lab system of measurement.Extrusion process variables included moisture content,screw speed,barrel temperature,and screw geometry.The influence of product temperature on the browning property of extrudates was significant(P<0.05).The color parameters were related to product temperature by a 4th degree polynomial(P<0.05).Hunter color scale values(L*,a*,b*,-L*a*/b*,Whiteness Index,and Yellowness Index)from extruded samples were analyzed to relate to extrusion process variables.Product temperature and browning properties were modeled and tested at various screw configurations and extrusion conditions.Product temperature and browning property models were verified using different screw geometries and other processing conditions with reasonable accuracy.展开更多
In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.C...In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.Clean fractionation solvent was used in different proportions of the constituents.Process efficiency was determined by lignin recovery,solvent composition,as well as time and temperature applied to each sequential process.Glucose yield during enzymatic hydrolysis and overall pretreatment were calculated.Optimal conditions(125℃,37 min,with the solvent composition of ester:ethanol:water=32.5:22.5:45)yielded a 20%lignin recovery,38%glucose yield during enzymatic hydrolysis and 26%xylose recovery in aqueous fraction.展开更多
A new kind of rigid polyurethane(PU)foam was synthesized from the oil phase of bio-oils from microwave-assisted pyrolysis of corn stover.The recipes for the PU foams consisted of polyol-rich bio-oils,water as blowing ...A new kind of rigid polyurethane(PU)foam was synthesized from the oil phase of bio-oils from microwave-assisted pyrolysis of corn stover.The recipes for the PU foams consisted of polyol-rich bio-oils,water as blowing agent,polyethylene glycol(PEG)as both polyol donor and plasticizer,diphenylmethane-4,4’-diisocyanate(polymeric MDI)as cross-linking agent,silicon-based surfactant,and tin-based catalyst.The mechanical properties of rigid foams were measured with universal testing machine(Instron4206).The effects of individual ingredients on the physical and mechanical properties of the foams were studied.It was found that water content,bio-oil content,and isocyanate dosage were important variables in making PU foams in terms of mechanical strength,density,and cellular structure Under optimal conditions,the compression strength of the prepared PU foams reached 1130 kPa with a density of 152.9 g/L.The results show that bio-oils are potential renewable polyol sources for making rigid PU foams.展开更多
Corn stover was liquefied using an industrial biodiesel glycerol as a liquefying agent at atmospheric pressure and low temperature.It was found that the liquefaction yield increased with increasing glycerol-to-corn st...Corn stover was liquefied using an industrial biodiesel glycerol as a liquefying agent at atmospheric pressure and low temperature.It was found that the liquefaction yield increased with increasing glycerol-to-corn stover ratios.Sulfuric acid,added as a catalyst,was found to improve liquefaction yield.The hydroxyl number,moisture content,acid number,pH value,viscosity,density,elemental composition,and higher heating value of the liquefied corn stover samples were determined.The liquefied corn stover showed a high hydroxyl number of 270-310 mg KOH/g.Fourier transform infrared spectroscopy(FTIR)results revealed the functional groups and confirmed the existence of the OH group in the liquefied corn stover,indicating that the liquefied corn stover is indeed a source of polyols and a potential chemical stock for the synthesis of polymers.展开更多
文摘Aqueous phase reforming (APR) of biomass derived feedstock producing hydrogen was reviewed. The APR process was discussed based on different feedstock categories such as sugars, polyols and ethanol. The mechanism of APR was analyzed referring to different structures of feedstock. The reaction pathways of APR were investigated. The usage of catalysts should be judged by feedstock on the requirement including C-C bond cleavage, water-gas shift (WGS) reaction, and catalyst maintenance. The prospects were concluded based on the recent works from bimetallic catalysts and high efficient supports. Examples of significant challenges of reducing catalyst cost and increasing catalyst stability have been discussed. The modification and utilization of alkane selectivity of APR processes for liquid fuel production was also investigated.
基金Department of Transport/Sun GrantUS Department of Agriculture/ Department of Energy+4 种基金Minnesota Legislative-Citizen Commission on Minnesota ResourcesMetropolitan Council Environmental ServicesUniversity of Minnesota MNDrive programsUniversity of Minnesota Center for BiorefiningChina Scholarship Council (CSC) for their financial support for this work
文摘The study focus was an examination of the hydrothermal pretreatment method applied to the lignocellulosic substrate, represented by the prairie cord grass, and comparison between different conditions based on the yield of glucose after enzymatic hydrolysis. The treatment did not involve any chemicals usage. Enzymatic hydrolysis was performed in order to examine the amount of glucose which was released from pretreated materials. The most efficient pretreatment conditions were at high temperature and relatively short reaction time (210°C and 10 min), after which the lignocellulose structure was the most available for enzymes actions which resulted in a pretreatment conversion rate of 97%. Temperature had a significant influence on glucose release during the hydrolysis, which was confirmed by the Michaelis-Menten and kinetic models. Kinetic models were used to fit the inhibitors and their conversion rates were related to temperature.
文摘The effect of catalysts on the microwave pyrolysis of aspen pellets was studied.A range of chlorides,nitrates and metal-oxides were added at 2%of the aspen mass(air dry aspen pellet weight basis).Chlorides in particular were found to favor liquid yield,especially the yield of water phase residue.Average liquid yield with added chlorides was 41%mass of the total biomass input,compared to 35%mass without catalyst.Metal-oxides were found to favor pyrolysis heavy oil,and thus total oil yield,since the yield of light oils seemed to be fairly constant.Nitrates were found to favor pyrolysis gas production.Pure light oils and light oils blended with diesel were found to be a potential diesel fuel substitute.
文摘This study investigated microwave pyrolysis of switchgrass with particle sizes from 0.5 mm to 4 mm and determined the effects of reaction temperature and time on the yields of bio-oil,syngas,and bio-char.A prediction model was satisfactorily developed to describe the bio-oil conversion yield as a function of reaction temperature and time.Second-order reaction kinetics was also developed to model the switchgrass pyrolysis.Switchgrass with different particle sizes was found to be similarly pyrolyzed by microwave heating.The research results indicated that thermochemical conversion reactions can take place rapidly in large-sized switchgrass by using microwave pyrolysis.GC-MS analysis indicates that the bio-oil contained a series of important and useful chemical compounds:phenols,aliphatic hydrocarbons,aromatic hydrocarbons,and furan derivatives.These chemical compounds evolved were related to the pyrolysis conditions.
基金supported by University of Minnesota IREE and Center for Biorefining and China Ministry of Education PCSIRT Program(IRT0540)Hubei Provincial Department of Education of China(No.Q200715004)Hubei Provincial Natural Science Foundation of China(No.2007ABA253).
文摘Bio-oil from thermochemical conversion of biomass is a complex mixture of polar and non-polar compounds,and cannot be used directly as a combustion engine fuel due to its low heating value,high viscosity,chemical instability,and incomplete volatility.Mixed-solvent extraction was developed to fractionate bio-oils from microwave-assisted pyrolysis of corn stover to produce light oil(a mixture of light and inflammable fuel oil components from bio-oil)with low viscosity and low combustion residue,and high value chemicals.Different fractions from bio-oil were characterized using GC/MS and TG,and a major chemical(hydroxy-butanedioic acid diethyl ester)was separated.
文摘Rice-glucose-lysine blend was extruded using a co-rotating twin-screw extruder.The effects of different extrusion conditions on the browning properties of extrudates were analyzed and compared using the CIE Lab system of measurement.Extrusion process variables included moisture content,screw speed,barrel temperature,and screw geometry.The influence of product temperature on the browning property of extrudates was significant(P<0.05).The color parameters were related to product temperature by a 4th degree polynomial(P<0.05).Hunter color scale values(L*,a*,b*,-L*a*/b*,Whiteness Index,and Yellowness Index)from extruded samples were analyzed to relate to extrusion process variables.Product temperature and browning properties were modeled and tested at various screw configurations and extrusion conditions.Product temperature and browning property models were verified using different screw geometries and other processing conditions with reasonable accuracy.
基金This work was supported by funding from the South Dakota Center for Bioprocessing Research and Development,Sun Grant Initiative and SDSU Agricultural Experiment Station.
文摘In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.Clean fractionation solvent was used in different proportions of the constituents.Process efficiency was determined by lignin recovery,solvent composition,as well as time and temperature applied to each sequential process.Glucose yield during enzymatic hydrolysis and overall pretreatment were calculated.Optimal conditions(125℃,37 min,with the solvent composition of ester:ethanol:water=32.5:22.5:45)yielded a 20%lignin recovery,38%glucose yield during enzymatic hydrolysis and 26%xylose recovery in aqueous fraction.
基金the Initiative for Renewable Energy and the Environment and Center for Biorefining at the University of Minnesota,Minnesota Environment and Natural Resources Trust Fund,US DOT/Sun Grant Initiative,and China Ministry of Education PCSIRT Program(IRT0540)。
文摘A new kind of rigid polyurethane(PU)foam was synthesized from the oil phase of bio-oils from microwave-assisted pyrolysis of corn stover.The recipes for the PU foams consisted of polyol-rich bio-oils,water as blowing agent,polyethylene glycol(PEG)as both polyol donor and plasticizer,diphenylmethane-4,4’-diisocyanate(polymeric MDI)as cross-linking agent,silicon-based surfactant,and tin-based catalyst.The mechanical properties of rigid foams were measured with universal testing machine(Instron4206).The effects of individual ingredients on the physical and mechanical properties of the foams were studied.It was found that water content,bio-oil content,and isocyanate dosage were important variables in making PU foams in terms of mechanical strength,density,and cellular structure Under optimal conditions,the compression strength of the prepared PU foams reached 1130 kPa with a density of 152.9 g/L.The results show that bio-oils are potential renewable polyol sources for making rigid PU foams.
基金This work was supported in part by grants from the Initiative for Renewable Energy and the Environment and Center for Biorefining at the University of Minnesota,Minnesota Environment and Natural Resources Trust Fund,US DOT/Sun Grant Initiative,DOE/USDA Joint Biomass Research Initiative,China Ministry of Education PCSIRT Program(IRT0540)Sate Key Laboratory of Food Science and Technology,Nanchang University(Project No.SKLF-TS-200814)for financial support.The authors also wish to thank AURI at Waseca,Minnesota for its generous support.
文摘Corn stover was liquefied using an industrial biodiesel glycerol as a liquefying agent at atmospheric pressure and low temperature.It was found that the liquefaction yield increased with increasing glycerol-to-corn stover ratios.Sulfuric acid,added as a catalyst,was found to improve liquefaction yield.The hydroxyl number,moisture content,acid number,pH value,viscosity,density,elemental composition,and higher heating value of the liquefied corn stover samples were determined.The liquefied corn stover showed a high hydroxyl number of 270-310 mg KOH/g.Fourier transform infrared spectroscopy(FTIR)results revealed the functional groups and confirmed the existence of the OH group in the liquefied corn stover,indicating that the liquefied corn stover is indeed a source of polyols and a potential chemical stock for the synthesis of polymers.
