Porous silica nano-flowers(KCC-1)immobilized Pt-Pd alloy NPs(Pt-Pd/KCC-1)with different mass ratios of Pd and Pt were successfully prepared by a facile in situ one-step reduction,using hydrazinium hydroxide as a reduc...Porous silica nano-flowers(KCC-1)immobilized Pt-Pd alloy NPs(Pt-Pd/KCC-1)with different mass ratios of Pd and Pt were successfully prepared by a facile in situ one-step reduction,using hydrazinium hydroxide as a reducing agent.The as-synthesized silica nanospheres possess radial fibers with a distance of 15 nm,exhibiting a high specific surface area(443.56 m^(2)·g^(-1)).Meanwhile,the obtained Pt-Pd alloy NPs are uniformly dispersed on the silica surface with a metallic particle size of 4-6 nm,which exist as metallic Pd and Pt on the surface of monodisperse KCC-1,showing the transfer of electrons from Pd to Pt.The as-synthesized 2.5%Pt-2.5%Pd/KCC-1 exhibited excellent catalytic activity and stability for the continuous dehydrogenation of 2-methoxycyclohexanol to prepare guaiacol.Compared with Pt or Pd single metal supported catalysts,the obtained 2.5%Pt-2.5%Pd/KCC-1 shows 97.2%conversion rate of 2-methoxycyclohexanol and 76.8%selectivity for guaiacol,which attributed to the significant synergistic effect of bimetallic Pt-Pd alloy NPs.Furthermore,turn over frequency value of the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs achieved 4.36 s^(-1),showing higher catalytic efficiency than other two monometallic catalysts.Reaction pathways of dehydro-aromatization of 2-methoxycyclohexanol over the obtained catalyst are proposed.Consequently,the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs prove their potential in the dehydrogenation of 2-methoxycyclohexanol,while the kinetics and mechanistic study of the dehydrogenation reaction over the catalyst in a continuous fixed-bed reactor may provide valuable information for the development of green,outstanding and powerful synthetic pathway of guaiacol.展开更多
Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl ha...Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl halides in an artificial seawater system using guaiacol as a precursor through laboratory simulation experiments.The influences of various environmental factors,including illumination time,radiation wavebands,illumination intensity,concentrations of guaiacol and halide ions(X^(-)),Fe^(3+),salinity,dissolved oxygen(DO),and pH value on the photochemical production of methyl halides were examined.We demonstrated that increased illumination intensity and duration promote the photochemical production of methyl halides,with a notable enhancement under UV-B radiation.Guaiacol and halide ions were identified as key precursors,and their high concentrations facilitated the formation of methyl halides.Additionally,different types of halide ions exhibited a competitive relationship in producing methyl halides.The study found that an increase in pH inhibited the photochemical formation of CH_(3)I due to the reaction between OH^(-)and·CH_(3).Dissolved oxygen was found to inhibit the photochemical formation of CH3I while promoting the formation of CH_(3)Cl.Conversely,an appropriate concentration of Fe^(3+)enhanced the photochemical production of methyl halides.Field observations indicated a high photochemical production of methyl halides in the natural waters near Qingdao’s coastal area,likely due to the high concentration of dissolved organic matter(DOM),which supports photochemical reactions.Furthermore,the photochemical production of methyl halides in natural seawater was significantly higher than in dark conditions,underscoring the importance of illumination in promoting these photochemical processes in seawater.展开更多
Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio（H/Ceff factor） in bio-oil,and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided ...Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio（H/Ceff factor） in bio-oil,and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition,reaction temperature,and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts,Ni Co/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/Cefffactor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed.Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.展开更多
Hydrodeoxygenation(HDO)of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance.However,developing new catalysts with high activity and excellent stability in ...Hydrodeoxygenation(HDO)of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance.However,developing new catalysts with high activity and excellent stability in an aqueous phase faces considerable challenges.Rare earth doping can effectively regulate the water exchange rate constant(WERC)value of the catalyst and play an important role in promoting the hydrolysis of ether bonds.Therefore,in this paper the bimetallic supported catalyst Ni-La_(2)O_(3)/H-ZSM-5 doped with rare earth metal La_(2)O_(3)was prepared,and used to catalyze the conversion of the lignin model co mpound guaiacol to cyclohexanol in the aqueous phase.The co nversion of guaiacol catalyzed by 10Ni-3La_(2)O_(3)/H-ZSM-5 reaches 100%,and the selectivity of the product cyclohexanol is 85%.A series of characterizations illustrate that the doping of La_(2)O_(3)causes the electron transfer between La_(2)O_(3)-Ni and changes the distribution of Ni,and a strong metal carrier interaction occurs between the bimetallic Ni-La_(2)O_(3)and H-ZSM-5.This can effectively promote the hydrolysis of the C-O ether bond in guaiacol and significantly improve the activity of the catalyst.The possible catalytic reaction mechanism of Ni-La_(2)O_(3)/H-ZSM-5 catalytic conversion of guaiacol was proposed.展开更多
We conducted a preliminarily study on the effects of dietary guaiacol on growth performance of abalone, Haliotis discus hannai Ino. Seven semi-purified diets were formulated with graded levels of guaiacol （0, 5, 10, ...We conducted a preliminarily study on the effects of dietary guaiacol on growth performance of abalone, Haliotis discus hannai Ino. Seven semi-purified diets were formulated with graded levels of guaiacol （0, 5, 10, 50, 100, 500, and 1 000 mg kgl）. Abalone （initial weight： 0.29 ± 0.01 g; initial shell length： 8.55 ± 0.27 mm） were fed with these diets in a re-circulated water system for 152 days. Guaiacol significantly improved the specific growth rate （SGR） （P〈0.05）; excessive dietary guaiacol （1 000 mg kg1） led to significantly high mortality （P〈0.05）, and lipid content in the soft body increased significantly after dietary guaiacol （P〈0.05）. Activities of catalase and phenoloxidase （PO） in the viscera were significantly stimulated by dietary guaiacol （P〈0.05）. Broken-line analysis based on SGR indicated that the minimum dietary guaiacol for the optimal growth of juvenile abalone is 15.43 mg ·kg^-1.展开更多
"H_(2)-free" HDO is a revolutionary route to circumvent the limitations of H_(2)-fed HDO reactors for biomass upgrading.This work demonstrates the viability of this economically appealing route when an adequ..."H_(2)-free" HDO is a revolutionary route to circumvent the limitations of H_(2)-fed HDO reactors for biomass upgrading.This work demonstrates the viability of this economically appealing route when an adequate catalyst is implemented.Herein,we have developed a new family of Pt catalysts supported on N-doped activated carbons for the H_(2)-free HDO process of guaiacol.Several N-donors have been used to tune the catalyst’s structural and electronic properties.As a general trend,the N-promoted samples are more selective towards oxygen-depleted products.The best performing material,namely Pt/PANI-AC reached outstanding guaiacol conversion values-ca.75% at 300℃ while displaying reasonable stability for multiple recycling operations.The advanced performance is ascribed to the modified electronic and acid-base properties which favor guaiacol activation and C-O cleavage,as well as the excellent dispersion of the Pt nano particles.展开更多
The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temp...The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temperature. Two kinds of group contribution models were used to estimate the molar heat capacities of both guaiacol and AGE, the average relative deviation is less than 10%. The standard molar enthalpies of combustion of guaiacol and AGE were- 3590.0 k J·mol^(-1)and- 4522.1 k J·mol^(-1) by a precise thermal isolation Oxygen Bomb Calorimeter. The standard molar enthalpies of formation of guaiacol and AGE in a liquid state at298.15 K were calculated to be- 307.95 k J·mol^(-1) and- 448.72 k J·mol^(-1), respectively, based on the standard molar enthalpies of combustion. The thermodynamic properties are useful for exploiting the new synthesis method, engineering design and industry production of AGE using guaiacol as a raw material.展开更多
Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydr...Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly manner.This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar.Highly selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic activity.Various characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and supports.This synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.展开更多
The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surfac...The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surface would lead to unexpected chemoselectivity toward important and challenging reactions.In this work,we have proposed and validated unique Ni-O-Ce-O_(v)enriched Ni/CeO_(2)catalysts prepared by a deposition-precipitation method,for the transfer hydrogenation of lignin-derived guaiacol toward cyclohexanol rather than benzene derivatives.The counter-intuitively designed high Ni loading Ni_(2)0/CeO_(2)catalyst(20 wt%Ni content)displays a distance of 0.5 nm for Ni/O_(v)pairs with a remarkable activity(TOF:166.5 h^(-1))and 90%+selectivity for C_(Ar)=C_(Ar)bond saturation,outperforming better metal-dispersed Ni_(5)/CeO_(2)catalyst with limited presence of Ni-O-Ce-O_(v)sites.The high hydrogenation activity against hydrogenolysis reactions on Ni_(2)0/CeO_(2)catalyst is attributed to tunable Ni/O_(v)distances,which constrain the cleavage of CAr-OH bond and deep deoxygenation.Such spatial distribution effect has also facilitated tandem dehydrogenation(O-H bond cleavage)and hydrogenation(C_(Ar)=C_(Ar)hydrogenation)reactions,leading to cyclohexanol as the target product in the absence of externally added H_(2).Insights into spatial distribution of O_(v)sites open an alternative perspective in designing efficient catalysts toward producing value-added cyclic oxygenates through upgrading of lignin compounds.展开更多
The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrar...The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes.展开更多
Abstract Catalysts Pt/TiO2 and NiMo/Al2O3 are highly active and selective for the hydrodeoxygenation of guaiacol in a fixed bed reactor at 300℃ and 7.1 MPa, leading to the hydrogenation of aromatic ring, followed by ...Abstract Catalysts Pt/TiO2 and NiMo/Al2O3 are highly active and selective for the hydrodeoxygenation of guaiacol in a fixed bed reactor at 300℃ and 7.1 MPa, leading to the hydrogenation of aromatic ring, followed by demethylation and dehydroxylation to produce cyclohexane. For a complete hydrodeoxygenation of guaiacol, metal sites and acid sites are required. NiMo/Al2O3 and Pt/ Al2O3 are more active and selective for cyclohexane formation as compared with Pt/TiO2 at 285 Al2O3 and 4 MPa. However, Pt/TiO2 is stable while the other two catalysts deactivate due to the nature and amount of coke formation during the reaction.展开更多
Lignin is generated as a waste biomass from pulp and paper industry.The majority of kraft lignin is currently combusted as a low-grade energy source.Lignin valorization has been considered a feasible option to sustain...Lignin is generated as a waste biomass from pulp and paper industry.The majority of kraft lignin is currently combusted as a low-grade energy source.Lignin valorization has been considered a feasible option to sustainable production of chemicals and liquid fuels in the long run.This study reports a novel thermolysis process that selectively converts black liquor lignin into guaiacol and its derivatives in highboiling-point hydrocarbon solvents:n-hexadecane(n-H)and 1-methyl naphthalene(1-MN).The operating pressure for lignin thermolysis in n-H and 1-MN is much lower than those in lignin liquefaction with low-boiling-point solvents,such as water,methanol,and ethanol.1-MN performed better than n-H in terms of lignin conversion and liquid yield.The liquid products were 56 wt%and 24 wt%for 1-MN and n-H as solvent respectively.Reaction temperature and reaction time rotating were investigated.Low temperature and short reaction time are favorable for generating Guaiacol.Compared to 1-MN as solvent,n-H promotes the production of guaiacol.The reaction mechanisms of lignin depolymerization to chemicals in different solvents were proposed.Solvent chemical properties and H abstraction processes from solvents play a key role in the selectivity of guaiacol.展开更多
基金supported by Natural Science Foundation of Henan Province of China(162300410253)the Open Research Fund of State Key Laboratory of Coking Coal Exploitation and Comprehensive Utilization,China Pingmei Shen-ma Group(41040220181107-8).
文摘Porous silica nano-flowers(KCC-1)immobilized Pt-Pd alloy NPs(Pt-Pd/KCC-1)with different mass ratios of Pd and Pt were successfully prepared by a facile in situ one-step reduction,using hydrazinium hydroxide as a reducing agent.The as-synthesized silica nanospheres possess radial fibers with a distance of 15 nm,exhibiting a high specific surface area(443.56 m^(2)·g^(-1)).Meanwhile,the obtained Pt-Pd alloy NPs are uniformly dispersed on the silica surface with a metallic particle size of 4-6 nm,which exist as metallic Pd and Pt on the surface of monodisperse KCC-1,showing the transfer of electrons from Pd to Pt.The as-synthesized 2.5%Pt-2.5%Pd/KCC-1 exhibited excellent catalytic activity and stability for the continuous dehydrogenation of 2-methoxycyclohexanol to prepare guaiacol.Compared with Pt or Pd single metal supported catalysts,the obtained 2.5%Pt-2.5%Pd/KCC-1 shows 97.2%conversion rate of 2-methoxycyclohexanol and 76.8%selectivity for guaiacol,which attributed to the significant synergistic effect of bimetallic Pt-Pd alloy NPs.Furthermore,turn over frequency value of the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs achieved 4.36 s^(-1),showing higher catalytic efficiency than other two monometallic catalysts.Reaction pathways of dehydro-aromatization of 2-methoxycyclohexanol over the obtained catalyst are proposed.Consequently,the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs prove their potential in the dehydrogenation of 2-methoxycyclohexanol,while the kinetics and mechanistic study of the dehydrogenation reaction over the catalyst in a continuous fixed-bed reactor may provide valuable information for the development of green,outstanding and powerful synthetic pathway of guaiacol.
基金funded by the Natural Science Foundation of Shandong Province,China(No.ZR2021MD034)the National Natural Science Foundation of China(No.42276039).
文摘Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl halides in an artificial seawater system using guaiacol as a precursor through laboratory simulation experiments.The influences of various environmental factors,including illumination time,radiation wavebands,illumination intensity,concentrations of guaiacol and halide ions(X^(-)),Fe^(3+),salinity,dissolved oxygen(DO),and pH value on the photochemical production of methyl halides were examined.We demonstrated that increased illumination intensity and duration promote the photochemical production of methyl halides,with a notable enhancement under UV-B radiation.Guaiacol and halide ions were identified as key precursors,and their high concentrations facilitated the formation of methyl halides.Additionally,different types of halide ions exhibited a competitive relationship in producing methyl halides.The study found that an increase in pH inhibited the photochemical formation of CH_(3)I due to the reaction between OH^(-)and·CH_(3).Dissolved oxygen was found to inhibit the photochemical formation of CH3I while promoting the formation of CH_(3)Cl.Conversely,an appropriate concentration of Fe^(3+)enhanced the photochemical production of methyl halides.Field observations indicated a high photochemical production of methyl halides in the natural waters near Qingdao’s coastal area,likely due to the high concentration of dissolved organic matter(DOM),which supports photochemical reactions.Furthermore,the photochemical production of methyl halides in natural seawater was significantly higher than in dark conditions,underscoring the importance of illumination in promoting these photochemical processes in seawater.
基金support from the National Hi-tech Research and Development Program of China (863 Program) (2012AA051801)the Fundamental Research Funds for the Central Universities (No.CXZZ13_0112)the Scientific Research Foundation of Graduate School of Southeast University (YBPY1408)
文摘Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio（H/Ceff factor） in bio-oil,and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition,reaction temperature,and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts,Ni Co/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/Cefffactor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed.Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.
基金Project supported by National Natural Science Foundation of China(21868026,22006079)the National First-class Discipline Construction Projectthe Project of Ningxia Key R&D Plan(2020BEB04009)。
文摘Hydrodeoxygenation(HDO)of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance.However,developing new catalysts with high activity and excellent stability in an aqueous phase faces considerable challenges.Rare earth doping can effectively regulate the water exchange rate constant(WERC)value of the catalyst and play an important role in promoting the hydrolysis of ether bonds.Therefore,in this paper the bimetallic supported catalyst Ni-La_(2)O_(3)/H-ZSM-5 doped with rare earth metal La_(2)O_(3)was prepared,and used to catalyze the conversion of the lignin model co mpound guaiacol to cyclohexanol in the aqueous phase.The co nversion of guaiacol catalyzed by 10Ni-3La_(2)O_(3)/H-ZSM-5 reaches 100%,and the selectivity of the product cyclohexanol is 85%.A series of characterizations illustrate that the doping of La_(2)O_(3)causes the electron transfer between La_(2)O_(3)-Ni and changes the distribution of Ni,and a strong metal carrier interaction occurs between the bimetallic Ni-La_(2)O_(3)and H-ZSM-5.This can effectively promote the hydrolysis of the C-O ether bond in guaiacol and significantly improve the activity of the catalyst.The possible catalytic reaction mechanism of Ni-La_(2)O_(3)/H-ZSM-5 catalytic conversion of guaiacol was proposed.
基金Supported by the Program for New Century Excellent Talents in University (NCET) (No.NCET-07-0785)
文摘We conducted a preliminarily study on the effects of dietary guaiacol on growth performance of abalone, Haliotis discus hannai Ino. Seven semi-purified diets were formulated with graded levels of guaiacol （0, 5, 10, 50, 100, 500, and 1 000 mg kgl）. Abalone （initial weight： 0.29 ± 0.01 g; initial shell length： 8.55 ± 0.27 mm） were fed with these diets in a re-circulated water system for 152 days. Guaiacol significantly improved the specific growth rate （SGR） （P〈0.05）; excessive dietary guaiacol （1 000 mg kg1） led to significantly high mortality （P〈0.05）, and lipid content in the soft body increased significantly after dietary guaiacol （P〈0.05）. Activities of catalase and phenoloxidase （PO） in the viscera were significantly stimulated by dietary guaiacol （P〈0.05）. Broken-line analysis based on SGR indicated that the minimum dietary guaiacol for the optimal growth of juvenile abalone is 15.43 mg ·kg^-1.
基金provided by the Department of Chemical and Process Engineering at the University of Surrey and the EPSRC grant EP/R512904/1the Royal Society Research Grant RSGR1180353financial support from Ministerio de Economía,Industria y Competitividad(Spain)through project MAT2016-80285-P。
文摘"H_(2)-free" HDO is a revolutionary route to circumvent the limitations of H_(2)-fed HDO reactors for biomass upgrading.This work demonstrates the viability of this economically appealing route when an adequate catalyst is implemented.Herein,we have developed a new family of Pt catalysts supported on N-doped activated carbons for the H_(2)-free HDO process of guaiacol.Several N-donors have been used to tune the catalyst’s structural and electronic properties.As a general trend,the N-promoted samples are more selective towards oxygen-depleted products.The best performing material,namely Pt/PANI-AC reached outstanding guaiacol conversion values-ca.75% at 300℃ while displaying reasonable stability for multiple recycling operations.The advanced performance is ascribed to the modified electronic and acid-base properties which favor guaiacol activation and C-O cleavage,as well as the excellent dispersion of the Pt nano particles.
文摘The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temperature. Two kinds of group contribution models were used to estimate the molar heat capacities of both guaiacol and AGE, the average relative deviation is less than 10%. The standard molar enthalpies of combustion of guaiacol and AGE were- 3590.0 k J·mol^(-1)and- 4522.1 k J·mol^(-1) by a precise thermal isolation Oxygen Bomb Calorimeter. The standard molar enthalpies of formation of guaiacol and AGE in a liquid state at298.15 K were calculated to be- 307.95 k J·mol^(-1) and- 448.72 k J·mol^(-1), respectively, based on the standard molar enthalpies of combustion. The thermodynamic properties are useful for exploiting the new synthesis method, engineering design and industry production of AGE using guaiacol as a raw material.
基金The financial support from the National Natural Science Foundation of China(Grant No.52276202)the National Key R&D Program of China(Grant No.2020YFC1910100)+4 种基金the Tsinghua University-Shanxi Clean Energy Research Institute Innovation Project Seed FundHuaneng Group Science and Technology Research Project(Grant No.KTHT-U22YYJC12)the International Joint Mission On Climate Change and Carbon NeutralityTsinghua-Toyota Joint Research Fundand State Key Laboratory of Chemical Engineering(Grant No.SKL-ChE-22A03)are gratefully acknowledged.
文摘Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly manner.This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar.Highly selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic activity.Various characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and supports.This synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.
基金supported by the National Natural Science Foundation of China(22078365,22478437)the Natural Science Foundation of Shandong Province(ZR2023MB076)。
文摘The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surface would lead to unexpected chemoselectivity toward important and challenging reactions.In this work,we have proposed and validated unique Ni-O-Ce-O_(v)enriched Ni/CeO_(2)catalysts prepared by a deposition-precipitation method,for the transfer hydrogenation of lignin-derived guaiacol toward cyclohexanol rather than benzene derivatives.The counter-intuitively designed high Ni loading Ni_(2)0/CeO_(2)catalyst(20 wt%Ni content)displays a distance of 0.5 nm for Ni/O_(v)pairs with a remarkable activity(TOF:166.5 h^(-1))and 90%+selectivity for C_(Ar)=C_(Ar)bond saturation,outperforming better metal-dispersed Ni_(5)/CeO_(2)catalyst with limited presence of Ni-O-Ce-O_(v)sites.The high hydrogenation activity against hydrogenolysis reactions on Ni_(2)0/CeO_(2)catalyst is attributed to tunable Ni/O_(v)distances,which constrain the cleavage of CAr-OH bond and deep deoxygenation.Such spatial distribution effect has also facilitated tandem dehydrogenation(O-H bond cleavage)and hydrogenation(C_(Ar)=C_(Ar)hydrogenation)reactions,leading to cyclohexanol as the target product in the absence of externally added H_(2).Insights into spatial distribution of O_(v)sites open an alternative perspective in designing efficient catalysts toward producing value-added cyclic oxygenates through upgrading of lignin compounds.
文摘The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes.
文摘Abstract Catalysts Pt/TiO2 and NiMo/Al2O3 are highly active and selective for the hydrodeoxygenation of guaiacol in a fixed bed reactor at 300℃ and 7.1 MPa, leading to the hydrogenation of aromatic ring, followed by demethylation and dehydroxylation to produce cyclohexane. For a complete hydrodeoxygenation of guaiacol, metal sites and acid sites are required. NiMo/Al2O3 and Pt/ Al2O3 are more active and selective for cyclohexane formation as compared with Pt/TiO2 at 285 Al2O3 and 4 MPa. However, Pt/TiO2 is stable while the other two catalysts deactivate due to the nature and amount of coke formation during the reaction.
文摘Lignin is generated as a waste biomass from pulp and paper industry.The majority of kraft lignin is currently combusted as a low-grade energy source.Lignin valorization has been considered a feasible option to sustainable production of chemicals and liquid fuels in the long run.This study reports a novel thermolysis process that selectively converts black liquor lignin into guaiacol and its derivatives in highboiling-point hydrocarbon solvents:n-hexadecane(n-H)and 1-methyl naphthalene(1-MN).The operating pressure for lignin thermolysis in n-H and 1-MN is much lower than those in lignin liquefaction with low-boiling-point solvents,such as water,methanol,and ethanol.1-MN performed better than n-H in terms of lignin conversion and liquid yield.The liquid products were 56 wt%and 24 wt%for 1-MN and n-H as solvent respectively.Reaction temperature and reaction time rotating were investigated.Low temperature and short reaction time are favorable for generating Guaiacol.Compared to 1-MN as solvent,n-H promotes the production of guaiacol.The reaction mechanisms of lignin depolymerization to chemicals in different solvents were proposed.Solvent chemical properties and H abstraction processes from solvents play a key role in the selectivity of guaiacol.
