The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and...The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.展开更多
Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal t...Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal treatment of Inner Mongolia lignite(IM)was carried out in a lab autoclave.The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy,and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy.The curve-fitting method was used to calculate the content of the functional groups quantitatively.The results show that hydrothermal treatment is an effective method for upgrading the lignite.The side chains of the aromatic ring in lignite are altered,while the main macromolecular structure remains nearly the same.The hydrothermal treatment of IM could be divided into three temperature-dependent stages.The first stage(<493 K)is the decomposition reaction of oxygen functional groups,where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K.In the second stage(493–533 K),hydrolysis of functional groups and hydrogen transfer between water and lignite occur.Here,the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533,and the content of quinone generates from the condensation of free phenol increased.The third stage(>533 K)involves breakage of the covalent bond,and the content of CH4 and CO in the emission gas clearly increase.展开更多
MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference(EMI)shielding materials.However,the deficiencies in strength and stability of MXene-contained paper impede its pract...MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference(EMI)shielding materials.However,the deficiencies in strength and stability of MXene-contained paper impede its practical applications.Herein,a composite paper was proposed to address the problems,in which a filter paper was modified with a three-layer structured surface via a facile layer-by-layer coating procedure.Specifically,the TEMPO-oxidized cellulose nanofibers(TOCN)/cationic starch(CS)/MXene gel layer and TOCN/MXene nacre structure layer ensured the good EMI shielding and mechanical performances of the composite paper,while the uppermost TOCN/CS hydrogel film layer mainly protected MXene.The composite paper achieved an EMI SE of 40.3 dB at a thickness of merely 0.1894 mm(SE/t value of ca.212.8 dB mm^(−1),SSE/t values of ca.13216 dB cm 2 g^(−1))and the total MXene dosage was 20 g m^(−2).Its tensile strength could be up to 11.7 MPa while the original filter paper was 6.4 MPa.Four pieces of this composite papers could be easily packed together to attain an EMI SE of nearly 70 dB.Importantly,the hydrogel film layer efficiently protected the MXene and maintained the EMI shielding performance of the composite paper when immersed in different liquids including water,HCl(1 M)and ethanol,due to the dense and compact structure of hydrogel film layer.This work provides a practical way to develop ultrathin,flexible and durable EMI shielding materials.展开更多
The reuse of biomass wastes is crucial toward today’s energy and environmental crisis,among which,biomass-based biochar as catalysts for biofuel and high value chemical production is one of the most clean and economi...The reuse of biomass wastes is crucial toward today’s energy and environmental crisis,among which,biomass-based biochar as catalysts for biofuel and high value chemical production is one of the most clean and economical solutions.In this paper,the recent advances in biofuels and high chemicals for selective production based on biochar catalysts from different biomass wastes are critically summarized.The topics mainly include the modification of biochar catalysts,the preparation of energy products,and the mechanisms of other high-value products.Suitable biochar catalysts can enhance the yield of biofuels and higher-value chemicals.Especially,the feedstock and reaction conditions of biochar catalyst,which affect the efficiency of energy products,have been the focus of recent attentions.Mechanism studies based on biochar catalysts will be helpful to the controlled products.Therefore,the design and advancement of the biochar catalyst based on mechanism research will be beneficial to increase biofuels and the conversion efficiency of chemicals into biomass.The advanced design of biochar catalysts and optimization of operational conditions based on the biomass properties are vital for the selective production of high-value chemicals and biofuels.This paper identifies the latest preparation for energy products and other high-value chemicals based on biochar catalysts progresses and offers insights into improving the yield of high selectivity for products as well as the high recyclability and low toxicity to the environment in future applications.展开更多
基金Financial support by Dual Initiative Project of Jiangsu Province and Changzhou University is gratefully acknowledgedSample analysis supported by Analysis and Testing Center,NERC Biomass of Changzhou University was also greatly acknowledged.
文摘The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.
基金This study was funded by National Key Basic Research Development Program of China(973Program,No.2011CB201304)Natural Science Foundation of China(51906021 and 51703014)+5 种基金National Key R&D Program of China(2018YFC1901203)Research Foundation for Advanced Talents of Jiangsu University(16JDG022)Changzhou University(ZMF17020034)Natural Science Foundation of Colleges in Jiangsu Province(19KJB480005)Changzhou Applied Basic Research Plan(CJ20190081)Science and Technology Project of Guangdong Province,PR China(No.2016A010105017)and(No.2017B040404009).
文摘Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal treatment of Inner Mongolia lignite(IM)was carried out in a lab autoclave.The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy,and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy.The curve-fitting method was used to calculate the content of the functional groups quantitatively.The results show that hydrothermal treatment is an effective method for upgrading the lignite.The side chains of the aromatic ring in lignite are altered,while the main macromolecular structure remains nearly the same.The hydrothermal treatment of IM could be divided into three temperature-dependent stages.The first stage(<493 K)is the decomposition reaction of oxygen functional groups,where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K.In the second stage(493–533 K),hydrolysis of functional groups and hydrogen transfer between water and lignite occur.Here,the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533,and the content of quinone generates from the condensation of free phenol increased.The third stage(>533 K)involves breakage of the covalent bond,and the content of CH4 and CO in the emission gas clearly increase.
基金supported by the National Natural Science Foundation of China(Nos.22178208,31901265,22078189)Special Support Program for High Level Talents of Shaanxi Provincethe Postdoctoral Science Foundation of Zhejiang Province.
文摘MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference(EMI)shielding materials.However,the deficiencies in strength and stability of MXene-contained paper impede its practical applications.Herein,a composite paper was proposed to address the problems,in which a filter paper was modified with a three-layer structured surface via a facile layer-by-layer coating procedure.Specifically,the TEMPO-oxidized cellulose nanofibers(TOCN)/cationic starch(CS)/MXene gel layer and TOCN/MXene nacre structure layer ensured the good EMI shielding and mechanical performances of the composite paper,while the uppermost TOCN/CS hydrogel film layer mainly protected MXene.The composite paper achieved an EMI SE of 40.3 dB at a thickness of merely 0.1894 mm(SE/t value of ca.212.8 dB mm^(−1),SSE/t values of ca.13216 dB cm 2 g^(−1))and the total MXene dosage was 20 g m^(−2).Its tensile strength could be up to 11.7 MPa while the original filter paper was 6.4 MPa.Four pieces of this composite papers could be easily packed together to attain an EMI SE of nearly 70 dB.Importantly,the hydrogel film layer efficiently protected the MXene and maintained the EMI shielding performance of the composite paper when immersed in different liquids including water,HCl(1 M)and ethanol,due to the dense and compact structure of hydrogel film layer.This work provides a practical way to develop ultrathin,flexible and durable EMI shielding materials.
基金supported by the National Natural Science Foundation of China(Grant No.52100185)the Natural Science Foundation of Hunan Province(Grant No.2021JJ40282)+2 种基金the Training Program for Excellent Young Innovators of Changsha(kq2106087,kq2106088)the Science and Technology Innovation Program of Hunan Province(2021RC2100,2021SK2040,2019SK2191)the National Key R&D Program of China(No.2018YFC1901203).
文摘The reuse of biomass wastes is crucial toward today’s energy and environmental crisis,among which,biomass-based biochar as catalysts for biofuel and high value chemical production is one of the most clean and economical solutions.In this paper,the recent advances in biofuels and high chemicals for selective production based on biochar catalysts from different biomass wastes are critically summarized.The topics mainly include the modification of biochar catalysts,the preparation of energy products,and the mechanisms of other high-value products.Suitable biochar catalysts can enhance the yield of biofuels and higher-value chemicals.Especially,the feedstock and reaction conditions of biochar catalyst,which affect the efficiency of energy products,have been the focus of recent attentions.Mechanism studies based on biochar catalysts will be helpful to the controlled products.Therefore,the design and advancement of the biochar catalyst based on mechanism research will be beneficial to increase biofuels and the conversion efficiency of chemicals into biomass.The advanced design of biochar catalysts and optimization of operational conditions based on the biomass properties are vital for the selective production of high-value chemicals and biofuels.This paper identifies the latest preparation for energy products and other high-value chemicals based on biochar catalysts progresses and offers insights into improving the yield of high selectivity for products as well as the high recyclability and low toxicity to the environment in future applications.
