Esterification of acrylic acid(AA) to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorptio...Esterification of acrylic acid(AA) to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate(ZS) loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20% (mass fraction) ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.展开更多
In this work, a series of SO4^2-/TiO2/γ-Al2O3 solid acid catalysts were synthesized by impregnation method, in which nano-TiO2 was prepared by sol–gel method, and then the nano-TiO2 sol was loaded on porous γ-Al2O3...In this work, a series of SO4^2-/TiO2/γ-Al2O3 solid acid catalysts were synthesized by impregnation method, in which nano-TiO2 was prepared by sol–gel method, and then the nano-TiO2 sol was loaded on porous γ-Al2O3 supporter through impregnation. The structure and property of catalyst were characterized by XRD, N2-BET,SEM, TEM, XPS, NH3-TPD, Pyridine-IR and FT-IR. In addition, the catalyst of chelate bidentate coordination acid center model was established. The catalytic performance test was carried out in the esterification of n-butyl alcohol with lauric acid and the catalyst showed excellent activity. The experimental results showed that the medium strength acid sites were more dominant active sites than the strong and weak acid sites for the rapid esterification reaction. Its kinetic behaviors and activation energy were studied for the esterification under the catalytic reaction condition.展开更多
A silica-supported zirconium based solid acid (ZS) has been used as catalyst for the Fries rearrangement of phenyl acetate (PA). The catalyst showed a higher PA conversion activity and a much higher selectivity for o...A silica-supported zirconium based solid acid (ZS) has been used as catalyst for the Fries rearrangement of phenyl acetate (PA). The catalyst showed a higher PA conversion activity and a much higher selectivity for o-hydroxyacetophenone (o-HAP) than for strongly acidic zeolite catalysts. The supported catalyst was characterized by XRD, IR, XPS, pyridine-TPD and the surface area measurements. The catalytic properties were influenced significantly by pretreatment temperature.展开更多
A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized...A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized with sidewall hydroxyl groups(SWCNTs–OH)and La^(3+) via sol–gel method.The freshly prepared catalyst was characterized by several methods,and the catalytic activity and stability of it were studied from the esterification of oleic acid and methanol.Results showed that the highest conversion of oleic acid was 93.1%(mass)and maintained as high as 88.7%(mass)after six cycles of La-PW-SiO_(2)/SWCNTs.The high catalytic activity and stability of La-PW-SiO_(2)/SWCNTs can be attributed to the strong electron withdrawing effect of La^(3+) on π bond of SWCNTs,because it can facilitate the formation of a large number of strong Lewis acid sites.Therefore,the reduction of catalytic activity of a solid acid catalyst due to the fact that hydration reaction of its Bronsted acid sites can be effectively reduced.La-PW-SiO_(2)/SWCNTs can be an efficient and economical catalyst,because it shows good catalytic activity and stability.展开更多
Antibiotic production wastewater usually contains high concentrations of antibiotic residues,which can cause instability and deterioration of biological wastewater treatment units and also domestication and proliferat...Antibiotic production wastewater usually contains high concentrations of antibiotic residues,which can cause instability and deterioration of biological wastewater treatment units and also domestication and proliferation of antibiotic-resistance bacteria.An effective pretreatment on antibiotics production wastewater is expected to selectively reduce the concentration of antibiotics and decrease the toxicity,rather than mitigate organic and other contaminants before further treatments.In this work,two polymer-based solid acids,PS-S and CPS-S bearing high concentrations of-SOH_(3)groups (up to 4.57 mmol/g),were prepared and successfully used for hydrolytic mitigation of 100 mg/L tylosin within 20 min.The co-existence of high concentrations of COD and humic substances did not affect the mitigation of tylosin obviously,while more than 500 mg/L of nitrogenous compounds suppressed the hydrolytic efficiency.Recycle and reuse experiments showed that the solid acids performed well in five cycles after regeneration.Three transformation products (P1,P2 and P3)were identified using UPLC-QTOF-MS/MS.Sugar moieties including mycarse,mycaminose,and mycinose detached and released simultaneously or in order from the 16-member lactone ring through desugarization,which led to a dramatic decrease in antibacterial activity as revealed by cytotoxicity evaluations using S.aureus.Ecotoxicity estimation indicated the acute toxicities of the hydrolyzed products to model species (e.g.,fish,daphnid and green algae) were classified as“not harmful”.This work suggested an effective and selective method to pretreat tylosin-contained production wastewater by using polymer-based solid acids.These results will shed light on effective elimination of antibiotics pollution from pharmaceutical industries through strengthening the pretreatments.展开更多
Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids.In this work,a series of novel sulfonic acid-functionalized core-shell Fe_(3)O_(4)@carbon microspher...Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids.In this work,a series of novel sulfonic acid-functionalized core-shell Fe_(3)O_(4)@carbon microspheres(Fe_(3)O_(4)@C-SO_(3)H)have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst.For the synthesis,core-shell Fe_(3)O_(4)@RF(resorcinol-formaldehyde)microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe_(3)O_(4)microspheres.After high-temperature carbonization,the microspheres were eventually treated by surface sulfonation,re sulting in Fe_(3)O_(4)@C-x-SO_(3)H(x stands for carbonization temperature)microspheres with abundant surface SO_(3)H groups.The obtained microspheres possess uniform core-shell structure,partially-graphitized carbon skeletons,superparamagnetic property,high magnetization saturation value of 10.6 emu/g,and rich SO_(3)H groups.The surface acid amounts can be adju sted in the range of 0.59-1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees.The magnetic Fe_(3)O_(4)@C-x-SO_(3)H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol,demonstrating high selectivity(97%)to benzaldehyde ethylene glycol acetal.More importantly,by applying an external magnetic field,the catalysts can be easily separated from the heterogeneous reaction solutions,which later show well preserved catalytic activity even after 9 cycles,revealing good recyclability and high stability.展开更多
Steam reforming(SR) of dimethyl ether(DME) was investigated for the production of hydrogen for fuel cells.The activity of a series of solid acids for DME hydrolysis was investigated.The solid acid catalysts were ZSM-5...Steam reforming(SR) of dimethyl ether(DME) was investigated for the production of hydrogen for fuel cells.The activity of a series of solid acids for DME hydrolysis was investigated.The solid acid catalysts were ZSM-5 [Si/Al = 25,38 and 50:denoted Z(Si/Al)] and acidic alumina(γ-Al2O3) with an acid strength order that was Z(25)>Z(38)>Z(50)>γ-Al2O3.Stronger acidity gave higher DME hydrolysis conversion.Physical mixtures containing a CuO-ZnO-Al2O3-ZrO2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR were used to examine the acidity effects on DME SR.DME SR activity strongly depended on the activity for DME hydrolysis.Z(25) was the best solid acid catalyst for DME SR and gave a DME conversion>90% [T = 24℃,n(H2O)/n(DME) = 3.5,space velocity=1179 ml·(g cat)-1·h-1,and P=0.1MPa].The influences of the reaction temperature,space velocity and feed molar ratio were studied.Hydrogen production significantly depended on temperature and space velocity.A bifunctional catalyst of CuO-ZnO-Al2O3-ZrO2 catalyst and ZSM-5 gave a high H2 production rate and CO2 selectivity.展开更多
Recently, increasing interest has been focused on the hydrolysis of carbohydrates to monosaccharides, among which, glucose and xylose as typical platform sugars can be used to produce chemicals and biofuels. As hetero...Recently, increasing interest has been focused on the hydrolysis of carbohydrates to monosaccharides, among which, glucose and xylose as typical platform sugars can be used to produce chemicals and biofuels. As heterogeneous catalysts, solid acids have gained extensive attention for biomass biorefinery and could replace the conventional process owing to their excellent properties, including acceptable acidity and easy separation. In particular, biochar-based solid acids derived from biomass are promising for biomass conversion owing to the low-cost of feedstocks and the simple preparation procedure. Herein, we attempt to provide a critical overview of biochar-based solid acids for hydrolysis of carbohydrates into glucose and xylose. The preparation methods and properties of biochar-based catalysts as well as the influence of their properties on catalytic performance were discussed in detail. We also highlight the major challenges facing the use of biochar-based solid acids for carbohydrate hydrolysis.展开更多
The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene (PE) catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mes...The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene (PE) catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves (SAPO1 and SAPO2) were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.展开更多
The liquid phase alkylation of catechol with tert-butyl alcohol to produce 4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite and novel acidic porous montmorillonite heteros...The liquid phase alkylation of catechol with tert-butyl alcohol to produce 4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite and novel acidic porous montmorillonite heterostructures (PMHs). Upon all catalysts tested, 4-TBC is the main product and 3-tert-butyl catechol (3-TBC) and 3,5-di-tert-butyl catechol are the side products. The synthetic PMHs showed higher conversion of catechol and better selectivity to 4-TBC compared to other solid acid catalysts tested. Over the PMHs derived from H-exchanged montmorillonite through template extraction processes, the suitable reaction temperature is ca 410 K, the ratio of catechol to tert-butyl alcohol is 1:2. Increasing the amount of catalyst (lower weight hourly space velocity) can improve the conversion of catechol and influence the selectivity slightly. The reasonable reaction time is ca 8 h.The type and strength of acidity of H-montmorillonite and PMH were determined by pyridine adsorption FT-IR and ammonia temperature-programmed desorption techniques. The medium and strong acid sites are conducive to producing 4-TBC and the weak acid sites to facilitating the 3-TBC formation. The differences between the PMHs from calcination and those fi'om extraction are attributed to proton migration and acidity change in the gallery surface.展开更多
Ionic liquid (IL), [BMIM]Cl-water was applied in cellulose pretreatment process and the pretreated cellulose was used in subsequent polyethylene glycol liquefaction process as a new application method. Cellulose recov...Ionic liquid (IL), [BMIM]Cl-water was applied in cellulose pretreatment process and the pretreated cellulose was used in subsequent polyethylene glycol liquefaction process as a new application method. Cellulose recovery rate and molecular weight value of pretreated cellulose were investigated to understand the influence of IL-water mixtures by adding the different amount of catalysis on cellulose crystalline structure. Gel permeation chromatograph, X-ray diffraction, Fourier transform infrared spectrometer and thermo gravimetric/differential thermal analysis were used to clarify the changes of pretreated cellulose. The results showed that the pretreated cellulose was improved in crystalline structure, molecular weight distribution and thermal stability. The liquefied residues from untreated cellulose and pretreated cellulose were considered as a significant index to determine the effect of IL-water mixture on cellulose. It suggested that the lower molecular weight of cellulose was obtained, the crystalline structure was disrupted and less order was formed. The liquefied residues result suggested that the lower residues at the latter stages of the reaction from the pretreated cellulose were observed.展开更多
A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solv...A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solvent and sulfonation. Physical characterization was detected to show that the carbon-based acid is amorphous with polycyclic aromatic carbon sheets attached plentiful -OH, -COOH, and -SO3H groups. The sulfonic acid density and total acid density of it reached 2.05 mmol·g-1 and 5.63 mmol·g-1, respectively by acid-base titration. As a solid acid catalyst, it showed excellent performance in the ketalization of cyclohexanone with glycol.展开更多
Based on starch and series of alkyl benzene sulfonic acid as the materials, a novel carbon-based solid acid catalyst is synthesized using hydrothermal method. This catalyst exhibits much higher catalytic activity in t...Based on starch and series of alkyl benzene sulfonic acid as the materials, a novel carbon-based solid acid catalyst is synthesized using hydrothermal method. This catalyst exhibits much higher catalytic activity in the reaction of esterification of Mono-fatty alcohol polyoxyethylene maleate esters with 1,4-butanediol. The structure of carbon-based solid acid catalyst was charactered by IR and XRD, characterizations showed that this catalyst exhibited high –SO3H loading. Reusability of the carbon-based solid acid catalyst for esterification showed that after recycling five times the activity remained unchanged.展开更多
Phosphoric acid treated niobic acid(NbP)was used for the dehydration of xylose to furfural in biphasic solvent system,which was found to exhibit the best performance among the tested catalysts.The excellent performanc...Phosphoric acid treated niobic acid(NbP)was used for the dehydration of xylose to furfural in biphasic solvent system,which was found to exhibit the best performance among the tested catalysts.The excellent performance of NbP could be explained by the better synergistic cooperation between Bro¨nsted and Lewis acid sites.Moreover,NbP showed good stability and no obvious deactivation or leaching of Nb could be observed after six continuous recycles.展开更多
基金Supported by the Research Fund for the Doctoral Program of Higher Education(No20050010014)the China Petroleum &Chemical Corporation ( No X503015 )the Key Discipline Construction Foundation of Beijing Education Committee ( NoXK100100643)
文摘Esterification of acrylic acid(AA) to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate(ZS) loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20% (mass fraction) ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.
基金Sichuan University and laboratory for their support.
文摘In this work, a series of SO4^2-/TiO2/γ-Al2O3 solid acid catalysts were synthesized by impregnation method, in which nano-TiO2 was prepared by sol–gel method, and then the nano-TiO2 sol was loaded on porous γ-Al2O3 supporter through impregnation. The structure and property of catalyst were characterized by XRD, N2-BET,SEM, TEM, XPS, NH3-TPD, Pyridine-IR and FT-IR. In addition, the catalyst of chelate bidentate coordination acid center model was established. The catalytic performance test was carried out in the esterification of n-butyl alcohol with lauric acid and the catalyst showed excellent activity. The experimental results showed that the medium strength acid sites were more dominant active sites than the strong and weak acid sites for the rapid esterification reaction. Its kinetic behaviors and activation energy were studied for the esterification under the catalytic reaction condition.
文摘A silica-supported zirconium based solid acid (ZS) has been used as catalyst for the Fries rearrangement of phenyl acetate (PA). The catalyst showed a higher PA conversion activity and a much higher selectivity for o-hydroxyacetophenone (o-HAP) than for strongly acidic zeolite catalysts. The supported catalyst was characterized by XRD, IR, XPS, pyridine-TPD and the surface area measurements. The catalytic properties were influenced significantly by pretreatment temperature.
基金supported by the National Natural Science Foundation of China(21766009)Program of Qingjiang Excellent Young Talents(Jiangxi University of Science and Technology)。
文摘A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized with sidewall hydroxyl groups(SWCNTs–OH)and La^(3+) via sol–gel method.The freshly prepared catalyst was characterized by several methods,and the catalytic activity and stability of it were studied from the esterification of oleic acid and methanol.Results showed that the highest conversion of oleic acid was 93.1%(mass)and maintained as high as 88.7%(mass)after six cycles of La-PW-SiO_(2)/SWCNTs.The high catalytic activity and stability of La-PW-SiO_(2)/SWCNTs can be attributed to the strong electron withdrawing effect of La^(3+) on π bond of SWCNTs,because it can facilitate the formation of a large number of strong Lewis acid sites.Therefore,the reduction of catalytic activity of a solid acid catalyst due to the fact that hydration reaction of its Bronsted acid sites can be effectively reduced.La-PW-SiO_(2)/SWCNTs can be an efficient and economical catalyst,because it shows good catalytic activity and stability.
基金supported by the National Natural Science Foundation of China (No. 51978052)Beijing Municipal Education Commission through the Innovative Transdisciplinary Program “Ecological Restoration Engineering (No. GJJXK210102)”。
文摘Antibiotic production wastewater usually contains high concentrations of antibiotic residues,which can cause instability and deterioration of biological wastewater treatment units and also domestication and proliferation of antibiotic-resistance bacteria.An effective pretreatment on antibiotics production wastewater is expected to selectively reduce the concentration of antibiotics and decrease the toxicity,rather than mitigate organic and other contaminants before further treatments.In this work,two polymer-based solid acids,PS-S and CPS-S bearing high concentrations of-SOH_(3)groups (up to 4.57 mmol/g),were prepared and successfully used for hydrolytic mitigation of 100 mg/L tylosin within 20 min.The co-existence of high concentrations of COD and humic substances did not affect the mitigation of tylosin obviously,while more than 500 mg/L of nitrogenous compounds suppressed the hydrolytic efficiency.Recycle and reuse experiments showed that the solid acids performed well in five cycles after regeneration.Three transformation products (P1,P2 and P3)were identified using UPLC-QTOF-MS/MS.Sugar moieties including mycarse,mycaminose,and mycinose detached and released simultaneously or in order from the 16-member lactone ring through desugarization,which led to a dramatic decrease in antibacterial activity as revealed by cytotoxicity evaluations using S.aureus.Ecotoxicity estimation indicated the acute toxicities of the hydrolyzed products to model species (e.g.,fish,daphnid and green algae) were classified as“not harmful”.This work suggested an effective and selective method to pretreat tylosin-contained production wastewater by using polymer-based solid acids.These results will shed light on effective elimination of antibiotics pollution from pharmaceutical industries through strengthening the pretreatments.
基金financially supported by the National Natural Science Foundation of China(Nos.21875044,52073064,22005058 and 22005057)National Key R&D Program of China(No.2020YFB2008600)+3 种基金Key Basic Research Program of Science and Technology Commission of Shanghai Municipality(No.20JC1415300)Program of Shanghai Academic Research Leader(No.19XD1420300)China Post-doctoral Science Foundation(Nos.2020M670973,BX20200085)the State Key Laboratory of Transducer Technology of China(No.SKT1904)。
文摘Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids.In this work,a series of novel sulfonic acid-functionalized core-shell Fe_(3)O_(4)@carbon microspheres(Fe_(3)O_(4)@C-SO_(3)H)have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst.For the synthesis,core-shell Fe_(3)O_(4)@RF(resorcinol-formaldehyde)microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe_(3)O_(4)microspheres.After high-temperature carbonization,the microspheres were eventually treated by surface sulfonation,re sulting in Fe_(3)O_(4)@C-x-SO_(3)H(x stands for carbonization temperature)microspheres with abundant surface SO_(3)H groups.The obtained microspheres possess uniform core-shell structure,partially-graphitized carbon skeletons,superparamagnetic property,high magnetization saturation value of 10.6 emu/g,and rich SO_(3)H groups.The surface acid amounts can be adju sted in the range of 0.59-1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees.The magnetic Fe_(3)O_(4)@C-x-SO_(3)H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol,demonstrating high selectivity(97%)to benzaldehyde ethylene glycol acetal.More importantly,by applying an external magnetic field,the catalysts can be easily separated from the heterogeneous reaction solutions,which later show well preserved catalytic activity even after 9 cycles,revealing good recyclability and high stability.
基金Supported by the Ministry of Science and Technology (G1999022408) and the National Natural Science Foundation of China (20773075).
文摘Steam reforming(SR) of dimethyl ether(DME) was investigated for the production of hydrogen for fuel cells.The activity of a series of solid acids for DME hydrolysis was investigated.The solid acid catalysts were ZSM-5 [Si/Al = 25,38 and 50:denoted Z(Si/Al)] and acidic alumina(γ-Al2O3) with an acid strength order that was Z(25)>Z(38)>Z(50)>γ-Al2O3.Stronger acidity gave higher DME hydrolysis conversion.Physical mixtures containing a CuO-ZnO-Al2O3-ZrO2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR were used to examine the acidity effects on DME SR.DME SR activity strongly depended on the activity for DME hydrolysis.Z(25) was the best solid acid catalyst for DME SR and gave a DME conversion>90% [T = 24℃,n(H2O)/n(DME) = 3.5,space velocity=1179 ml·(g cat)-1·h-1,and P=0.1MPa].The influences of the reaction temperature,space velocity and feed molar ratio were studied.Hydrogen production significantly depended on temperature and space velocity.A bifunctional catalyst of CuO-ZnO-Al2O3-ZrO2 catalyst and ZSM-5 gave a high H2 production rate and CO2 selectivity.
基金supported by grants from the Program for National Natural Science Foundation of China(No.21576103)the Guangdong Program for Support of Top-notch Young Professionals(No.2016TQ03Z585)the Guangzhou Science and Technology Plan Project(No.201707010059)
文摘Recently, increasing interest has been focused on the hydrolysis of carbohydrates to monosaccharides, among which, glucose and xylose as typical platform sugars can be used to produce chemicals and biofuels. As heterogeneous catalysts, solid acids have gained extensive attention for biomass biorefinery and could replace the conventional process owing to their excellent properties, including acceptable acidity and easy separation. In particular, biochar-based solid acids derived from biomass are promising for biomass conversion owing to the low-cost of feedstocks and the simple preparation procedure. Herein, we attempt to provide a critical overview of biochar-based solid acids for hydrolysis of carbohydrates into glucose and xylose. The preparation methods and properties of biochar-based catalysts as well as the influence of their properties on catalytic performance were discussed in detail. We also highlight the major challenges facing the use of biochar-based solid acids for carbohydrate hydrolysis.
基金the support of the National Natural Science Foundation of China (No. 20174039) the Ministry of Science and Technology of China (No. 2005CB623800).
文摘The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene (PE) catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves (SAPO1 and SAPO2) were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.
基金Supported by the National Natural Science Foundation of China (No. 20376075) the Natural Science Foundation of Zhejiang Province (No. 201057).
文摘The liquid phase alkylation of catechol with tert-butyl alcohol to produce 4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite and novel acidic porous montmorillonite heterostructures (PMHs). Upon all catalysts tested, 4-TBC is the main product and 3-tert-butyl catechol (3-TBC) and 3,5-di-tert-butyl catechol are the side products. The synthetic PMHs showed higher conversion of catechol and better selectivity to 4-TBC compared to other solid acid catalysts tested. Over the PMHs derived from H-exchanged montmorillonite through template extraction processes, the suitable reaction temperature is ca 410 K, the ratio of catechol to tert-butyl alcohol is 1:2. Increasing the amount of catalyst (lower weight hourly space velocity) can improve the conversion of catechol and influence the selectivity slightly. The reasonable reaction time is ca 8 h.The type and strength of acidity of H-montmorillonite and PMH were determined by pyridine adsorption FT-IR and ammonia temperature-programmed desorption techniques. The medium and strong acid sites are conducive to producing 4-TBC and the weak acid sites to facilitating the 3-TBC formation. The differences between the PMHs from calcination and those fi'om extraction are attributed to proton migration and acidity change in the gallery surface.
文摘Ionic liquid (IL), [BMIM]Cl-water was applied in cellulose pretreatment process and the pretreated cellulose was used in subsequent polyethylene glycol liquefaction process as a new application method. Cellulose recovery rate and molecular weight value of pretreated cellulose were investigated to understand the influence of IL-water mixtures by adding the different amount of catalysis on cellulose crystalline structure. Gel permeation chromatograph, X-ray diffraction, Fourier transform infrared spectrometer and thermo gravimetric/differential thermal analysis were used to clarify the changes of pretreated cellulose. The results showed that the pretreated cellulose was improved in crystalline structure, molecular weight distribution and thermal stability. The liquefied residues from untreated cellulose and pretreated cellulose were considered as a significant index to determine the effect of IL-water mixture on cellulose. It suggested that the lower molecular weight of cellulose was obtained, the crystalline structure was disrupted and less order was formed. The liquefied residues result suggested that the lower residues at the latter stages of the reaction from the pretreated cellulose were observed.
文摘A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solvent and sulfonation. Physical characterization was detected to show that the carbon-based acid is amorphous with polycyclic aromatic carbon sheets attached plentiful -OH, -COOH, and -SO3H groups. The sulfonic acid density and total acid density of it reached 2.05 mmol·g-1 and 5.63 mmol·g-1, respectively by acid-base titration. As a solid acid catalyst, it showed excellent performance in the ketalization of cyclohexanone with glycol.
文摘Based on starch and series of alkyl benzene sulfonic acid as the materials, a novel carbon-based solid acid catalyst is synthesized using hydrothermal method. This catalyst exhibits much higher catalytic activity in the reaction of esterification of Mono-fatty alcohol polyoxyethylene maleate esters with 1,4-butanediol. The structure of carbon-based solid acid catalyst was charactered by IR and XRD, characterizations showed that this catalyst exhibited high –SO3H loading. Reusability of the carbon-based solid acid catalyst for esterification showed that after recycling five times the activity remained unchanged.
基金supported by the Natural Science Foundation of China (No.21106143)100-talent project of Dalian Institute of Chemical Physics (DICP)the Independent Innovation Foundation of State Key Laboratory of Catalysis (No.R201113)
文摘Phosphoric acid treated niobic acid(NbP)was used for the dehydration of xylose to furfural in biphasic solvent system,which was found to exhibit the best performance among the tested catalysts.The excellent performance of NbP could be explained by the better synergistic cooperation between Bro¨nsted and Lewis acid sites.Moreover,NbP showed good stability and no obvious deactivation or leaching of Nb could be observed after six continuous recycles.
基金Fund supported by the National Natural Science Foundation of China(No.20376075)Zhejiang Provincial Natural Science Foundation(No.201057)are acknowledged.