The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such ...The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids （HPAs）, viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] （TPA）, Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P＋aq] （DMAA）, Dodeca-Molyhdo Phosphoric acid （PMA） on clay （MontmoriUonite, K-10） and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.展开更多
The alkylation of toluene with methanol to selective formation of p-xylene has been systematically studied. ZSM-12 （MTW）/ZSM-5 co-crystalline zeolite in 40：60 proportions have been synthesized by the same molar gel...The alkylation of toluene with methanol to selective formation of p-xylene has been systematically studied. ZSM-12 （MTW）/ZSM-5 co-crystalline zeolite in 40：60 proportions have been synthesized by the same molar gel composition, but at different temperatures and periods than that of ZSM-12 and ZSM-5, separately. All the prepared samples are characterized by XRD, SEM, BET, and XRF. The activity of toluene alkylation was investigated with a mixture of toluene and methanol as a feed over the ZSM-12, ZSM-12/ZSM-5 co-crystalline, ZSM-5, and physical mixture of ZSM-12/ZSM-5. From characterization, it is observed that the ZSM-12/ZSM-5 co-crystalline material is different from that of ZSM-12, ZSM-5, and their physical mixture. Further, the ZSM-12/ZSM-5 co-crystalline zeolite produces the highest content of xylene and has better selectivity for p-xylene than ZSM-12, ZSM-5, and their physical mixture.展开更多
The global consumption of p-xylene(PX)for the production of polymers has raised serious concerns about its impact on the environment.As various reports have shown the risks that PX could pose to human health,research ...The global consumption of p-xylene(PX)for the production of polymers has raised serious concerns about its impact on the environment.As various reports have shown the risks that PX could pose to human health,research into cost-effective remedial methods to remove PX from the environment has gained attraction.In this work,a hierarchical porous crab shell biochar(KCS)was synthesized,characterized,and evaluated for its efficiency to remove PX from aqueous solution.The characterizations of KCS,including the porous structure,surface functional group,phase structure,and surface morphology,were discussed by N_(2) adsorption-desorption,FTIR,XRD,and SEM.Batch adsorption experiments showed that the maximum adsorption capacity of PX on KCS was 393 mg/g within 5 min,larger than most biological/biomass materials,mainly due to the higher specific surface area of 2046 m^(2)/g,and abundant lipophilic functional groups.Subsequent adsorption kinetics study indicated a pseudo-second-order model which implied that the adsorption of PX was due to chemisorption.Thermodynamic parameters showed that the values ofΔH°andΔG°were both negative,indicating that the PX adsorption process on KCS was spontaneous and exothermic.The performance of KCS in delivering a cost-effective,fast,and efficient solution for the removal of PX from aqueous solution would greatly benefit current environmental remediation efforts.展开更多
Vapor-liquid equilibrium composition and temperature were measured for binary andternary mixtures of benzene,toluene and p-xylene at 101.33 kPa The equilibrium cell of Boubliketal.was modified for the present study.Th...Vapor-liquid equilibrium composition and temperature were measured for binary andternary mixtures of benzene,toluene and p-xylene at 101.33 kPa The equilibrium cell of Boubliketal.was modified for the present study.The experimental vapor-liquid equilibrium data were corre-lated with the Wilson equation.展开更多
The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinitie...The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.展开更多
A combination of photochlorination ofp-xylene and succedent Friedel-Crafts alkylation polymerization was firstly used in the preparation of the hypercrosslinked adsorptive resin. The data of GC-MS and GC showed that a...A combination of photochlorination ofp-xylene and succedent Friedel-Crafts alkylation polymerization was firstly used in the preparation of the hypercrosslinked adsorptive resin. The data of GC-MS and GC showed that a series of chlorizates were produced when p-xylene was photochlorinated. Hypercrosslinked resins could be synthesized by copolymerization, self-polymerization of chlorizates or post crosslinking reaction. The chemical structure and micromorphology of the porous resins were characterized by BET, FF-IR, SEM and elementary analysis （EA）. The results showed that the novel adsorptive resins possess high BET surface near to 1038 m^2/g and large pore volumes range from 0.5 to 1.2 cm^3/g.展开更多
The process of p-xylene liquid phase oxidation to produce purified terephthalic acid(PTA)involves a series of liquid phase radical reactions,chemical absorption,reac-tive crystallization,and evaporation.A commercial P...The process of p-xylene liquid phase oxidation to produce purified terephthalic acid(PTA)involves a series of liquid phase radical reactions,chemical absorption,reac-tive crystallization,and evaporation.A commercial PTA production flow sheet includes a number of unit operations,which construct a complex process system.In this paper,a review of research and development(R&D)works on PTA process carried out in Zhejiang University during recent years is introduced.The works cover the oxidation and crystallization kinetics,gas-liquid mass transfer and evaporation,reactor modeling,database development,novel reactor design,process modeling,simulation,and optimi-zation.The author emphasizes the viewpoint through this case study that chemical reaction engineering should be developed to process system engineering to extend its scope,and particular attention should be paid on reactor and process modeling.展开更多
The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performan...The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid （PTA） were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X （X = Cl, OCH3） and Y （Y = H, CH3, Cl） groups bonded to the aromatic rings of the Co （Ⅱ） complexes were investigated.展开更多
The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （...The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.展开更多
An attempt has been made to prepare terephthalic acid（TPA） by solvent-free oxidation of p-xylene（PX） with air over tetra（pchlorophenylporphinato） manganese chloride（T（p-Cl）PPMnCl） and cobalt acetate.The co-c...An attempt has been made to prepare terephthalic acid（TPA） by solvent-free oxidation of p-xylene（PX） with air over tetra（pchlorophenylporphinato） manganese chloride（T（p-Cl）PPMnCl） and cobalt acetate.The co-catalysis between T（p-Cl）PPMnCl and Co（OAc）_2 has been discovered under solvent-free conditions.TPA yield could be increased significantly when T（p-Cl）PPMnCl and Co（OAc）_2 were used together.The addition of T（p-Cl）PPMnCl into the reaction mixture over Co（OAc）_2 significantly accelerated the rate-determining step of the oxidation process of PX to TPA.The effect of temperature on reaction was also investigated.展开更多
P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,pero...P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.展开更多
Shape-selective zeolites(UZ-x/y) were synthesized by a one-pot method using TPAOH(y) and/or MeEt3 N^+I^-(x) as templates.The use of MeEt3 N^+I^- affects the crystal growth and the distribution of acid sites on the ext...Shape-selective zeolites(UZ-x/y) were synthesized by a one-pot method using TPAOH(y) and/or MeEt3 N^+I^-(x) as templates.The use of MeEt3 N^+I^- affects the crystal growth and the distribution of acid sites on the external surface of the zeolites.The catalysts show excellent catalytic activity towards toluene alkylation with CH3 Br.With toluene conversion of 36.3% and p-xylene selectivity of 66.2%,HZ-40/0 is the most effective among the prepared catalysts,showing a p-xylene yield of 21.2%.The improved para-selectivity is mainly due to the decrease of acid sites on the external surface of the catalysts.展开更多
With the growing consumption of oil, the production of /?-xylene(PX) from renewable biomass has gained significant attention recently. This work demonstrated that cellulose, a main component in lignocellulosic biomass...With the growing consumption of oil, the production of /?-xylene(PX) from renewable biomass has gained significant attention recently. This work demonstrated that cellulose, a main component in lignocellulosic biomass, was directly converted into PX over the Mg/P surface-modified zeolites. The catalysts modified by the incorporation of P2O5 and MgO into HZSM-5(HZ) promoted the isomerization of zw-/o-xylenes to p-xylene. The PX selectivity was greatly enhanced using the modified zeolites due to the deactivation of external surface and the adjustment of pore entrance. In addition, the addition of methanol to cellulose was beneficial to increase the selectivity of xylenes due to the alkylation reactions and the Diels-Alder reactions between cellulose-derived furans and methanol-derived olefins. The highest PX yield of 10.7%(molar fraction) with a high PX selectivity in xylenes(97.1%) was obtained over the 10%Mg/5%P/HZ catalyst. The reaction pathway for the formation ofp-xylene was addressed according to the study of the key reactions and the characterization of catalysts.展开更多
文摘The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids （HPAs）, viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] （TPA）, Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P＋aq] （DMAA）, Dodeca-Molyhdo Phosphoric acid （PMA） on clay （MontmoriUonite, K-10） and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.
文摘The alkylation of toluene with methanol to selective formation of p-xylene has been systematically studied. ZSM-12 （MTW）/ZSM-5 co-crystalline zeolite in 40：60 proportions have been synthesized by the same molar gel composition, but at different temperatures and periods than that of ZSM-12 and ZSM-5, separately. All the prepared samples are characterized by XRD, SEM, BET, and XRF. The activity of toluene alkylation was investigated with a mixture of toluene and methanol as a feed over the ZSM-12, ZSM-12/ZSM-5 co-crystalline, ZSM-5, and physical mixture of ZSM-12/ZSM-5. From characterization, it is observed that the ZSM-12/ZSM-5 co-crystalline material is different from that of ZSM-12, ZSM-5, and their physical mixture. Further, the ZSM-12/ZSM-5 co-crystalline zeolite produces the highest content of xylene and has better selectivity for p-xylene than ZSM-12, ZSM-5, and their physical mixture.
基金supported by the Natural Science Foundation of Zhejiang Province of China(No.LQ16D060004)Key Research and Development Projects of Zhejiang Province of China(No.2018C02043)+1 种基金Demonstration Project of Marine Economic Innovation and Development of Zhoushan City of ChinaDemonstration Project of Marine Economic Innovation and Development of Yantai City of China(No.YHCX-SW-L-201705).
文摘The global consumption of p-xylene(PX)for the production of polymers has raised serious concerns about its impact on the environment.As various reports have shown the risks that PX could pose to human health,research into cost-effective remedial methods to remove PX from the environment has gained attraction.In this work,a hierarchical porous crab shell biochar(KCS)was synthesized,characterized,and evaluated for its efficiency to remove PX from aqueous solution.The characterizations of KCS,including the porous structure,surface functional group,phase structure,and surface morphology,were discussed by N_(2) adsorption-desorption,FTIR,XRD,and SEM.Batch adsorption experiments showed that the maximum adsorption capacity of PX on KCS was 393 mg/g within 5 min,larger than most biological/biomass materials,mainly due to the higher specific surface area of 2046 m^(2)/g,and abundant lipophilic functional groups.Subsequent adsorption kinetics study indicated a pseudo-second-order model which implied that the adsorption of PX was due to chemisorption.Thermodynamic parameters showed that the values ofΔH°andΔG°were both negative,indicating that the PX adsorption process on KCS was spontaneous and exothermic.The performance of KCS in delivering a cost-effective,fast,and efficient solution for the removal of PX from aqueous solution would greatly benefit current environmental remediation efforts.
文摘Vapor-liquid equilibrium composition and temperature were measured for binary andternary mixtures of benzene,toluene and p-xylene at 101.33 kPa The equilibrium cell of Boubliketal.was modified for the present study.The experimental vapor-liquid equilibrium data were corre-lated with the Wilson equation.
基金This work is supported by the National Natural Science Foundation of China(Grant No.2007205).
文摘The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.
基金support of the National Natural Science Foundation of China(Nos.20574063 and 21004055)
文摘A combination of photochlorination ofp-xylene and succedent Friedel-Crafts alkylation polymerization was firstly used in the preparation of the hypercrosslinked adsorptive resin. The data of GC-MS and GC showed that a series of chlorizates were produced when p-xylene was photochlorinated. Hypercrosslinked resins could be synthesized by copolymerization, self-polymerization of chlorizates or post crosslinking reaction. The chemical structure and micromorphology of the porous resins were characterized by BET, FF-IR, SEM and elementary analysis （EA）. The results showed that the novel adsorptive resins possess high BET surface near to 1038 m^2/g and large pore volumes range from 0.5 to 1.2 cm^3/g.
基金financial support provided by the National Natural Science Foundation of China(Grant No.20076039)Zhejiang University“211”Foundation for Key Discipline Constructionthe financial support in part provided by SINOPEC,Yizheng Chemical Fiber Co.Ltd,Yangzi Petrochemical Co.Ltd,Shanghai Petrochemical Co.Ltd,Zhejiang Hualian Sunshine Co.Ltd,China Tex Ind Eng Ins.,Honeywell(China)Co.Ltd and BP America Inc.
文摘The process of p-xylene liquid phase oxidation to produce purified terephthalic acid(PTA)involves a series of liquid phase radical reactions,chemical absorption,reac-tive crystallization,and evaporation.A commercial PTA production flow sheet includes a number of unit operations,which construct a complex process system.In this paper,a review of research and development(R&D)works on PTA process carried out in Zhejiang University during recent years is introduced.The works cover the oxidation and crystallization kinetics,gas-liquid mass transfer and evaporation,reactor modeling,database development,novel reactor design,process modeling,simulation,and optimi-zation.The author emphasizes the viewpoint through this case study that chemical reaction engineering should be developed to process system engineering to extend its scope,and particular attention should be paid on reactor and process modeling.
基金supported by the National Natural Science Foundation of China(No.2007205).
文摘The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid （PTA） were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X （X = Cl, OCH3） and Y （Y = H, CH3, Cl） groups bonded to the aromatic rings of the Co （Ⅱ） complexes were investigated.
基金The authors gratefully acknowledge the grants from the National Natural Science Foundation of China(No.20072025)Education 0ffice Foundation of Sichuan Province(No.2005C012)Sichuan Provincial Department of Science&Technology(No.2006J13-143)in support of this work.
文摘The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.
文摘An attempt has been made to prepare terephthalic acid（TPA） by solvent-free oxidation of p-xylene（PX） with air over tetra（pchlorophenylporphinato） manganese chloride（T（p-Cl）PPMnCl） and cobalt acetate.The co-catalysis between T（p-Cl）PPMnCl and Co（OAc）_2 has been discovered under solvent-free conditions.TPA yield could be increased significantly when T（p-Cl）PPMnCl and Co（OAc）_2 were used together.The addition of T（p-Cl）PPMnCl into the reaction mixture over Co（OAc）_2 significantly accelerated the rate-determining step of the oxidation process of PX to TPA.The effect of temperature on reaction was also investigated.
基金financially supported by the Natural Science Foundation of Hebei(Nos.F2020202027 and F2020202067)the Major National Science and Technology Special Projects(No.2016ZX02301003-004-007)+1 种基金the National Natural Science Foundation of China(No.21271139)the Natural Science Foundation of Tianjin(No.17JCTPJC54500)。
文摘P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.
基金Supported by the National Natural Science Foundation of China(21273067,21476065,21671062,21725602)Program for Changjiang Scholars and Innovative Research Team in University(IRT1238)the Fundamental Research Funds for the Central Universities
文摘Shape-selective zeolites(UZ-x/y) were synthesized by a one-pot method using TPAOH(y) and/or MeEt3 N^+I^-(x) as templates.The use of MeEt3 N^+I^- affects the crystal growth and the distribution of acid sites on the external surface of the zeolites.The catalysts show excellent catalytic activity towards toluene alkylation with CH3 Br.With toluene conversion of 36.3% and p-xylene selectivity of 66.2%,HZ-40/0 is the most effective among the prepared catalysts,showing a p-xylene yield of 21.2%.The improved para-selectivity is mainly due to the decrease of acid sites on the external surface of the catalysts.
文摘With the growing consumption of oil, the production of /?-xylene(PX) from renewable biomass has gained significant attention recently. This work demonstrated that cellulose, a main component in lignocellulosic biomass, was directly converted into PX over the Mg/P surface-modified zeolites. The catalysts modified by the incorporation of P2O5 and MgO into HZSM-5(HZ) promoted the isomerization of zw-/o-xylenes to p-xylene. The PX selectivity was greatly enhanced using the modified zeolites due to the deactivation of external surface and the adjustment of pore entrance. In addition, the addition of methanol to cellulose was beneficial to increase the selectivity of xylenes due to the alkylation reactions and the Diels-Alder reactions between cellulose-derived furans and methanol-derived olefins. The highest PX yield of 10.7%(molar fraction) with a high PX selectivity in xylenes(97.1%) was obtained over the 10%Mg/5%P/HZ catalyst. The reaction pathway for the formation ofp-xylene was addressed according to the study of the key reactions and the characterization of catalysts.
