lmprovement of the charge separation of titanosilicate molecular sieves is critical to their use asphotocatalysts for oxidative organic transformations.In this work,MFI TS-1 molecular sievenanosheets(TS-1 NS)were synt...lmprovement of the charge separation of titanosilicate molecular sieves is critical to their use asphotocatalysts for oxidative organic transformations.In this work,MFI TS-1 molecular sievenanosheets(TS-1 NS)were synthesized by a low-temperature hydrothermal method using a tai-lored diquaternary ammonium surfactant as the structure-directing agent.Introducing Ni^2+cationsat the ion-exchange sites of the TS-1 NS framework significantly enhanced its photoactivity in aero-bic alcohol oxidation.The optimized Ni cation-functionalized TS-1 NS(Ni/TS-1 NS)provide impres-sive photoactivity,with a benzyl alcohol(BA)conversion of 78.9%and benzyl aldehyde(BAD)se-lectivity of 98.8%using O as the only oxidant under full light irradiation;this BAD yield is approx-imately six times greater than that obtained for bulk TS-1,and is maintained for five runs.The ex-cellent photoactivity of Ni/TS-1 NS is attributed to the significantly enlarged surface area of thetwo-dimensional morphology TS-1 NS,extra mesopores,and greatly improved charge separation.Compared with bulk TS-1,Ni/TS-1 NS has a much shorter charge transfer distance.Theas-introduced Ni species could capture the photoelectrons to further improve the charge separa-tion.This work opens the way to a class of highly selective,robust,and low-cost titanosilicate mo-lecular sieve-based photocatalysts with industrial potential for selective oxidative transformationsand pollutant degradation.展开更多
Current bio-ethanol production entails the enzymatic depolymerization of cellulose,but this process shows low efficiency and poor economy.In this work,we developed a consecutive aqueous hydrogenolysis process for the ...Current bio-ethanol production entails the enzymatic depolymerization of cellulose,but this process shows low efficiency and poor economy.In this work,we developed a consecutive aqueous hydrogenolysis process for the conversion of corn-stalk cellulose to produce a relatively high concentration of bio-ethanol(6.1 wt%)without humin formation.A high yield of cellulose(ca.50 wt%)is extracted from corn stalk using a green solvent(80 wt%1,4-butanediol)without destroying the structure of the lignin.The first hydrothermal hydrogenolysis step uses a Ni–WO_(x)/SiO_(2)catalyst to convert the high cumulative concentration of cellulose(30 wt%)into a polyol mixture with a 56.5 C%yield of ethylene glycol(EG).The original polyol mixture is then subjected to subsequent selective aqueous-phase hydrogenolysis of the C–O bond to produce bioethanol(75%conversion,84 C%selectivity)over the modified hydrothermally stable Cu catalysts.The added Ni component favors the good dispersion of Cu nanoparticles,and the incorporated Au3+helps to stabilize the active Cu^(0)-Cu^(+)species.This multi-functional catalytic process provides an economically competitive route for the production of cellulosic ethanol from raw lignocellulose.展开更多
文摘lmprovement of the charge separation of titanosilicate molecular sieves is critical to their use asphotocatalysts for oxidative organic transformations.In this work,MFI TS-1 molecular sievenanosheets(TS-1 NS)were synthesized by a low-temperature hydrothermal method using a tai-lored diquaternary ammonium surfactant as the structure-directing agent.Introducing Ni^2+cationsat the ion-exchange sites of the TS-1 NS framework significantly enhanced its photoactivity in aero-bic alcohol oxidation.The optimized Ni cation-functionalized TS-1 NS(Ni/TS-1 NS)provide impres-sive photoactivity,with a benzyl alcohol(BA)conversion of 78.9%and benzyl aldehyde(BAD)se-lectivity of 98.8%using O as the only oxidant under full light irradiation;this BAD yield is approx-imately six times greater than that obtained for bulk TS-1,and is maintained for five runs.The ex-cellent photoactivity of Ni/TS-1 NS is attributed to the significantly enlarged surface area of thetwo-dimensional morphology TS-1 NS,extra mesopores,and greatly improved charge separation.Compared with bulk TS-1,Ni/TS-1 NS has a much shorter charge transfer distance.Theas-introduced Ni species could capture the photoelectrons to further improve the charge separa-tion.This work opens the way to a class of highly selective,robust,and low-cost titanosilicate mo-lecular sieve-based photocatalysts with industrial potential for selective oxidative transformationsand pollutant degradation.
文摘Current bio-ethanol production entails the enzymatic depolymerization of cellulose,but this process shows low efficiency and poor economy.In this work,we developed a consecutive aqueous hydrogenolysis process for the conversion of corn-stalk cellulose to produce a relatively high concentration of bio-ethanol(6.1 wt%)without humin formation.A high yield of cellulose(ca.50 wt%)is extracted from corn stalk using a green solvent(80 wt%1,4-butanediol)without destroying the structure of the lignin.The first hydrothermal hydrogenolysis step uses a Ni–WO_(x)/SiO_(2)catalyst to convert the high cumulative concentration of cellulose(30 wt%)into a polyol mixture with a 56.5 C%yield of ethylene glycol(EG).The original polyol mixture is then subjected to subsequent selective aqueous-phase hydrogenolysis of the C–O bond to produce bioethanol(75%conversion,84 C%selectivity)over the modified hydrothermally stable Cu catalysts.The added Ni component favors the good dispersion of Cu nanoparticles,and the incorporated Au3+helps to stabilize the active Cu^(0)-Cu^(+)species.This multi-functional catalytic process provides an economically competitive route for the production of cellulosic ethanol from raw lignocellulose.
