The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of reactants.Maintaining excellent pore structure under strict reaction condit...The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of reactants.Maintaining excellent pore structure under strict reaction conditions is of utmost importance.In this work,sphericalγ-Al_(2)O_(3)support with a bimodal pore structure,composed of macropores and mesopores,was successfully synthesized using dodecane as the pore-forming agent through the oil–ammonia column-shaping method.The morphology and internal pore structure of the alumina were found to be influenced by the amount of surfactant added and ultrasound treatment conditions.Notably,when concentration of surfactant was 4‰and ultrasound voltage of 20 V was applied,the resultingγ-Al_(2)O_(3)-4‰-20 displayed a highly concentrated distribution of macropores with an average pore size of 100 nm,resulting in an impressive porosity of 69.21%.In contrast,the untreated sample ofγ-Al_(2)O_(3)-0-0 only exhibited a mesoporous distribution with a porosity of 54.03%.Moreover,after being subjected to a hydrothermal treatment in a high temperature(600°C)and high humidity(water vapor)environment for 120 h,theγ-Al_(2)O_(3)-4‰-20 sample maintained a high BET specific surface area of 170.9 m^(2)g^(−1)and mercury intrusion porosimetry specific surface area of 263.3 m^(2)g^(−1).展开更多
Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution wer...Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column.Due to the surface tension,spherical gel particles were formed in the oil column.The spherical gel particles were then aged and washed by deionized water and dried at 120 ℃ for 12 h and then calcined at 600 ℃ for 8 h,960 ℃ for 8 h or 1200 ℃ for 12 h.X-ray diffraction and nitrogen adsorption-desorption measurements indicated that the presence of zirconia prevents the sintering of alumina and the obtained ZrO_(2)-Al_(2)O_(3) composites have much larger surface areas than pure alumina.Temperature-programmed desorption of ammonia results illustrated that the addition of zirconia leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina.Thus,the spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites prepared in this way were shown to be suitable for high temperature catalytic processes as a catalyst support.展开更多
Spherical porous alumina(Al_(2)O_(3))materials hold critical importance in industrial catalysis,but their direct synthesis remains a significant challenge.Herein,we report a hydrogen bond-enhanced monomicelle assembly...Spherical porous alumina(Al_(2)O_(3))materials hold critical importance in industrial catalysis,but their direct synthesis remains a significant challenge.Herein,we report a hydrogen bond-enhanced monomicelle assembly strategy for synthesizing uniformly monodispersed mesoporous Al_(2)O_(3) microspheres.This synthesis features the introduction of glycerol with abundant hydroxyl groups(-OH)to form the hydrogen bond network between the alumina-based monomicelles.The hydrogen bond network reduces the crosslinking rate of the Al_(2)O_(3) oligomers and matches it with the micelle assembly rate,thereby enabling the direct synthesis of mesoporous Al_(2)O_(3) microspheres in solution.The resultant mesoporous Al_(2)O_(3) microspheres exhibit uniform spherical morphology(~1.3μm),a high specific surface area(144 m2·g^(-1)),a large pore size(~7.8 nm),and abundant Lewis acid sites.Moreover,this strategy is universal for organic and inorganic Al_(2)O_(3) precursors,overcoming the limitations of precursor compatibility.The mesoporous Al_(2)O_(3) microspheres loaded with uniformly distributed PtSn nanoparticles are utilized as a highly efficient catalyst for propane dehydrogenation to propylene.The catalyst exhibits high propane conversion rate(~41%),high selectivity to propylene(>98%),a low deactivation rate constant(0.004 h^(-1))and remarkable long-term stability(~200 h)under industrial conditions at 550℃.展开更多
基金National Key R&D Program of China(grant No.2022YFA1503400)Lanzhou Petrochemical Research Center project,and Programs for Foreign Talent(grant No.G2021106012L).
文摘The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of reactants.Maintaining excellent pore structure under strict reaction conditions is of utmost importance.In this work,sphericalγ-Al_(2)O_(3)support with a bimodal pore structure,composed of macropores and mesopores,was successfully synthesized using dodecane as the pore-forming agent through the oil–ammonia column-shaping method.The morphology and internal pore structure of the alumina were found to be influenced by the amount of surfactant added and ultrasound treatment conditions.Notably,when concentration of surfactant was 4‰and ultrasound voltage of 20 V was applied,the resultingγ-Al_(2)O_(3)-4‰-20 displayed a highly concentrated distribution of macropores with an average pore size of 100 nm,resulting in an impressive porosity of 69.21%.In contrast,the untreated sample ofγ-Al_(2)O_(3)-0-0 only exhibited a mesoporous distribution with a porosity of 54.03%.Moreover,after being subjected to a hydrothermal treatment in a high temperature(600°C)and high humidity(water vapor)environment for 120 h,theγ-Al_(2)O_(3)-4‰-20 sample maintained a high BET specific surface area of 170.9 m^(2)g^(−1)and mercury intrusion porosimetry specific surface area of 263.3 m^(2)g^(−1).
基金supported by the National Natural Science Foundation of Chinathe 111 Project (B07004)the Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT0406)
文摘Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column.Due to the surface tension,spherical gel particles were formed in the oil column.The spherical gel particles were then aged and washed by deionized water and dried at 120 ℃ for 12 h and then calcined at 600 ℃ for 8 h,960 ℃ for 8 h or 1200 ℃ for 12 h.X-ray diffraction and nitrogen adsorption-desorption measurements indicated that the presence of zirconia prevents the sintering of alumina and the obtained ZrO_(2)-Al_(2)O_(3) composites have much larger surface areas than pure alumina.Temperature-programmed desorption of ammonia results illustrated that the addition of zirconia leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina.Thus,the spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites prepared in this way were shown to be suitable for high temperature catalytic processes as a catalyst support.
基金supported by the National Key R&D Program of China(No.2022YFA1503501)the National Natural Science Foundation of China(Nos.22088101,52473273,U24A20488 and U21A20329)+2 种基金Shanghai Pilot Program for Basic Research-FuDan University 21TQ1400100(No.21TQ008)Shanghai International Science and Technology Partnership Project(No.23520750400)“Shuguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.22SG02).
文摘Spherical porous alumina(Al_(2)O_(3))materials hold critical importance in industrial catalysis,but their direct synthesis remains a significant challenge.Herein,we report a hydrogen bond-enhanced monomicelle assembly strategy for synthesizing uniformly monodispersed mesoporous Al_(2)O_(3) microspheres.This synthesis features the introduction of glycerol with abundant hydroxyl groups(-OH)to form the hydrogen bond network between the alumina-based monomicelles.The hydrogen bond network reduces the crosslinking rate of the Al_(2)O_(3) oligomers and matches it with the micelle assembly rate,thereby enabling the direct synthesis of mesoporous Al_(2)O_(3) microspheres in solution.The resultant mesoporous Al_(2)O_(3) microspheres exhibit uniform spherical morphology(~1.3μm),a high specific surface area(144 m2·g^(-1)),a large pore size(~7.8 nm),and abundant Lewis acid sites.Moreover,this strategy is universal for organic and inorganic Al_(2)O_(3) precursors,overcoming the limitations of precursor compatibility.The mesoporous Al_(2)O_(3) microspheres loaded with uniformly distributed PtSn nanoparticles are utilized as a highly efficient catalyst for propane dehydrogenation to propylene.The catalyst exhibits high propane conversion rate(~41%),high selectivity to propylene(>98%),a low deactivation rate constant(0.004 h^(-1))and remarkable long-term stability(~200 h)under industrial conditions at 550℃.
