The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness ...The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.展开更多
Ni-advanced weathering steel holds paramount importance in marine atmospheric environments,especially those with heightened Cl^(−)concentrations.The meticulous compositional design plays a crucial role in establishing...Ni-advanced weathering steel holds paramount importance in marine atmospheric environments,especially those with heightened Cl^(−)concentrations.The meticulous compositional design plays a crucial role in establishing a rust layer capable of withstanding intrusion by Cl^(−),making it imperative for the viability of coating-free weathering steel in marine atmospheric environments.This study explores the corrosion evolution and corrosion-resistant mechanisms within a steady-state rust layer in 3Ni weathering steel,with a particular focus on the role of Mo in challenging marine atmospheric conditions.The findings unequivocally demonstrate that the augmentation of the protective properties of the rust layer is directly correlated with an increase in Mo content,transitioning from 0.5 to 1.5 wt.%.This transition is most evident in the reduction of the corrosion rate for the 3Ni-Mo steel,dropping from an initial 1.74 mm a^(−1)to a robust 1.31 mm a^(−1)after 768 h of corrosion exposure.The heightened Mo content expedites the formation of a stable and durable rust layer,significantly enriching the proportion ofα-FeOOH within this protective layer.The stabilized rust layer of 3Ni-Mo weathering steel exhibits a distinct three-layer structure,comprising an outer layer primarily ofγ-FeOOH,an intermediate layer mainly composed of Fe_(2)O_(3)/Fe_(3)O_(4),and an inner layer predominantly composed ofα-FeOOH andβ-FeOOH.Additionally,an alkaline interface enriched with NiFe_(2)O_(4)and CuFe_(2)O_(4)develops between the inner layer and the substrate.Firstly,Mo promotes the deposition of MoO_(2),MoO_(3),and molybdate on both the inner layer and alkaline steel-rust interface to repair corrosion pits and fill cracks.Secondly,Mo facilitates the generation of compounds such as NiFe_(2)O_(4)and CuFe_(2)O_(4),which heightens the electronegativity of the intermediate rust layer and the steel-rust interface,preventing Cl^(−)-induced interface acidification and pitting corrosion.The higher Mo content expedites the formation of this alkaline interface and promotes inner layer densification.Most significantly,Mo creates additional nucleation sites for hydroxide oxides through oxide formation,leading to the formation of nano-sizedα-FeOOH andβ-FeOOH within the inner layer thereby enhancing the stability and compactness of the inner layer.These synergistic effects fortify the resilience of 3Ni-Mo advanced weathering steel in corrosive environments,ultimately strengthening its capacity to withstand environmental challenges.展开更多
基金supported by the Joint Funds of National Key R&D Program of China(2018YFB0604603)the National Natural Science Foundation of China(21536009,21776229)+2 种基金Science and Technology Plan Projects of Shaanxi Province(2017ZDCXL-GY-10-03,2018ZDXMGY-167)The Young Science and Technology Star Project of Shaanxi Province(2017KJXX-62)Science and Technology Program of Yulin(2018-2-22)。
文摘The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.
基金the National Key R&D Program of China(No.2021YFB3701700)Gang Niu appreciates the support from the National Natural Science Foundation of China(No.52304389)+2 种基金Gang Niu and Huibin Wu appreciate the support from the Fundamental Research Funds for the Central Universities(No.FRFBD-23-01)Gang Niu appreciates the support from the China Postdoctoral Science Foundation(No.2022M720402)Na Gong appreciates the support from the Structural Metal Alloy Program(SMAP),Grant No.A18B1b0061,and Manufacturing of Multi-Material Net-Shape Parts with Heterogeneous Properties(MMNH),Grantno.M22K5a0045 inA∗STAR.
文摘Ni-advanced weathering steel holds paramount importance in marine atmospheric environments,especially those with heightened Cl^(−)concentrations.The meticulous compositional design plays a crucial role in establishing a rust layer capable of withstanding intrusion by Cl^(−),making it imperative for the viability of coating-free weathering steel in marine atmospheric environments.This study explores the corrosion evolution and corrosion-resistant mechanisms within a steady-state rust layer in 3Ni weathering steel,with a particular focus on the role of Mo in challenging marine atmospheric conditions.The findings unequivocally demonstrate that the augmentation of the protective properties of the rust layer is directly correlated with an increase in Mo content,transitioning from 0.5 to 1.5 wt.%.This transition is most evident in the reduction of the corrosion rate for the 3Ni-Mo steel,dropping from an initial 1.74 mm a^(−1)to a robust 1.31 mm a^(−1)after 768 h of corrosion exposure.The heightened Mo content expedites the formation of a stable and durable rust layer,significantly enriching the proportion ofα-FeOOH within this protective layer.The stabilized rust layer of 3Ni-Mo weathering steel exhibits a distinct three-layer structure,comprising an outer layer primarily ofγ-FeOOH,an intermediate layer mainly composed of Fe_(2)O_(3)/Fe_(3)O_(4),and an inner layer predominantly composed ofα-FeOOH andβ-FeOOH.Additionally,an alkaline interface enriched with NiFe_(2)O_(4)and CuFe_(2)O_(4)develops between the inner layer and the substrate.Firstly,Mo promotes the deposition of MoO_(2),MoO_(3),and molybdate on both the inner layer and alkaline steel-rust interface to repair corrosion pits and fill cracks.Secondly,Mo facilitates the generation of compounds such as NiFe_(2)O_(4)and CuFe_(2)O_(4),which heightens the electronegativity of the intermediate rust layer and the steel-rust interface,preventing Cl^(−)-induced interface acidification and pitting corrosion.The higher Mo content expedites the formation of this alkaline interface and promotes inner layer densification.Most significantly,Mo creates additional nucleation sites for hydroxide oxides through oxide formation,leading to the formation of nano-sizedα-FeOOH andβ-FeOOH within the inner layer thereby enhancing the stability and compactness of the inner layer.These synergistic effects fortify the resilience of 3Ni-Mo advanced weathering steel in corrosive environments,ultimately strengthening its capacity to withstand environmental challenges.
