In order to improve the scheelite flotation with sodium oleate(NaOL),the effect of a non-ionic polyoxyethylene ether(JFC-5)on the floatability of scheelite was investigated through flotation experiments at10°C,co...In order to improve the scheelite flotation with sodium oleate(NaOL),the effect of a non-ionic polyoxyethylene ether(JFC-5)on the floatability of scheelite was investigated through flotation experiments at10°C,compared with60mg/L NaOL alone,the recovery of scheelite is improved from22%to85%in the presence of JFC-5with a mass ratio of20%at pH10.Moreover,the resistance to Ca2+of NaOL is increased.The adsorption mechanism was analyzed by zeta potential measurement,contact angle measurement and X-ray photoelectron spectroscopy(XPS)analysis.The results show that the adsorption of NaOL on scheelite surface is enhanced after adding JFC-5due to the more negative zeta potentials and larger contact angles of scheelite.And the co-adsorption of NaOL and JFC-5is confirmed by XPS analysis,so it is indicated that the adsorption of JFC-5decreases the electrostatic repulsion between the oleate ions,resulting in the stronger adsorption of NaOL on scheelite surface.In short,the mixed NaOL/JFC-5collector can effectively improve scheelite flotation.展开更多
The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques inc...The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.展开更多
基金Project(2016RS2016)supported by Hunan Provincial Science and Technology Leader(Innovation Team of Interface Chemistry of Efficient and Clean Utilization of Complex Mineral Resources)China
文摘In order to improve the scheelite flotation with sodium oleate(NaOL),the effect of a non-ionic polyoxyethylene ether(JFC-5)on the floatability of scheelite was investigated through flotation experiments at10°C,compared with60mg/L NaOL alone,the recovery of scheelite is improved from22%to85%in the presence of JFC-5with a mass ratio of20%at pH10.Moreover,the resistance to Ca2+of NaOL is increased.The adsorption mechanism was analyzed by zeta potential measurement,contact angle measurement and X-ray photoelectron spectroscopy(XPS)analysis.The results show that the adsorption of NaOL on scheelite surface is enhanced after adding JFC-5due to the more negative zeta potentials and larger contact angles of scheelite.And the co-adsorption of NaOL and JFC-5is confirmed by XPS analysis,so it is indicated that the adsorption of JFC-5decreases the electrostatic repulsion between the oleate ions,resulting in the stronger adsorption of NaOL on scheelite surface.In short,the mixed NaOL/JFC-5collector can effectively improve scheelite flotation.
文摘The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.
