The bimetallic catalyst Ru-Pt/ γ -Al 2O 3 was prepared by impregnating H 2PtCl 6 and RuCl 3 aqueous solution in the presence of PVP(40 000). Its catalytic performance in selective hydrogenation of \{ p -chloronitrobe...The bimetallic catalyst Ru-Pt/ γ -Al 2O 3 was prepared by impregnating H 2PtCl 6 and RuCl 3 aqueous solution in the presence of PVP(40 000). Its catalytic performance in selective hydrogenation of \{ p -chloronitrobenzene\}( p -CNB) was studied. The results indicate that the activity of Ru-Pt/ γ -Al 2O 3[\{ n (ruthenium)\}∶ n (platinum)=4∶1] is much higher than that of Ru/ γ -Al 2O 3,while the amount of dehalogenation product(aniline) and other by-products are much fewer than that by using Pt/ γ -Al 2O 3 as the catalyst. There is synergistic effect of ruthenium and platinum in bimetallic catalyst for selective hydrogenation of p -CNB. Under the reaction conditions t =50 ℃, p H 2 = 1.0 MPa, reaction time 60 min,\{ n (substrate)∶\} n (total amount of metal content)=1000∶1,the conversion of p -CNB and the selectivity to p -chloroaniline( p -CNA) by using Ru-Pt/ γ -Al 2O 3 as the catalyst are 48.2% and 85.9%,respectively. The effect of other metal cations(introduced to the reaction system with the corresponding metal chloride solution) on the reaction was investigated. It was found that catalytic performance of Ru-Pt/ γ -Al 2O 3 could be greatly improved by modfication of some metal cations. When Co 2+ and Ni 2+ were used as modifiers for the catalyst Ru-Pt/ γ -Al 2O 3 under above mentioned reaction conditions,the conversions of p -CNB increase to 74.5% and 87.8%,as well as the selectivities of p -CAN increase to 98.9% and 99.4%,respectively. Fe 3+ and Sn 4+ were the best modifiers for Ru-Pt/ γ -Al 2O 3 under the same reaction conditions. The conversions of p -CNB and the selectivities of p -CAN can reach 100% and >99.0%,respectively. However,the catalysts can be poisoned by Zn 2+ and Sn 2+ .展开更多
The effects of different surfactants (cationic, anionic and nonionic) on 1 dodecene hydroformylation catalyzed by water soluble rhodium TPPTS [P( m C 6H 4SO 3Na) 3] complex in two phase catalytic system were studied. ...The effects of different surfactants (cationic, anionic and nonionic) on 1 dodecene hydroformylation catalyzed by water soluble rhodium TPPTS [P( m C 6H 4SO 3Na) 3] complex in two phase catalytic system were studied. The results showed that the cationic surfactant efficiently increased the reaction rate, owing to the solubilization of olefin in micelle and owing to the electrostatic interaction between the positive micelle and the negative catalytic active intermediates, HRh(CO) x [P( m C 6H 4SO 3) 3] n 3n- , which favored the coordination with olefin. The nonionic surfactant, which has only the solubilization for olefin, just increased slightly the rate. However, the anionic surfactant inhibited the reaction owing to the electrostatic repulsion between the negative micelle and the catalytic active intermediates. When the benzene sulfonated salt substituted by hydrophobic group was added, the molar ratio of normal aldehyde to iso aldehyde increased dramatically from 6 5 to 22 3 for 1 dodecene hydroformylation in the presence of cetyltrimethylammonium bromide (CTAB). This may be attributed to the formation of tighter micelle caused by the insertion of the substituted benzene sulfonate into the palisade layer, which favored the formation of normal aldehyde with lower steric hindrance. The fact that the addition of substituted benzene sulfonate could not improve the regioselectivity for normal aldehyde in the presence of benzyltetradecyldimethylammoniun chloride (BDAC) supported the above hypothesis, because BDAC has larger cationic head and favors the formation of iso aldehyde than CTAB, therefore, the combination of the proper additives could attain highly regioselective hydroformylation in two phase catalytic system.展开更多
文摘The bimetallic catalyst Ru-Pt/ γ -Al 2O 3 was prepared by impregnating H 2PtCl 6 and RuCl 3 aqueous solution in the presence of PVP(40 000). Its catalytic performance in selective hydrogenation of \{ p -chloronitrobenzene\}( p -CNB) was studied. The results indicate that the activity of Ru-Pt/ γ -Al 2O 3[\{ n (ruthenium)\}∶ n (platinum)=4∶1] is much higher than that of Ru/ γ -Al 2O 3,while the amount of dehalogenation product(aniline) and other by-products are much fewer than that by using Pt/ γ -Al 2O 3 as the catalyst. There is synergistic effect of ruthenium and platinum in bimetallic catalyst for selective hydrogenation of p -CNB. Under the reaction conditions t =50 ℃, p H 2 = 1.0 MPa, reaction time 60 min,\{ n (substrate)∶\} n (total amount of metal content)=1000∶1,the conversion of p -CNB and the selectivity to p -chloroaniline( p -CNA) by using Ru-Pt/ γ -Al 2O 3 as the catalyst are 48.2% and 85.9%,respectively. The effect of other metal cations(introduced to the reaction system with the corresponding metal chloride solution) on the reaction was investigated. It was found that catalytic performance of Ru-Pt/ γ -Al 2O 3 could be greatly improved by modfication of some metal cations. When Co 2+ and Ni 2+ were used as modifiers for the catalyst Ru-Pt/ γ -Al 2O 3 under above mentioned reaction conditions,the conversions of p -CNB increase to 74.5% and 87.8%,as well as the selectivities of p -CAN increase to 98.9% and 99.4%,respectively. Fe 3+ and Sn 4+ were the best modifiers for Ru-Pt/ γ -Al 2O 3 under the same reaction conditions. The conversions of p -CNB and the selectivities of p -CAN can reach 100% and >99.0%,respectively. However,the catalysts can be poisoned by Zn 2+ and Sn 2+ .
文摘The effects of different surfactants (cationic, anionic and nonionic) on 1 dodecene hydroformylation catalyzed by water soluble rhodium TPPTS [P( m C 6H 4SO 3Na) 3] complex in two phase catalytic system were studied. The results showed that the cationic surfactant efficiently increased the reaction rate, owing to the solubilization of olefin in micelle and owing to the electrostatic interaction between the positive micelle and the negative catalytic active intermediates, HRh(CO) x [P( m C 6H 4SO 3) 3] n 3n- , which favored the coordination with olefin. The nonionic surfactant, which has only the solubilization for olefin, just increased slightly the rate. However, the anionic surfactant inhibited the reaction owing to the electrostatic repulsion between the negative micelle and the catalytic active intermediates. When the benzene sulfonated salt substituted by hydrophobic group was added, the molar ratio of normal aldehyde to iso aldehyde increased dramatically from 6 5 to 22 3 for 1 dodecene hydroformylation in the presence of cetyltrimethylammonium bromide (CTAB). This may be attributed to the formation of tighter micelle caused by the insertion of the substituted benzene sulfonate into the palisade layer, which favored the formation of normal aldehyde with lower steric hindrance. The fact that the addition of substituted benzene sulfonate could not improve the regioselectivity for normal aldehyde in the presence of benzyltetradecyldimethylammoniun chloride (BDAC) supported the above hypothesis, because BDAC has larger cationic head and favors the formation of iso aldehyde than CTAB, therefore, the combination of the proper additives could attain highly regioselective hydroformylation in two phase catalytic system.
