多相—匀相杂合催化剂L-Rh/SiO_2上烯烃氢甲酰化的研究
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摘要
多相催化和匀相催化是催化领域的两大类型。前者具有易分离的特点。而后者具有高活性、高选择性和反应条件温和等优点，在烯烃氢甲酰化方面有重要应用。然而，匀相催化剂和产品的分离是困扰氢甲酰化工业生产的一大难题。本论文研制了一种新型烯烃氢甲酰化催化剂。
本文利用有机-无机杂化的概念，首次用有机膦配体L的电子效应直接修饰多相催化剂Rh／SiO_2制备L-Rh／SiO_2多相-匀相杂合催化剂。在浆态床烯烃氢甲酰化反应中，发现该催化剂在373K、1.0MPa的温和条件下具有高活性、高选择性，远远高于Rh／SiO_2的活性和选择性，与相应的匀相催化剂性能相当。其中P(OPh)_3-Rh／SiO_2上1-己烯氢甲酰化的TOF(转换频率)高达5184h~(-1)，比Rh／SiO_2多相催化剂的活性提高上百倍。
利用TG、~31P MAS NMR、XPS、TPD和FTIR表征技术，对L-Rh／SiO_2催化剂进行了表征。发现L-Rh／SiO_2催化剂上配体L和表面Rh原子存在配位作用。考察了CO、H_2和C_2H_4在PPh_3-Rh／SiO_2上吸附及作用状态。首次发现PPh_3-Rh／SiO_2气固相氢甲酰化中，Rh原子配位PPh_3后的线式吸附CO是烯烃氢甲酰化活性中心。
用水溶性配体TPPTS改性Rh／SiO_2制备了水／有机和支撑水相TPPTS-Rh／SiO_2催化剂体系。在支撑水相TPPTS-Rh/SiO_2催化体系基础上，研制了复合负载金属-支撑水相催化剂SAP／M-SiO_2，研究了多相和匀相组分间的协同作用。
The field of catalysis is mainly divided into heterogeneous one and homogeneous one. The former has the advantage of easy separation of catalysts from the products; the latter can be operated under mild conditions with high activity and selectivity, especially in the olefins hydroformylation process. However, homogeneous catalysts are difficult to be recovered from hydroformylation products. In this paper, a kind of new catalysts for olefins hydroformylation was studied.
For the first time, an idea of organic-inorganic hybrid catalysis leads to the originality of a hybrid of heterogeneous and homogeneous catalysts. The organic phosphine ligands (L) were directly used to modify the Rh/SiO2 to prepare L-Rh/SiO2 catalysts for olefins hydroformylation. The results showed that the catalytic performances of hydroformylation over L-Rh/SiO2 catalyst were higher than those of Rh/SiO2 catalyst, and were comparable to those of the corresponding homogeneous catalysts. The TOF of 1-hexene hydroformylation over P(OPh)3-Rh/SiO2 catalyst was up to 51841h-1, which was hundreds of times as many as that of Rh/SiO2 catalyst.
By means of TG, 31PMAS NMR, XPS, TPD and FTIR techniques for the characterization of L-Rh/SiO2 catalysts, the coordination bond between phosphine ligands and Rh atom and the valence state of the surfacial Rh are made clear before and after the CO/H2 adsorbed on the PPh3-Rh/Si02. Through the IR characterization of adsorption state of CO, H2 and C2L4 on PPh4-Rh/SiO2 under reaction conditions,
it is found that linearly CO bonded on Rh coordinated with PPh3 ligands is the catalytic active site of PPh3-Rh/SiO2 catalyst for ethylene hydroformylation under gas-solid phase conditions.
The water-soluble TPPTS ligand is employed to coordinate Rh/SiO2 to prepare the TPPTS-Rh/SiO2 catalyst, which is usble in water-oil biphasic and supported aqueous-phase catalysis system. Finally, The combined supported metal and supported aqueous-phase (SAP/M-SiO2) catalysts were prepared by immobilizing the homogeneous catalytic phase in the pores of supported metal catalysts. Synergistic assistance of heterogeneous component for SAP component on SAP/M-SiO2 catalysts was also investigated.
本文利用有机-无机杂化的概念，首次用有机膦配体L的电子效应直接修饰多相催化剂Rh／SiO_2制备L-Rh／SiO_2多相-匀相杂合催化剂。在浆态床烯烃氢甲酰化反应中，发现该催化剂在373K、1.0MPa的温和条件下具有高活性、高选择性，远远高于Rh／SiO_2的活性和选择性，与相应的匀相催化剂性能相当。其中P(OPh)_3-Rh／SiO_2上1-己烯氢甲酰化的TOF(转换频率)高达5184h~(-1)，比Rh／SiO_2多相催化剂的活性提高上百倍。
利用TG、~31P MAS NMR、XPS、TPD和FTIR表征技术，对L-Rh／SiO_2催化剂进行了表征。发现L-Rh／SiO_2催化剂上配体L和表面Rh原子存在配位作用。考察了CO、H_2和C_2H_4在PPh_3-Rh／SiO_2上吸附及作用状态。首次发现PPh_3-Rh／SiO_2气固相氢甲酰化中，Rh原子配位PPh_3后的线式吸附CO是烯烃氢甲酰化活性中心。
用水溶性配体TPPTS改性Rh／SiO_2制备了水／有机和支撑水相TPPTS-Rh／SiO_2催化剂体系。在支撑水相TPPTS-Rh/SiO_2催化体系基础上，研制了复合负载金属-支撑水相催化剂SAP／M-SiO_2，研究了多相和匀相组分间的协同作用。
The field of catalysis is mainly divided into heterogeneous one and homogeneous one. The former has the advantage of easy separation of catalysts from the products; the latter can be operated under mild conditions with high activity and selectivity, especially in the olefins hydroformylation process. However, homogeneous catalysts are difficult to be recovered from hydroformylation products. In this paper, a kind of new catalysts for olefins hydroformylation was studied.
For the first time, an idea of organic-inorganic hybrid catalysis leads to the originality of a hybrid of heterogeneous and homogeneous catalysts. The organic phosphine ligands (L) were directly used to modify the Rh/SiO2 to prepare L-Rh/SiO2 catalysts for olefins hydroformylation. The results showed that the catalytic performances of hydroformylation over L-Rh/SiO2 catalyst were higher than those of Rh/SiO2 catalyst, and were comparable to those of the corresponding homogeneous catalysts. The TOF of 1-hexene hydroformylation over P(OPh)3-Rh/SiO2 catalyst was up to 51841h-1, which was hundreds of times as many as that of Rh/SiO2 catalyst.
By means of TG, 31PMAS NMR, XPS, TPD and FTIR techniques for the characterization of L-Rh/SiO2 catalysts, the coordination bond between phosphine ligands and Rh atom and the valence state of the surfacial Rh are made clear before and after the CO/H2 adsorbed on the PPh3-Rh/Si02. Through the IR characterization of adsorption state of CO, H2 and C2L4 on PPh4-Rh/SiO2 under reaction conditions,
it is found that linearly CO bonded on Rh coordinated with PPh3 ligands is the catalytic active site of PPh3-Rh/SiO2 catalyst for ethylene hydroformylation under gas-solid phase conditions.
The water-soluble TPPTS ligand is employed to coordinate Rh/SiO2 to prepare the TPPTS-Rh/SiO2 catalyst, which is usble in water-oil biphasic and supported aqueous-phase catalysis system. Finally, The combined supported metal and supported aqueous-phase (SAP/M-SiO2) catalysts were prepared by immobilizing the homogeneous catalytic phase in the pores of supported metal catalysts. Synergistic assistance of heterogeneous component for SAP component on SAP/M-SiO2 catalysts was also investigated.
引文
[1] 王桂茹．催化剂与催化作用．大连：大连理工大学出版社，2000．6-8
[2] M. Barteau, et al. Future directions of catalysis science-Workshop. Catal Lett, 2001, 76(3-4): 111-124
[3] G. A. Petsko. Design by necessity. Nature, 2000, (403): 606-607
[4] F. R. Hartley. Supported Metal Complexes, Dordrecht: D.Reidel Publishing Company, 1985
[2] M. Barteau, et al. Future directions of catalysis science-Workshop. Catal Lett, 2001, 76(3-4): 111-124
[3] G. A. Petsko. Design by necessity. Nature, 2000, (403): 606-607
[4] F. R. Hartley. Supported Metal Complexes, Dordrecht: D.Reidel Publishing Company, 1985