The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the...The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pres surized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃ The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Rh-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.展开更多
Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon ...Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon atoms for an aluminium atomplus a phosphorus atom is predominant. Such substitution is limited in a certain domainof the crystal and "silicon rich" regions are thus generated. 1H MAS spectra reveal that asmall arnount of silicon atoms substitute phosphorus only and SiOHAl groups are formed,which provides the acidic source for the molecular sieves. Si-VPI-5 prepared with silicagel as the silicon source exhibits a higher content of SiOHAl groups than that preparedwith (EtO)4Si.展开更多
The sodium positions in the doped NASICON solld solution Na3Zr2-xYxSi2-x .P1+xO12 system were investigated by using 23Na NMR techniques. The results of NMR indicats that the surroundings of the sodium cations in compo...The sodium positions in the doped NASICON solld solution Na3Zr2-xYxSi2-x .P1+xO12 system were investigated by using 23Na NMR techniques. The results of NMR indicats that the surroundings of the sodium cations in compounds with different compositions are different because the network structures are disordered by replacement of Y3+ for Zr4+ ions in the crystal structure. While the composition x is small, the sodiam cations locate at two sites, Na(1) and Na(2) sites, in the structure. With x increasing,the surroundings of the sodium cations change and the position of the sodium cations is of only one kind at x=1.2. These results are important for understanding the crystal rule and the effect of the doped cation on the surroundings of the sodium cations in Na3Zr2-xYxSi2-xP1+xO12 solid state solution system.展开更多
文摘The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pres surized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃ The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Rh-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.
文摘Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon atoms for an aluminium atomplus a phosphorus atom is predominant. Such substitution is limited in a certain domainof the crystal and "silicon rich" regions are thus generated. 1H MAS spectra reveal that asmall arnount of silicon atoms substitute phosphorus only and SiOHAl groups are formed,which provides the acidic source for the molecular sieves. Si-VPI-5 prepared with silicagel as the silicon source exhibits a higher content of SiOHAl groups than that preparedwith (EtO)4Si.
文摘The sodium positions in the doped NASICON solld solution Na3Zr2-xYxSi2-x .P1+xO12 system were investigated by using 23Na NMR techniques. The results of NMR indicats that the surroundings of the sodium cations in compounds with different compositions are different because the network structures are disordered by replacement of Y3+ for Zr4+ ions in the crystal structure. While the composition x is small, the sodiam cations locate at two sites, Na(1) and Na(2) sites, in the structure. With x increasing,the surroundings of the sodium cations change and the position of the sodium cations is of only one kind at x=1.2. These results are important for understanding the crystal rule and the effect of the doped cation on the surroundings of the sodium cations in Na3Zr2-xYxSi2-xP1+xO12 solid state solution system.
