MCM-41 zeolite and Iron (Ⅱ) -Phen/MCM-41 zeolite have been preparedand characterized by XRD,IR, NH3-TPD, BET and UV-Vis. The Iron(Ⅱ)-Phen/MCM-41 zeolite+30% H2O2 system is capable for catalyzing hydroxylation of Phe...MCM-41 zeolite and Iron (Ⅱ) -Phen/MCM-41 zeolite have been preparedand characterized by XRD,IR, NH3-TPD, BET and UV-Vis. The Iron(Ⅱ)-Phen/MCM-41 zeolite+30% H2O2 system is capable for catalyzing hydroxylation of Phenol.展开更多
In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initia...In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied.The results of XRD,TEM N_2-adsorption-desorption,NH_3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals,and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5.Catalytic cracking of n-dodecane(550℃,4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance,with the improvement higher than 87%in the catalytic activities and 21%in the deactivation rate compared with untreated zeolites.This could be ascribed to their suitable pore structure,which enhanced the diffusion of reactant molecules in pores of catalysts.展开更多
The reaction mechanism for alkylation of benzene with propylene over the β zeolite and the MCM-22 zeolite were investigated respectively by in-situ IR spectrometry. Three types of experiments were carried out. （1） ...The reaction mechanism for alkylation of benzene with propylene over the β zeolite and the MCM-22 zeolite were investigated respectively by in-situ IR spectrometry. Three types of experiments were carried out. （1） IR spectra of the gas-phase propylene, benzene and isopropyl benzene were recorded. （2） IR spectra of the above-mentioned substances as adsorbates that have combined with the zeolite wafer were recorded. （3） IR spectra of the reaction modes were recorded. The test results showed that the alkytation reaction over the zeolite β was ascribed to the mechanism of carbonium ions, whereas the alkylation reaction over the zeolite MCM-22 was ascribed to the synchronous reaction mechanism.展开更多
The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure o...The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure on the performance of MCM-22 zeolite for catalytic skeletal isomerization of 1-hexene was examined. The experimental results showed that at a steam treatment temperature of 500℃, a reaction temperature of 270℃, a space velocity of 1.0 h-1 and a reaction pressure of 0.2 MPa, the MCM-22 zeolite exhibited excellent performance for catalytic skeletal isomerization of 1-hexene with the i-hexene yield reaching 66.15%. Compared with other commonly used molecular sieve catalysts, the MCM-22 zeolite catalyst exhibited better catalytic performance for skeletal isomerization of 1-hexene.展开更多
文摘MCM-41 zeolite and Iron (Ⅱ) -Phen/MCM-41 zeolite have been preparedand characterized by XRD,IR, NH3-TPD, BET and UV-Vis. The Iron(Ⅱ)-Phen/MCM-41 zeolite+30% H2O2 system is capable for catalyzing hydroxylation of Phenol.
基金Supported by the National Natural Science Foundation of China(U123213421306132)the Doctoral Program of Higher Education(20120032120008)
文摘In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied.The results of XRD,TEM N_2-adsorption-desorption,NH_3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals,and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5.Catalytic cracking of n-dodecane(550℃,4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance,with the improvement higher than 87%in the catalytic activities and 21%in the deactivation rate compared with untreated zeolites.This could be ascribed to their suitable pore structure,which enhanced the diffusion of reactant molecules in pores of catalysts.
文摘The reaction mechanism for alkylation of benzene with propylene over the β zeolite and the MCM-22 zeolite were investigated respectively by in-situ IR spectrometry. Three types of experiments were carried out. （1） IR spectra of the gas-phase propylene, benzene and isopropyl benzene were recorded. （2） IR spectra of the above-mentioned substances as adsorbates that have combined with the zeolite wafer were recorded. （3） IR spectra of the reaction modes were recorded. The test results showed that the alkytation reaction over the zeolite β was ascribed to the mechanism of carbonium ions, whereas the alkylation reaction over the zeolite MCM-22 was ascribed to the synchronous reaction mechanism.
文摘The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure on the performance of MCM-22 zeolite for catalytic skeletal isomerization of 1-hexene was examined. The experimental results showed that at a steam treatment temperature of 500℃, a reaction temperature of 270℃, a space velocity of 1.0 h-1 and a reaction pressure of 0.2 MPa, the MCM-22 zeolite exhibited excellent performance for catalytic skeletal isomerization of 1-hexene with the i-hexene yield reaching 66.15%. Compared with other commonly used molecular sieve catalysts, the MCM-22 zeolite catalyst exhibited better catalytic performance for skeletal isomerization of 1-hexene.
