ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve...ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N_2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h^(-1),and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.展开更多
This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized...This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P> 0.05) at 95% confidence level,evaluated by SPSS analysis.展开更多
Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental result...Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental results show that the synergy effect of Phen and TTA exists in Eu^(3+) complexes. But when the ligands of Bipy and TTA coexist in europium complex, the synergy effect does not exist. If a solution of a europium complex has a specific electron configuration of excited state, the solution of the complex has an intensity of fluorescence and a quantum yield. 2.5×10^(-5) mol·L^(-1) Eu(Phen)_2(TTA)_2(NO_3)_3 solution (λ_(ex)=347.0 nm) possesses a maximal quantum yield (0.25) and the strongest fluorescent intensity. The nanosized mesoporous molecular sieves possess spherical cage structure that is fit for preparation of composite materials with encapsulation method. The research results of XRD and IR show that the guest molecule is encapsulated into the channels of the host. The thermostability of the guest molecule in the channels of the host (CH_3)_3Si-MCM-41 is enhanced. The fluorescent intensity and the half-life of nanosized composites of (CH_3)_3Si-MCM-41 and Eu^(3+) complexes are stronger and longer than those of encapsulation products of MCM-41 and Eu^(3+) complexes. Supramolecular encapsulation products emit characteristic radiation of Eu^(3+) ion, vesting in the transitions of (()~5D_0→()~7F_J) (J=0, 1, 2, 3, 4), respectively; each excitation peak of fluorescent spectra of the composites is assigned to an excited electron configuration of Eu^(3+) ion. The host with lipophilic channels is more favourable to fluorescence of the rare earth complex than hydrophilic mesoporous molecular sieve; The fluorescent intensity of (CH_3)_3Si-MCM-41-Eu(Phen)(TTA)_3(NO_3)_3 can match with that of Eu(Phen)(TTA)_3(NO_3)_3 powder sample. These results could be assumed to result from strong radiation absorption of the guest complex molecule (blue shift of maximum excitation wavelength), greatly reducing of silanol group vibration relaxation of the host (CH_3)_3Si-MCM-41, energy transfer from host to guest, and presence of discrete luminescent center associated with nanosized material structures. The selectivity of host to guest and the interaction between the host and the guest influence greatly the luminescent properties of supramolecular system.展开更多
文摘ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N_2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h^(-1),and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.
基金The financial supported by Nakhon Ratchasima Rajabhat University,Nakhon Ratchasimathe National Research Council of Thailand+3 种基金Center of Excellence for Innovation in Chemistry (PERCH-CIC)Office of the Higher Education CommissionMinistry of Education and Materials Chemistry Research CenterDepartment of Chemistry Faculty of Science,Khon Kaen University,Thailand
文摘This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P> 0.05) at 95% confidence level,evaluated by SPSS analysis.
文摘Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental results show that the synergy effect of Phen and TTA exists in Eu^(3+) complexes. But when the ligands of Bipy and TTA coexist in europium complex, the synergy effect does not exist. If a solution of a europium complex has a specific electron configuration of excited state, the solution of the complex has an intensity of fluorescence and a quantum yield. 2.5×10^(-5) mol·L^(-1) Eu(Phen)_2(TTA)_2(NO_3)_3 solution (λ_(ex)=347.0 nm) possesses a maximal quantum yield (0.25) and the strongest fluorescent intensity. The nanosized mesoporous molecular sieves possess spherical cage structure that is fit for preparation of composite materials with encapsulation method. The research results of XRD and IR show that the guest molecule is encapsulated into the channels of the host. The thermostability of the guest molecule in the channels of the host (CH_3)_3Si-MCM-41 is enhanced. The fluorescent intensity and the half-life of nanosized composites of (CH_3)_3Si-MCM-41 and Eu^(3+) complexes are stronger and longer than those of encapsulation products of MCM-41 and Eu^(3+) complexes. Supramolecular encapsulation products emit characteristic radiation of Eu^(3+) ion, vesting in the transitions of (()~5D_0→()~7F_J) (J=0, 1, 2, 3, 4), respectively; each excitation peak of fluorescent spectra of the composites is assigned to an excited electron configuration of Eu^(3+) ion. The host with lipophilic channels is more favourable to fluorescence of the rare earth complex than hydrophilic mesoporous molecular sieve; The fluorescent intensity of (CH_3)_3Si-MCM-41-Eu(Phen)(TTA)_3(NO_3)_3 can match with that of Eu(Phen)(TTA)_3(NO_3)_3 powder sample. These results could be assumed to result from strong radiation absorption of the guest complex molecule (blue shift of maximum excitation wavelength), greatly reducing of silanol group vibration relaxation of the host (CH_3)_3Si-MCM-41, energy transfer from host to guest, and presence of discrete luminescent center associated with nanosized material structures. The selectivity of host to guest and the interaction between the host and the guest influence greatly the luminescent properties of supramolecular system.
