We have shown that MgO can be dispersed on γ Al 2O 3 with different loadings. The observed dispersion capacity of MgO on the surface of γ Al 2O 3 is higher than the theoretical monolayer dispersion val...We have shown that MgO can be dispersed on γ Al 2O 3 with different loadings. The observed dispersion capacity of MgO on the surface of γ Al 2O 3 is higher than the theoretical monolayer dispersion value. The surface area and the maximum in the pore size distribution gradually decrease with the increase in MgO content at low loadings. The surface area and the maximum in the pore size distribution of MgO/ γ Al 2O 3 decrease more rapidly when the MgO content is large because the pores of γ Al 2O 3 become blocked. When small amounts of MgO are dispersed on the surface of γ Al 2O 3, the catalyst is very active and shows a good selectivity for the synthesis of glycol ethers.展开更多
MCM 41 materials with a well ordered long range structure, a large pore size and a high surface area have been synthesized. Their surface properties including the number and the nature of the surface hydroxyl group...MCM 41 materials with a well ordered long range structure, a large pore size and a high surface area have been synthesized. Their surface properties including the number and the nature of the surface hydroxyl groups and surface hydrophobicity/hydrophilicity have been investigated by means of 29 Si MAS NMR and FT IR spectra and TPD of probe molecules. The results clearly show that the surface of MCM 41 has an abundance of acidic silanol groups, and that the hydrophobicity/hydrophilicity can be modified by the introduction of Al and transition metals Ti, Cr, Ni and Fe into it.展开更多
The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity ...The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity of CLDH decrease when CLDH reforms LDH- the so called 'memory effect'. The influence of the 'memory effect' on the CLDH returning to LDH was studied by the hydration reaction. It is shown that the 'memory effect' is not complete, and the decreases of the Mg/Al molar ratio of LDH and the crystallite size due to the increase of the hydration reaction time result in the drop of the activity and the selectivity.展开更多
文摘We have shown that MgO can be dispersed on γ Al 2O 3 with different loadings. The observed dispersion capacity of MgO on the surface of γ Al 2O 3 is higher than the theoretical monolayer dispersion value. The surface area and the maximum in the pore size distribution gradually decrease with the increase in MgO content at low loadings. The surface area and the maximum in the pore size distribution of MgO/ γ Al 2O 3 decrease more rapidly when the MgO content is large because the pores of γ Al 2O 3 become blocked. When small amounts of MgO are dispersed on the surface of γ Al 2O 3, the catalyst is very active and shows a good selectivity for the synthesis of glycol ethers.
基金Supported by the National Natural Science Foundation of China(No. 2 0 1730 0 3) and State Key Basic Research Projectof China(No. 2 0 0 0 0 4 80 0 9)
文摘MCM 41 materials with a well ordered long range structure, a large pore size and a high surface area have been synthesized. Their surface properties including the number and the nature of the surface hydroxyl groups and surface hydrophobicity/hydrophilicity have been investigated by means of 29 Si MAS NMR and FT IR spectra and TPD of probe molecules. The results clearly show that the surface of MCM 41 has an abundance of acidic silanol groups, and that the hydrophobicity/hydrophilicity can be modified by the introduction of Al and transition metals Ti, Cr, Ni and Fe into it.
文摘The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity of CLDH decrease when CLDH reforms LDH- the so called 'memory effect'. The influence of the 'memory effect' on the CLDH returning to LDH was studied by the hydration reaction. It is shown that the 'memory effect' is not complete, and the decreases of the Mg/Al molar ratio of LDH and the crystallite size due to the increase of the hydration reaction time result in the drop of the activity and the selectivity.
