Preparation,Characterization and Catalytic Properties of Mesoporous Molecular Sieve Modified by A1and Zr
|Keywords||Mesoporous molecular sieves Modification Catalytic Esterification Palmitic acid methyl ester|
Mesoporous molecular sieve SBA-15was synthesized under acidic conditions by usingnon-ionic surfactant P123as the template and tetraethoxysilane（TEOS） as the silica source.Mesoporous molecular sieve MCM-41was synthesized under alkaline conditions by usingcetyltrimethylammonium bromide as the template and TEOS as the silica source. UsingSBA-15and MCM-41as carriers, solid acid catalysts of SO42-/Al2O3-ZrO2/SBA-15andSO42-/Al2O3-ZrO2/MCM-41were prepared with methods of urea hydrolysis and impregnation.The synthesis conditions for catalysts were investigated by experiments. The preparationconditions of SO42-/Al2O3-ZrO2/SBA-15was that the mass fraction of ZrO2loaded onSBA-15was30%，concentration of sulfuric acid solution0.5mol/L, calcination temperatureof550℃and calcination time of3h. The synthesis conditions of SO42-/Al2O3-ZrO2/MCM-41was that the mass fraction of ZrO2Loaded on MCM-41was40%, concentration of sulfuricacid solution0.5mol/L, calcination temperature of550℃and calcination time4h.The skeleton structure, apparent morphology and pore structure of solid acid catalystabove were characterizied by methods of IR,TG-DTG,XRD,SEM and N2adsorption-desorption techniques. The characterization results indicated that the modifiedmesoporous materials were still typical mesoporous structure and did not change mesoporouschannel structure of molecular sieve. The two solid acid catalysts showed good catalyticactivity in the reaction of palmitic acid methylester.The optimum conditions for theesterification over SO42-/Al2O3-ZrO2/SBA-15as catalyst were that the amount of catalyst1.2g, reaction time9h, molar ratio of acid to alcohol1:12.The optimum conditions forSO42-/Al2O3-ZrO2/MCM-41as catalyst were that the amount of catalyst1.0g, reaction time10h, molar ratio of acid to alcohol1:14.