Preparation, Characterization And Performance Study Of Modified MCM-41Mesoporous Molecular Sieves

MCM-41mesoporous molecular sieves possess high surface areas, well-orderedpore structures and modifiable hole surface, which are widely applied in the fields ofadsorption, separation, catalysis, and so on. The performance of MCM-41will beimproved greatly after modification. In this paper, MCM-41mesoporous materials withdoping Pd, Cu and loading HPW （phosphotungstic acid） were synthesized and used incatalytic and adsorption reactions. The structure of mesoporous materials werecharacterized by using various analytical techniques, such as X-ray diffraction （XRD）,infrared spectrum （FT-IR）, scanning electron microscopy （SEM）, N₂adsorption-desorption and atomic absorption （AAS）. These mesoporous materials wereapplied in catalytic and adsorption respectively, this paper includs the following threeparts of contents:Mesoporous molecular sieve with various of palladium （Pd-MCM-41） weresynthesized by one step method assisted with microwave, Heck Vinylation wasperformed to explore the effect of amount of base, reaction temperature, reaction timeand amount of catalyst on the catalytic performance of Pd-MCM-41. In solvent-freecondition, the catalytic efficiency of Heck reaction with triethylamine as base was96%using5.21wt%Pd-MCM-41for2h at100℃. The greater the Pd content is, the higherthe cinnamic acid yield will be. The catalyst was recovered and the yield was obtainedto be87%in five cycles. The results indicated that the Pd-MCM-41shows remarkablecatalytic activity toward Heck reaction and can be recycled for repeated use.Mesoporous molecular sieve with various of copper （Cu-MCM-41） weresynthesized by one step method in room temperature. The adsorbent dosage, initialconcentration of MB and reaction time were studied to explore the effect ofCu-MCM-41for the removal of MB （methylene blue）. The adsorption rates of15mg L-1MB by10mg of Cu-MCM-41-1, Cu-MCM-41-2, and Cu-MCM-41-3werefound to be93%,94%, and97%respectively at30min. The Cu content had a certaininfluence on the removal of MB that the adsorption rate was improved greatly withincrease of Cu. The adsorption mechanism on MB was discussed briefly in the end.HPW was loaded in MCM-41and Cu-MCM-41. The adsorbent dosage, the solutionof pH, reaction time and initial concentration of RB were studied to explore the effect ofmaterials for the removal of RB （Rhodamine B）. A preliminary study suggested the adsorption capacity of Cu-MCM-41was better than that of HPW-MCM-41,Cu-HPW-MCM-41and MCM-41. The adsorption rate of10mg·L-1RB by15mg ofCu-MCM-41was found to be97%at pH=7. The final results indicated thatCu-MCM-41was a kind of excellent adsorbent for the removal of MB and RB, and thismaterial was suitable for the treatment of dye wastewater.