Mesoporous MCM-41 materials modified by zinc have been prepared by non hydrothermal procedure. Zinc has been introduced by the direct synthesis (DS), template ion-exchange (TIE) and wet impregnation (WI) methods. The catalysts were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy-scanning electron microscopy (EDX-SEM), thermogravimetric and differential thermal analyses (TGA-DTA), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption/desorption measurements. The obtained catalysts were investigated for hydration of CO2 and its precipitation as CaCO3 at room temperature. We investigated the effect of synthesis method and cationic template on catalytic activity of Zn/MCM-41 catalysts. The results showed that template containing Zn/MCM-41 prepared by template ion exchange technique has high CO2 hydration activity. This high activity is due to the presence of strong basic sites. It was also found that this catalyst can be easily recovered from the reaction mixture and reused without activation.

Abstract: Two approaches for metal ion incorporation were employed to introduce Zn into MCM-41; Direct Synthesis (DS) and Wet Impregnation (WI). The ionic template was removed by two different methods: calcination and solvent extraction. For comparison, a series of template-containing mesoporous Zn/MCM-41 was also synthesized without surfactant removal. The catalysts were examined in a three component reaction to afford benzoxanthene derivative. The templae-containing Zn/MCM-41 showed particularly the highest activity. This activity is due to both Lewis acid sites and the ionic template. This catalyst could be reused without loss of its catalytic activity because the organic template does not leach during the reaction. It is also very efficient for the synthesis of a hydroxanthene derivative.

Resumen: Para introducir Zn en MCM-41 se utilizaron dos estrategias: la síntesis directa (DS) y la impregnación húmeda (WI). Se sintetizaron series de materiales Zn/MCM-41 con plantilla y sin ella. En algunos sólidos la plantilla se eliminó ya sea por calcinación o por extracción por solventes. Los sólidos se examinaron en la reacción de tres componentes para obtener los bensoxantenos. El catalizador con plantilla mostró la mayor actividad, que se explica en términos de la presencia tnato de sitios ácidos de Lewis como de la plantilla iónica. Este catalizador se volvió a utilizar sin pérdida en la actividad catalítica debido a que la plantilla no se lixivia durante la reacción. También se encontró que este catalizador es útil para la síntesis de derivados hidroxantenos.

Tetra-sulfoftalocianina de cobalto (CoPcS) foi ancorada quimicamente à superfície das MCM-41 e MCM-48 modificadas com aminas. Estas sílicas mesoporosas foram preparadas por processo hidrotérmico. Misturas físicas de CoPc em MCM-41 e em MCM-48 também foram preparadas para fins de comparação. Os quatro catalisadores preparados, 10 wt.% CoPcS/NH2-MCM-41, 10 wt.% CoPcS/NH2-MCM-48, 10 wt.% CoPc/MCM-41 e 10 wt.% CoPc/MCM-48 foram caracterizados por difratometria de raios X (XRD), espectroscopia de reflectância difusa UV-Vis e análise de superfície específica BET. A atividade catalítica dos catalisadores imobilizados foi testada na epoxidação aeróbica de cicloexeno. CoPcS/NH2-MCM-41 e CoPcS/NH2-MCM-48 mostraram relativamente elevada seletividade para epóxido, mas baixa conversão de cicloexeno comparada a CoPc/MCM-41 e CoPc/MCM-48. Nenhum processo lixiviação da metaloftalocianina dos catalisadores imobilizados por ligação química foi observado no meio reacional e esses catalisadores puderam ser reutilizados quatro vezes.

Cobalt tetrasulfophthalocyanine (CoPcS) was chemically anchored to amine-modified MCM-41 and MCM-48 surface. These mesoporous silica were prepared by hydrothermal procedure. Physical mixtures of CoPc in MCM-41 and in MCM-48 were also prepared for comparison purposes. The four prepared catalysts, 10 wt.% CoPcS/NH2-MCM-41, 10 wt.% CoPcS/NH2-MCM-48, 10 wt.% CoPc/MCM-41 and 10 wt.% CoPc/MCM-48, were characterized by X-ray diffractometry (XRD), diffuse reflectance UV-Vis spectroscopy and BET specific surface analysis. The catalytic activity of the immobilized catalysts was tested in the aerobic epoxidation of cyclohexene. CoPcS/NH2-MCM-41 and CoPcS/NH2-MCM-48 showed relatively high epoxide selectivity but low conversion of cyclohexene compared to CoPc/MCM-41 and CoPc/MCM-48. No leaching of metallophthalocyanine from the catalysts immobilized by chemical bonding into the reaction medium was observed and these catalysts could be reused four times.