Highly dispersed metal incorporated hexagonal mesoporous silicates for catalytic cyclohexanone oxidation to adipic acid

Adipic acid is a dicarboxylic acid of great industrial importance,mainly used in the production of nylon-6,6 and polyurethane.The use of nitric acid as an oxidant in the industrial production of adipic acid poses significant carbon footprint to the environment.Clean adipic acid synthesis methods using a heterogeneous catalyst with H2O2 as oxidant and water as solvent have potential advantages of low catalyst cost,easy synthesis and recovery,cleanness and environmental protection.In this work,hexagonal mesoporous silicate materials were synthesized by a sol–gel method and evaluated for cyclohexanol/cyclohexanone oxidation to adipic acid.The physical and chemical properties of Fe-HMS were characterized by XRD,HR-TEM,BET and UV–Vis.The experimental results showed that Fe-HMS materials show pore sizes ranging from 2–3 nm.W-and Mo-based polyoxometalates were also evaluated and compared to the Fe-based HMS catalysts.To improve the adipic acid yield,the influence of the transition metal as well as the effect of metal loading,reaction temperature and catalyst amount on the catalytic performances of Fe-HMS have been investigated in details.When Si/Fe atomic ratio=100,Fe-HMS catalyst shows the highest activity,with a cyclohexanone conversion of 92.3%and adipic acid selectivity of 29.4%.The reaction pathway of cyclohexanone oxidation was further proposed based on experimental data.

Deposition of Layer-by-layer Inorganic-organic Nano-hybrid Ultrathin Films onto SBA-15

Deposition of inorganic-organic nano-hybrid ultrathin films onto mesoporous silicate materials has been proven possible by using layer-by-layer assembly method. In combination with sol-gel method, titania, subsequently dye molecules (or polymer) were successfully fabricated onto the inner wall of SBA-15. Their structures were preliminarily characterized by FTIR and solid-state UV-Vis spectroscopy, thermal analysis, and BET surface area measurements, respectively.

Experimental and theoretical studies on the removal mechanism of formaldehyde from water by mesoporous calcium silicate

Most porous materials with high specific surface area and diverse internal structures possess good adsorption ability.In this work,a tremella-like mesoporous calcium silicate hydrate(CSH)with high adsorption capacity was successfully prepared via a facile hydrothermal method.The adsorption effect and adsorption mechanism of the as-prepared calcium silicate hydrate(APCSH)towards formaldehyde from water were investigated systematically.Results indicate that AP-CSH has high Ca/Si ratio(1.95),large specific surface area(122.83 m2 g-1)and exhibits excellent adsorption capacity.The results of batch adsorption experiments show that AP-CSH can remove formaldehyde from water rapidly and effectively with the maximum removal efficiency of 98.94%.The adsorption process agrees well with the pseudo-second-order and Freundlich isotherm model.Furthermore,regeneration can be achieved by simply immersing AP-CSH in absolute ethanol and the removal efficiency can still reach about 99.50%after five cycles.The adsorption mechanism was also studied by experimental analyses and molecular dynamics simulation.Both experimental results and theoretical simulation support that formaldehyde adsorption over AP-CSH belongs to chemical adsorption.