Shinae Jun

Synthesis of ordered mesoporous carbon molecular sieves CMK-1

Highly ordered mesoporous carbon molecular sieves designated as CMK-1 were synthesized using mesoporous MCM-48 silica with various pore diameters as templates, sucrose as a carbon source and sulfuric acid as the carbonization catalyst. The effect of the sucrose-to-sulfuric acid ratio on the structure of the resultant carbon, the effect of the pyrolysis temperature, and the optimum amounts of sucrose for MCM-48 with various pore diameters have been investigated. These results show that the synthesis method can be accurately controlled to obtain the highly ordered mesoporous carbon molecular sieves in a large scale.

Hydrothermal stability of MCM-48 improved by post-synthesis restructuring in salt solution

Abstract The hydrothermal stability of the mesoporous silica molecular sieves MCM-48 has been found to increase if the as-synthesized materials containing surfactant are heated in an aqueous solution of salts. Although the optimum treatment conditions depended on details of the synthesis procedures, this post-synthesis technique led to a significant improvement in the hydrothermal stability of various MCM-48 materials that were synthesized using cationic surfactants alone or cationic-neutral surfactant mixtures. These results were concluded as due to the restructuring effects of the pore walls by magic angle spinning 29 Si NMR spectroscopy, nitrogen adsorption and scanning electron microscopy.

07-O-01 - Ordered mesoporous carbon molecular, sieves by templated synthesis: the structural varieties

Publisher Summary This chapter discusses the template synthesis of ordered mesoporous carbon (OMC) molecular sieves. OMC of various structures, designated as CMK-1∼5, have been synthesized by the carbonization of sucrose, furfuryl alcohol, or other carbon sources inside silica or aluminosilicate mesopores that are interconnected into three-dimensional networks, such as in MCM-48, SBA-1, and SBA-15. The mesoporous carbon molecular sieves, obtained after template removal, show transmission electron microscopy (TEM) images and X-ray diffraction (XRD) patterns characteristic of the ordered arrangement of uniform mesopores. The OMC, which are opening up a new area of the nanoporous materials, exhibit high Brunauer–Emmett–Telle (BET) specific surface areas, excellent thermal stability in inert atmospheres, and strong resistance to attack by acids and bases.

Ordered mesoporous carbon molecular sieves with functionalized surfaces

Abstract Ordered mesoporous carbon molecular sieves designated as CMK-1 and CMK-5 were synthesized by using nanocasting technique with the synthetic procedures reported previously. After carboxylic acid groups were generated on the carbon frameworks through the partial oxidation with nitric acid, pore walls of the mesoporous carbons were functionalized with various organic and organometallic functional groups using esterification and amidization reactions. Mn-Schiff base complex grafted on the mesoporous carbon surface by using ester bond formation showed remarkable catalytic activity for partial oxidation of cyclohexene. The mesoporous carbons were also functionalizable with tetraethylenepentamine (TEPA), which could be used for the effective removal of heavy metal ions.

29-P-27-Fabrication of honeycomb structures with powder MCM-48 silica

Publisher Summary This chapter discusses a fabrication of honeycomb structures with powder MCM-48 silica. Macroscopic honeycomb structures are fabricated with powder MCM-48 silicas by an extrusion process using bentonite or pseudobohemite as binder. The products are characterized by the X-ray diffraction patterns, specific BET surface areas, and compressive strengths after sintered at temperatures as high as 750°C. The fabrication process for MCM-48 has been investigated. The result shows that stabilities of the raw MCM-48 materials are the bottleneck limiting the fabrication process. High-quality honeycombs retaining the wellordered mesoporous structure are obtained when MCM-48 is stabilized by the postsynthesis hydrothermal treatments before the fabrication. However, without the postsynthesis treatment, the MCM-48 structure is almost lost during the fabrication process.

Friedel-crafts alkylation over Al-incorporated mesoporous honeycomb

Abstract Catalytic activity of Friedel-Crafts alkylation of toluene with benzyl alcohol has been measured over the Al-incorporated mesoporous honeycomb. The honeycomb was fabricated using MCM-48 and pseudobohemite as inorganic binder and the incorporation of aluminum was performed either by direct implementation of AlCl3 or by slurry mixing before the extrusion. Hydrothermal stability and compressive strength can be improved with the increase of the aluminum content. High catalytic activity of Friedel-Crafts alkylation was observed for the honeycomb containing Al initially in the slurry mixture.