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Synthesis And Characterization Of Porous Carbons Using MCM-48 And NaY Molecular Sieves As Template

Posted on:2006-11-05Degree:MasterType:Thesis
Country:ChinaCandidate:G WuFull Text:PDF
GTID:2121360152985376Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Instability in the oil markets and increase in environmental concerns have stimulated research for alternative transportation fuels. One alternative to gasoline is natural gas, which consists primarily of methane (85-95%) with minor amounts of ethane, other higher-order hydrocarbons, nitrogen, and carbon dioxide.Activated carbons (AC) are studied as the storage of natural gas by adsorption forms. It shows by research that the ideal AC should have an average micropore width of 2.0 run for the adsorption natural gas system. However, the complexity of the carbon structure prevents the conventional activation processes from preparing carbon materials with strictly controlled pore structure, although voluminous research has been done and great effort has been made toward the control of pore size and its distribution. To meet such a requirement, many novel approaches to control pore structure have been developed. Melocular sieves, such as MCM-48 and NaY, are characterized by their regular channel structure and are utilized for synthesizing unique carbon materials.In this work, mesoporous molecular sieve MCM-48 by hydrothermal method using nonionic surfactant p-Octyl polyethylene glycol phenyl ether and cationic surfactant cetyltrimethyl-ammonium bromide (CTAB) as co-template were synthesized. The synthesis was conducted at a very low mass fraction mixed surfactants (about 5.6%) and a very low molar ratio of total surfactants to silica (about 0.174:1). At the same time, zeolite NaY was synthesized by hydrothermal method using silica sol, aluminium sulfate, sodium hydroxide and deioned water.Porous carbon with controlled pore size distributions between 1.0nm and 3.0nm were synthesized using zeolite NaY as a template. Acetylacetone was employed as a carbon precursor to prepare porous carbons by impregnation method and CVD method. The porous carbon prepared exhibited two kind of pore structure: microporus and mesoporous, with surface area, microporisity and micropore volume of 1351m2/g, 0.63 and 0.892cm3/g respectively. Other carbon precursors are used such as citric acid, furfuryl alcohol and phenolic resin.Mesoporous carbon was fabricated using molecular sieve of MCM-48 as template, which is lower ordered in pore structure, which shows a peak at 2 θ =2.8°. Citric acid and furfurylalcohol were employed as carbon precursor to prepare mesoporous carbons with surface area of 1072 m2/g and 0.87cm3/g respectively. Citric acid also improved the acidity of molecular sieves when mesoporous carbons are synthesized.
Keywords/Search Tags:molecular sieves, inorganic templation, porous carbon
PDF Full Text Request
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