One-pot Synthesis Of Phenolic Resin Modified PW/Ti-SiO₂-PR Mesoporous Nanocomposites And The Catalytic Performance In Esterification

Biodiesel as a kind of renewable clean energy takes on numerous excellent merits such as reproducibility,biodegradability,high-flash and effective lubrication and so on.Microacid residues after burning can help to prolong the lifetime of catalyst and oil in the engine.Biodiesel can be obtained by the esterification and transesterification catalyzed by acidic catalysts in the industrial field.Among the catalysts for esterification,solid acid catalysts can effectively avoid some defects such as corrosivity,low surface area,difficult to recycle and eviromental pollution and so on.The choice of proper carriers and effective acidic sites are the key steps to obtain catalysts with excellent stability and even catalytic activity.The highlight in this paper is that phenolic resin polymer as the organic precursor and tetraethyl orthosilicate as inorganic precursor,so that the excellent qualities of phenolic resin such as thicker mesoporous wall,stronger hydrophobicity,good alkali resistance and cheaper material price and so on,and the advantages of the silicon mesoporous such as high specific surface area and pore volume,adjustable and regular pore size,good water stability and mechanical stability and so on,can be existed in the carrier at the same time.the different strengths in the mesoporous nanocomposites can be complementary.Meanwhile,double-acidic sites can help to maintain higher catalytic activity.The specific research contents as follows:A series of organic-inorganic PW/Ti-SiO₂-PR mesoporous nanocomposites have been synthesized by the novel one-pot hydrothermal tactic and evaporation-induced co-assembly method using polyethylene oxide-polypropylene oxide-polyethylene oxide?PEO-PPO-PEO,P123?as the template agent,phenolic resin?PR?as organic-functionized part,tetraethyl orthosilicate?TEOS?as silica source,phosphato-tungstic acid?HPW?and titanium trichloride?TiCl₃?as the precursor of double-acidic sites.The effect of HPW,Ti species and PR loading amount to the prepared mesoporous nanocomposites had been discussed.The prepared mesoporous nanocomposites were characterized by Transmission Electron Microscope?TEM?,Scanning Electron Microscope?SEM?,X-ray Diffraction?XRD?and N₂ adsorption-desorption to prove the structure,Fourier Transform Infrared Spectra?FT-IR?,Ultraviolet-visible absorption Spectra?UV-vis?,X-ray Photoelectron Spectroscopy?XPS?and Inductive Coupled Plasma Emission Spectrometer?ICP?to prove the existing of elements type and active sites amount,Thermogravimetric Analysis?TGA?and Intelligent Gravity Analyzer to prove the heat endurance and hydrophobicity.The results demonstrate that the prepared nanocomposites own highly order,large specific surface area?487-828 m²/g?and pore volume?0.17-0.2 cm³/g?,uniform pore size?6.9-7.8nm?.The organic phenolic resin,inorganic tetraethyl orthosilicate and two kinds of acdic sites homogeneously spread into the mesoporous wall.The hydrophobicity can be adjusted by the polymer amount.The Keggin structure of the HPW has finally been maintained.In addition,the effect of the catalyst types and amounts,acid loading amounts,react temperatures and times,the acid/methanol mole ratios and recycle numbers to the catalytic yield had been studied by the catalytic esterification of oleic acid and methanol to produce methyl oleate?MO?.when the reaction happen 8 h under the condition of 2.6 wt%prepared 0.4PW/Ti?0.05?-SiO₂-PR0.25,oleic acid/methanol mole ratio is 1/20 and temperature is 100^oC,it proves that the yield of MO can up to 95.24%at the first use and70%at the seventh recycle.It indicates that the improvement of hydrophobicity by polymer and the introduce of double active sites can effectively enhance the catalytic activity of the mesoporous nanocomposites.