Abstract
The Fe, Zn, and Mn-modified SiO2-Al2O3 catalysts for the glycerol vapor-phase cyclocondensation with ethanediamine (ED) to 2-pyrazinemethanol (2-PMol) and 2-methylpyrazine (2-MP) in a fixed-bed system were prepared by coprecipitation and characterized by N2 adsorption–desorption, X-ray powder diffraction, and NH3 temperature-programmed desorption (NH3-TPD) in the present work. The results showed that the Mn-modified SiO2-Al2O3 catalyst with a SiO2/Al2O3 molar ratio 15.84 and 6% Mn gave the highest catalytic activity for formation of 2-PMol (53.1%) and 2-MP (42.9%). Mn species could cause the modulation of the acidic species of catalysts, improving the glycerol cyclocondensation with ED to 2-PMol, and also acted as the catalytic centers for the hydrodehydration of 2-PMol to 2-MP. However, too many strong acidic sites could lead to ED self-cyclocondensation to form a by-product pyrazine. The optimum temperature was tested to be 380°C for the cyclocondensation over a 6%Mn-SiO2-Al2O3 catalyst. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:377–382, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21026
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