Synthesis of amine-functionalized mesoporous silica basic catalysts for biodiesel production

• Amine-functionalized MCM-41 catalysts were prepared.
• The CP/MAS NMR showed that the bases are covalently bounded to the mesoporous MCM-41.
• The catalysts were studied in the transesterification of soybean oil with methanol.
• Up to 99% yield in biodiesel was obtained with the guanidine-derived catalyst.

Amine-functionalized MCM-41 were prepared for use as basic heterogeneous catalysts in trasesterification of soybean oil to produce biodiesel. The fuctionalization was obtained by reacting the silanol groups of the MCM-41 material with 3-amino-propyl-triethoxy-silane, or in two steps by firstly reacting the MCM-41 with 3-chloro-propyl-triethoxy-silane and then, undergoing nucleophilic substitution with piperazine or with a guanidine-derived compound (1,5,7-triazabicyclo [4,4,0] dec-5-ene). The introduction of the organic moieties was confirmed by 29Si and 13C CPMAS NMR spectroscopy, as well as by chemical analysis (CHN). The catalysts were tested in the transesterification of soybean oil with methanol. Up to 99% yield in biodiesel at 70 °C and 3 h of reaction were obtained with the guanidine-derived catalyst. The other amine-derived catalysts were less active for the production of biodiesel, presenting lower yields under more severe reaction conditions. These results can be explained by the intrinsic basicity of the amines.

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