| The lignocellulosic based molecule, gamma-Valerolactone (GVL), has been identified as a promising platform chemical because, in addition to serving directly as a fuel additive or green solvent, it has a number of derivatives with applications towards fuel additives, high value chemicals, polymer precursors, or directly as biofuels. A strategy of producing renewable transportation fuels has been proposed by Bond et al. where alkenes produced from the decarboxylation of gamma-valerolactone (GVL) are oligomerized into higher molecular weight alkenes (Bond et al., 2010a). However, the decarboxylation of GVL over a solid acid catalyst, such as amorphous silica-alumina (ASA) leads to significant catalyst deactivation during the reaction. The solid acids H-ZSM5, ASA, niobia, niobium phosphate, and sulfated zirconia, were all tested for GVL decarboxylation. The aluminosilicate materials exhibited the highest initial activity; but varying degrees of catalyst deactivation lowered the overall performance of the materials. To better understand the properties that influence catalyst activity and stability, series of ASA and sodium exchanged H-ZSM5 samples were also investigated. The initial rate of GVL decarboxylation was found to generally increase with Bronsted acid site density across the materials; but a more meaningful correlation was obtained when materials of equivalent acid strength were compared. Additionally, it was realized that catalyst deactivation in the GVL reaction system is solely a physical phenomenon and can therefore be influenced by tailoring certain physical properties. Ultimately it was determined that an ideal catalyst for GVL decarboxylation should have an aluminosilicate framework, a high density of Bronsted acid sites, strong acid strength, and mesoporous sized pores. From these criteria, it is suggested that a tailored ASA, aluminum-containing MCM-41, or Amberlyst-70 would be well suited for GVL decarboxylation. |
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