(544ed) Analysis of Kinetics in the Ring-Opening Reaction and Decarboxylation of ?-Valerolactone and Pentenoic Acids over Zeolite Catalysts

Lignocellulose is an attractive carbon source because of its abundance and low cost. Through conversion of lignocellulosic biomass, γ-valerolactone (GVL), an important intermediate for generating jet fuel, diesel, and gasoline, can be produced. For example, over acid catalysts, GVL undergoes ring-opening reaction and decarboxylation, forming a mixture of pentenoic acid (PEA), carbon dioxide, and butene. Butene, in particular, can be used for the production of C₁₂ – C₁₆ branched liquid alkanes, which are essential components of aviation fuels. Aluminosilicates, specifically amorphous silica alumina and ZSM-5 (MFI zeolite) appear to offer the highest activity for ring-opening and decarboxylation. We have reported that, on a per-active site basis, ZSM-5 catalysts are significantly more active than amorphous silica alumina. This observation may be attributed the different distributions and local environments of Bronsted Acid Sites and Lewis Acid Sites in these materials.

The aim of this study is to understand the thermochemistry and reaction kinetics that govern both ring opening and decarboxylation. In particular, we are interested in determining whether changes in the pore structure of various amorphous and crystalline aluminosilicates has an impact on macroscopically observable reactivity. We have previously obtained extensive kinetic data on GVL ring opening and decarboxylation over amorphous silica alumina, and the current study expands our consideration of these kinetics over various zeolites. Specifically, production distributions and species production rates are measured over a variety of MFI, BEA, FAU, and FER zeolites. This has generated a robust data set, which is subsequently used to regress various microkinetic parameters that describe the elementary kinetics of ring opening and decarboxylation. By comparing variation in elementary kinetic parameters over various aluminosilicates, we try to figure out the link between reactivity in GVL/PEA interconversion and decarboxylation and catalyst structure.