Carbon Chain Length Increase Reactions of Platform Molecules Derived from C5 and C6 Sugars

Abstract

The production of liquid fuels from lignocellulose-derived platform molecules has attracted much interest in recent years. Platform molecules mostly have a shorter carbon chain length, compared to liquid fuels, which have a typical chain length varying between 4 and 25 carbon atoms, whereas aviation and especially diesel fuel have a carbon chain length exceeding 10 carbon atoms. For this reason, some carbon chain length increase reactions are required. In this article, carbon chain length increase reactions are compared for typical lignocellulose-derived platform molecules. The focus is placed on the ability of the molecules to participate in self-condensation reactions in a controlled manner. Hydrogen plays a key role when producing fuels from platform molecules. Hydrotreatment is applied not only when converting the products from a carbon chain length increase reaction into hydrocarbons but also for modifying the functional groups of the model compounds and, thereby, their reactivity.

Hydrodeoxygenation of Levulinic Acid Dimers on a Zirconia-Supported Ruthenium Catalyst

“…Bold is not necessary; however, we think that it quite nicely highlights that it is not just a number, but the 'name' of the individual dimer also.only to other products, but also to less reactive dimers, such as dimers 200 and 202 in all the catalytic experiments. The reactions of dimers 214a, 214b, and 216 in hydrogenating conditions through HDO and further lactone formation were also observed by Käldström et al [7]. In addition to dimers 214a, 214b, and 216, dimer 198 was mainly consumed in the catalytic experiments, whereas dimers 200 and 202 were formed.…”

“…The LA dimer mixture was prepared as described by Käldstöm et al [7], who used a 0.7% Pd catalyst on Amberlyst CH28 ion-exchange resin at 120 • C to convert LA into dimers via aldol self-condensation in a fixed-bed reactor under hydrogen pressure. The chemicals in the analytics were obtained from Sigma-Aldrich and used without further purification: nonanoic acid (98%), tetrahydrofuran (LiChrosolv ® , ≥99.9%), tetrahydrofuran-d 8 (99.5 atom.% D), 2-butanol (99%), 2-propanol (≥99.5%), acetonitrile (Riedel-de Haën, 99.90%), formic acid (VWR Chemicals, 99%), levulinic acid (Merck, for synthesis), azelaic acid (Alfa Aesar, 96%), dodecanedioic acid (Fluka, ≥98%), and stearic acid (>99%).…”

“…In order to produce, e.g., bio-based jet fuel or diesel, extended carbon chains (>C 6 ), which could be further deoxygenated to alkanes, have received attention [5,6]. Various ways to increase the carbon chain length of the lignocellulosic platform chemicals exist: aldol condensation, ketonization, and alkene oligomerization [7]. These reactions lead to heavier compounds, for example dimer or trimer structures [7].…”

“…Various ways to increase the carbon chain length of the lignocellulosic platform chemicals exist: aldol condensation, ketonization, and alkene oligomerization [7]. These reactions lead to heavier compounds, for example dimer or trimer structures [7].…”

“…The structure and production of LA dimers through aldol condensation was first described by Blessing and Petrus [18]. Recently, the production of LA dimers has been described by several authors using hydrogenating conditions with a Pd containing ion-exchange resin as a catalyst, basic MgZr oxide catalysts in water, or ZnCl2 catalyst in trichloroacetic acid [7,[19][20][21]. The formation of LA dimers in hydrogenating conditions and the mixture of identified LA dimers in the feed used in this work are presented in Scheme 1.…”