Production of Gasoline Fuel from Alga‐Derived Botryococcene by Hydrogenolysis over Ceria‐Supported Ruthenium Catalyst

Abstract

Hydrogenolysis of hydrogenated botryococcene (Hy‐Bot) was conducted over various supported Ru catalysts, Ir/SiO2, and Pt/SiO2–Al2O3. Ru/CeO2 with very high dispersion showed the highest yield (70 %) of gasoline‐range (C5–C12) alkanes at 513 K. The main gasoline‐range products were dimethylalkanes. This yield is comparable to or higher than the gasoline yields from botryococcene in the literature, which were obtained at much higher temperature. Ir/SiO2 also showed a high fuel yield, but the activity was much lower than that with the Ru catalysts. The reaction over Pt/SiO2–Al2O3 slowed down before total conversion of Hy‐Bot was achieved. Ru/CeO2 was stable in the hydrogenolysis of Hy‐Bot without loss of activity and selectivity during reuses. The carbon balance was low for the hydrogenolysis of Hy‐Bot over all catalysts if the main products are heavy hydrocarbons, whereas for the hydrogenolysis of squalane the carbon balance was kept near 100 %. 1H NMR spectra of the product mixture and thermogravimetric analyses of the product mixture and the recovered catalyst revealed that the formation of aromatic compounds, polymeric products, and coke was negligible for the carbon balance. In a model reaction using substrate compounds with a substructure of Hy‐Bot, only 2,5‐dimethylhexane, which has a C6 chain with two Cprimary−Ctertiary bonds, produced a cyclic product, 1,4‐dimethylcyclohexane, which has a higher boiling point than the substrate. This dehydrocyclization reaction makes the product distribution in the hydrogenolysis of Hy‐Bot more complex.

Selective Hydrodeoxygenation of Vegetable Oils and Waste Cooking Oils to Green Diesel Using a Silica-Supported Ir-ReO x Bimetallic Catalyst

“…Ir-ReO x /SiO 2 and Ru-ReO x /SiO 2 achieve quantitative stearic acid conversion andh ighs electivity to linear C 18 alkane (94 %) as the sole product over the Ir-ReO x /SiO 2 catalyst (entry 1) or a mixture of C 18 and C 17 alkanes (total 93 %) when using the Ru-ReO x /SiO 2 catalyst( entry 2). [51][52][53] In contrast, Ir-ReO x /SiO 2 gave rise to C 18 alkane with very high selectivity. The resultso ft he latter two catalysts are consistent with prior reports of Pd-Re-and Pt-Re-catalyzed hydrogenationo fc arboxylic acids and esters.…”

Selective C−C Hydrogenolysis of Alkylbenzenes to Methylbenzenes with Suppression of Ring Hydrogenation

“…CeO 2 supports gave much higher activity than other supports. This is in contrast to the hydrogenolysis of alkanes where Ru(4)/CeO 2 873 catalyst shows significantly lower activity than Ru(4)/SiO 2 973 catalyst . As described later, the higher activity of Ru/CeO 2 than other Ru catalysts shown in Figure can be mostly (although not totally) explained by the difference of dispersion.…”

“…Recently, we have developed Ru/CeO 2 catalyst with very small Ru particles (<1.5 nm) prepared by treatment with inert gas at 573 K after impregnation ,. This C−C dissociation catalyst shows good regioselectivity toward inner C−C bonds instead of terminal C−C bonds of alkanes . We also developed Ru‐VO x /SiO 2 catalyst with small Ru ensembles which give similar good regioselectivity, although the modification of V decreases the activity of Ru .…”

Selective Synthesis of Botryococcene Pentaepoxide ‐ The Chemical Modifications of the Algal Biomass Oil

“…Biomass resources that have been applied for substitution of hydrocarbon‐based petroleum are basically produced from edible biomass such as plant‐derived oils and sugar but most of them are hard to be the substitution for their various contents of oxygen. On the other hand, some microalgae efficiently produce hydrocarbons with exclusion of heteroatoms, which could be next‐generation biomass. Among many fresh water microalgae, Botryococcus braunii produces a variety of noncyclic and cyclic terpene hydrocarbon oils called “botryococcene” outside of the cell .…”