2 research outputs found
Endothermic Reforming of <i>n</i>‑Hexane on Metal (Pt, Ga) Containing H‑ZSM‑5 at High Pressures
The
supercritical, high-pressure reaction of <i>n</i>-hexane
over H-ZSM-5, with and without the addition of Pt and Ga,
has been studied for application to endothermic reforming in scramjet
engines. The endothermicities of the reactions were determined from
the product distributions. For unpromoted H-ZSM-5, the product distribution
indicated that the endothermicity is low and decreases with increasing
pressure. The addition of Ga to H-ZSM-5 has a relatively small effect
on <i>n</i>-hexane conversion but significantly increases
the endothermicity of the reaction by increasing the selectivity to
form small aromatics. The HÂ(Ga)-ZSM-5 catalyst showed no deactivation
for at least 5 h at 633 K and 137 bar of <i>n</i>-hexane.
By contrast, the addition of Pt had a minor effect on both the rate
and the reaction endothermicity
Diels–Alder and Dehydration Reactions of Biomass-Derived Furan and Acrylic Acid for the Synthesis of Benzoic Acid
Routes to benzoic acid starting from
furanî—¸obtained from
hemicellulose in high yieldî—¸and methyl acrylate are reported.
These routes involve Diels–Alder and dehydration reactions
of furan and acrylic acid (or methyl acrylate) in a two-step reaction
protocol that minimizes side reactions. The Diels–Alder reaction
of furan and methyl acrylate (or acrylic acid) was run at 298 K and
was catalyzed by Lewis acidic (Hf-, Zr-, and Sn-Beta) zeolite catalysts,
and achieving a high turnover frequency (∼2 h<sup>–1</sup>) and no side reactions were observed. The oxanorbornene product
was dehydrated at low temperatures (298 to 353 K) in mixtures of methanesulfonic
acid and acetic anhydride in 96% yield. This is compared to an only
1.7% yield of methyl benzoate obtained for the dehydration of the
oxanorbornene in neat methanesulfonic acid. The effect of oxanorbornene
concentration and stereochemistry was found not to decrease the yield
of aromatics, while dehydration of the carboxylic acid form of the
oxanorbornene led to a decrease in selectivity to 43% at complete
conversion in mixtures of methanesulfonic acid and acetic anhydride.
This reaction sequence could be an important entry point for selectively
directing high-yield, hemicellulose-derived furans to aromatic products
used in the existing chemical process industry