No abstract

No abstract

Homogeneous gas-phase pyrolysis of ethane by continuous CO 2 laser irradiation was used in our experiments for bulk heating of the reaction mixture. Laser energy was absorbed by ethylene, the main product of ethane dehydrogenation, and transferred to the reaction medium via collisional relaxation. A mechanism of ethane dehydrogenation is suggested to describe the pyrolysis process. The mechanism is autocatalytic in respect of ethylene and includes ethane-ethylene interaction with the formation of methyl and propyl radicals. Rate constants of elementary reactions, selectivity, and yields of pyrolysis products were determined. The composition of ethane dehydrogenation products determined in the experiments was substantially different from the calculated thermodynamic equilibrium composition.

Catalytic depolymerization of birch-wood organosolv lignin was studied in supercritical ethanol at 260 ºC. Three different acid-basic materials namely sepiolite, zeolite ZSM-5 supported on Al 2 O 3 and Sibunit graphite-like mesoporous carbon promoted via oxidation were tested as catalysts. Moreover, Ru-containing catalysts based on these supports were studied. Among the catalysts without ruthenium, Sibunit matherial was found to produce highest yield of liquid products due to the highest amount of surface acid sites. Precipitating Ru significantly increases the activity of all three supports. Using Ru-containing Sibunit catalyst in lignin depolymerization process allows to avoid coke formation, increases the amount of aromatic monomers and the total yield of liquid products up to 76 %. The yield obtained in best catalytic experiment is more then twice higher compared to the process without any catalyst.

No abstract