Ung Gi Hong

Catalytic Decomposition of Lignin Model Compounds to Aromatics over Acidic Catalysts

Recent progress on the catalytic decomposition of lignin model compounds to aromatics was reported in this review. Cesium-exchanged heteropolyacid catalysts (CsxH3.0−xPW12O40), palladium catalysts supported on cesium-exchanged heteropolyacid (Pd/CsxH3.0−xPW12O40), and palladium catalysts supported on various activated carbon aerogels (ACAs) (Pd/ACA-SO3H (X), Pd/XCs2.5H0.5PW12O40/ACA, Pd/CsxH3.0−xPW12O40/ACA, and Pd/Cs2.5H0.5PW12O40/ACA-SO3H) were prepared, and they were employed for the decomposition of C–O bond in lignin to aromatics. Phenethyl phenyl ether, benzyl phenyl ether, and 4-phenoxyphenol were used as dimeric lignin model compounds representing for β-O-4, α-O-4, and 4-O-5 bonds in lignin, respectively. It was observed that CsxH3.0−xPW12O40 and Pd/CsxH3.0−xPW12O40 were highly active for the decomposition of phenethyl phenyl ether and benzyl phenyl ether to aromatics. However, these catalysts showed very low catalytic performance in the decomposition of 4-phenoxyphenol. Palladium catalysts supported on various ACAs (Pd/ACA-SO3H (X), Pd/XCs2.5H0.5PW12O40/ACA, Pd/CsxH3.0−xPW12O40/ACA, and Pd/XCs2.5H0.5PW12O40/ACA-SO3H) were efficient for the decomposition of 4-phenoxyphenol to aromatics. Acidity of the catalysts played a key role in determining the catalytic performance in the decomposition of 4-phenoxyphenol to aromatics.

Microporous and mesoporous ZSM-5 catalyst for catalytic cracking of C5 raffinate to light olefins.

ZSM5 catalysts (PAM(X)-ZSM5) with micropores and mesopores were prepared using polyacrylamide (PAM) as a soft template at different PAM content (X = 0, 0.12, 0.25, 0.53, 0.64, and 0.78 wt%), and they were applied to the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. The effect of PAM content of PAM(X)-ZSM5 catalysts on the physicochemical properties and catalytic activities was investigated. N2 adsorption-desorption isotherms of PAM(X)-ZSM5 catalysts exhibited a broad hysteresis loop at high relative pressure, indicating the existence of mesopores in the catalysts. It was found that the catalytic performance of PAM(X)-ZSM5 catalysts was closely related to the mesoporosity of the catalysts. Conversion of C5 raffinate and yield for light olefins showed volcano-shaped trends with respect to mesopore/micropore volume ratio of the catalysts. Thus, an optimal PAM content was required to achieve maximum production of light olefins through catalytic cracking of C5 raffinate over microporous and mesoporous PAM(X)-ZSM5 catalysts.