Comparative study of Cu/ZnO/Al 2 O 3 (CZA) catalysts with different Cu loading in CO and CO 2 hydrogenation at 250 C under atmospheric pressure was investigated. Results showed that methanol was the major product for CO hydrogenation, while the main product for CO 2 hydrogenation was CO. High Cu loading catalyst exhibited high catalytic activity in both CO and CO 2 hydrogenation. Low Cu loading catalyst showed deactivation with time on stream after 1-2 h by coke formation containing both amorphous and graphitic cokes for both CO and CO 2 hydrogenation.
Abstract. In this present study, the catalytic dehydration of ethanol over three different Al-based solid acid catalysts including H-beta zeolite (HBZ), modified H-beta zeolite with γ-Al2O3 (Al-HBZ) and mixed γ-χ phase of Al2O3 (M-Al) catalysts was investigated. The ethanol dehydration reaction was performed at temperature range of 200 to 400 o C. It revealed that all catalysts exhibited higher ethanol conversion with increased temperatures. At low temperatures (ca. 200 to 250 o C), diethyl ether (DEE) was obtained as a major product for all catalysts. However, with increased temperatures (ca. 300 to 400 o C), ethylene was a major product. Among all catalysts, HBZ exhibited the highest ethanol conversion giving the ethylene yield of 99.4% at 400 o C. This can be attributed to the largest amount of weak acid sites present in HBZ, which is related to the Brønsted acid. It should be mentioned that HBZ also rendered the highest catalytic activity for every reaction temperature. As the results, HBZ catalyst is promising to produce ethylene and DEE from ethanol, which is considered as cleaner technology.
This study aims to investigate the production of ethylene and diethyl ether from ethanol via catalytic dehydration using Si- and Al-based catalysts with Pd modification. First, six catalysts including H-beta zeolite (HBZ), mixed phases of γ-χ-AlO (M-Al) and γ-AlO (G-Al) with and without Pd modification (0.5 wt%) were prepared. The catalytic dehydration of vaporized ethanol at temperature ranging from 200 to 400°C was performed over the catalysts. For ethylene production, the most promising catalyst is HBZ (giving ethylene yield of ca. 99% at 400°C), whereas Pd modification has no significant effect on ethylene production. Considering the production of diethyl ether, it is produced at lower temperature (ca. 250°C) than that of ethylene. The most active catalyst to produce diethyl ether is HBZ with Pd modification (giving diethyl ether yield of ca. 48% at 250°C). Thus, increased diethyl ether yield can be achieved with Pd modification at low temperature for the HBZ catalyst. Other catalysts such as M-Al and G-Al can also produce significant amounts of ethylene. To elucidate the effect of Pd modification on these catalysts, different characterization techniques such as nitrogen physisorption (BET and BJH methods), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and ammonia temperature-programmed desorption were performed and further discussed in more detail.
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