Eco-Friendly and Sustainable Process for Converting Hydrous Bioethanol to Butanol

Abstract

The purpose of the study was the development of water-resistant catalyst and catalytic processes for the conversion of hydrous ethanol to 1-butanol. Water, in hydrous ethanol, strongly inhibits conversion to 1-butanol on solid catalysts. In this study, the nonstoichiometric P-deficient hydroxyapatite containing carbonate anions (C-HAP), Ca10−x/2(PO4)6−x(CO3)x(OH)2, displayed good performance in the Guerbet condensation of hydrated ethanol to 1-butanol, after proper stabilization of reaction conditions. Hydrous ethanol (96 wt%) was converted on C-HAP formed as extrudates with silica binder at 400 °C and weight jour space velocity (WHSV) = 0.5–1.0 h−1 to yield 21–23% 1-butanol and 73–74% selectivity. It displayed stable operation for up to 170 h on streams conducted in bench and mini-pilot rigs with catalyst loadings of 2 and 50 cm3, respectively. The process simulation employed the recycling of ethanol without laboratory verification to reach 68% theoretical yield of 1-butanol. The techno-economic analysis demonstrated the feasibility of this process, showing that it may be profitable depending on the prices of hydrated ethanol and 1-butanol.

Carbon-Supported Mg–Al Oxide Hybrid Catalysts for Aqueous Ethanol Conversion into 1-Butanol in a Flow Reactor

“…Various catalysts have been investigated for this purpose, including individual and doped oxides such as MgO, − Al 2 O 3 , ZrO 2 , , hydrotalcite-derived Mg–Al mixed oxides, − Ca-hydroxyapatites with different Ca/P ratios, − and metals (Cu and Ni) deposited on various supports. − The abovementioned studies have been performed with anhydrous ethanol as feed. A few studies − have been carried out with aqueous ethanol. The acid–base properties of these materials and especially the balance between acidity and basicity , determine their activity in the key steps of the process, namely, ethanol dehydrogenation and aldol condensation.…”