Synthesis of higher alcohols from syngas: exploring the parameter space and conceptual process design

Different reaction conditions were evaluated in the synthesis of higher alcohols over an 11%-CuFeCoK/SiO₂ catalyst. The temperature range tested was 250 to 300 °C, pressure 10 to 30 bar, and the gas hourly space velocity of 1000 to 3000 mL h^-1g_cat^-1 all under a constant H₂:CO ratio of 2. At low CO conversions it was possible to achieve high selectivity to alcohols, while at high conversions side reactions forming CO₂ and alkanes became more dominating. Based on the experimental work, conceptual process design for alcohol production was conducted considering the main product, the aqueous alcohol mixture, and a gaseous by-product. The composition of the gaseous by-product had a H₂:CO molar ratio of 2, making it suitable for downstream Fischer-Tropsch and/or methanol synthesis, and a low content of other compounds. Due to high alcohol selectivity only at low CO conversion, recycling of the gases was taken into account in the conceptual process design and it was found that by recycling 98% of the absorbed CO₂ and 70% of the gaseous by-products a 50% electricity demand and 20% reactor volume decrease could be achieved.