Evaluation of Concentrated Halogen Acid Hydrolysis Processes for Alcohol Fuel Production

摘要

Cellulose may be hydrolyzed by acid to form glucose, which can then be fermented to produce ethanol. Dilute acid processes have relatively low yields (55 to 75%) because the rate of sugar degradation is rapid at the high temperatures necessary for the hydrolysis of crystalline cellulose. In low-temperature, concentrated-acid processes, the crystalline cellulose is decrystallized, allowing the hydrolysis reaction to occur at much lower temperatures where sugar degradation is negligible. Therefore, the concentrated-acid proceses give high yields and produce relatively clean hydrolyzates. Concentrated-acid hydrolysis may be carried out either with hydrochloric acid, hydrofluoric acid, or sulfuric acid. This report evaluates three halogen acid hydrolysis processes: liquid-phase HCl, gas-phase HCl, and liquid-phase HF. The processes are compared on the basis of the predicted selling price of ethanol produced. This report applies a consistent balance-of-plant design and set of economic assumptions to different processes to provide insights into the important internal parameters and the relative advantages and disadvantages of each. 49 refs., 20 figs., 21 tabs. (ERA citation 10:043946)