Evaluation of sulfuric acid hydrolysis processes for alcohol fuel production

This report evaluates three sulfuric acid hydrolysis processes (percolation, high-temperature dilute acid, and low-temperature concentrated acid) to determine (1) the ultimate potential of each process, (2) important research issues, and (3) the relative advantages and disadvantages of each process. The plants evaluated produce 50 million gallons of ethanol per year. The report defines a complete cellulose-to-ethanol process with sections for hydrolysis, neutralization, fermentation, and purification. A computer simulation calculates material and energy balances for the entire plant, estimates the capital cost, and computes the required ethanol selling price. The high-temperature, dilute acid process operates at approximately 240/sup 0/C, uses 1% acid as the catalyst, and produces yields between 50% and 60% of theoretical. Percolation processes use lower acid concentrations and temperatures, and the reaction takes appreciably longer. The yield is increased to 75% of theoretical at the expense of production a more dilute sugar solution for fermentation. The low-temperature, high-acid concentration process has very high yields but requires significantly more acid than the other processes. 38 references, 28 figures, 17 tables.