Pressing global issues, such as climate change and declining energy security, have led to an increasing interest in the use of renewable feedstocks for fuel production. These feedstocks include lignocellulosic materials, such as waste biomass from the agriculture and forest industries.
Ethanol is commonly produced by fermentation of sugars from agricultural feedstock — mostly corn and sugarcane. Several processes to produce ethanol by fermenting lignocellulosic materials have been developed. Two such processes have been introduced by American Process Inc. (Atlanta, Ga.; www.americanprocess.com), one of which was covered in this column last year (Chem. Eng., November 2013, p. 26). The other cellulosic ethanol process is discussed below.
The process for cellulosic ethanol production depicted in Figure 1 is similar to the AVAP process described in the World Intellectual Property Organization (Geneva, Switzerland; www.wipo.int) patent published by American Process Inc. (W.O. Patent 2011/044378A1).
FIGURE 1. Cellulosic ethanol production process similar to the AVAP process from American Process Inc.
Pretreatment. The biomass is heated with a solution of SO2, ethanol and water and then fractionated into its three…