Lignocellulosic Biomass Pretreatment Using Gaseous Ammonia


To achieve high yields of glucose and other products for use in biofuels and bio-based chemicals lignocellulose must first be pretreated. The goal of pretreatment is to decrease the crystallinity of cellulose increase the biomass surface area remove hemicellulose and break the lignin seal. Current pretreatments use liquid ammonia dilute acid organosolvents and steam among others. Each of these methods has drawbacks in its ability to effectively and efficiently pretreat and process lignocellulosic biomass. Michigan State University’s invention Gaseous Ammonia Pretreatment (GAP) uses hot ammonia gas rather than liquid ammonia to pretreat biomass in a reactor. The hot ammonia gas condenses on the biomass and reacts with the water that is used to wet the biomass prior to adding the ammonia gas. During the GAP process the raw biomass is more uniformly treated by ammonia and requires much shorter pretreatment time. Therefore this method has the potential to be a less expensive and more effective raw biomass pretreatment process. At present pretreatment cost is considered one of the primary bottlenecks for the development of biorefinery technology. Applications: GAP can impact a number of applications including- (1) Animal feed production particularly dairy feed (2) Raw biomass pretreatment for the biofuels industry (3) Building materials industry (4) Bio-based chemicals industry IP Protection Status: Patent pending


(1) Faster pretreatment time: Using the GAP process it is possible to rapidly reach the desired pretreatment temperature of 100-150 degrees Celsius instantly thereby reducing the biomass residence time to 5-15 minutes in total. Ammonia in the delivery vessel is preheated and ensures condensation of hot ammonia gas on the raw biomass causing an instantan rise in temperature. (2) Limited or no ammonia recovery: Use of hot gaseous ammonia along with hot steam and inert gas/air limits the need to recover ammonia as is required in other pretreatment processes. In competing processes the ammonia recovery step is expensive in terms of time and energy costs. (3) Less temperature degradation of raw biomass: Current biomass pretreatments such as dilute acid pretreatments tend to “over degrade” the raw biomass due to higher temperatures. (4) Pretreatment residence time reduction: Competing processes can require long biomass residence time (hours to weeks) which are expensive and inconvenient to scale. (5) No impact...

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