Scale-up of a novel non-enzymatic cellulose-to-glucose hydrolysis process

Conference Dates

June 19-24, 2016


The acidic hydrolysis of cellulose to glucose followed by its subsequent fermentation to ethanol has been an intensive research topic over the last decades. On a global scale, cellulosic resources are by far the most promising alternative to first generation starch for bioethanol production. However, such processes are still struggling to reach economy due to the high investment (CAPEX) and operating costs (OPEX) required especially in a market where fossil fuels are so affordable (Feb 2016). Despite the severe restrictions associated with the production of second generation sugars (assuming a target price comparable to sugar at $5.96 USD/kg – Feb. 2016), a patented three-step method developed by the Industrial Research Chair on Cellulosic Ethanol and Biocommodities (CRIEC-B) shows significant potential to counter the classical restrictions associated with such process. The first step of the process is performed in concentrated acidic solution resulting in a decrystallization of the cellulose macromolecule, then the mixture is treated again (post-hydrolysis) at higher temperature allowing conversion of cellulose to glucose. After a patented separation step, the reactants are isolated from the carbohydrates allowing an optimal recuperation of the chemicals used for the reaction. As well, optimization of this process was performed in order to maximize glucose production while minimizing operation as well as fermentation inhibitors. In order to understand the parameters of this process, the decrystallized cellulose was analyzed using XRD and SEM in order to determine the minimum liquid/solid ratio needed for the process. In addition, the post-hydrolysis step was optimized using experimental design in order to maximize glucose yield while minimizing water consumption. After hydrolysis, the glucose solutions were fermented into ethanol at high yield using a commercial grade non-GMO yeast. Hydrolysis was performed on several biomasses such as softwood cellulose and hemp cellulose. Finally, a scaled-up pilot plant based on this process is currently being designed in order to validate the economic viability of this process at larger scale as well as to verify the constraints generated from a scale modification. The targeted pilot facilities will be used for the hydrolysis of cellulose in order to produce a system with a total capacity of 100 000L/y. One of the main challenge of this scale-up is the high corrosiveness of the media associated with the other restrictions and chemicals used in the process as well as the high viscosity occurring when cellulose is originally destructured. In this work, investigations were made in order to find a low cost corrosive and solvent-resistant material that could be used in the temperature range corresponding to the process. The end game will be to validate cost-effective process for the production of second-generation bioethanol from cellulosic resources.

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