(562h) Kinetic Modeling and Techno-Economic Analysis of a Sugar Production Process Via Hydrolysis of Lignocellulosic Biomass

There is increasingly more emphasis on the development of sustainable technologies for production of energy, fuel, and chemicals. Among many options of sustainable energy sources, lignocellulosic biomass is the only large-scale sustainable carbon source available¹. Generation of value-added products requires degradation of three major polymeric components¹ of lignocellulosic biomass, namely, cellulose, hemicellulose, and lignin to relatively smaller oligomeric or monomeric units.

C5 (e.g., xylose) and C6 (e.g., glucose) sugars are two of the most important platform intermedia for lignocellulose conversion., production of which can be viable through the hydrolysis process where the glycosidic linkages between the monosaccharides² are broken in presence of a catalyst. To recover C5 and C6 sugars from biomass, one of the main technologies is acid-catalyzed hydrolysis that can be performed in presence of either concentrated acid or dilute acid as the catalyst. Concentrated acid hydrolysis (CAH) method has various advantages over dilute acid hydrolysis (DAH) like lower operating temperature, high sugar yield, and low degradation of sugars during hydrolysis. Although there are several limitations of the CAH such as the costs of large amount of concentrated acid(s), corrosion-resistant reactors, and acid recovery process, the interest in CAH has been renewed recently due to the development of acid recovery technologies, and high flexibility of CAH for efficiently handling various types of biomass feedstocks³. Existing kinetic model for CAH have been developed for only synthetic components^4,5 and not for the true biomass. In this work, a kinetic model of the CAH is developed, and kinetic parameters are optimally estimated by using the experimental data. A kinetic model of the DAH is also developed. First-principles dynamic models of the batch reactors for CAH and DAH are developed. These reactors are scaled up to the commercial scale. Models of the separation section are also developed for separation of products from the unconverted reactants. In addition, a model is developed for recovering the acid from hydrolysate and recycling it. An economic model of the plant is developed. Techno-economic analysis and optimization are undertaken for maximizing the net present value that takes into account both capital and operating costs and time value of money. Design variables such as the reactor dimensions are optimized along with optimizing the key operating variables such as residence time, catalyst concentration and reaction temperature. Impact of the biomass composition on optimal design and operating variables is evaluated.

References:

1. Zhou, Z., Liu, D. & Zhao, X. Conversion of lignocellulose to biofuels and chemicals via sugar platform: An updated review on chemistry and mechanisms of acid hydrolysis of lignocellulose. Renewable and Sustainable Energy Reviews vol. 146 at https://doi.org/10.1016/j.rser.2021.111169 (2021).
2. Shen, X. J., Huang, P. L., Wen, J. L. & Sun, R. C. A facile method for char elimination during base-catalyzed depolymerization and hydrogenolysis of lignin. Fuel Process. Technol. 167, 491–501 (2017).
3. Wijaya, Y. P. et al. Comparative study on two-step concentrated acid hydrolysis for the extraction of sugars from lignocellulosic biomass. Bioresour. Technol. 164, 221–231 (2014).
4. Kanchanalai, P., Temani, G., Kawajiri, Y. & Realff, M. J. Hydrolysis & crystallinity. BioResources vol. 11 (2016).
5. Camacho, F., González-Tello, P., Jurado, E. & Robles, A. Microcrystalline-cellulose hydrolysis with concentrated sulphuric acid. J. Chem. Technol. Biotechnol. 67, 350–356 (1996).