Use of Raman spectroscopy for continuous monitoring and control of lignocellulosic biorefinery processes

Abstract

The production of fuels and chemicals from lignocellulosic biomass demands efficient processes to compete with fossil fuel-derived products. Key biorefinery processes, such as enzymatic hydrolysis of cellulose and microbial fermentation, can be monitored by advanced sensors in real time, providing information about reactant and product concentration, contamination, and reaction progress. Spectroscopic techniques such as Raman spectroscopy provide a means of quickly and accurately assessing many types of reaction mixtures non-destructively, in real time, and with no costly sample preparation and analysis time. Raman spectroscopy techniques have been developed to accurately quantify a number of compounds present in lignocellulosic processes, and methods have been developed to overcome the presence of fluorescent compounds that can increase the spectral background. Online Raman sensors also can provide the feedback measurements necessary for advanced process controls (APCs). Specifically, model predictive control, a common APC used extensively throughout similar processing industries, is especially well suited for ensuring optimal production of bio-based chemicals from lignocellulosic material.Article note: A collection of invited papers based on presentations at the 2 nd Brazilian Symposium on Biorefineries (II SNBr), Brasília, Brazil, 24-26 September 2013.

Benchmarking real-time monitoring strategies for ethanol production from lignocellulosic biomass

“…However, the Raman signal is relatively weak and attenuated mainly by the suspended solid particles and by the background fluorescence emitted by lignin [48], altogether, limiting its potential for in-line monitoring. Ewanick et al [49,50] UV-Vis spectroscopy is often not considered as a method for real-time monitoring of fermentations because it cannot detect many key compounds (e.g. glucose or ethanol) and because the light scattering caused by the suspended solid particles dominates the absorption process [35,52].…”

Simultaneous Raman and Infrared Spectroscopy of Stable Isotope Labelled Escherichia coli

“…Raman and infrared spectroscopies have been extensively used separately as phenotyping tools in a wide range of microbial metabolomics investigations including studying the effects of antibiotics in bacteria [ 11 , 12 ], classifying and identifying microbial species and strains [ 2 , 3 , 13 ], effects of environmental factors on microbial growth [ 14 , 15 ], and microbial-derived products such as beverages [ 16 , 17 ], biofuels [ 18 , 19 ] and other products for human and animal health. Both methods are often used together in the same study in a complementary way as each technique may be advantageous when studying certain types of samples or biological processes as a result of their different basic working principles [ 3 , 14 , 20 , 21 , 22 ].…”

Measuring Plant Metabolite Abundance in Spearmint (Mentha spicata L.) with Raman Spectra to Determine Optimal Harvest Time

“…In other words, I ( v ) R ∝ N . Several research groups have demonstrated the potential of using Raman spectroscopy and univariate calibration with a calibration curve for real-time monitoring of lignocellulosic bioethanol production, including pretreatment, hydrolysis, and fermentation steps. − However, the complexity of biomass and biomass-derived samples often limits the utility of univariate calibration with these types of samples. Another direction for quantitative analysis is to use Raman spectra along with data from another analysis method (such as HPLC) to build regression models.…”