Analysis of Single-Step Pretreatments for Lignocellulosic Platform Isolation as the Basis of Biorefinery Design

Abstract

Biorefinery feasibility is highly influenced by the early design of the best feedstock transformation pathway to obtain value-added products. Pretreatment has been identified as the critical stage in biorefinery design since proper pretreatment influences subsequent reaction, separation, and purification processes. However, many pretreatment analyses have focused on preserving and valorizing six-carbon sugars for future use in bioconversion processes, leaving aside fractions such as hemicellulose and lignin. To date, there has been no pretreatment systematization for the removal of lignocellulosic fractions. This work defines pretreatment efficacy through operational, economic, environmental, and social indicators. Thus, using the data reported in the literature, as well as the results of the simulation schemes, a multi-criteria weighting of the best-performing schemes for the isolation or removal of cellulose, hemicellulose, and lignin was carried out. As a main result, it was concluded that dilute acid is the most effective for cellulose isolation and hemicellulose removal for producing platform products based on six- and five-carbon sugars, respectively. Additionally, the kraft process is the best methodology for lignin removal and its future use in biorefineries. The results of this work help to elucidate a methodological systematization of the pretreatment efficacy in the design of biorefineries as an early feasibility stage considering sustainability aspects.

Sustainability assessment of lignocellulosic biorefineries based on sequential pretreatments

“…The rice husk was initially ground to a size of 0.3 cm before either a sequential or single‐stage pretreatment scheme. DA pretreatment was performed at 180 °C using 2% H 2 SO 4 at 6.25 L kg −1 substrate, while WAO was at 195 °C at a feed ratio of 30 kg substrate per 500 kg water and 1 kg Na 2 CO 3 with air addition up to 5 bar 8 . Supporting Information, Tables S2 and S3 show the lignocellulosic removal used for the DA‐WAO sequence and the composition of the hydrolysates.…”

“…DA pretreatment was performed at 180 °C using 2% H 2 SO 4 at 6.25 L kg −1 substrate, while WAO was at 195 °C at a feed ratio of 30 kg substrate per 500 kg water and 1 kg Na 2 CO 3 with air addition up to 5 bar. 8 Supporting Information, Tables S2 and S3 show the lignocellulosic removal used for the DA-WAO sequence and the composition of the hydrolysates. After pretreatment, the hydrolysates were separated by filtration, and the water-insoluble solid (WIS) was washed at a 10:1 waterto-substrate mass ratio.…”

“…This distribution was established to avoid subjectivity in allocating importance to each dimension. S I was calculated as the weighted values of s j and OI j , where j represents each dimension evaluated as shown in Eqns (7) and (8).…”

“…7 In biorefineries, pretreatment has been identified as the core stage during the design as it depends on the feedstock composition or the platform products to be obtained, affecting the subsequent reaction or downstream stages. 8 However, many pretreatments have been proposed as single-step technologies for subsequent valorization of a platform product. 9 Consequently, comprehensive biomass valorization is not promoted by leaving aside fractions or streams rich in valuable composition.…”

Comparative Analysis of Trifluoracetic Acid Pretreatment for Lignocellulosic Materials

“…It causes an increase in CapEx for equipment (dimensions, as well as more equipment for recirculation) and in OpEx (cost of acids and quantities). Therefore, evaluating multiple economic pretreatments is necessary to establish a more complete and decisive analysis of TFA pretreatment performance [49]. However, economic analyses to complete processes such as fermentation to ethanol have been widely reported in the literature, but only a few have determined those analyses to yield C5 and C6 sugars.…”