An integrated deep eutectic solvent-ionic liquid-metal catalyst system for lignin and 5-hydroxymethylfurfural production from lignocellulosic biomass: Technoeconomic analysis

Recent advances in biorefineries based on lignin extraction using deep eutectic solvents: A review

Considering the urgent need for alternative biorefinery schemes based on sustainable development, this review aims to summarize the state-of-the-art in the use of deep eutectic solvent pretreatment to fractionate lignocellulose, with a focus on lignin recovery. For that, the key parameters influencing the process are discussed, as well as various strategies to enhance this pretreatment efficiency are explored. Moreover, this review describes the challenges and opportunities associated with the valorization of extraction-derived streams and highlights recent advancements in solvent recovery techniques. Furthermore, the utilization of computational models for process design and optimization is introduced, as the initial attempts at the economic and environmental assessment of this lignocellulosic bioprocess based on deep eutectic solvents. Overall, this review offers a comprehensive perspective on the recent advances in this emerging field and serves as a foundation for further research on the potential integration of deep eutectic pretreatment in sustainable multi-product biorefinery schemes.

The key role of pretreatment for the one-step and multi-step conversions of European lignocellulosic materials into furan compounds

Nowadays, an increased interest from the chemical industry towards the furanic compounds production, renewable molecules alternatives to fossil molecules, which can be transformed into a wide range of chemicals and biopolymers. These molecules are produced following hexose and pentose dehydration. In this context, lignocellulosic biomass, owing to its richness in carbohydrates, notably cellulose and hemicellulose, can be the starting material for monosaccharide supply to be converted into bio-based products. Nevertheless, processing biomass is essential to overcome the recalcitrance of biomass, cellulose crystallinity, and lignin crosslinked structure. The previous reports describe only the furanic compound production from monosaccharides, without considering the starting raw material from which they would be extracted, and without paying attention to raw material pretreatment for the furan production pathway, nor the mass balance of the whole process. Taking account of these shortcomings, this review focuses, firstly, on the conversion potential of different European abundant lignocellulosic matrices into 5-hydroxymethyl furfural and 2-furfural based on their chemical composition. The second line of discussion is focused on the many technological approaches reported so far for the conversion of feedstocks into furan intermediates for polymer technology but highlighting those adopting the minimum possible steps and with the lowest possible environmental impact. The focus of this review is to providing an updated discussion of the important issues relevant to bringing chemically furan derivatives into a market context within a green European context.

Effective one-pot chemoenzymatic cascade catalysis of biobased feedstock for synthesizing 2,5-diformylfuran in a sustainable reaction system

2,5-Diformylfuran, which can be prepared via the oxidation of biobased HMF, has received considerable attention because of its potential applications in producing furan-based chemicals and functional materials, such as biofuels, polymers, fluorescent material, vitrimers, surfactants, antifungal agents and medicines. This work aimed to develop an efficient one-pot process for chemoenzymatic transformation of biobased substrate to 2,5-diformylfuran with deep eutectic solvent (DES) Betaine:Lactic acid ([BA][LA]) catalyst and oxidase biocatalyst in [BA][LA]-H₂O. Using waste bread (50 g/L) and D-fructose (18.0 g/L) as feedstocks in [BA][LA]-H₂O (15:85, vol/vol), the yields of HMF were 32.8% (15 min) and 91.6% (90 min) at 150 °C, respectively. These prepared HMF could be biologically oxidized to 2,5-diformylfuran by Escherichia coli pRSFDuet-GOase, achieving a productivity of 0.631 g 2,5-diformylfuran/(g fructose) and 0.323 g 2,5-diformylfuran/(g bread) after 6 h under the mild performance condition. This bioresourced intermediate 2,5-diformylfuran was effectively synthesized from biobased feedstock in an environmentally-friendly system.

Significantly enhanced enzymatic hydrolysis of waste rice hull through a novel surfactant-based deep eutectic solvent pretreatment

The potential of green solvents, specifically deep eutectic solvents (DESs), has piqued the interest of researchers in the field of lignocellulose pretreatment. To enhance the enzymatic digestion efficiency of waste rice hull (RCH), an effective pretreatment approach was developed using the DES [AA][CATB], which was made with acetic acid (AA) and cetyltrimethylammonium bromide (CTAB). The results showed that [AA][CATB] improved enzymatic saccharification by 3.7 times compared to raw RCH and efficiently eliminated lignin (38.7%) and removed xylan (42.9%). The improvement in enzymatic hydrolysis efficiency was then interpreted by a series of characterizations that showed a great morphological changed RCH with an obvious accessibility increase and a lignin surface area and hydrophobicity reduction. This work demonstrates that functional, and easily recoverable DESs have potential for improving the efficiency of lignocellulose pretreatment in biorefineries, providing a promising approach for developing green solvents and achieving more sustainable and efficient biorefinery processes.

Techno-economic analysis of ionic liquid pre-treatment integrated pyrolysis of biomass for co-production of furfural and levoglucosenone

In the current work, a techno-economic analysis of pyrolysis of choline glycinate pre-treated biomass has been presented for the co-production of furfural and levoglucosenone along with hemicellulose, lignin and biochar as other byproducts. The mass balance suggested that the 1800 kg/h dry sugarcane straw biorefinery plant could produce about 260 kg/h furfural and 65 kg/h levoglucosenone. The minimum selling price of furfural and levoglucosenone were also estimated and the values were 1640 and 3590 AU$/tonne at 11.1 % biomass loading with 99 % ionic liquid recycling for furfural and levoglucosenone as the target products, respectively. The base case analysis suggested around 6.9 MAU$ NPV with a payback period of 15.4 years. The sensitivity analysis suggested that biomass loading, ionic liquid recycling and cost, waste heat recovery, furfural yield, interest rate and capital cost are the major influential factors for both the minimum selling price of furfural and levoglucosenone.

Deep eutectic solvents for improved biomass pretreatment: Current status and future prospective towards sustainable processes

Pretreatment processes - recognized as critical steps for efficient biomass refining - have received much attention over the last two decades. In this context, deep eutectic solvents (DES) have emerged as a novel alternative to conventional solvents representing a step forward in achieving more sustainable processes with both environmental and economic benefits. This paper presents an updated review of the state-of-the-art of DES-based applications in biorefinery schemes. Besides describing the fundamentals of DES composition, synthesis, and recycling, this study presents a comprehensive review of existing techno-economic and life cycle assessment studies. Challenges, barriers, and perspectives for the scale-up of DES-based processes are also discussed.

Process intensification strategies for green solvent mediated biomass pretreatment

Demonstrated to be highly effective for lignocellulosic biomass pretreatment, deep eutectic solvent (DES) has attracted increasing attention owing to its advantages of simple synthesis, relatively low chemical cost, and better biocompatibility as compared to certain ionic liquids. Here we provide a critical review of the status of the design/selection of DES for the pretreatment of biomass feedstocks with an emphasis on the process intensification strategies: 1) integration of microwave, ultrasound, and high solid extrusion for pretreating biomass, 2) one-pot DES pretreatment, enzymatic hydrolysis, and fermentation, 3) strategies for DES recycling and product recovery; and 4) recent progress on molecular simulations toward understanding the interactions between DES and biomass compounds such as lignin and cellulose. Lastly, we provide perspectives toward cost-effective, continuous, high-solid, environmental-benign, and industrial-relevant applications and point to future research directions to address the challenges associated with DES pretreatment.

A review on strategies to reduce ionic liquid pretreatment costs for biofuel production

Worldwide demand for renewable energy has promoted the considerable exploration of biofuel production from lignocellulosic biomass. Ionic liquid pretreatment is of great interest to render biomass amenable for biofuel production, however, its unaffordable cost stimulates significant attention to the feasibility of commercialization. This review aims to compile the latest advances with respect to reducing production costs for ionic liquids-based biorefineries. Protic ionic liquids offer relatively low synthesis costs, but excessive antisolvent washing of the pretreated biomass is often inevitable. Recovering ionic liquids requires several separation and purification steps, and the reuse of ionic liquids could significantly lose functionality due to the degradation. It is promising to screen ionic liquids-tolerant enzymes and strains for one-pot saccharification and fermentation without solid-liquid separation, however, there is still a need for subsequent recovery of ionic liquids. Additionally, technoeconomic analysis and life cycle assessment are highly recommended to evaluate the economic and environmental impacts.

1-Butyl-3-methylimidazolium acetate pretreatment of giant reed triggering yield improvement of biohydrogen production via photo-fermentation

Ionic liquids (ILs) have been considered as promising alternatives to traditional reagent for lignocellulosic biomass pretreatment because of their tunable physicochemical and "green" properties. In the study, the influence of 1-Butyl-3-methylimidazolium acetate ([Bmim]acetate) pretreatment of giant reed on H2 yield improvement via photo-fermentation (PF) was evaluated. Under the optimal pretreatment conditions (6 g/L [Bmim]acetate at 70 °C for 4 h), the delignification of giant reed was up to 26.7 %. In addition, the sugar yield (9.5 g/L) and hydrogen yield (72.3 mL/g TS) from giant reed were enhanced by 1.7-fold and 61.7 % over those of untreated giant reed, respectively. Moreover, ternary analysis showed that retention time had the strongest effect on delignification, sugar yield and hydrogen yield of giant reed compared to pretreatment temperature and [Bmim]acetate loading. These experimental results indicated that [Bmim]acetate pretreatment of giant reed is an effective approach to enhance the hydrogen yield via PF.

Recent Progress in Processing Cellulose Using Ionic Liquids as Solvents

Cellulose-based materials have attracted great attention due to the demand for eco-friendly materials and renewable energy alternatives. An increase in the use of these materials is expected in the coming years due to progressive decline in the supply of petrochemicals. Based on the limitations of cellulose in terms of dissolution/processing, and focused on green chemistry, new cellulose production techniques are emerging, such as dissolution and functionalization in ionic liquids which are known as green solvents. This review summarizes the recent ionic liquids used in processing cellulose, including pretreatment, hydrolysis, functionalization, and conversion into bio-based platform chemicals. The recent literatures investigating the progress that ILs have made in their transition from academia to commercial application of cellulosic biomass are also reviewed.