Bio-based Chemicals Research Articles

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.

The role and performance of isolated zirconia sites on mesoporous silica for aldol condensation of furfural with acetone

Furfural is an important bio-based platform chemical in the production of valuable products such as biofuel intermediates and polymeric materials. In this work, isolated Zr on mesoporous silica catalysts at varied Zr loading were prepared and evaluated for aldol condensation of furfural with acetone to 4-(2-furyl)− 3-buten-2-one(FAc) and 1,5-bis-(2-furanyl)− 1,4-pentadien-3-one(F2Ac). A remarkable effect of the Zr loading on the catalyst performance is revealed. The catalysts are characterized by XRD, BET, NH3-TPD, Py-FTIR, XPS, UV–visible, and TGA. The connectivity of Zr was characterized by XPS and UV–visible spectroscopy. For the 25 wt% Zr loading, Zr is present predominantly as isolated monomeric species on mesoporous SiO2. The types and densities of different acid sites of the catalysts are measured with Py-FTIR analysis. The results show that isolated Zr on mesoporous SiO2 enhanced Lewis acid site densities and exhibited superior catalytic activity for aldol condensation between furfural and acetone to produce FAc and F2Ac.

Niobium and Zirconium Phosphates as Green and Water-Tolerant Catalysts for the Acid-Catalyzed Valorization of Bio-Based Chemicals and Real Lignocellulosic Biomasses

Commercial niobium and synthesized zirconium phosphates were tested as water-tolerant heterogeneous acid catalysts in the hydrothermal conversion of different bio-based substrates. Different acid-catalyzed reactions were performed using biomass-derived model compounds and more complex real lignocellulosic biomasses as the substrate. The conversion of glucose and cellulose was preliminarily investigated. Then, a wide plethora of raw lignocellulosic biomasses, such as conifer wood sawdust, Jerusalem artichoke, sorghum, miscanthus, foxtail millet, hemp and Arundo donax, were valorized towards the production of water-soluble saccharides, 5-hydroxymethylfurfural (HMF), levulinic acid (LA) and furfural. The different catalytic performances of the two phosphates were explained on the basis of their acid features, total acidity, Brønsted/Lewis acid sites ratio and strength. Moreover, a better insight into their structure–acidity relationship was proposed. The different acid properties of niobium and zirconium phosphates enabled us to tune the reaction towards target products, achieving from glucose maximum HMF and LA yields of 24.4 and 24.0 mol%, respectively. Remarkably, when real Jerusalem artichoke biomass was adopted in the presence of niobium and zirconium phosphate, maximum yields of furanic compounds and cellulose-derived sugars of 12.7 and 50.0 mol%, respectively, were obtained, after only 1 h of reaction. The synthesized hydrolysates, which were found to be rich in C5 and C6 carbohydrates, can be better exploited for the cascade production of more added-value bio-products.

Light-Driven Synthetic Biology: Progress in Research and Industrialization of Cyanobacterial Cell Factory.

Light-driven synthetic biology refers to an autotrophic microorganisms-based research platform that remodels microbial metabolism through synthetic biology and directly converts light energy into bio-based chemicals. This technology can help achieve the goal of carbon neutrality while promoting green production. Cyanobacteria are photosynthetic microorganisms that use light and CO2 for growth and production. They thus possess unique advantages as “autotrophic cell factories”. Various fuels and chemicals have been synthesized by cyanobacteria, indicating their important roles in research and industrial application. This review summarized the progresses and remaining challenges in light-driven cyanobacterial cell factory. The choice of chassis cells, strategies used in metabolic engineering, and the methods for high-value CO2 utilization will be discussed.

Engineering Caldicellulosiruptor bescii with Surface Layer Homology Domain-Linked Glycoside Hydrolases Improves Plant Biomass Solubilization.

Extremely thermophilic Caldicellulosiruptor species solubilize carbohydrates from lignocellulose through glycoside hydrolases (GHs) that can be extracellular, intracellular, or cell surface layer (S-layer) associated. Caldicellulosiruptor genomes sequenced so far encode at least one surface layer homology domain glycoside hydrolase (SLH-GH), representing six different classes of these enzymes; these can have multiple binding and catalytic domains. Biochemical characterization of a representative from each class was done to determine their biocatalytic features: four SLH-GHs from Caldicellulosiruptor kronotskyensis (Calkro_0111, Calkro_0402, Calkro_0072, and Calkro_2036) and two from Caldicellulosiruptor hydrothermalis (Calhy_1629 and Calhy_2383). Calkro_0111, Calkro_0072, and Calhy_2383 exhibited β-1,3-glucanase activity, Calkro_0402 was active on both β-1,3/1,4-glucan and β-1,4-xylan, Calkro_2036 exhibited activity on both β-1,3/1,4-glucan and β-1,4-glucan, and Calhy_1629 was active only on arabinan. Caldicellulosiruptor bescii, the only species with molecular genetic tools as well as already a strong cellulose degrader, contains only one SLH-GH, Athe_0594, a glucanase that is a homolog of Calkro_2036; the other 5 classes of SLH-GHs are absent in C. bescii. The C. bescii secretome, supplemented with individual enzymes or cocktails of SLH-GHs, increased in vitro sugar release from sugar cane bagasse and poplar. Expression of non-native SLH-GHs in vivo, either associated with the S-layer or as freely secreted enzymes, improved total carbohydrate solubilization of sugar cane bagasse and poplar by up to 45% and 23%, respectively. Most notably, expression of Calkro_0402, a xylanase/glucanase, improved xylose solubilization from poplar and bagasse by over 70% by C. bescii. While Caldicellulosiruptor species are already prolific lignocellulose degraders, they can be further improved by the strategy described here. IMPORTANCE Caldicellulosiruptor species hold promise as microorganisms that can solubilize the carbohydrate portion of lignocellulose and subsequently convert fermentable sugars into bio-based chemicals and fuels. Members of the genus have surface layer (S-layer) homology domain-associated glycoside hydrolases (SLH-GHs) that mediate attachment to biomass as well as hydrolysis of carbohydrates. Caldicellulosiruptor bescii, the most studied member of the genus, has only one SLH-GH. Expression of SLH-GHs from other Caldicellulosiruptor species in C. bescii significantly improved degradation of sugar cane bagasse and poplar. This suggests that this extremely thermophilic bacterium can be engineered to further improve its ability to degrade specific plant biomasses by inserting genes encoding SLH-GHs recruited from other Caldicellulosiruptor species.

Integrating Torrefaction of Pulp Industry Sludge with Anaerobic Digestion to Produce Biomethane and Volatile Fatty Acids: An Example of Industrial Symbiosis for Circular Bioeconomy

Industrial symbiosis, which allows the sharing of resources between different industries, could help to improve the overall feasibility of bio-based chemicals production. In that regard, this study focused on integrating the torrefaction of pulp industry sludge with anaerobic digestion. More specifically, anaerobic digestion (AD) of pulp sludge-derived torrefaction condensate (TC) was studied to evaluate the biomethane and volatile fatty acid (VFA) potential. The torrefaction condensate produced at 275 and 300 °C was used in AD. The volatile solid content (VS) was 6.69 and 9.01% for the condensate produced at 275 and 300 °C, respectively. The organic fraction of TC mainly contained acetic acid, 2-furanmethanol, and syringol. The methane yield was in the range of 481–772 mL/g VS for the mesophilic and 401–746 mL/g VS for the thermophilic process, respectively. The VFA yield was in the range of 1.1 to 3.4 g/g VS for mesophilic and from 1.5 to 4.7 g/g VS in thermophilic conditions, when methanogenesis was inhibited. Finally, pulp sludge TC is a feasible feedstock to produce platform chemicals like VFA. However, at higher substrate loading, signs of process inhibition were observed because of the relatively increasing concentration of microbial inhibitors

Multigram Synthesis of Pure HMF and BHMF.

5-Hydroxymethylfurfural (HMF) is a bio-based platform chemical that can be used as a building block to produce several compounds with diverse applications. Even though HMF synthesis holds promise for a greener future, the current state of technology and the high production cost limit its competitiveness on an industrial scale. In this prospect, we have developed a multigram-scale procedure for HMF by reacting d-fructose with Purolite CT275DR—an acidic resin—in a dimethyl carbonate (DMC)/tetraethyl ammonium bromide (TEAB) biphasic system. Reactions performed in an autoclave for 2 h at 110 °C using up to 40 gram of d-fructose resulted in an overall HMF yield of 70%. HMF was purified by a custom-made procedure leading to ca 50% of the pure crystalline product; meanwhile, the residual HMF-rich oil was directly reduced to bis(hydroxymethyl)furan (BHMF). Green metrics and the Ecoscale algorithm were used to evaluate the sustainability of the herein-proposed procedure in comparison with previously reported works.

Valorization of cheese whey to lactobionic acid by a novel strain Pseudomonas fragi and identification of enzyme involved in lactose oxidation

BackgroundEfficient upgrading of inferior agro-industrial resources and production of bio-based chemicals through a simple and environmentally friendly biotechnological approach is interesting Lactobionic acid is a versatile aldonic acid obtained from the oxidation of lactose. Several microorganisms have been used to produce lactobionic acid from lactose and whey. However, the lactobionic acid production titer and productivity should be further improved to compete with other methods.ResultsIn this study, a new strain, Pseudomonas fragi NL20W, was screened as an outstanding biocatalyst for efficient utilization of waste whey to produce lactobionic acid. After systematic optimization of biocatalytic reactions, the lactobionic acid productivity from lactose increased from 3.01 g/L/h to 6.38 g/L/h in the flask. In batch fermentation using a 3 L bioreactor, the lactobionic acid productivity from whey powder containing 300 g/L lactose reached 3.09 g/L/h with the yield of 100%. Based on whole genome sequencing, a novel glucose dehydrogenase (GDH1) was determined as a lactose-oxidizing enzyme. Heterologous expression the enzyme GDH1 into P. putida KT2440 increased the lactobionic acid yield by 486.1%.ConclusionThis study made significant progress both in improving lactobionic acid titer and productivity, and the lactobionic acid productivity from waste whey is superior to the ever reports. This study also revealed a new kind of aldose-oxidizing enzyme for lactose oxidation using P. fragi NL20W for the first time, which laid the foundation for further enhance lactobionic acid production by metabolic engineering.Graphical

Fabrication of Z-scheme CdS/H5PMo10V2O40/g-C3N4 for the photocatalytic depolymerization of lignin into aromatic monomers

As the most abundant resource composed of aromatic groups in nature, lignin harbors significant potential for the production of bio-based fuels and chemicals. In recent years, solar-driven photocatalysis with its mild, low cost and environmental benign, has been employed for lignin depolymerization. Herein, we designed a Z-scheme CdS/H5PMo10V2O40/g-C3N4 (CdS/HPA-2/CN) photocatalyst via hydrothermal method for the photocatalytic depolymerization of lignin. The prepared CdS/HPA-2/CN presents a nanoflower-like morphology with the average diameter of ∼600 nm. With the presence of electron-mediated HPA-2, CdS/HPA-2/CN exhibits the enhanced separation and transfer capacity of photogenerated charge carriers through Z-scheme mechanism. Result shows that the total yield (Y) of vanillin and vanillic acid from lignin depolymerization over optimized CdS/HPA-2/CN can reach to 32.7 mg/g lignin in DMF/formic acid (v/v = 40/10) for 4 h. Reusability experiment of optimized CdS/HPA-2/CN displays that Y (26.5 mg/g lignin) can still reach to 81.0% of initial one after three cycles. Qualitative analysis of depolymerized products reveals that most components are aromatic compounds with the dominant products of vanillin and vanillic acid. Evidence also shows that photocatalysis promotes the reaction and small molecular products increased significantly after depolymerization. In addition, mechanism experiments and electron spin resonance tests exhibit that h+, ·O2− and ·OH took part in lignin depolymerization together and the effect sequence was ·O2− > ·OH > h+. In this work, as an electron mediator, HPA-2 provides the inspiration for construction of Z-scheme heterojunction, and CdS/HPA-2/CN exhibits enormous potential in lignin depolymerization by photocatalysis.

Study on vanillin triggered degradable epoxy via facile one-pot synthesis

• Vanillin triggered degradable epoxy was prepared through a one-pot method. • The degradable materials show comparable properties with the commercialized epoxy. • Epoxy containing Schiff base has admirable degradability in acidic THF solutions. A facile one-pot synthesis method to prepare degradable epoxy materials is introduced in this study. Rather than elaborately preparing new epoxies or hardeners, this method developed here is based on a conventional epoxy-amine system, which has better adaptability. Vanillin, a bio-based chemical was selected to trigger the degradation by reacting with epoxy and amine to generate Schiff base linkage. The fabricated degradable materials show comparable thermal, mechanical and insulating properties with their amine-cured counterpart, therefore can be applied as an eco-friendly substitute. A high degradation rate was achieved at a specific acid/organic solvent ratio, while the materials display admirable acidic resistance under other circumstances, which is beneficial for practical application.

A neoteric approach for the complete valorization of Typha angustifolia leaf biomass: A drive towards environmental sustainability.

Exploring new biomass resources and developing a sustainable process for holistic utilization has become crucial due to the high demand for bio-based chemicals as alternatives to petrochemicals. Herein, we describe a novel approach to valorize the Typha angustifolia leaves, underutilized biomass into cellulose, hemicellulose and lignin nanoparticles. The process was framed in a sequence to isolate hemicellulose in the first step due to its highly reactive nature and then separate cellulose and lignin. Among the various natural deep eutectic solvents used in screening experiments, LA/ChCl (2:1) was chosen for hemicellulose solubilization and a dissolution yield of 95.97±1.8% was obtained in 30min at 240W microwave power. Then the residual solid was delignified using NaOCl2 at 180W microwave power and a yield of 97±0.75% was obtained in 15min. Dissolved hemicellulose and lignin were precipitated using anti-solvents. The proposed approach achieved a recovery yield of 95.5±1.2% cellulose, 91.9±2.6% hemicellulose and 89.5±1.6% lignin. Subsequently, the isolated particles were converted into nanoparticles by intense ultrasonication. Spherical shaped nanocellulose, nanohemicellulose and nanolignin were obtained with an average size of 76±7nm, 86±9nm, and 64±5nm, respectively. The produced nanocellulose had a crystallinity of 77.36% with the thermal stability of 265°C. Nanohemicellulose and nanolignin were found to be semicrystalline with thermal stability up to 245°C and 275°C, respectively. The characterization results of the nanoparticles isolated from Typha angustifolia leaves are indicative of their wide range of biomedical and material science applications. This research could open a window for complete utilization of biomass in biorefinery and sustainable management of an invasive plant Typha angustifolia.

PURE: Prototyping emerging products from lignocellulose by zero waste pathways

PURE: Prototyping emerging products from lignocellulose by zero waste pathways This ERC PoC project studies the viability of lignocellulose-based resources for the synthesis of potentially fully bio-based speciality chemicals. It aims at introducing novel and sustainable yet cost-effective chemical manufacturing processes to a multi-billion market. Its objectives are to confirm the feasibility of upscaling it to an industrially relevant scale, outlining a solid strategy delineating the optimum product-market fit and paths towards commercialisation.

An interactive metabolic map of bio-based chemicals

Metabolic engineering for the bio-based production of chemicals requires thorough understanding of metabolic reactions including enzymes, cofactors, reactants, and products. Here we present an interactive bio-based chemicals map that visualizes compounds, enzymes, and reaction pathways together with strategies for the production of chemicals by biological, chemical, and combined methods.

D-Lactic Acid Production from Sugarcane Bagasse by Genetically Engineered Saccharomyces cerevisiae.

Lactic acid (LA) is a promising bio-based chemical that has broad applications in food, nutraceutical, and bioplastic industries. However, production of the D-form of LA (D-LA) from fermentative organisms is lacking. In this study, Saccharomyces cerevisiae harboring the D-lactate dehydrogenase (DLDH) gene from Leuconostoc mesenteroides was constructed (CEN.PK2_DLDH). To increase D-LA production, the CRISPR/Cas12a system was used for the deletion of gpd1, gpd2, and adh1 to minimize glycerol and ethanol production. Although an improved D-LA titer was observed for both CEN.PK2_DLDHΔgpd and CEN.PK2_DLDHΔgpdΔadh1, growth impairment was observed. To enhance the D-LA productivity, CEN.PK2_DLDHΔgpd was crossed with the weak acid-tolerant S. cerevisiae BCC39850. The isolated hybrid2 showed a maximum D-LA concentration of 23.41 ± 1.65 g/L, equivalent to the improvement in productivity and yield by 2.2 and 1.5 folds, respectively. The simultaneous saccharification and fermentation using alkaline pretreated sugarcane bagasse by the hybrid2 led to an improved D-LA conversion yield on both the washed solid and whole slurry (0.33 and 0.24 g/g glucan). Our findings show the exploitation of natural yeast diversity and the potential strategy of gene editing combined with conventional breeding on improving the performance of S. cerevisiae for the production of industrially potent products.

Review on development of ionic liquids in lignocellulosic biomass refining

Lignocellulosic biomass as the renewable and abundant resource in the earth can be transformed into bio-based chemicals and fuels with high added value, which is the preferable substitute for traditional fossil resources. The design and improvement of catalysts and pretreatment solvents are crucial to achieve the low-cost, efficient, and green conversion of biomass resources. Ionic liquids exhibit many advantages in biomass pretreatment and conversion because of their high catalytic efficiency, high solubility, unique molecular structure, and recyclable property. The present review aimed to summarize the research achievements and progress of ionic liquids as solvents or catalysts in the pretreatment of lignocellulosic biomass, transformation of polysaccharides into platform chemicals and isolation, depolymerization, and functional modification of lignin. The review concludes with a brief perspective on possible challenges and strategies for the sustainable development of ionic liquids in lignocellulosic biomass refining.

A 3D printed photoreactor for investigating variable reaction geometry, wavelength, and fluid flow.

Research in the field of photochemistry, including photocatalysis and photoelectrocatalysis, has been revitalized due to the potential that photochemical reactions show in the sustainable production of chemicals. Therefore, there is a need for flexible photoreactor equipment that allows for the evaluation of the geometry, light wavelength, and intensity of the vessel, along with the fluid flow in various photochemical reactions. Light emitting diodes (LEDs) have narrow emission spectra and can be either pulsed or run continuously; being flexible, they can be arranged to fit the dimensions of various types of the reactor vessel, depending on the application. This study presents a 3D printed photoreactor with the ability to adjust distances easily and switch between high-power LED light sources. The reactor design utilizes customized printed circuit boards to mount varying numbers and types of LEDs, which enables multiple wavelengths to be used simultaneously. These LED modules, comprised of heat sinks and cooling fans, fulfill the higher heat dissipation requirements of high-power LEDs. The flexibility of the reactor design is useful for optimizing the reaction geometry, flow conditions, wavelength, and intensity of photochemical reactions on a small scale. The estimates for incident light intensity under five possible reactor configurations using ferrioxalate actinometry are reported so that comparisons with other photoreactors can be made. The performance of the photoreactor for differing vessel sizes and distances, in both the flow and batch modes, is given for a photochemical reaction on 2-benzyloxyphenol-a model substance for lignin and applicable in the production of biobased chemicals.

Synthesis and utilization of meso and microporous catalysts for the valorization of newspaper waste to bio-based chemicals using Choline chloride as biodegradable solvent

The present study develops an effective and sustainable catalytic system using mesoporous (KIT-6 and NbKIT-6) and microporous catalysts (ZIF-8) for the conversion of newspaper waste to value-added products such as TRS (Total reducing sugars) and 5-HMF (5-Hydroxymethyl furfural). The bio-based products were produced using green and biodegradable solvent Choline chloride in presence of sustainable catalysts under mild operating conditions at 1 atm pressure. The study demonstrated the potential of monophasic (Choline chloride and Catalyst) and biphasic (Choline chloride, Catalyst and Extracting solvent) system and revealed their comparative insights. It was observed that both the systems were highly effective but the purity and stability of products were higher in the biphasic system compared to the monophasic system. The synthesised catalysts possess high surface area 588.528, 534.414 and 351.85 m2/g with pore volume 0.7587, 0.3574 and 0.2362 cc/g for KIT-6, NbKIT-6 and ZIF respectively. The selected extracting solvents were found to be promising and the maximum 5-HMF yield was found to be 62.12%, 73.45% and 79.66% in DMSO medium using KIT-6 (160 °C, 135 min), NbKIT-6 (140 °C, 90 min) and ZIF-8 (140 °C, 105 min) catalysts respectively. Also, all the catalysts are reusable for up to five runs with minimal loss in catalyst activity. The proposed catalytic system will help to resolve the challenges associated with biorefineries in terms of product separation and recyclability of catalysts.

An ultrasensitive nanofiber-based assay for enzymatic hydrolysis and deep-sea microbial degradation of cellulose

SummarySubstrates for enzymatic reactions, such as cellulose and chitin, are often insoluble in water. The enzymatic degradation of these abundant organic polymers plays a dominant role in the global carbon cycle and has tremendous technological importance in the production of bio-based chemicals. In addition, biodegradation of plastics is gaining wide attention. However, despite the significance, assaying these degradation reactions remains technically challenging owing to the low reaction rate, because only the surface of the substrate is accessible to the enzymes. We developed a nanofiber-based assay for the enzymatic hydrolysis of cellulose. This assay facilitated the quantification of the enzymatic hydrolysis of <1 ng crystalline cellulose. Utilization of the assay for the functional screening of cellulolytic microorganisms revealed an unprecedented genetic diversity underlying the production of deep-sea cellulase. This study reiterates that interdisciplinary efforts, such as from nanotechnology to microbiology, are critical for solving sustainability challenges.

KBBE: The knowledge-based bioeconomy: Concept, status and future prospects

The article outlines the pioneering role of Christian Patermann in developing the Knowledge-Based Bioeconomy (KBBE), which was largely based on agriculture, forestry, fishery, and aquaculture to produce food and feed, bio-based fuels and chemicals. Later it was condensed into the concept of the Bioeconomy. Today, the focus is on closing material cycles, which has evolved the KBBE concept into that of the Circular Bioeconomy. In line with the European Green Deal it aims on the development of competitive, sustainable, and circular bio-based solutions while addressing climate neutrality, environmental performance, safety, and social acceptance and thus, respecting our planetary boundaries.The article will outline how this pioneering thinking triggered new collaborations among stakeholders working in different sectors across value chains, including private-public consortia, such as the international Cluster Industrial Biotechnology (CLIB cluster), which will be used as example of the translation of bioeconomy concepts products and processes.

An Innovative, Green Cascade Protocol for Grape Stalk Valorization with Process Intensification Technologies

Valorization of agri-food residues to produce bio-based platform chemicals will enhance the transition to the bio-economy era. To this end, a sustainable process has been developed for the overall valorization of grape stalks (GS) according to a circular approach, starting from the lignin fraction to further deal with the cellulose-rich residue. This non-conventional protocol fully adheres to green chemistry principles, exploiting the so-called enabling technologies—mainly ultrasound and microwaves—for energy-saving innovative processes. Firstly, ultrasound-assisted extraction (UAE, 40 kHz, 200 W) demonstrated to be an excellent technique for GS delignification combined with natural deep eutectic solvents (NaDESs). Delignification enables isolation of the pertinent lignin framework and the potential to obtain a polyphenol-rich liquid fraction, focusing on the valorization of GS as source of bioactive compounds (BACs). Among the NaDESs employed, the combination of choline chloride (ChCl) and levulinic acid (LevA) (ChLevA) presented noteworthy results, enabling a delignification higher than 70%. LevA is one of the top-value biobased platform chemicals. In this work, a flash microwave (MW)-assisted process was subsequently applied to the cellulose-rich fraction remained after delignification, yielding 85% LevA. The regeneration of this starting compound to produce ChLevA can lead to a further biomass delignification cycle, thus developing a new cascade protocol for a full valorization of GS.