Underutilized Feedstock Research Articles

Transcriptomic characterization of recombinant Clostridium beijerinckii NCIMB 8052 expressing methylglyoxal synthase and glyoxal reductase from Clostridium pasteurianum ATCC 6013.

Biological production of commodity chemicals from abundant waste streams such as whey permeate represents an opportunity for decarbonizing chemical production. Whey permeate remains a vastly underutilized feedstock for bioproduction purposes. Thus, enhanced understanding of the cellular and metabolic repertoires of lactose-mediated production of chemicals such as butanol promises to identify new targets that can be fine tuned in recombinant and native microbial strains to engender stronger coupling of whey permeate-borne lactose to value-added chemicals. Our results highlight new genetic targets for future engineering of C. beijerinckii for improved butanol production on lactose and ultimately in whey permeate.

Improved Electrosynthesis of Biomass Derived Furanic Compounds via Nitroxyl Radical Redox Mediation.

Biomass is an abundantly available, underutilized feedstock for the production of bulk and fine chemicals, polymers, and sustainable and biodegradable plastics that are traditionally sourced from petrochemicals. Among potential feedstocks, 2,5-furan dicarboxylic acid (FDCA) stands out for its potential to be converted to higher-value polymeric materials such as polyethylene furandicarboxylate (PEF), a bio-based plastic alternative. In this study, the sustainable, electrocatalytic oxidation of stable furan molecule 2,5-bis(hydroxymethyl)furan (BHMF) to FDCA is investigated using a variety of TEMPO derivative electrocatalysts in a mediated electrosynthetic reaction. Three TEMPO catalysts (acetamido-TEMPO, methoxy-TEMPO, and TEMPO) facilitate full conversion to FDCA in basic conditions with >90% yield and >100% Faradaic efficiency. The remaining three TEMPO catalysts (hydroxy-TEMPO, oxo-TEMPO, and amino-TEMPO) all perform intermediate oxidation of BHMF in basic conditions but do not facilitate full conversion to FDCA. On the basis of pH studies completed on all TEMPO derivatives to assess their electrochemical reversibility and response to substrate, pH and reversibility play significant roles in the catalytic ability of each catalyst, which directly influences catalyst turnover and product formation. More broadly, this study also highlights the importance of an effective and rapid electroanalytical workflow in mediated electrosynthetic reactions, demonstrating how voltammetric catalyst screening can serve as a useful tool for predicting the reactivity and efficacy of a catalyst-substrate electrochemical system.

Techno-economic analysis of biomass value-added processing informed by pilot scale de-ashing of paper sludge feedstock

Paper sludge biomass represents an underutilized feedstock rich in pulped and processed cellulose which is currently a waste stream with significant disposal cost to industry for landfilling services. Effective fractionation of the cellulose from paper sludge presents an opportunity to yield cellulose as feedstock for value-added processes. A novel approach to cellulose fractionation is the sidehill screening system, herein studied at the pilot-plant scale. Composition analysis determined ash removal and carbohydrate retention of both sidehill and high-performance benchtop screening systems. Sidehill screening resulted in greater carbohydrates retention relative to benchtop screening (90% vs 66%) and similar ash removal (95% vs 98%). Techno-economic analysis for production of sugar syrup yielded a minimum selling price of $331/metric ton of sugar syrup including disposal savings, significantly less than a commercial sugar syrup without fractionation. Sensitivity analysis showed that screening conditions played a significant role in economic feasibility for cellulosic yield and downstream processes.

Enhanced Biochar Production via Co-Pyrolysis of Biomass Residual with Plastic Waste after Recycling Process

Biomass pyrolysis for oil production results in biochar byproduct, whose characteristics can be improved by the reuse of waste plastics. While the plastic recycling process leads to a large amount of plastic waste that cannot be reused, this underutilized feedstock holds the potential for coprocessing with biomass, thereby increasing the likelihood of producing valuable biochar products. This study sought to evaluate how the inclusion of plastic waste influences the pyrolysis of biomass residue. To this end, sawdust and hardwood biomass were chosen as materials to investigate how the presence of plastics might alter the properties of the resulting chars. Synergies were observed among the biomass components, particularly in samples with higher lignin content from hardwood biomass, which resulted in increased biochar yields. The results showed that a 20% blend of plastic waste with wood at 300°C produced a solid char with a yield of 40% by weight. Co-pyrolysis of the biochar derived from blends of 20 wt. % PP with both sawdust and hardwood resulted in significant enhancement of various properties of the resulting biochar, including surface area, carbon content, hydrophobicity, and aromaticity. This enhancement had a favorable effect on the carbon content and calorific values of the biochar. These enhanced properties significantly contributed to the biochar’s capacity for sorbing substances like various heavy metals. It can be proved that this result showed the importance of the energy content of biochar and its potential use for renewable applications. The beneficial combined effect seen in the plastic blends can be credited to the interaction between the biomass and polymer components, resulting in the production of fewer volatile products at higher temperatures. It can be suggested that biochar from biowaste and plastic waste not only reduces environmental impact but also converts it into a valuable and eco-friendly product.

Lignosulfonate-Based Ionic Liquids as Asphaltene Dispersants.

Asphaltenes are recognized as being troublesome from upstream to downstream in the oil industry due to their tendency to precipitate and self-associate. Their extraction from asphaltenic crude oil for a cost-effective refining process is a crucial and critical challenge in the oil and gas sector. Lignosulfonate (LS), as a by-product of the wood pulping process in the papermaking industry, is a highly available and underutilized feedstock. This study aimed to synthesize novel LS-based ionic liquids (ILs) by reacting lignosulfonate acid sodium salt [Na]2[LS] with different alkyl chains of piperidinium chloride for asphaltene dispersion. The synthesized ILs, 1-hexyl-1-methyl-piperidinium lignosulfonate [C6C1Pip]2[LS], 1-octyl-1-methyl-piperidinium lignosulfonate [C8C1Pip]2[LS], 1-dodecyl-1-methyl-piperidinium lignosulfonate [C12C1Pip]2[LS] and 1-hexadecyl-1-methyl-piperidinium lignosulfonate [C16C1Pip]2[LS] were characterized using FTIR-ATR and 1H NMR for functional groups and structural confirmation. The ILs depicted high thermal stability because of the presence of a long side alkyl chain and piperidinium cation following thermogravimetric analysis (TGA). Asphaltene dispersion indices (%) of ILs were tested by varying contact time, temperature and ILs concentration. The obtained indices were high for all ILs, with a dispersion index of more than 91.2% [C16C1Pip]2[LS], representing the highest dispersion at 50,000 ppm. It was able to lower asphaltene particle size diameter from 51 nm to 11 nm. The kinetic data of [C16C1Pip]2[LS] were consistent with the pseudo-second-order kinetic model. The dispersion index (%), asphaltene particle growth and the kinetic model agreed with the molecular modeling studies of the HOMO-LUMO energy of IL holds.

On piston engines as hydrocarbon gas reformers for modular, distributed chemical production

Hydrocarbon gases, and especially stranded gases such as those produced as a byproduct of tight oil production, are an underutilized feedstock that is often flared, vented, or reinjected. Improved utilization of stranded gas faces two primary technical/economic challenges. First, the gas is inherently distributed geographically and the supply varies temporally, which requires rethinking the characteristics of the chemical plant used to process the gas. Second, methane—the primary constituent of hydrocarbon gases—is relatively inert and requires activation through a synthesis gas intermediate prior to conversion to useful products. This methane activation step requires reforming chemistry which adds to the cost and complexity of the plant. This paper explores the potential of piston engines as non-catalytic, partial-oxidation reformers, providing an enabling technology for distributed production of chemicals from stranded gas resources. The motivation for using an engine in this process is to take advantage of the modular, scalable, fast-responding characteristics of engines, leveraging this highly developed and mass-manufactured device for purposes beyond power generation or transportation. This paper provides a perspective on technical, economic, and environmental aspects of engine reforming for production of low-carbon fuels and chemicals from stranded gas.

Mechanistic Studies for Pd(II)(O2) Reduction Generating Pd(0) and H2O: Formation of Pd(OH)2 as a Key Intermediate.

Molecular oxygen (O2) remains to be an ideal yet underutilized feedstock for the oxidative transformation of organic substrates and renewable energy systems such as fuel cells. Palladium (Pd) has shown particular promise in enabling these applications. The present study describes a Pd-mediated O2 reduction to water via C-H activation of 9,10-dihydroanthracene (DHA) by a Pd(II) η2-peroxo complex 1O2. The reaction yields stoichiometric anthracene and Pd(0) product 1 and is notable in two respects. First, plots of concentrations of the reaction participants over time have distinctly sigmoidal shapes, indicating that conversion accelerates over time and implying autocatalysis. Second, the reaction proceeds via a genuine monometallic Pd(II) dihydroxide 1(OH)2 directly observed to grow and decay as an intermediate. Confirming its role as an intermediate, the dihydroxide 1(OH)2 was found to mediate C-H oxidation of DHA on par in activity with the peroxo compound 1O2. Mechanistic studies with density functional theory (DFT) calculations suggested that both 1O2 and 1(OH)2 react with DHA by hydrogen atom transfer (HAT) and that autocatalysis in the 1O2 reaction results from oxidative addition of the initial Pd(II) complex 1O2 to the Pd(0) product 1. This reaction forms a transient bis(μ-oxo) Pd(II) dimer 1O21 that is more active in the HAT oxidation of DHA than the initial 1O2.

FAST PYROLYSIS OF SULFUR-FREE LIGNIN FROM ALKALINE PULPING WITH A HOT-WATER PRETREATMENT STAGE

"The pyrolytical conversion of birch (Betula pendula/pubescens) lignin fractions separated from hot-water pretreatment/sulfur-free delignification black liquors was investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Based on pyrolytical data, the main condensable compounds were organized into respective component groups, and the relative mass portions of the pyrolysis products (mainly monomer-related fragmented products) formed during pyrolysis of various feedstocks were determined. It could be concluded that relatively pure aromatic fractions, mainly of guaiacol and syringol origin, without carbohydrate impurities, could be produced by this integrated biorefinery approach, in which all biomass fractions can be utilized for manufacturing biobased chemicals and chemical precursors. It could be determined that the formation of the individual pyrolytical components was characteristically dependent on the utilized production conditions (i.e., alkali charge, temperature, pretreatment), creating the possibility for adjustment of the process parameters for pronounced production of desired product fractions. Hence, it could be concluded that this sulfur-free concept facilitated the environmentally friendly production of aromatics, without the need for removing sulfur or carbohydrates-derived impurities from the liquid feedstocks. The practical importance of the approach presented in this manuscript lies in the development of rapid and reliable characterization tools for various lignocellulosics-originated feedstocks possessing potential for thermochemical conversion and for creating novel biorefinery concept alternatives for producing aromatics and chemical precursors from currently underutilized feedstock, lignin."

(Invited) Carbon Dioxide As a Sustainable One-Carbon Precursor in Electrochemical Synthesis

Carbon dioxide is an abundant and under-utilized feedstock in synthetic chemistry. At present, the most common one-carbon (C1) precursor is methane, which is converted to syngas via steam methane reforming under harsh conditions, for use in the synthesis of diverse chemicals, including acids, alcohols, and hydrocarbons. One strategy for developing a carbon-negative path for chemical synthesis is to replace steam methane reforming with carbon dioxide reduction to carbon monoxide, along with hydrogen evolution. These reactions can be conduced in a modular fashion through electrochemical routes powered by renewable electricity. I will present methods by which highly-dispersed metal phthalocyanine catalysts heterogenized on carbon paper supports can achieve high turnover frequencies for converting carbon dioxide to carbon monoxide at room temperature. A second strategy for utilizing CO2 as a C1 precursor involves direct carboxylation of intermediates in organic synthesis, circumventing the need to produce syngas as an intermediate. Our group has shown sustainable routes whereby carbon-halogen and carbon-nitrogen bonds can be carboxylated and elucidated the mechanism by which this transformation occurs. These methods will be discussed in the context of the diverse scales at which decarbonization of the chemical industry needs to occur to secure a sustainable paradigm for producing critical chemicals and materials.

Butyric Acid Generation by Clostridium tyrobutyricum from Low-Moisture Anhydrous Ammonia (LMAA) Pretreated Sweet Sorghum Bagasse.

Sweet sorghum bagasse (SSB) is an under-utilized feedstock for biochemical conversion to biofuels or high value chemicals. One such chemical that can be generated biochemically and applied to a wide array of industries from pharmaceuticals to the production of liquid transportation fuels is butyric acid. This work investigated cultivating the butyric acid producing strain Clostridium tyrobutyricum ATCC 25755 on low-moisture anhydrous ammonia (LMAA) pretreated SSB. Pretreated SSB hydrolysate was detoxified and supplemented with urea for shake flask batch fermentation to show that up to 11.4g/L butyric acid could be produced with a selectivity of 87% compared to other organic acids. Bioreactor fermentation with pH control showed high biomass growth, but a similar output of 11.3g/L butyric acid was achieved. However, the butyric acid productivity increased to 0.251g/L∙hr with a butyric acid yield of 0.29g/g sugar consumed. This butyric acid output represented an 83% theoretical yield. Further improvements in butyric acid titer and yield can be achieved by optimizing nutrient supplementation and incorporating fed-batch fermentation processing of pretreated SSB hydrolysate. Construction of ZGO:Sr NR- and ZGC@PDA NP-driven ratiometric aptasensor for CEA detection.

Lignin Source and Structural Characterization.

Lignin is a primary component of lignocellulosic biomass and an underutilized feedstock in the growing pulping and biofuel industries. Currently, over 50 million tons of industrial lignin are produced annually from pulping and bioethanol processes in the world. Around 95 % of industrial lignin is burned as fuel in heat and power plants due to its complicated, destructive, and condensed structures hindering direct industrial utilization, while the remaining 5 % of lignin is used for potential applications, such as additives, binders, dispersants, and surfactants, through modification. Meanwhile, different biorefinery processes also produce a considerable amount of lignin with various structural features and properties. The development of technologies for its structural characterization is currently desirable for lignin valorization, which will improve the techno-economics of applications of lignins in industries.

(Invited) Carbon Dioxide as a Sustainable One-carbon Synthon

Carbon dioxide is an abundant and under-utilized feedstock in synthetic chemistry. At present, the most common one-carbon (C1) synthon is methane, which is converted to syngas via steam methane reforming under harsh conditions, for use in the synthesis of diverse chemicals, including acids, alcohols, and hydrocarbons. As an example, carbon monoxide can be used to conduct carbonylation reactions for extending carbon chains. An alternative C1 synthon involves direct use of carbon dioxide for carboxylation reactions in organic synthesis, circumventing the need to produce syngas as an intermediate and providing a carbon-negative route for chemical synthesis. Our group has shown sustainable routes whereby carbon-halogen and carbon-nitrogen bonds can be carboxylated and elucidated the mechanism by which this transformation occurs. These methods will be discussed in the context of the diverse scales at which decarbonization of the chemical industry needs to occur to secure a sustainable paradigm for producing critical chemicals and materials.

Fast pyrolysis of mannan-rich ivory nut (Phytelephas aequatorialis) to valuable biorefinery products

Ivory nut residues from the palm Phytelephas aequatorialis were converted via fast pyrolysis into a set of valuable biorefinery products, being (i) pyrolysis liquids rich in levomannosan and 5-hydroxymethyl furfural (5-HMF), (ii) biochar, with potential for soil applications, (iii) and non-condensable gases with potential for upgrading and syngas processes. The ivory nut residues were mannan-rich leftovers from button manufacturing in Ecuador. A handful of studies, dating back from the 20th century, have investigated gram-scale valorization of ivory nut to e.g. mannose. Nevertheless, advances in science and technology on biorefinery products called for a comprehensive reassessment of the valorization potential of this underutilized feedstock. A fully equipped, continuously operated lab-scale reactor (200 g.h−1 feed) was used for pyrolysis at 350 °C and 500 °C. The pyrolysis liquid yield was 57.53 wt% at 350 °C and 60.36 wt% at 500 °C. The aqueous phase obtained at 350 °C contained 17.5 wt% (d.b.) anhydrosugars, of which 90% was levomannosan, and contained 11.6 wt% (d.b.) furans, of which 56% was 5-HMF and 17% furfural. The carbon stability of the biochars, measured with the Edinburgh accelerated ageing tool, were 40.6% and 64.6%, respectively. Non-condensable gases during pyrolysis at 350 °C only were composed of CO2 and CO (CO2:CO molar ratio of 4:1), while at 500 °C, gases were obtained with a CO2:CO:H2:CH4 molar ratio of 9:9:4:1. Overall, the results demonstrate that pyrolysis of ivory nut holds potential as starting point for valuable biorefinery products.

Conversion of non-edible Argemone Mexicana seed oil into biodiesel through the transesterification process

ABSTRACTIn the present research work, a promising and underutilized feedstock, Argemone Mexicana (AM) seed oil is converted into biodiesel through the two-step transesterification process using hot plate magnetic stirrer. The physicochemical properties of AM biodiesel (Argemone Mexicana oil methyl ester; AMOME), established through standard procedures and found well within the EN14214 standard limits. In this experimental study different variables such as methanol to oil molar ratio, reaction time, and amount of catalyst used are taken into consideration. The experimental outcomes show that the best yield for the conversion of AM seed oil into biodiesel is achieved up to 94% for methanol to oil molar ratio of 6:1 with 60 min heating time for two different catalyst concentrations. Thus the biodiesel production with 0.4% catalyst concentration is found more eco-friendly due to lesser use of catalyst. Finally, it is resolved from the results obtained by the experiment that biodiesel produced from AM seed oil may be used as a potential substitute for natural diesel fuel.

Effects of Pretreatments on Yields, Selectivity and Properties of Products from Pyrolysis of Phragmites australis (Common Reeds)

Phragmites australis (PHA) is a grass-type biomass, commonly known as reed grass, which has the potential to be a valuable energy and chemical feedstock due to its high yield (4.5–7 kg biomass m−2 year−1). It is demonstrated that the physicochemical properties and composition of phragmites can be altered by subjecting the feedstock to a combined acid hydrolysis at various level of acid concentrations and torrefaction pre-treatment processes. In this paper, we conducted fast pyrolysis on pretreated PHA, resulting in bio-oil with significantly higher selectivity towards levoglucosenone and appreciably reduced amounts of ketones and aldehydes being produced. The experiments demonstrated that 4% H3PO4 acid hydrolysis and 220 °C torrefaction combined pretreatments prior to fast pyrolysis resulted in 17 times increase of relative selectivity to levoglucosenone in the bio-oil portion along with a reduction of ketones and aldehydes relative concentrations from 23% to 13%. Pyrolysis of pretreated PHA produced higher amount of biochar. The phosphorus-enriched biochar offers a potential usage for soil amendment or sorbent material. This study presents an opportunity to convert this underutilized feedstock into valuable bio-based products. Additional in-depth investigation is essential to gather more data for assessing the economic and sustainability features of the proposed process.

Ultrasonic-assisted production of biodiesel from Manilkara Zapota (L.) seed oil

ABSTRACTThis paper investigates a novel method for the intensification of biodiesel production via alkali-catalyzed transesterification of an underutilized feedstock, Manilkara zapota (L.) seed oil (MZO) using ultrasonic energy. The effects of the oil to methanol molar ratio (1:5–1:7), catalyst concentration (0.5–1.5 wt%), and reaction temperature (30–50°C) have been investigated using an ultrasonic frequency of 20 kHz and an ultrasonic power of 50 Watt. Optimal conversion of 97% was achieved in 20 min in an ultrasonic cavitation reactor with 1:6 molar ratio of oil to methanol, 1 wt% of catalyst, and 50°C of reaction temperature. The transesterification process is repeated with a conventional (mechanical stirring) method at optimum conditions (1:6 molar ratio, 1 wt% catalyst concentration, and 50°C reaction temperature). Biodiesel obtained from the ultrasonic method and the conventional method was then compared for their percentage yield and physicochemical properties. Ultrasonic transesterification process gave a maximum yield of 97% by weight of M. zapota biodiesel along with enhanced physiochemical characteristics. Therefore, it is concluded that ultrasonic process is the most effective method for converting MZO into biodiesel. The major properties of M. zapota oil methyl ester (MZME) met the requirements of EN 14214 biodiesel standard and therefore M. zapota (L.) seed oil can be a possible substitute to petro diesel.

Performance Assessment of an Allothermal Auger Gasification System for On-Farm Grain Drying

Biomass gasification is a well-developed technology with the potential to convert agricultural residues to value-added products. The availability of on-farm gasifiers that can handle low-density agricultural wastes such as soybean residue, an underutilized feedstock, is limited. Therefore, the goal of this research was to install and assess an allothermal, externally heated, auger gasifier capable of converting agricultural wastes to combustible gas for on-farm grain drying. The system was used to convert soybean residues under different reactor temperature, i.e., 700°C, 750°C, 800°C, and 850°C. The results showed that increasing the reactor temperature from 700°C to 850°C increased the producer gas molar fractions of H2, CO, and CH4, from 1.1% to 1.5%, from 15.0% to 23.8%, and from 5.1% to 7.7%, respectively. The higher heating value of the producer gas reached 6.3 MJ/m3 at reactor temperature of 850°C. Specific gas yield increased from 0.32 to 0.58 m3/kgbiomass while char and particulate yield decreased from 41.7% to 33.6% by increasing the reactor temperature from 700°C to 850°C. Maximum carbon sequestration achieved, in the form of biochar-carbon, was 32% of the raw feedstock carbon. Gasification of collectable soybean residues from 1 acre would be sufficient to dry 1132 kg of soybean seeds (the average yield from one acre)

Plant Biomass from Grasses: An Underutilized Feedstock for Microbial Production of Chemicals and Biopolymers

Plant biomass from grasses is an underutilized feedstock for the microbial production of chemicals and biopolymers. Hydrolysates of this type of plant biomass provide sufficient levels of glucose or xylose to support specialty chemical and biopolymer production. Considering the availability of these grasses worldwide, additional studies are needed to determine whether the production of industrially important chemicals and biopolymers from grasses using microbial bioconversion is feasible.