Biofuel Precursors Research Articles

Design of Heterogeneous Catalysts for the Conversion of Furfural to C5 Derivatives: A Brief Review

Technological development made in the field of biomass application allows synthesizing several high-value products, such as furfuraldehyde. Furfural, produced through sequential hydrolysis and dehydration reactions from biomass, is considered a platform molecule and a precursor of several other chemicals and biofuels that are generated following reactions such as hydrogenation, hydrodeoxygenation, and decarboxylation. This review aims to reveal the environmental-friendly mechanisms followed for producing furfural derivatives and the design of catalysts and supports. Redox and acid-base properties of the molecules have been discussed. The stability, the details of the surface area, and the applications of the molecules to reduce the bottlenecks faced in the industrial production of bioproducts have been explored.

Bifunctional hybrid organosiliceous catalysts for aldol condensation – hydrogenation tandem reactions of furfural in continuous-flow reactor

A series of organic-inorganic hybrid bifunctional organosiliceous catalysts with accessible pendant amine groups as single basic sites (such as propylamine, diethylamine, pyrrolidine) and Pd nanoparticles was prepared from suitable synthesis processes. Pd/MCM-41 silica decorated with propylamine groups was highly active and selective for the single-reactor tandem aldol condensation/crotonization reaction between furfural with methyl isobutyl ketone, followed by hydrogenation, to access renewable biosolvent and biofuel precursors in the branched alkane range at mild temperature (80–100 ºC). The catalyst was characterized in detail using XRD, C and N elemental analysis, ICP-OES, TGA/DTA, HR-TEM, N2 adsorption/desorption at 77 K, solid-state 13C and 29Si MAS NMR and FT-IR spectroscopy CO2 as acid probe. The catalyst was robust when operated in a dual fixed-bed reactor achieving steady 20 % furfural conversion for 12 h on stream with preferential formation of 1-(furan-2-yl)− 5-methylhexan-3-one.

Development of a High Oleic Cardoon Cell Culture Platform by SAD Overexpression and RNAi-Mediated FAD2.2 Silencing.

The development of effective tools for the sustainable supply of phyto-ingredients and natural substances with reduced environmental footprints can help mitigate the dramatic scenario of climate change. Plant cell cultures-based biorefineries can be a technological advancement to face this challenge and offer a potentially unlimited availability of natural substances, in a standardized composition and devoid of the seasonal variability of cultivated plants. Monounsaturated (MUFA) fatty acids are attracting considerable attention as supplements for biodegradable plastics, bio-additives for the cosmetic industry, and bio-lubricants. Cardoon (Cynara cardunculus L. var. altilis) callus cultures accumulate fatty acids and polyphenols and are therefore suitable for large-scale production of biochemicals and valuable compounds, as well as biofuel precursors. With the aim of boosting their potential uses, we designed a biotechnological approach to increase oleic acid content through Agrobacterium tumefaciens-mediated metabolic engineering. Bioinformatic data mining in the C. cardunculus transcriptome allowed the selection and molecular characterization of SAD (stearic acid desaturase) and FAD2.2 (fatty acid desaturase) genes, coding for key enzymes in oleic and linoleic acid formation, as targets for metabolic engineering. A total of 22 and 27 fast-growing independent CcSAD overexpressing (OE) and CcFAD2.2 RNAi knocked out (KO) transgenic lines were obtained. Further characterization of five independent transgenic lines for each construct demonstrated that, successfully, SAD overexpression increased linoleic acid content, e.g., to 42.5%, of the relative fatty acid content, in the CcSADOE6 line compared with 30.4% in the wild type (WT), whereas FAD2.2 silencing reduced linoleic acid in favor of the accumulation of its precursor, oleic acid, e.g., to almost 57% of the relative fatty acid content in the CcFAD2.2KO2 line with respect to 17.7% in the WT. Moreover, CcSADOE6 and CcFAD2.2KO2 were also characterized by a significant increase in total polyphenolic content up to about 4.7 and 4.1 mg/g DW as compared with 2.7 mg/g DW in the WT, mainly due to the accumulation of dicaffeoyl quinic and feruloyl quinic acids. These results pose the basis for the effective creation of an engineered cardoon cells-based biorefinery accumulating high levels of valuable compounds from primary and specialized metabolism to meet the industrial demand for renewable and sustainable sources of innovative bioproducts.

Nanoarchitectonics of sulfonated biochar from pine needles as catalyst for conversion of biomass derived chemicals to value added products

Utilizing waste lignocellulosic biomass to synthesize biofuel precursors constructs an important way to solve the current energy crisis. In this work, we have prepared a sulfonated acid catalyst from pine needles derived biochar using chlorosulfonic acid for conversion of fructose to levulinic acid and levulinic acid to ethyl levulinate. In the best optimized conditions, sulfonated biochar as a catalyst exhibited excellent catalytic activity for the fructose conversion to levulinic acid and its esterification to ethyl levulinate with yield 33% and 97%.

The Effects of Carbon Source and Growth Temperature on the Fatty Acid Profiles of Thermobifida fusca.

The aerobic, thermophilic Actinobacterium, Thermobifida fusca has been proposed as an organism to be used for the efficient conversion of plant biomass to fatty acid-derived precursors of biofuels or biorenewable chemicals. Despite the potential of T. fusca to catabolize plant biomass, there is remarkably little data available concerning the natural ability of this organism to produce fatty acids. Therefore, we determined the fatty acids that T. fusca produces when it is grown on different carbon sources (i.e., glucose, cellobiose, cellulose and avicel) and at two different growth temperatures, namely at the optimal growth temperature of 50°C and at a suboptimal temperature of 37°C. These analyses establish that T. fusca produces a combination of linear and branched chain fatty acids (BCFAs), including iso-, anteiso-, and 10-methyl BCFAs that range between 14- and 18-carbons in length. Although different carbon sources and growth temperatures both quantitatively and qualitatively affect the fatty acid profiles produced by T. fusca, growth temperature is the greater modifier of these traits. Additionally, genome scanning enabled the identification of many of the fatty acid biosynthetic genes encoded by T. fusca.

Hydrogenation of Lignin‐derived Phenolic Compounds over Ru/C Enhanced by Al2O3 Catalyst at Room Temperature

AbstractHydrogenation is a promising strategy for the lignin‐derived phenolic compounds to produce platform chemical compounds and high‐value biofuel precursors. In this study, an efficient hydrogenation of phenol over Ru/C enhanced by Al2O3 catalyst at room temperature was proposed, with phenol conversion and cyclohexanol selectivity both close to 100 %. The addition of Al2O3 can make a significant difference on the phenol adsorption by the introduction of abundant Lewis acid site, which enabled to activate aromatic rings by changing the electrophilic substitution reaction of aromatic groups and trigger the occurrence of phenol hydrogenation under the catalysis of Ru/C. The Lewis acid site and metal site cooperated with each other and promoted the conversion of phenol to cyclohexanol as the final products. Moreover, a variety of other phenolic or aromatic compounds were also tested. The steric effects derived from the different substituted groups on aromatic rings had a significant influence on the hydrogenation performances.

One‐Pot Conversion of Glucose into 5‐Hydroxymethylfurfural using MOFs and Brønsted‐Acid Tandem Catalysts (Adv. Sustainable Syst. 5/2022)

Glucose Conversion In article number 2100444, Jose M. Campos-Martin and co-workers report that glucose obtained from abundant non-edible biomass, can be directly converted to 5-hydroxymethylfurfural (5-HMF), a versatile precursor of biofuels or bioplastics. A tandem catalyst is employed that combines a metal organic framework that isomerizes glucose to fructose, and a polyoxometalate that dehydrates fructose to 5-HMF.

Sustainable production of biofuel precursors by aldol condensation with biomass-derived 5-methylfurfural

Renewable 5-methylfurfural was subjected to a ‘green’ base- catalyzed aldol condensation with a variety of ketones to afford the corresponding furan-containing α,β-unsaturated carbonyl compounds with high yields and selectivities. The products obtained can serve as precursors for the long- chained fuel-grade liquid bio-alkanes.

Catalytic Hydroconversion of 5-HMF to Value-Added Chemicals: Insights into the Role of Catalyst Properties and Feedstock Purity.

5-hydroxymethylfurfural (HMF) is an important bio-derived platform molecule that is generally obtained from hexoses via acid-catalyzed dehydration. It can be effectively transformed into a variety of value-added derivatives, thus being an ideal candidate for fossil replacement. Both HMF oxidation and hydrogenation processes enable the synthesis of numerous chemicals, monomers for polymerization, and biofuel precursors. This Review summarizes the most recent advances in heterogeneous catalytic hydroconversion of HMF into valuable chemicals with strong focus on 2,5-bishydroxymethyl furan (BHMF), 2,5-bishydroxymethyltetrahydrofuran (BHMTHF), and 2,5-dimethyltetrahydrofuran (DMTHF). In addition, multifunctional catalytic systems that enable a tunable production of various HMF derived intermediates are discussed. Within this chemistry, the surprising impact of HMF purity on the catalytic performance, such as selectivity and activity, during its upgrading is highlighted. Lastly, the remaining challenges in the field of HMF hydroconversion to the mentioned chemicals are summarized and discussed, taking into account the knowledge gain of catalyst properties and feedstock purity.

Coupling wastewater valorization with sustainable biofuel production: Comparison of lab- and pilot-scale biomass yields of Chlorella sorokiniana grown in wastewater under photoautotrophic and mixotrophic conditions

Microalgae are the important biofuel precursors and their economic cultivation can be boosted under mixotrophic (MT) conditions while employing different industrial wastewaters containing organic carbon. In the current research, the quantitative analysis of microalgal biomass production under MT and photoautotrophic (PT) cultivation conditions both at lab and pilot scales was studied. For the purpose, a pre-identified microalgal species Chlorella sorokiniana was cultivated mixotrophically and photoautotrophically at lab and pilot scales. Artificially prepared wastewater containing 2% (w/v) sugarcane molasses was used for MT cultivation. However, for PT cultivation, atmospheric CO2 was the only carbon source. After 15 days of aerobic incubation, microalgal biomass was harvested and analyzed for biomass productivity. Cultivation conditions and cultivation scale posed significant and non-significant impact, respectively on biomass productivities. However, biomass productivity was comparatively higher for the biomass raised under MT conditions at lab scale. The recorded values of biomass productivity were 88.75 ± 9.51 and 127.68 ± 7.91 mg L−1 d−1 for the biomass raised at lab scale under PT and MT conditions, respectively. Pilot-scale cultivation depicted biomass productivities as 83.49 ± 7.87 and 124.88 ± 3.76 mg L−1 d−1 under PT and MT conditions, respectively. High biomass production under MT conditions may suggest the elevated production of biofuels from microalgae. Future studies on biomass production while utilizing different industrial wastewaters at pilot scale and in open raceway ponds are needed for viable production of microalgae-based fuels.

Liquid Organic Hydrogen Carriers (LOHCs) as H‐Source for Bio‐Derived Fuels and Additives Production

AbstractLiquid organic hydrogen carriers (LOHCs) are attractive materials for their ability to generate in situ hydrogen that may be directly used to produce target biofuel precursors, fuels or fuel additives. Indeed, the replacement of fossil feedstock is an urgent necessity for shifting toward a carbon neutral energy economy. Several desired chemicals and fuels derived from renewable sources can be accessed by hydrogenation reactions and among the LOHCs used for this purpose, formic acid and small‐sized alcohols (methanol or isopropanol) represent very promising alternatives to classic dangerous molecular hydrogen. In this review article, a comprehensive overview about the mechanisms of hydrogen‐transfer processes for different LOHCs is given. This evaluation is necessary for large‐scale implementation of LOHCs in sustainable fuel production. The catalysts’ design rationale and the criteria behind the choice of appropriate reaction conditions are reviewed in detail, since they represent crucial parameters for in situ hydrogen generation. Also the domino/cascade‐type processes influence the LOHC selection, promoting the realization of energy and cost saving protocols in a step and atom economical way.

An optimized ChIP-Seq framework for profiling histone modifications in Chromochloris zofingiensis.

The eukaryotic green alga Chromochloris zofingiensis is a reference organism for studying carbon partitioning and a promising candidate for the production of biofuel precursors. Recent transcriptome profiling transformed our understanding of its biology and generally algal biology, but epigenetic regulation remains understudied and represents a fundamental gap in our understanding of algal gene expression. Chromatin immunoprecipitation followed by deep sequencing (ChIP‐Seq) is a powerful tool for the discovery of such mechanisms, by identifying genome‐wide histone modification patterns and transcription factor‐binding sites alike. Here, we established a ChIP‐Seq framework for Chr. zofingiensis yielding over 20 million high‐quality reads per sample. The most critical steps in a ChIP experiment were optimized, including DNA shearing to obtain an average DNA fragment size of 250 bp and assessment of the recommended formaldehyde concentration for optimal DNA–protein cross‐linking. We used this ChIP‐Seq framework to generate a genome‐wide map of the H3K4me3 distribution pattern and to integrate these data with matching RNA‐Seq data. In line with observations from other organisms, H3K4me3 marks predominantly transcription start sites of genes. Our H3K4me3 ChIP‐Seq data will pave the way for improved genome structural annotation in the emerging reference alga Chr. zofingiensis.

Switching Carbon Metabolic Flux for Enhanced Production of Sesquiterpene-Based High-Density Biofuel Precursor in Engineered Yeast

Switching Carbon Metabolic Flux for Enhanced Production of Sesquiterpene-Based High-Density Biofuel Precursor in Engineered Yeast

Acid functionalized hydrochar as heterogeneous catalysts for solventless synthesis of biofuel precursors

Synthesis of biofuel precursors via the hydroxyalkylation alkylation reaction by using acid functionalized hydrochar catalysts.

Flux balance analysis for overproduction of organic acids by Synechocystis sp. PCC 6803 under dark anoxic condition

Cyanobacteria have recently been considered as potential organisms for metabolic engineering with an objective to improve its ability to synthesize biofuel precursors and other value-added products. A modified version of the genome-scale metabolic model of Synechocystis sp. PCC 6803 model organism was used to theoretically demonstrate the flux distribution in the central carbon metabolism towards optimal accumulation of organic acids, namely succinate, acetate, lactate and malate. We further validate the model using experimental data reported by Hasunuma et al. Met. Engg. Comm., 2016, 3, 130–141 for organic acid synthesis under dark anoxic conditions from glycogen accumulated during photoautotrophic growth conditions by sequestering atmospheric CO2. We show that key limiting factors are redox balance causing gluconeogenesis, availability of CO2 and channeling of carbon flux to TCA cycle, in addition to the rate of breakdown of glycogen. Sodium bicarbonate supplementation enhances succinate production flux by eliminating the CO2 limitations for the phosphoenolpyruvate (PEP) to oxaloacetate biochemical reaction catalyzed by PEP carboxylase. A combined strategy of supplementation with NaHCO3 and increased temperature can only offer ~25% of the theoretical maximum succinate production. We suggest possible metabolic pathway interventional approaches to improve the succinate productivity.

Identification and detection of biofuel precursor cumene (benzene, (1-methylethyl)-) by spectroscopic and chromatographic techniques

Identification and detection of biofuel precursor cumene (benzene, (1-methylethyl)-) by spectroscopic and chromatographic techniques

Synthesis of 5-hydroxymethylfurfural from glucose, fructose, cellulose and agricultural wastes over sulfur-doped peanut shell catalysts in ionic liquid

In this study, waste peanut shells were sulfur-impregnated and used as acid catalysts in the presence of an ionic liquid for the conversion of fructose, glucose, and cellulose into 5-hydroxymethylfurfural, a useful chemical intermediate for biofuel production. Effects of sulfur-doping duration (1 h and 5 h), solvent type and proportion, reaction temperature (130 °C, 140 °C, and 150 °C), time (30–240 min), catalyst-to-substrate ratio (1–2.5 m/m), and agricultural residue (peanut shell, Canada wheat straw, water hyacinth, stalk, and reed) on HMF yields were investigated. Monophasic and biphasic ionic liquids such as [amim]Cl, [bmim]HSO4, and [emim]Cl were employed in combination with choline chloride and dimethyl sulfoxide to improve HMF yields. Results show that peanut shells subjected to prolonged sulfur impregnation produced higher HMF yields. At 130 °C and 2 h, HMF yields from fructose and glucose reached 94.6% and 55.1%, respectively. Higher reaction temperatures improved HMF yields and accelerated conversion rates for the sugar substrates. Moreover, HMF production from waste biomass namely, peanut shells, peanut stalk, Canadian wheat straw, reed, and water hyacinth were examined in separate one-pot catalytic reactions. Overall, the study showed the effectiveness of sulfur-doped peanut shells as solid acid catalysts for the synthesis of HMF from various sources and the results may be used in designing large-scale production of furanic biofuel precursors from agricultural wastes.

Ordered mesoporous zirconium silicates as a catalyst for biofuel precursors synthesis

Zirconium incorporated three-dimensional ordered mesoporous silica (FDU-5) catalysts with different Si/Zr (100, 50 and 25) ratios were synthesized using an Evaporation Induced Self Assembly (EISA) method to maximize the incorporation of zirconium sites in the silica framework. The physicochemical properties of the synthesized materials were characterized by several techniques such as XRD, N2 sorption, diffuse reflectance UV–Vis, TEM, ammonia TPD, ICP-OES and pyridine adsorbed FT-IR. The catalytic activity was evaluated in acid-catalyzed esterification of glycerol with acetic acid. The effects of different reaction parameters were studied to optimize the maximum yields, such as reaction temperature, catalyst loading, acid/alcohol molar ratio, and reaction time. Esterification of glycerol with levulinic acid and levulinic acid with ethanol was also performed to synthesize fuel precursors. Reaction results showed that the prepared Zr-FDU-5(25) material was a very high catalytic activity, which depended mostly on the zirconium species' availability on the surfaces and framework. This zirconium containing FDU-5 material was very active in the esterification reaction and selective product formation at certain reaction conditions. The selected catalyst was recycled five times without significant loss in its activity.

One-dimensional titanate nanotube materials: heterogeneous solid catalysts for sustainable synthesis of biofuel precursors/value-added chemicals-a review.

One-dimensional (1D) titanate nanotubes materials (protonated titanate nanotube (HTNT) and sodium titanate nanotube (NaTNT)) have been reported as low-cost and efficient catalytic materials in chemical syntheses for the production of biofuel precursors with interesting catalytic performance exhibited, even better than some commonly used zeolites, H-MOR, H-β, SO42−/Al2O3, and H-ZSM-5 solid catalysts with environmental benign in focus when compared with homogeneous catalytic materials. This mini-review expressly revealed the significance and potential of using HTNT and NaTNT as sustainable and environmentally benign solid catalysts/supports in various chemical reactions. The critical assessment of biomass valorization and titanate nanostructured materials as catalysts/supports via Green Chemistry approach, #7 (use of renewable feedstocks), #9 (use of catalyst against stoichiometry) and United Nations (UN) Sustainable Development Goals (SDGs), #7 (affordable and clean energy; ensure access to inexpensive, reliable, sustainable, and new energy), is presented as integrated pathways to meet environmental benign technology toward sustainability. Hence, this work follows in the pattern of recent formulated features reported for solid catalysts—‘PYSSVR’ concept, which means P–production cost, Y–yield, S–stability, S–selectivity, V–versatility, and R–reusability.Graphical

Selective Demethoxylation of Lignin-Derived Methoxyphenols to Phenols over Lignin-Derived-Biochar-Supported Mo2C Catalysts

Hydrodeoxygenation (HDO) can convert methoxyphenols in lignin-derived bio-oil to phenols, a precursor of biofuels. In this work, Mo2C/C catalysts were prepared with lignin-derived biochar as a carbon source for the HDO reaction of guaiacol. The carburization degree of catalyst precursors was tuned by varying the carburization temperature and activation method, thus affecting the activity of the catalyst. Higher carburization temperatures promoted the formation of active Mo2C species at the expense of inactive MoOx and MoSx species. In addition to the high carburization temperature (800 °C), biochar also needed to be activated by H3PO4, HNO3, or a two-step process to obtain Mo2C species. The use of hydrocarbon solvents could reduce the competitive adsorption of the solvent over reactants while inhibiting the side reactions involving solvents, such as alkylation and etherification. Optimized 12.5Mo2C/C–H3PO4 (800) offered a high guaiacol conversion of 98.7% and a phenol yield of 66.8% under the optimum conditions. The yield of methanol was as high as 39.5%, indicating that the demethoxylation reaction was dominant. The catalytic system also exhibited high activity for the HDO of other lignin-derived methoxyphenols to produce phenols.