Route For Biofuel Production Research Articles

Environmentally-friendly preparation of Sn(II)-BDC supported heteropolyacid as a stable and highly efficient catalyst for esterification reaction

Facilitating energy resource deficiency and environmental contamination, this work focuses on sustainable biodiesel production through the esterification reactions of oleic acid (OA) with methanol. To address the reaction, a novel heterogeneous acid catalyst, 12-tungstophosphoric acid (TPA) immobilized on Sn-based MOFs (Sn(II)-BDC) was synthesized via a simple, green solvent, and easy-to-implement synthesis strategy for the first time, and applied effectively for esterification process of OA to produce biodiesel. The structure and composition of as-obtained catalyst have been verified using XRD, FTIR, N2 physisorption, SEM, EDX, TG, Py-FTIR, TPD-NH3, and XPS techniques. The obtained TPA/Sn(II)-BDC catalyst was found to be the best with 60 wt% of TPA loading, which resulted in an OA conversion of 91.7 % at optimized conditions of 0.15 g catalyst loading and methanol to OA molar ratio of 20:1 at temperature of 120 °C in 4 h, and the excellent performance arises from available pores structure, large amounts of acidic sites, good stability and the synergistic catalytic effect of TPA and Sn(II)-BDC. Furthermore, the composite catalyst reusability has been studied for five cycles, and it exhibits an acceptable conversion. This research provides a green and large-scale synthesis route for the sustainable production of biofuels by constructing heteropolyacids/Sn-based MOFs synergistic catalysts.

Impact of Synergy Partner Cel7B on Cel7A Binding Rates: Insights from Single-Molecule Data.

Enzymatic degradation of cellulosic biomass is a well-established route for the sustainable production of biofuels, chemicals, and materials. A strategy employed by nature and industry to achieve an efficient degradation of cellulose is that cellobiohydrolases (or exocellulases), such as Cel7A, work synergistically with endoglucanases, such as Cel7B, to achieve the complete degradation of cellulose. However, a complete mechanistic understanding of this exo-endo synergy is still lacking. Here, we used single-molecule fluorescence microscopy to quantify the binding kinetics of Cel7A on cellulose when it is acting alone on the cellulose fibrils and in the presence of its synergy partner, the endoglucanase Cel7B. To this end, we used a fluorescently tagged Cel7A and studied its binding in the presence of the unlabeled Cel7B. This provided the single-molecule data necessary for the estimation of the rate constants of association kON and dissociation kOFF of Cel7A for the substrate. We show that the presence of Cel7B does not impact the dissociation rate constant, kOFF. But, the association rate of Cel7A decreases by a factor of 2 when Cel7B is present at a molar proportion of 10:1. This ratio has previously been shown to lead to synergy. This decrease in association rate is observed in a wide range of total enzyme concentrations, from sub nM to μM concentrations. This decrease in kON is consistent with the formation of cellulase clusters recently observed by others using atomic force microscopy.

A Sustainable Microalgae-Mediated Molybdenum(V) Bioremediation: Effective Removal and Biofuel Production Potential

BackgroundWith growing global pollution concerns, the environmental hazards posed by molybdenum (Ⅴ) discharge >10 ppm, especially from steel and semiconductor industries have escalated environmental risks. Unfortunately, sustainable methods for Mo(V) removal are limited. This study presents an environmentally friendly solution utilizing microalgae for effective Mo(V) treatment. Notably. the generated microalgal biomass serves the dual purpose of addressing molybdenum pollution and contributing to biofuel production, offering economic incentives. MethodsSelected microalgae Chlorella sorokiniana SU1 were used for treating Mo(V). The goal is to maximize Mo(V) removal over 18 days, ensuring sufficient biomass and lipid yields. Optimizing pH and temperature, directed by zeta potential analysis, improves Mo(V) removal efficiency. FTIR analysis validates Mo(V) adsorption through the reactive groups on the algal cell wall. Significant findingsChlorella sorokiniana SU1 is a highly effective agent for Mo(V) removal, achieving an impressive removal rate of 82.78 mgL−1. Additionally, the resultant treatment demonstrates noteworthy microalgal biomass and lipid yields of 2.35 and 0.71 g L−1, respectively. The tactical pH and temperature optimization further augments the molybdenum removal efficiency. This innovative study addresses molybdenum pollution and also gives a sustainable route for biofuel production through generated microalgal biomass, establishing a promising technique for commercial-scale molybdenum bioremediation.

Advanced strategies for effective treatment of vanadium (III) polluted water by potential microalgae

BackgroundEnvironmental concerns are escalating globally due to rising pollution, with heavy metals like vanadium posing health risks even at 2 ppm. Industries like steel and semiconductors discharge vanadium, presenting environmental hazards. However, there's a lack of sustainable treatment methods for vanadium removal. This study aims to develop an eco-friendly microalgae vanadium treatment while utilizing microalgal biomass for biofuels, offsetting treatment expenses. MethodsPotential microalgae is chosen for vanadium (III) treatment. Over an 18-days period, maximum V(III) removal was aimed with adequate biomass and lipid yields. pH and temperature optimization enhances vanadium removal, guided by zeta potential analysis. FTIR confirms vanadium adsorption via algal cell wall reactive groups. Significant FindingsThe study demonstrates a viable solution for the pressing issue of vanadium pollution. Chlorella sorokiniana TU5 effectively removes V(III), achieving a substantial removal rate of 20.38 mgL−1. Moreover, the generated microalgal biomass showed a biomass yield of 2.3 gL−1 and a lipid yield of 577.3 mgL−1. The strategic optimization of pH and temperature further enhances the vanadium removal capacity. This approach not only addresses vanadium pollution but also provides a sustainable route for biofuel production using microalgal biomass, positioning it as a promising technique for industrial-scale vanadium bioremediation.

Continuous-flow CvFAP photodecarboxylation of palmitic acid under environmentally friendly conditions

The fatty acid photodecarboxylase from Chlorella variabilis NC64A (CvFAP) promotes the elimination of CO2 from fatty acids (Cn) producing the corresponding hydrocarbon (Cn-1). Therefore, this enzyme is of great biotechnological interest since it can be used in alternative biofuel production routes matching the concept of green chemistry. However, due to its recent discovery, this reaction still requires optimizations, which was the focus of the present work together with the application of continuous flow system. The results in batch reactors showed the importance of using high power LED lamps (300 W) to reduce the reaction time for full conversion (30 min, >99%). In another approach, a continuous flow system demonstrated high potential, as it enabled full conversion with a half concentration of enzyme extract in a very short residence time of 15 min. Furthermore, the use of less expensive and sustainable light sources, not previously reported for reactions with CvFAP, were evaluated with full conversion (>99%) after 1 h for continuous flow reactions using 300 W common white LED lamp and based preliminary batch reactions investigations using direct sunlight. Thus, important advances and new perspectives for CvFAP photodecarboxylation reactions could be achieved with the present report.

Bottlenecks and potentials for the gasification of lignocellulosic biomasses and Fischer-Tropsch synthesis: A case study on the production of advanced liquid biofuels in Brazil

Brazil is one of the major players in the biofuels market worldwide, and its existing biorefining infrastructure can be used as the basis to support the implementation of new advanced biofuel production routes at a large scale. This paper demonstrates the benefits of the integration of both biochemical and thermochemical processes and how this configuration has the potential to overcome the main barriers that the Biomass-to-Liquids (BtL) route currently faces. Important bottlenecks such as the high equipment costs, low industrial process efficiency, and high feedstock prices were studied in detail by assessing a series of production scenarios that take into account the Brazilian context for building new biorefinery plants. By carrying out a techno-economic analysis aided by a simulation framework (the Virtual Sugarcane Biorefinery), we evaluated the potential technological synergies of a BtL plant processing sugarcane bagasse and straw integrated into a first-generation sugarcane ethanol distillery. Results in this paper indicate that it is possible to achieve economic feasibility with the implementation of the BtL route in the country. Under a base scenario, a greenfield plant would be very close to the range of economic viability (IRR from 10 to 12% per year), whereas more optimistic economic conditions (e.g., lower CAPEX and higher fuel prices) would induce even better results (IRR greater than 16% per year). Doubling the milling capacity also favors the BtL process, with IRR reaching 20% per year if the best economic conditions are achieved in the Brazilian context.

Rapidly Improving High Light and High Temperature Tolerances of Cyanobacterial Cell Factories Through the Convenient Introduction of an AtpA-C252F Mutation.

Photosynthetic biomanufacturing is a promising route for green production of biofuels and biochemicals utilizing carbon dioxide and solar energy. Cyanobacteria are important microbial platforms for constructing photosynthetic cell factories. Toward scaled outdoor cultivations in the future, high light and high temperature tolerances of cyanobacterial chassis strains and cell factories would be determinant properties to be optimized. We proposed a convenient strategy for rapidly improving high light and high temperature tolerances of an important cyanobacterial chassis Synechococcus elongatus PCC 7942 and the derived cell factories. Through introduction and isolation of an AtpA-C252F mutation, PCC 7942 mutants with improved high light and high temperature tolerances could be obtained in only 4 days with an antibiotics-free mode. Adopting this strategy, cellular robustness and sucrose synthesizing capacities of a PCC 7942 cell factory were successfully improved.

Modeling and optimization of polyethylene glycol (PEG) addition for cost-efficient enzymatic hydrolysis of lignocellulose

Enzyme consumption is a key cost in the lignocellulosic sugar route for production of biofuels and chemicals, and polyethylene glycol (PEG) is a low-cost additive that improves hydrolysis efficiency. Despite many studies in this area, the relation of benefit over cost of PEG addition remains unclear. This article describes principles for expressing the effect of PEG as an equivalent enzyme amount, by merging PEG adsorption kinetics with a standardized enzyme dosage response. This model allows cost optimization of PEG addition by marginal analysis, as a function of enzyme dosage, solids concentration and price-ratio of enzyme and PEG. The model is based on the novel observations that the relative increase in apparent enzyme dosage by PEG addition is constant regardless of the absolute enzyme dosage, and that the increase correlates linearly with adsorption of PEG on hydrothermally pretreated wheat straw. The optimum ranged for most cases between 7 and 14 mg PEG per g substrate. The addition of PEG was attractive only above a threshold price-ratio, which decreased from 7.0–1.4 as enzyme dosage increased from 2 to 10 cost units per g substrate, showing that the incentive for introducing PEG to the process becomes stronger as the enzyme dosage increases.

Effect of temperature and surfactant on biomass growth and higher-alcohol production during syngas fermentation by Clostridium carboxidivorans P7

Hexanol–butanol–ethanol fermentation from syngas by Clostridium carboxidivorans P7 is a promising route for biofuel production. However, bacterial agglomeration in the culture of 37 °C severely hampers the accumulation of biomass and products. To investigate the effect of culture temperature on biomass growth and higher-alcohol production, C. carboxidivorans P7 was cultivated at both constant and two-step temperatures in the range from 25 to 37 °C. Meanwhile, Tween-80 and saponin were screened out from eight surfactants to alleviate agglomeration at 37 °C. The results showed that enhanced higher-alcohol production was contributed mainly by the application of two-step temperature culture rather than the addition of anti-agglomeration surfactants. Furthermore, comparative transcriptome revealed that although 37 °C promoted high expression of genes involved in the Wood–Ljungdahl pathway, genes encoding enzymes catalyzing acyl-condensation reactions associated with higher-alcohol production were highly expressed at 25 °C. This study gained greater insight into temperature-effect mechanism on syngas fermentation by C. carboxidivorans P7.

Potential of two-stage cultivation in microalgae biofuel production

Microalgae are a group of microorganisms considered to be a potential source of next-generation biofuel owing to high photosynthetic rate. However, biofuel compounds including lipid, carbohydrate, and hydrogen are not sufficiently produced by microalgae under normal conditions; therefore economical viability of microalgal biofuel production has not reached the ultimate stage of commercial viability. In order to overcome the above limitation, various stress conditions have been applied on microalgae to boost lipid, carbohydrate and hydrogen production. Even though stress conditions increases the production of biofuel compounds, microalgae growth is severely affected. In this regard, a two-stage cultivation mode wherein first stage involving high biomass production under media optimized heterotrophic condition and second stage involving lipid, carbohydrate and hydrogen accumulation under stress integrated phototrophic mode is considered as a potential route for biofuel production in microalgae. The present review critically evaluates various two-stage strategies adopted in microalgal biofuel production by comparing lipid, carbohydrate and hydrogen productivities with that of single stage cultivation. In addition, advantages of two-stage cultivation including co-product generation, less bacterial contamination, improved biodiesel quality, auto-flocculation, and bioremediation potential are also discussed. Finally, the paper summarizes the two-stage cultivation modes by identifying the bottlenecks and suggesting the future potentialities of the process.

Anaerobic conversion of the hydrothermal liquefaction aqueous phase: fate of organics and intensification with granule activated carbon/ozone pretreatment

Hydrothermal liquefaction (HTL) is considered to be a promising route for biofuel production from wet biomass.

The contributions of Prof. Jan Szargut to the exergy and environmental assessment of complex energy systems

This paper describes how the scientific contributions of Prof. Szargut and his co-workers have inspired the academic activities of the Exergy Team of the Laboratory of Environmental and Thermal Engineering (LETE) of the Polytechnic School of the University of Sao Paulo. The work of Prof. Szargut was at first used for preparing a course on Exergy Analysis, which has been taught since 1992 to MSc and Ph.D. students of the graduate program in Mechanical Engineering of the Polytechnic School of the University of Sao Paulo. Since then, the methods and concepts established by Prof. Szargut have played an important role in the development of the various research lines at LETE for the past fifteen years. Complex thermodynamic systems, such as petroleum production and refining plants, biofuel production routes, combined production of ethanol and electricity technologies, aircraft systems, environmental impact mitigation processes, CO2 capture units, ammonia production facilities, and the human body and its systems were analyzed using the concepts and tools suggested by Prof Szargut. The present article illustrates how the application of exergy analysis, thermoeconomic and environmental performance indicators, cumulative exergy consumption, definition of reference environment and chemical exergy can serve different purposes when evaluating thermodynamic systems.

Methanol production via black liquor co-gasification with expanded raw material base – Techno-economic assessment

Entrained flow gasification of black liquor combined with downstream-gas-derived synthesis of biofuels in Kraft pulp mills has shown advantages regarding energy efficiency and economic performance when compared to combustion in a recovery boiler. To further increase the operation flexibility and the profitability of the biofuel plant while at the same time increase biofuel production, black liquor can be co-gasified with a secondary feedstock (blend-in feedstock). This work has evaluated the prospects of producing biofuels via co-gasification of black liquor and different blend-in feedstocks (crude glycerol, fermentation residues, pyrolysis liquids) at different blend ratios. Process modelling tools were used, in combination with techno-economic assessment methods. Two methanol grades, crude and grade AA methanol, were investigated. The results showed that the co-gasification concepts resulted in significant increases in methanol production volumes, as well as in improved conversion efficiencies, when compared with black liquor gasification; 5–11 and 4–10 percentage point in terms of cold gas efficiency and methanol conversion efficiency, respectively. The economic analysis showed that required methanol selling prices ranging from 55 to 101 €/MWh for crude methanol and 58–104 €/MWh for grade AA methanol were obtained for an IRR of 15%. Blend-in led to positive economies-of-scale effects and subsequently decreased required methanol selling prices, in particular for low cost blend-in feedstocks (prices below approximately 20€/MWh). The co-gasification concepts showed economic competitiveness to other biofuel production routes. When compared with fossil fuels, the resulting crude methanol selling prices were above maritime gas oil prices. Nonetheless, for fossil derived methanol prices higher than 80 €/MWh, crude methanol from co-gasification could be an economically competitive option. Grade AA methanol could also compete with taxed gasoline. Crude glycerol turned out as the most attractive blend-in feedstock, from an economic perspective. When mixed with black liquor in a ratio of 50/50, grade AA methanol could even be cost competitive with untaxed gasoline.

Development of an automated method for modelling of bio-crudes originating from biofuel production processes based on thermochemical conversion

The prominence of biofuel research is growing as the global energy policies focus on renewable energy technologies. Accurate process design and simulation is required when evaluating technological and market capabilities of large scale, novel, fuel production processes. Thermochemical decomposition, employed in various biofuel production routes (pyrolysis, liquefaction, and so on) yields complex liquid mixtures (bio-crudes) containing numerous compounds. The process simulation of such processes must accurately represent the physical, thermodynamic and chemical properties of bio-crudes, while reducing complexity to a point where it can be handled by a process simulator in a time effective manner. In this work, a software employing automated modelling of bio-crudes based on raw experimental data, has been developed. The program output is a ready-to-use reduced mixture, including all product phases and in mass balance with the Proximate and Ultimate analyses of the feedstock biomass material. As there are many approaches to bio-crude modelling, the novelty of this method lies in the combination of the minimization of the number of components needed and the minimization of the level of artificiality introduced in the system. The automation of the method allowed for fast reduction and optimization of seven experimental data sets which were then validated by process simulation.

Microbial electrosynthesis: CO<sub>2</sub> fixation driven by electricity

Carbon dioxide (CO2) is a widespread carbon resource on the earth. The biological conversion of CO2 into organic compounds is an important route for production of biofuels and bio-based chemicals. Owing to the insufficient energy supply and inefficient catalytic activities, the efficiency for biological CO2 fixation remains to be low. The electricity-driven reduction of CO2 using whole microorganisms, which termed as microbial electrosynthesis, provides a novel strategy for biological conversion of CO2. This review summarizes recent advances on microbial electrosynthesis, which covers the microorganisms used for electrosynthesis, extracellular electron transfer, and selection of electrode materials. Furthermore, future challenges and prospects of microbial electrosynthesis were discussed.

Enhanced biofuel processes utilizing separate lignin and carbohydrate processing of lignocellulose

ABSTRACTEnhanced biofuel production routes utilizing separate lignin and carbohydrate processing of lignocellulose are analyzed and compared with two conventional routes; the methanol and methane production via syngas from biomass. The enhanced processes studied are: hydrocarbons production by hydrogenation of biomass based sugars by hydrogen obtained from lignin gasification, and ethanol production by biomass hydrolysis and fermentation and conversion of residual lignin into methanol via syngas. The analysis of processes was done by rigorous flowsheet modeling including power production calculations and realistic heat integration and evaluation based on energy yield, greenhouse gas (GHG) reduction and net present value (NPV). The enhanced processes via separate lignin and sugar processing can run in two modes: either being energy self-sufficient or utilizing external low temperature heat and power. The processes can operate with high efficiency as ‘waste heat and power to gas and liquids’ processes for producing liquid or gaseous fuels especially when excess energy is available e.g. in summer. Of all the processes studied the enhanced hydrocarbon production process integrated with external low temperature heat source gave the largest GHG reduction and highest NPV. External low temperature heat and electricity is converted into fuels in 136% higher heating value (116% lower heating value) efficiency.

Algae-based biofuel production as part of an industrial cluster

This paper presents a study on the production of biofuels from algae cultivated in municipal wastewater in Gothenburg, Sweden. A possible biorefinery concept is studied based on two cases; Case A) combined biodiesel and biogas production, and Case B) only biogas production. The cases are compared in terms of product outputs and impact on global CO2 emissions mitigation. The area efficiency of the algae-based biofuels is also compared with other biofuel production routes. The study investigates the collaboration between an algae cultivation, biofuel production processes, a wastewater treatment plant and an industrial cluster for the purpose of utilizing material flows and industrial excess heat between the actors. This collaboration provides the opportunity to reduce the CO2 emissions from the process compared to a stand-alone operation. The results show that Case A is advantageous to Case B with respect to all studied factors. It is found that the algae-based biofuel production routes investigated in this study has higher area efficiency than other biofuel production routes. The amount of algae-based biofuel possible to produce corresponds to 31 MWfuel for Case A and 26 MWfuel in Case B.

Isobutanol production from cellobiose in Escherichia coli

Converting lignocellulosics into biofuels remains a promising route for biofuel production. To facilitate strain development for specificity and productivity of cellulosic biofuel production, a user friendly Escherichia coli host was engineered to produce isobutanol, a drop-in biofuel candidate, from cellobiose. A beta-glucosidase was expressed extracellularly by either excretion into the media, or anchoring to the cell membrane. The excretion system allowed for E. coli to grow with cellobiose as a sole carbon source at rates comparable to those with glucose. The system was then combined with isobutanol production genes in three different configurations to determine whether gene arrangement affected isobutanol production. The most productive strain converted cellobiose to isobutanol in titers of 7.64 ± 0.19g/L with a productivity of 0.16g/L/h. These results demonstrate that efficient cellobiose degradation and isobutanol production can be achieved by a single organism, and provide insight for optimization of strains for future use in a consolidated bioprocessing system for renewable production of isobutanol.

Immobilization of Lipase from Candida rugosa on Mesoporous MCM 41

The use of enzymatic route for production of biofuels is growing up due the mild reaction conditions that this method provides, as well as reducing SOx emission. To reduce costs, it’s necessary to immobilize the enzyme, making possible to use it continuously as biocatalyst. The aim of this work was to measure the influence of the mass of support and pH used for immobilization of commercial lipase from Candida rugosa acquired by Sigma laboratory. The immobilization method chosen was adsorption on mesoporous and hydrophobic support MCM 41, this has been treated with nitric acid 10% v/v to remove any organic residue. Then, 20 ml of enzymatic solution in phosphate buffer (pH 6.0, 7.0 and 8.0; 50 mM) and 1 g/L was placed under constant stirring with 0.30 and 0.45 g of support. Aliquots were taken from the reaction medium and analyzed by spectrophotometry at 10 minutes intervals. A volume of 0.2 ml of supernatant was put with 1.8 ml of substrate p-NFL at 0.18 g/L, and the absorbance at 410 nm was analyzed. In four cases there was a sharp reduction of supernatant’s activity at first 10 minutes, that ratifies the big affinity of the enzyme for the support and the negative influence of pH about the activity. Using the calibration curve, it was possible to calculate the final activity of each immobilization batch. This work suggests the occurrence of diffusional effects, which means that the enzyme mobility was restricted due the excessive amount of support, and then, it lost a part of accessibility to substrate, reflecting in not expressive activity values, and changing the state of ionization of the components of the system.

Transesterifications using a hydrocalumite synthesized from waste slag: an economical and ecological route for biofuel production

Blast furnace slag (BFS), a high volume byproduct resulting from iron-making processes, was used as a low-cost and abundant precursor for preparing a hydrocalumite, and the thus prepared slag-made hydrocalumite and its derivatives were applied for transesterifications of esters including triglycerides. In the transesterification of n-ethyl butyrate, calcined samples provided higher catalytic activities than those of the as-synthesized hydrocalumite due to the interfusion of slag-derived impurity elements, such as Fe and Mn, which act as catalyst promoters. Furthermore, the catalyst calcined at 800 °C in air worked as an efficient catalyst for the transesterification of soybean oil with methanol, affording up to 97% yield of fatty acid methyl esters (FAME) after 6 h under relatively moderate reaction conditions (i.e., methanol/soybean oil = 12, reaction temperature = 60 °C, use of 1 wt% catalyst), and its catalytic performance was reproduced even after air-exposure for 1 day. It is believed that the slag-made hydrocalumite can replace existing solid base catalysts as a low-cost alternative for biodiesel production and potentially contribute to the sustainable chemical processes in an economical and ecological way.