Glycerol Feeding Research Articles

Boosting conversion of waste activated sludge to methane during anaerobic digestion via facilitating direct interspecies electron transfer with glycerol

Possibility of boosting conversion of waste activated sludge to methane via facilitating direct interspecies electron transfer with glycerol was explored. Methane yields with 5 %/8 % glycerol were 1.18/1.31 folds higher than that without glycerol. After removing methane yields from glycerol, methane yields with 5 %/8 % glycerol was still 17 %/19 % higher than that without glycerol. Electron transfer coefficients for charge/discharge in sludge with 8 % glycerol were 1.12/1.39 folds higher than that without glycerol. Analysis of conductivity-temperature responses found that conductivity of sludge with 8 % glycerol exhibited an exponential increase when temperature was declined, similar to that with 8 % ethanol. However, conductivity of sludge with 8 % glycerol was one order of magnitude higher than that with 8 % ethanol. Electrochemical Fourier transform infrared spectra showed that reversible changes of bands associated with c-type cytochrome in sludge with 8 % glycerol were more intense than that with 8 % ethanol. Analysis of microbial communities showed that glycerol feeding increased the abundance of Methanospirillum hungatei JF-1, and specially enriched Tangfeifania diversioriginum, Syntrophomonas zehnderi OL-4 and Trichococcus pasteurii. These results indicated that glycerol feeding facilitated the better direct interspecies electron transfer than ethanol feeding that had been previously documented during anaerobic digestion of waste activated sludge.

Kinetics-based development of two-stage continuous fermentation of 1,3-propanediol from crude glycerol by Clostridium butyricum

BackgroundGlycerol, as a by-product, mainly derives from the conversion of many crops to biodiesel, ethanol, and fatty ester. Its bioconversion to 1,3-propanediol (1,3-PDO) is an environmentally friendly method. Continuous fermentation has many striking merits over fed-batch and batch fermentation, such as high product concentration with easy feeding operation, long-term high productivity without frequent seed culture, and energy-intensive sterilization. However, it is usually difficult to harvest high product concentrations.ResultsIn this study, a three-stage continuous fermentation was firstly designed to produce 1,3-PDO from crude glycerol by Clostridium butyricum, in which the first stage fermentation was responsible for providing the excellent cells in a robust growth state, the second stage focused on promoting 1,3-PDO production, and the third stage aimed to further boost the 1,3-PDO concentration and reduce the residual glycerol concentration as much as possible. Through the three-stage continuous fermentation, 80.05 g/L 1,3-PDO as the maximum concentration was produced while maintaining residual glycerol of 5.87 g/L, achieving a yield of 0.48 g/g and a productivity of 3.67 g/(L·h). Based on the 14 sets of experimental data from the first stage, a kinetic model was developed to describe the intricate relationships among the concentrations of 1,3-PDO, substrate, biomass, and butyrate. Subsequently, this kinetic model was used to optimize and predict the highest 1,3-PDO productivity of 11.26 g/(L·h) in the first stage fermentation, while the glycerol feeding concentration and dilution rate were determined to be 92 g/L and 0.341 h−1, separately. Additionally, to achieve a target 1,3-PDO production of 80 g/L without the third stage fermentation, the predicted minimum volume ratio of the second fermenter to the first one was 11.9. The kinetics-based two-stage continuous fermentation was experimentally verified well with the predicted results.ConclusionA novel three-stage continuous fermentation and a kinetic model were reported. Then a simpler two-stage continuous fermentation was developed based on the optimization of the kinetic model. This kinetics-based development of two-stage continuous fermentation could achieve high-level production of 1,3-PDO. Meanwhile, it provides a reference for other bio-chemicals production by applying kinetics to optimize multi-stage continuous fermentation.Graphical

Synergistic approach for enhanced production of polyhydroxybutyrate by Bacillus pseudomycoides SAS-B1: Effective utilization of glycerol and acrylic acid through fed-batch fermentation and its environmental impact assessment

The continual rise in the consumption of petroleum-based synthetic polymers raised a significant environmental concern. Bacillus pseudomycoides SAS-B1 is a gram-positive rod-shaped halophilic bacterium capable of accumulating Polyhydroxybutyrate (PHB)-an intracellular biodegradable polymer. In the present study, the optimal conditions for cell cultivation in the seed media were developed. The optimal factors included a preservation age of 14 to 21 days (with 105 to 106 cells/mL), inoculum size of 0.1 % (w/v), 1 % (w/v) glucose, and growth temperature of 30 °C. The cells were then cultivated in a two-stage fermentation process utilizing glycerol and Corn Steep Liquor (CSL) as carbon and nitrogen sources, respectively. PHB yield was effectively increased from 2.01 to 9.21 g/L through intermittent feeding of glycerol and CSL, along with acrylic acid. FTIR, TGA, DSC, and XRD characterization studies were employed to enumerate the recovered PHB and determine its physicochemical properties. Additionally, the study assessed the cradle-to-gate Life Cycle Assessment (LCA) of PHB production, considering net CO2 generation and covering all major environmental impact categories. The production of 1000 kg of PHB resulted in lower stratospheric ozone depletion and comparatively reduced carbon dioxide emissions (2022.7 kg CO2 eq.) and terrestrial ecotoxicity (9.54 kg 1,4-DCB eq.) than typical petrochemical polymers.

Separation of cobalt and nickel from ethylene glycol and glycerol feed solution in chloride media by non-aqueous solvent extraction with Cyphos IL 101

A non-aqueous solvent extraction (NASX) process for the separation of cobalt and nickel from ethylene glycol and glycerol/water feed solutions using the ionic liquid Cyphos IL 101 has been investigated. The use of undiluted Cyphos IL 101 was critically assessed and compared with solvent extraction systems in which toluene, p-cymene, Shellsol A150, and Shellsol GS190 were used as diluents. While the extraction of cobalt(II) chloride from aqueous solution was possible only at high chloride concentrations, extraction percentages of cobalt higher than 80 % were observed from ethylene glycol and glycerol/water feeds containing 0.8 mol·L-1 NaCl. Separation factors over 40,000 for cobalt and nickel could be achieved for extraction with undiluted Cyphos IL 101 from 2.4 mol·L-1 NaCl ethylene glycol and 1.6 mol·L-1 NaCl glycerol feeds. The distribution ratio of cobalt increased with increasing temperatures in both NASX systems. Studies on the mutual solubility showed that Cyphos IL 101 is highly soluble in ethylene glycol at 21 °C (i.e. phosphorus contents up to 432 mg∙L-1), but it turned out that impurities contributed for 400 mg∙L-1 to this value. On the other hand, only 87 mg∙L-1 of Cyphos IL 101 dissolved in glycerol at 21 °C. Finally, a conceptual flowsheet for the separation of cobalt and nickel by NASX is presented, including extraction, stripping, and recovery of the solvents.

Production and Purification of Soy Leghemoglobin from Pichia pastoris Cultivated in Different Expression Media

Plant-based meat alternatives, exemplified by Impossible Foods’ Impossible Burger, offer a sustainable, ethical substitute for traditional meat, closely mimicking the taste and appearance of meat by utilizing soy leghemoglobin (LegH), a 16 kDa holoprotein found in soy plants structurally similar to heme in animal meat. Cultivation medium plays an important role in bioprocess development; however, medium development or optimization can be labor intensive, and thus the use of previously reported media can be enticing. In this study, we explored the expression of recombinant LegH in Pichia pastoris in various reported cultivation media (BSM, BMGY, FM22, D’Anjou, BSM/2, and RDM) and using different feeding approaches (µ-stat and mixed feed with sorbitol). Our findings indicate that optimization techniques tailored to the specific process did not increase LegH yields, highlighting the need to investigate strain-specific strategies. We also utilized the collected process data to create and train a novel artificial neural network-based soft sensor for estimating cell biomass, relying solely on standard bioreactor measurements (such as stirrer speed, dissolved oxygen, O2 enrichment, base feed, glycerol feed, methanol feed, and reactor volume). This soft sensor proved to be robust and exhibited a strong correlation (3.72% WCW) with experimental data.

Influence of alumina fixed-bed in steam reforming of glycerol for hydrogen production

In this study, hydrogen production by steam reforming was carried out in a tubular fixed-bed reactor. The influence of some operating variables such as temperature, flow rate of the feeding glycerol solution and space velocity on hydrogen production under a non-catalyzed reaction was analyzed. The results showed that the hydrogen yield increased with temperature and decreased with the space velocity. As the feedstock flow rate increased, the hydrogen yield decreased rapidly. Compared with a reference experiment without fixed-bed, the use of non-porous alumina fixed-bed showed better results. Under the best reaction conditions (900 °C and a feedstock flow rate of 0.85 g/min), 17 L/h of syngas were obtained, with a purity of about 55% of hydrogen and a production of 2.7 moles of hydrogen by mol of glycerol.

Techno-commercial viability of glycerol valorization to 1,2- and 1,3-propanediol using pinch technology

Glycerol is a low-value by-product in biodiesel industries and an important platform chemical in biorefinery with vast derivative potentials. 1,2- and 1,3-Propanediol (PDO) are vital polymer precursors. Valorizing glycerol to PDOs is thus a promising approach for producing renewable chemicals and improving the economics of biodiesel industries. Therefore, this work demonstrated the techno-economic feasibility of PDOs for 100–2000 metric tons per day glycerol feed rate. 1,2-PDO was produced by selective hydrogenolysis of glycerol, while microbial batch and fed-batch fermentation of glycerol was considered for manufacturing 1,3-PDO with the co-production of 2,3-butanediol and ethanol. Pinch analysis was applied for process integration that reduced utility demands by around 19% for 1,2-PDO and 12–16% for 1,3-PDO. However, utilities were still major operating costs in these processes. Besides, utility consumptions and capital expenditures were considerably higher for 1,3-PDO by batch fermentation than 1,2-PDO due to low glycerol concentration (50 g/L). 1,3-PDO production cost (USD 3.42/kg) by batch fermentation was thus much more than 1,2-PDO (USD 0.98/kg). The minimum unitary selling price was USD 1.15 for 1,2-PDO and USD 4.90 for 1,3-PDO (batch) for 8.5% rate of return and five years payback period. However, the microbial 1,3-PDO produced by fed-batch fermentation was economically viable, with USD 0.78 and USD 1.02 as unitary production costs and minimum selling price.

Continuous production of succinic acid from glycerol: A complete experimental and computational study

In this work, a bioprocess for the fermentation of A. succinogenes for the production of succinic acid from glycerol was developed, employing a continuous bioreactor with recycle. Moreover, a new bioprocess model was constructed, based on an existing double substrate limitation model, which was validated with experimental results for a range of operating parameters. The model was used to successfully predict the dynamics of the continuous fermentation process and was subsequently employed in optimisation studies to compute the optimal conditions, dilution rate, reflux rate and feed glycerol concentration, that maximise the productivity of bio-succinic acid. In addition, a Pareto front for optimal volumetric productivity and glycerol conversion combinations was computed. Maximum volumetric productivity of 0.518 g/L/h, was achieved at the optimal computed conditions, which were experimentally validated. This is the highest bio-succinic acid productivity reported so far, for such a continuous bioprocess.

Aluminum-based activation of natural zeolite for glycerol steam reforming

In this work, aluminum-based activated zeolite is employed for the first time in glycerol steam reforming. AlCl3 and Al(OH)3 were used as the activator agents for the natural zeolite. NiMo/Zeolite catalysts were prepared for the glycerol steam reforming process by impregnation and characterized by XRD and XRF. The characterization results showed that the activation by AlCl3 and Al(OH)3 could modify the chemical composition and crystallinity of the zeolite. Silica extraction occurred due to the activation by Al(OH)3, while AlCl3 caused an aluminum removal in the zeolite framework. Amorphization of zeolite structure was involved in zeolite activation by Al(OH)3. Glycerol steam reforming processes employed NiMo/Zeolite-AlCl3 and NiMo/Zeolite-Al(OH)3, which were carried out in a fixed-bed reactor at 250 °C. The glycerol-water mole ratio was varied 9:1, 4:1 and 3:2. NiMo/Zeolite-AlCl3 yielded a higher hydrogen product than NiMo/Zeolite-Al(OH)3 with a lower glycerol feed concentration.

Heterogeneous Catalysts for Glycerol Biorefineries: Hydrogenolysis to 1,2-Propylene Glycol.

Research on the use of biomass resources for the generation of energy and chemical compounds is of great interest worldwide. The development and growth of the biodiesel industry has led to a parallel market for the supply of glycerol, its main by-product. Its wide availability and relatively low cost as a raw material make glycerol a basic component for obtaining various chemical products and allows for the development of a biorefinery around biodiesel plants, through the technological integration of different production processes. This work proposes a review of one of the reactions of interest in the biorefinery environment: the hydrogenolysis of glycerol to 1,2-propylene glycol. The article reviews more than 300 references, covering literature from about 20 years, focusing on the heterogeneous catalysts used for the production of glycol. In this sense, from about 175 catalysts, between bulk and supported ones, were revised and discussed critically, based on noble metals, such as Ru, Pt, Pd, and non-noble metals as Cu, Ni, Co, both in liquid (2-10 MPa, 120-260 °C) and vapor phase (0.1 MPa, 200-300 °C). Then, the effect of the main operational and decision variables, such as temperature, pressure, catalyst/glycerol mass ratio, space velocity, and H2 flow, are discussed, depending on the reactors employed. Finally, the formulation of several kinetic models and stability studies are presented, discussing the main deactivation mechanisms of the catalytic systems such as coking, leaching, and sintering, and the presence of impurities in the glycerol feed. It is expected that this work will serve as a tool for the development of more efficient catalytic materials and processes towards the future projection of glycerol biorefineries.

Hydrogen production via supercritical water gasification of glycerol enhanced by simple structured catalysts

The supercritical water gasification (ScWG) technology is a promising alternative for H2-rich gas production from renewable sources, such as residual glycerol from biodiesel manufacture. Combined with heterogeneous catalysts, the ScWG process can achieve improved selectivity towards the desired products and high conversion efficiency in short reaction times. In this work, the efficiency of a synthesized Ni-based catalyst supported in cordierite (CRD) honeycomb structure on the ScWG of glycerol was evaluated and compared with two commercial automotive catalysts. Initially, to determine the best experimental conditions, the ScWG experiments were conducted in the absence of catalysts at constant conditions pressure (25 Mpa) and volumetric flow rate (10 mL min−1). The temperature range of 400–700 °C and glycerol feed composition between 10 and 34 wt% were evaluated. The catalysts evaluated were characterized by SEM-EDS, XRD, N2 adsorption/desorption, XRF, WDS and TGA. The liquid and gaseous products were analyzed by TOC and gas chromatography, respectively. Results indicated that Ni/CRD catalyst showed the highest H2 yield (5.38 mol H2 per mol of glycerol fed) and long-term stability. Additionally, a comparison between the experimental results on the ScWG of glycerol and simulated thermodynamic equilibrium data was also reported. Thus, results demonstrated the great potential of the prepared catalyst to improve H2-rich gas production from glycerol gasification.

Biorefining of corn stover for efficient production of bioethanol, biodiesel, biomethane, and value-added byproducts

The present study investigated an integrated biorefinery that employed corn stover as the feedstock for sustainable bioethanol, biodiesel, biogas, chitosan, glycerol, and animal feed production. Corn stover was initially subjected to dilute acid pretreatment (1.8 % v/v H2SO4, 121 °C, and 22 min) followed by enzymatic hydrolysis with a commercial cellulase (37 °C, 72 h) to promote the release of glucose (∼93 wt%) and xylose (∼89 wt%). Mucor indicus fungus was then employed to convert the released sugars into bioethanol, glycerol, and fungal biomass with yields of 0.38 g g−1, 36 mg g−1, and 0.51 g g−1, respectively. The biomass of M. indicus was processed to extract chitosan (6 mg g−1 fungal biomass) and lipids (297 mg g−1 fungal biomass). The lipid was subsequently converted to biodiesel via transesterification in the presence of HCl/ MeOH with the yield of 0.54 g g−1 fungal lipid. The defatted biomass residue was then converted to biogas with 81 % theoretical yield through anaerobic digestion. To ensure process circularity, the nutritional values of pretreated and hydrolyzed corn stover were also investigated with their suitability as livestock. It was determined that 158.1 thousand tons of dry corn stover, which was annually collectible in Iran, could be used for the production of 137.6 kg chitosan, 10.4 ton animal feed, 870.0 kg glycerol, 40.7 million litters ethanol, 2.8 million m3 biodiesel, and 449.2 million m3 biomethane. The utilization of the produced ethanol, biodiesel, and biomethane in transporting sector was shown to have the potential of facilitating 4.3 million tons of equivalent carbon dioxide and a 197.8 million dollars reduction of associated social costs.

Techno-economic analysis of methanol synthesis from syngas derived from steam reforming of crude glycerol

AbstractDue to the large amount of crude glycerol produced as a by-product by the biodiesel industry, alternative technologies for converting glycerol to value-added fuels such as syngas have been proposed. By employing four main processes, the syngas could further be used to produce methanol. The first process is steam reforming (STR) where the crude glycerol is converted into syngas. The next step is a three-unit pressure swing adsorption (PSA) system which is employed to condition the syngas into the required stoichiometric ratio. The final two process are the methanol synthesis and methanol purification processes. The effects of STR temperature, steam-to-glycerol ratio (SGR), methanol synthesis temperature and pressure were all investigated. The results obtained shows that 0.29 kgMeOH/kgCG can be obtained through this process at STR of 650 ℃, SGR of 9, and methanol synthesis temperature and pressure of 250 ℃ and 80 bar respectively. In addition, a methanol production plant capacity of 6.8 tonnes/hr of crude glycerol feed for a 20-year plant life was investigated. The result from the economic analysis carried out shows that production of methanol from glycerol is economically feasible with net present value (NPV), return on investment, (ROI), discounted payback period (DPBP) and net production cost (NPC) of $74.2 million, 17%, 4.59 years, and 85₵/kgMeOH respectively. The sensitivity analysis results show that the revenue from sales of methanol and byproducts (hydrogen and methane), the manufacturing cost, the cost of raw materials, as well as fixed capital investment (FCI) were the most sensitive economic parameters.

Enhancing Antimicrobial Peptide Productivity in Pichia pastoris (Muts Strain) by Improving the Fermentation Process Based on Increasing the Volumetric Methanol Consumption Rate

The instability of the protein expression in Pichia pastoris strains has been an issue for various peptide productions. Some modifications to the traditional fermentation process could potentially solve the problem. Here, we consider a four-stage fermentation process to express the CAP2 (cell-penetrating antimicrobial peptide 2) candidate in P. pastoris KM71H, a slow methanol utilization strain. During the fermentation process, CAP2 productivity is limited (6.15 ± 0.21 mg/L·h) by the low overall methanol consumption (approximately 645 g), which is mainly the result of the slow methanol utilization of the P. pastoris KM71H. To overcome this limitation, we increased the cell concentration two-fold prior to the induction stage. A fed-batch process with exponential and dissolved oxygen tension (DOT) stat feeding strategies was deployed to control the glycerol feed, resulting in an increase in cell concentration and enhancement of the volumetric methanol consumption rate. The improved fermentation process increased the overall methanol consumption (approximately 1070 g) and the CAP2 productivity (13.59 ± 0.24 mg/L·h) by 1.66 and 2.21 times, respectively. In addition, the CAP3 (cell-penetrating antimicrobial peptide 3) candidate could also be produced using this improved fermentation process at a high yield of 3.96 ± 0.02 g/L without any further optimization. Note that there was no oxygen limitation during the improved fermentation process operating at high cell density. This could be due to the controlled substrate addition via the DOT stat system.

A comparative study of zirconia supported nickel and/or ruthenium catalysts for glycerol steam reforming

The physico-chemical properties of Ni, Ru, Ru–Ni monoclinic ZrO2 catalysts were studied and their catalytic activities in the glycerol steam reforming reaction (GSR) were compared. The catalysts were prepared by the wet impregnation method, calcined at 600 °C and characterized using XRD, BET, H2-TPR and CO2-TPD techniques. The XRD analyses revealed varying crystallite sizes depending on the active phase nature and composition. The H2-TPR analyses demonstrated that the reducibility of the active metal oxide species and its dispersion were affected by the active phase composition. The CO2-TPD analyses revealed that surface modification following impregnation modified the basic properties of the catalysts. The catalytic activity tests (T = 400–700 °C, WGFR 9:1, flow rate of 0.025 mL/min) showed that the nickel based catalysts were active while the ruthenium based catalyst was inactive. Combining ruthenium and nickel over zirconia led to smaller Ni particle sizes and a better metal dispersion both of which contributed to higher H2 yields and an increased coke resistance. During 24 h on stream, the combined Ru–Ni/ZrO2 catalyst maintained a higher total glycerol conversion compared to the Ni/ZrO2 catalyst. Only filamentous coke was identified on the spent catalysts after the stability tests. For a higher water to glycerol feed ratio (WGFR 46:1), encapsulating coke was formed over Ru–Ni/ZrO2 leading to the blockage of active sites and a more rapid catalyst deactivation.

Optimal control of a nonlinear state-dependent impulsive system in fed-batch process

Optimal control technique is crucial to improve the yield of microbial fermentation production. In this paper, we propose a nonlinear control system with state-dependent impulses, where the impulsive volume of feeding glycerol and the critical concentration of glycerol for occurring impulse are the control variables, to formulate 1,3-propanediol (1,3-PD) fed-batch production process. We also discuss a quantity of important properties for this control system. Then, we analyze the sensitivity of system state with respect to the kinetic parameters. We further propose a constrained optimal control model governed by the control system with state-dependent impulses. The existence of the optimal impulsive controls is established. For solving this problem, we utilize an exact penalty method to transform the problem into an optimization problem with only box constraints. Moreover, an improved differential evolution method is developed to seek the optimal impulsive strategy. Finally, numerical simulation results demonstrate that, by using the optimal impulsive strategies, final 1,3-PD concentration is considerably increased under the nominal parameter values and disturbances of kinetic parameters have significant effects on the optimal final 1,3-PD yield.

Environmental conditions during glycerol bioconversion affect 3-hydroxypropionic acid bioproduction by Limosilactobacillus reuteri DSM 17938.

3-Hydroxypropionic acid (3-HP) is a platform molecule whose biological production was carried out by the bacterium Limosilactobacillus reuteri according to a two-step process: first, a growth phase in batch mode on glucose, then a glycerol bioconversion into 3-HP in fed-batch mode. With the objective of improving 3-HP bioproduction, this study aimed at defining the operating conditions during the bioconversion phase that increases the bioproduction performance. A central composite rotatable design allowed testing various pH levels and specific glycerol feeding rates. By establishing response surfaces, optimal conditions have been identified that were different depending on the considered output variable (final 3-HP quantity, 3-HP production yield and production rate). Of them, 3-HP final quantity and 3-HP production yield were maximized at pH6.0 and at specific glycerol feeding rates of 60 and 55 mggly gCDW -1 h-1 , respectively. The specific 3-HP production rate was the highest at the upper limit of the specific substrate feeding rate (80 mggly gCDW -1 h-1 ) but was not affected by the pH. An additional experiment was carried out at pH6.0 and a specific glycerol feeding rate of 80 mggly gCDW -1 h-1 to validate the previous observations. In conclusion, the results showed a significant improvement of 3-HP concentration by 13%, of specific production rate by 34% and of 3-HP volumetric productivity by 39%, as compared to the initial values.

Improved fed-batch processes with Wickerhamomyces anomalus WC 1501 for the production of d-arabitol from pure glycerol

Backgroundd-Arabitol, a five-carbon sugar alcohol, represents a main target of microbial biorefineries aiming to valorize cheap substrates. The yeast Wickerhamomyces anomalus WC 1501 is known to produce arabitol in a glycerol-based nitrogen-limited medium and preliminary fed-batch processes with this yeast were reported to yield 18.0 g/L arabitol.ResultsFed-batch fermentations with W. anomalus WC 1501 were optimized using central composite design (CCD). Dissolved oxygen had not a significant effect, while optimum values were found for glycerol concentration (114.5 g/L), pH (5.9), and temperature (32.5 °C), yielding 29 g/L d-arabitol in 160 h, a conversion yield of 0.25 g of arabitol per g of consumed glycerol, and a volumetric productivity of 0.18 g/L/h. CCD optimal conditions were the basis for further improvement, consisting in increasing the cellular density (3✕), applying a constant feeding of glycerol, and increasing temperature during production. The best performing fed-batch fermentations achieved 265 g/L d-arabitol after 325 h, a conversion yield of 0.74 g/g, and a volumetric productivity of 0.82 g/L/h.ConclusionW. anomalus WC 1501 confirmed as an excellent producer of d-arabitol, exhibiting a remarkable capability of transforming pure glycerol. The study reports among the highest values ever reported for microbial transformation of glycerol into d-arabitol, in terms of arabitol titer, conversion yield, and productivity.Graphical

Evaluation of Porous Honeycomb-Shaped CuO/CeO2 Catalyst in Vapour Phase Glycerol Reforming for Sustainable Hydrogen Production

This study presented an optimisation study of two-stage vapour-phase catalytic glycerol reforming (VPCGR) using response surface methodology (RSM) with a central composite experimental design (CCD) approach. Characterisation through Brunauer–Emmett–Teller analysis (BET), small-angle X-ray scattering (SAXS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM) and particle X-ray diffraction (PXRD) were carried out to understand the physiochemical activity of the honeycomb morphology CuO/CeO2 catalyst. Notably, in this study, we achieved the desired result of glycerol conversion (94%) and H2 production (81 vol.%) under the reaction condition of Cu species loading (10 wt.%), reaction temperature (823 K), WHSV (2 h−1) and glycerol concentration (15 wt.%). From the RSM analysis, an optimum predicted model for VPCGR was obtained and further integrated into Microsoft Excel and Aspen Plus to perform an energy analysis of the VPCGR plant at a scale of 100 kg h−1 of glycerol feed. As a whole, this study aimed to provide an overview of the technical operation and energy aspect for a sustainable frontier in glycerol reforming.

Media engineering in marine diatom Phaeodactylum tricornutum employing cost-effective substrates for sustainable production of high-value renewables.

Phaeodactylum tricornutum is a marine diatom, rich in omega-3 polyunsaturated fatty acids especially eicosapentaenoic acid (EPA) and brown pigment, that is, fucoxanthin. These high-value renewables (HVRs) have a high commercial and nutritional relevance. In this study, our focus was to enhance the productivities of such renewables by employing media engineering strategy via., photoautotrophic (P1, P2, P3) and mixotrophic (M1, M2, M3, M4) modes of cultivation with varying substrate combinations of carbon (glycerol: 0.1m) and nitrogen (urea: 441mm and/or sodium nitrate: 882mm). Our results demonstrate that mixotrophic [M4] condition supplemented with glycerol (0.1m) and urea (441mm) feed enhanced productivities (mgL-1 day-1 ) as follows: biomass (770.0), total proteins (36.0), total lipids (22.0), total carbohydrates (23.0) with fatty acid methyl esters (9.6), EPA (2.7), and fucoxanthin (1.1), respectively. The overall yield of EPA represents 28% of total fatty acids in the mixotrophic [M4] condition. In conclusion, our improved strategy of feeding urea to a glycerol-supplemented medium defines a new efficient biomass valorization paradigm with cost-effective substrates for the production of HVRs in oleaginous diatoms P. tricornutum.