Docosane Research Articles

Homogeneous Catalysis for Sustainable Energy: Hydrogen and Methanol Economies, Fuels from Biomass, and Related Topics.

As the world pledges to significantly cut carbon emissions, the demand for sustainable and clean energy has now become more important than ever. This includes both production and storage of energy carriers, a majority of which involve catalytic reactions. This article reviews recent developments of homogeneous catalysts in emerging applications of sustainable energy. The most important focus has been on hydrogen storage as several efficient homogeneous catalysts have been reported recently for (de)hydrogenative transformations promising to the hydrogen economy. Another direction that has been extensively covered in this review is that of the methanol economy. Homogeneous catalysts investigated for the production of methanol from CO2, CO, and HCOOH have been discussed in detail. Moreover, catalytic processes for the production of conventional fuels (higher alkanes such as diesel, wax) from biomass or lower alkanes have also been discussed. A section has also been dedicated to the production of ethylene glycol from CO and H2 using homogeneous catalysts. Well-defined transition metal complexes, in particular, pincer complexes, have been discussed in more detail due to their high activity and well-studied mechanisms.

IM-5 zeolite with abundant narrow mesopores and modulated acidity as stable and selective cracking catalyst

High-performance IM-5 was prepared by tetrapropylammonium hydroxide (TPAOH) and NaOH alkaline treatment. The modification of combined alkaline treatment on the pore and acidity were systematically characterized. The 29 Si NMR results indicated that Si(4Si, 0Al) sites were protected by tetrapropylammonium cation (TPA + ) at low TPAOH/(NaOH + TPAOH) molar ratio, while the protection effect extended to some Si(3Si, 1Al) sites at TPAOH/(NaOH + TPAOH) ratio of 75%. And, the amount of strong Brønsted acid sites decreased significantly from 255 μmolg −1 to 119 μmolg −1 under the optimal TPAOH/NaOH alkaline treatment conditions. Compared to NaOH treatment alone, the mesopore volume and external surface area of IM-5 were further increased with TPAOH introduced, meanwhile, the mesopore size was shrunken into the range of 2–10 nm centered at 5 nm. Compared to NaOH treated IM-5 catalyst, the TPAOH/NaOH treated one exhibited higher initial light olefins yield (53.4% vs. 45.2% for n -heptane cracking) and better catalytic stability and regeneration properties. The abundant narrow mesopores contributed into high tolerance ability to coke deposition in IM-5 catalysts, as confirmed by TGA results. • TPAOH/NaOH treatment led to abundant well-spread mesopores in IM-5. • TPAOH/NaOH treatment lowered the amount of strong Brønsted acid sites. • TPA + extended protection effect to framework aluminum at high TPAOH concentration. • TPAOH/NaOH treated IM-5 reached high light olefins yield of 53.4%. • TPAOH/NaOH treated IM-5 kept stable in 5 regeneration cycles.

Characterisation of radiogenic monoalkenes in Australian oils and condensate

Thirteen Australian oils and one condensate, covering oil reservoir ages from Mesoproterozoic to Early Cretaceous, show monoalkene contents varying from 0.01 to 22.3 wt% of the whole liquid. Radiolysis of saturated hydrocarbons is the most likely process leading to oils with high alkene contents. The major radiolytic component is an unresolved complex mixture (UCM). The bulk of the resolved alkene compounds are positional isomers of n-alkenes. Methyl branched and cyclohexyl alkenes are minor components. Internal n-alkene isomers have a trans configuration dominant over the cis isomer. The oil with the longest reservoir residence time shows the highest content of internal n-alkenes relative to terminal 1-alkenes as well as the highest trans/cis ratio, suggesting the extended time has resulted in rearrangement to near thermodynamic equilibrium of the congruent monoalkenes. The radiolytic monoalkenes in the Ordovician-reservoired oil with the highest alkene content is likely influenced by a higher probability of intermolecular interactions and different product pathways in a complex mixture. Here, the relative proportion of alkene mimics the relative abundance of n-alkanes, suggesting that radiolytic C–C bond cleavage is suppressed when the alkene/alkane ratio is elevated and that the preferred pathway of n-alkane radiolysis favours the production of terminal monoalkenes. Radiolysis of the alkane UCM together with crosslinking and branching of n-alkane-derived radiolysis products contribute to the higher relative proportion of the alkene UCM. The similar carbon and hydrogen isotopic ratios of the n-alkanes and n-alkenes supports a parent–daughter relationship.

Selective ethylene oligomerization based on Fe-containing metal-organic coordination polymer catalysts

One-dimensional, two-dimensional and three-dimensional Fe-containing metal-organic coordination polymer (1D/2D/3D-Fe-MOCP) catalysts have been solvothermally synthesized and evacuated at different temperatures to give a series of 1D-Fe, 2D-Fe and 3D-Fe catalysts used for ethylene oligomerization performed in slurry batch mode. Their catalytic performances were investigated with the aid of AlEt2Cl cocatalyst, and moderate catalytic activities and high selectivities to low carbon olefins C4, C6, C8, and C10 were observed. Moreover, the oligomerization product distributions differed depending on various factors such as the structural dimension, ligand type, framework flexibility, distances between metal atoms, et al. 1D-Fe catalyst evacuated at 150 °C for 8 hours showed high C8 olefin selectivity up to 94.90% with the catalytic activity of 6.28 × 105 g/mol(Fe)•h•atm. However, 2D-Fe and 3D-Fe catalysts showed relatively low catalytic activity and low selectivity for C8 olefin.

Catalytic pyrolysis of biomass over Fe-modified hierarchical ZSM-5: Insights into mono-aromatics selectivity and pyrolysis behavior using Py-GC/MS and TG-FTIR

Catalytic pyrolysis has recently aroused great interest for the high potential in upgrading bio-oils as renewable energy. However, conventional catalysts often exert diffusion resistance to large intermediate oxygenates. In this study, Fe-modified hierarchical ZSM-5 prepared by alkali and Fe loading of 2, 4, 6, 8 wt% were characterized by the analysis of XRD, BET, TEM, and NH3-TPD. Catalytic pyrolysis of poplar sawdust via Fe-modified hierarchical ZSM-5 was conducted using Py-GC/MS and TG-FTIR. The results indicated that alkali treatment and Fe loading of the catalyst introduced a hierarchical and porous structure and improved its acidity, leading to high mono-aromatics and olefins selectivity. The hierarchical ZSM-5 with 4 wt% Fe loading exhibited superior performance with high selectivity towards mono-aromatics of 15.30%. TG-FTIR analysis shows the volatiles release characteristics and FTIR spectra were consistent with pyrolysis behavior. Kinetic analysis reveals Fe-modified hierarchical ZSM-5 lowers the apparent activation energy in catalytic pyrolysis of poplar sawdust.

Relationship between Acidity and Activity on Propane Conversion over Metal-Modified HZSM-5 Catalysts

A systematic study of the comparative performances of different metal-impregnated HZSM-5 catalysts (Zn, Ga, Mo, Co, and Zr) for propane conversion is presented. The physicochemical properties of catalysts were characterized by means of XRD, BET, SEM, TEM, FTIR, XPS, 27Al MAS NMR, NH3-TPD and Py-FTIR. It was found that the acidities of the catalysts were significantly influenced by loading metal. More specifically, Mo-, Co- or Zr-modified catalysts showed a large metal size and low acidic density, resulting high olefin selectivity, while Zn- or Ga-modified catalysts maintained their small metal size and acidic density, and mainly reduced B/L due to the Lewis acid sites created by Zn or Ga species, resulting in high aromatics selectivity. Experimental results also showed that there is a balance between metals size and medium and strong acidity on propane conversion. Moreover, based on the different acidity of metal-modified HZSM-5 catalysts, the mechanism of propane conversion was also discussed.

Using a Chromatographic Pseudophase Model To Elucidate the Mechanism of Olefin Separation by Silver(I) Ions in Ionic Liquids.

Silver(I) ions undergo selective olefin complexation and have been utilized in various olefin/paraffin separation techniques such as argentation chromatography and facilitated transport membranes. Ionic liquids (ILs) are solvents known for their low vapor pressure, high thermal stability, low melting points, and ability to promote a favorable solvation environment for silver(I) ion-olefin interactions. To develop highly selective separation systems, a fundamental understanding of analyte partitioning to the stationary phase and the thermodynamic driving forces behind solvation is required. In this study, a chromatographic model treating silver(I) ions as a pseudophase is constructed and employed for the first time to investigate the olefin separation mechanism in silver(I) salt/IL mixtures. Stationary phases containing varying amounts of noncoordinated silver(I) salt ([Ag+][NTf2-]) dissolved in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C10MIM+][NTf2-]) IL are utilized to determine the partition coefficients of various analytes including alkanes, alkenes, alkynes, aromatics, aldehyde, esters, and ketones. As ligand coordination to silver(I) ions is known to lower its olefin complexation capability, this study also examines two different types of coordinated silver(I) ion pseudophases, namely, monocoordinated silver(I) salt ([Ag+(1-decyl-2-methylimidazole, DMIM)][NTf2-]) and dicoordinated silver(I) salt ([Ag+(1-methylimidazole, MIM)(DMIM)][NTf2-]). The extent of olefin partitioning to the coordinated silver(I) ion pseudophases over the carrier gas and IL decreased by up to two orders of magnitude. Values for enthalpy, entropy, and free energy of solvation were determined for the three silver(I) ion-containing systems. Olefin retention was observed to be enthalpically dominated, while ligand coordination to the silver(I) ion pseudophase resulted in variations for both enthalpic and entropic contributions to the free energy of solvation. The developed model can be used to study chemical changes that occur in silver(I) ions over time as well as identify optimal silver(I) salt/IL mixtures that yield high olefin selectivity.

Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements

Abstract. The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10 s (2 km) merged and gap-filled observations of the key reactive species driving the chemical budgets of O3 and CH4 (O3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, other organic nitrates), consisting of 146 494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80 %–90 % of the total reactivity lies in the top 50 % of the parcels and 25 %–35 % in the top 10 %, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. In other words, accurate simulation of the least reactive 50 % of the troposphere is unimportant for global budgets. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2 km ATom data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find excellent agreement with the loss of O3 and CH4 but sharp disagreement with production of O3. The models sharply underestimate O3 production below 4 km in both Pacific and Atlantic basins, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-to-what-matters, set of metrics for model evaluation.

Kinetic Study on Microwave-Assisted Oligomerization of 1-Decene over a HY Catalyst

A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different reaction temperatures and times. Higher reaction temperature resulted in increasing formation of dimers and trimers. The oligomerization reaction yielded 80% conversion, 54.2% dimer product, 22.3% trimer product and 3.4% heavier product at 483 K for a reaction time of 3 h. The best fit kinetic model for the dimerization reaction was formulated from an assumption of no vacant reaction sites. For the trimerization reaction, a molecule of dimer (C20) formed on the active site, interacted with a molecule of 1-decene in the bulk solution to form a molecule of trimer (C30). Apparent activation energies for the dimerization and trimerization reactions were 70.8 ± 0.8 and 83.6 ± 0.9 kJ/mol, respectively. The C13-NMR spectrum indicated that the oligomer product contained a significant portion of highly branched hydrocarbons, causing a substantial reduction in the viscosity index compared to conventional poly-alpha olefin lubricant (PAO).

Directed evolution of prenylated FMN-dependent Fdc supports efficient in vivo isobutene production

Isobutene is a high value gaseous alkene used as fuel additive and a chemical building block. As an alternative to fossil fuel derived isobutene, we here develop a modified mevalonate pathway for the production of isobutene from glucose in vivo. The final step in the pathway consists of the decarboxylation of 3-methylcrotonic acid, catalysed by an evolved ferulic acid decarboxylase (Fdc) enzyme. Fdc belongs to the prFMN-dependent UbiD enzyme family that catalyses reversible decarboxylation of (hetero)aromatic acids or acrylic acids with extended conjugation. Following a screen of an Fdc library for inherent 3-methylcrotonic acid decarboxylase activity, directed evolution yields variants with up to an 80-fold increase in activity. Crystal structures of the evolved variants reveal that changes in the substrate binding pocket are responsible for increased selectivity. Solution and computational studies suggest that isobutene cycloelimination is rate limiting and strictly dependent on presence of the 3-methyl group.

Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route toward contra-Thermodynamic Olefins.

We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access to contra-thermodynamic olefins, elusive by E2 eliminations.

Micellization of Rhamnolipid Biosurfactants and Their Applications in Oil Recovery: Insights from Mesoscale Simulations.

The dissipative particle dynamics (DPD) mesoscopic method is used to investigate the self-assembly of rhamnolipid congeners and their aggregation behaviors with paraffins including nonane and pentadecane. The coarse-grained force field is parameterized by combining molecular dynamics (MD) simulations, COSMOtherm calculations, and available experimental data. This model reproduces the vesicular formation of α-l-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-C10-C10) reported by all-atom MD simulations. The vesicle composed of Rha-C10-C10 is found to be most stable at a surfactant concentration of 100-146 mM based on asphericity analysis. The architecture of rhamnolipid congeners affects the morphology of their aggregates. Di-rhamno-di-lipidic dRha-C16-C16 forms vesicles with a thicker unilamellar layer of 3.2 nm. Rha-C16-C16 forms vesicles at a lower concentration of 70 mM, but the enclosed water space collapses when the surfactant concentration increases. dRha-C10-C10 forms wormlike micelles, which agglomerate into a torus and interconnected network at higher concentrations. In the presence of alkane molecules, dRha-C10-C10 maintains its wormlike micellar morphology with alkane molecules wrapped inside the aggregates. For Rha-C10-C10, Rha-C16-C16, and dRha-C16-C16, nonane molecules are distributed in the hydrophobic subdomain formed by rhamnolipid molecules. Spherical vesicles are formed at a surfactant concentration of 50 mM and then develop into ellipsoidal vesicles when the concentration increases to 125 mM. When mixed with pentadecane, the alkane molecules are aggregated and surrounded by surfactants forming a core-shell structure at a low surfactant concentration of 20 mM. At higher alkane and surfactant concentrations, the morphologies develop into disk micelles, wormlike micelles, and vesicles, with pentadecane molecules being distributed and packed with rhamnolipids. The obtained simulation results suggest that these biosurfactants have potential as environmental remediation agents.

A systematic multi-isotope approach to unravel methane origin in groundwater: Example of an aquifer above a gas field in southern New Brunswick (Canada)

Following the large increase in unconventional hydrocarbon production in North America and elsewhere in the last 15 years, many jurisdictions have implemented groundwater monitoring programs to verify whether these subsurface industrial activities impact shallow groundwater quality. The interpretation of groundwater monitoring results typically relies mostly on dissolved alkane chemical and isotopic composition to infer the potential presence of thermogenic hydrocarbons presumed to originate from a deep source, which may indicate contamination. However, ambiguous results are frequently obtained, and post-genetic processes are often suspected to have modified the original gas composition. Here, we present a systematic approach to identify alkane origin with greater certainty, by thoroughly investigating four processes that may affect dissolved hydrocarbon gas: 1) late-stage methanogenesis, 2) oxidation (of methane or higher alkanes), 3) mixing between different gas sources, and 4) secondary methanogenesis. This is achieved by using empirical equations and fractionation factors available in the literature, combined to site-specific isotopic tracers (δ13CCH4, δ2HCH4, δ2HH2O, δ13CDIC) in groundwater samples. This approach is being tested and applied to a study area located in southern New Brunswick, Canada. The area overlies the McCully gas field from which unconventional natural gas is produced since 2003, and the nearby Elgin area, a prospective area for condensates. Results demonstrate that the presence of methane in groundwater is not related to the proximity of gas wells. In a few shallow wells located very close to producing gas wells in the McCully gas field, methane and ethane were detected, and the compositional and isotopic data sometimes seemed to point towards a thermogenic origin. However, consideration of the four processes led to the conclusion that the gas was of microbial origin, and that it had been oxidized to various levels. In contrast, thermogenic gas was detected in groundwater in the Elgin area, where no commercial production has yet taken place. In this area the natural hydrocarbon gas context is more complex, and the gas from some of the wells was affected by mixing, oxidation, and late-stage methanogenesis. Finally, the approach used in this paper has proven capable of disentangling the original isotopic signature from post-genetic modifications and, despite initial ambiguity, has shown no evidence that past hydraulic fracturing in the McCully gas field has affected shallow groundwater quality.

Energy Analysis and Remixing Effect of Thermal Coupling Petlyuk Column for Natural Gas Liquid (NGL) Fractionation Train

In this work, a non-conventional distillation sequence with thermal coupling (Petlyuk Column) was presented as a technique to perform the separation of the NGL consist of ethane, propane, butane or other higher alkanes. The improvements were investigated through the energy analysis and remixing effect. From the result obtained, it was found that the Petlyuk arrangement consumes less amount of energy and able to reduce the remixing effects as compared to the conventional column sequencing. The Petlyuk arrangement saved about 44.49% and 12.83% in terms of cooling and heating duty, respectively. The overall annual energy saving shown by this arrangement is 39.22%. This arrangement proved to be able to prevent the remixing effect occurrence that contributes to thermal and separation inefficiency. The desired separation efficiency also obtained by this arrangement as all the product specifications are met. The ability in avoiding remixing effect by the Petlyuk column permits a significant reduction in CO2 emission with an average of 29.43 % of each equipment involved. Hence, it can be concluded that the Petlyuk arrangement model is a better alternative to be implemented in the NGL fractionation train.

Thermocapillary effects during the melting in microgravity of phase change materials with a liquid bridge geometry

A detailed numerical investigation of the melting of phase change materials (PCMs) in microgravity is presented. We consider the high Prandtl number alkane n-octadecane and quantify the effect of thermocapillary convection on the heat transfer observed during axisymmetric melting with a liquid bridge geometry. The phase change is studied by varying key dimensionless parameters including Marangoni (Ma) and Stefan (Ste) numbers, which are selected by the applied temperature difference between the circular supports, and geometry, which is characterised by the aspect ratio Γ=L/R and the dimensionless volume V. The case of cylindrical geometry with V=1 is considered first, and detailed analyses of the effect of both Ma (Ste) and Γ on heat transport and the type of oscillatory flow that appears in the liquid phase are provided. The results are compared with those available in the literature for rectangular geometry, demonstrating an improvement of approximately 50% for the cylindrical case. We further extend the analysis to noncylindrical configurations with V≠1 that correspond to stable liquid bridges when fully melted.

Towards a greater olefin share in polypropylene cracking – Amorphous mesoporous aluminosilicate competes with zeolites

For plastic waste cracking the path for production of high olefins yield without loose in gasoline fraction is an intriguing option. Among the commercial FAU zeolites of different properties and mesoporous HAlMCM-48 materials, the catalysts of polypropylene (PP) cracking being able to operate in low-temperature regime was searched. The aim was to investigate the effects of the presence of mesopore system in the context of internal and external acidic features on PP cracking. The advanced operando FT-IR and UV–vis characterization coupled with GC and MS analysis offered insight into the nature of active species during cracking reaction as well as into the nature of coke deposit formed after reaction. The results for series of FAU zeolites were faced with mesoporous HAIMCM-48 as the catalyst of similar cracking competence, as it will be documented.

Novel Perovskites Containing Ba, Mg, Ca, Nb, Fe and Ta for Electrochemical Oxidative Coupling of Methane

Methane is the major component of many gas sources such as natural gas and shale gas and more than 500 million tons of methane is produced every year. Unfortunately, most of it is burnt as an energy source due to difficulties in converting it into easily transportable fuels. Oxidative and non-oxidative coupling of methane (OCM and NOCM) has been actively researched to produce ethylene and higher olefins from methane although catalysts with commercially viable conversion rates have not been developed yet.[1] Electrochemical OCM (EC-OCM) is gaining attention due to its ability to regulate the oxide ion flux that will help reduce the over-oxidation of methane while also helping to activate methane.[2] Fe based catalysts have been shown to activate methane in both OCM and NOCM although suffer from coking related durability challenges. We have developed two novel perovskites comprising Ba, Ca, Mg, Nb and Ta where incorporation of Fe in the crystal lattice has resulted in mixed ionic electronic conductivity. Their physical and chemical properties are evaluated using TGA, XRD, XPS and FT-IR measurements. We further examined these catalysts for EC-OCM along with structural and chemical stability characterizations. Both these perovskites show very good chemical stability in methane under EC-OCM conditions. TGA under methane environment further reveal adsorption of methane on our perovskite material at about 600°C. Ethylene production was observed to increase with increasing Fe content in the perovskite structure. In this presentation we report our findings on the application of both perovskites towards EC-OCM and discuss potential future directions. References Schwach, X. Pan, and X. Bao, “Direct Conversion of Methane to Value-Added Chemicals over Heterogeneous Catalysts: Challenges and Prospects,” Chem. Rev., 117, 8497, 2017.Zhu, S. Hou, X. Hu, J. Lu, F. Chen, and K. Xie, “Electrochemical conversion of methane to ethylene in a solid oxide electrolyzer,” Nat. Commun., 10, 1173, 2019.

GC-MS based metabolite profiling and antioxidant activity of solvent extracts of Allium chinense G Don leaves

Allium chinense, a main source of “Xiebai” drug in Chinese traditional medicine and commonly known as Ganoderma lucidum belongs to the family Amaryllidaceae. The main focus of this research was to quantify the secondary metabolites, antioxidant potential and study the GC- MS based metabolite profile of different solvent leaf extracts of A. chinense. The reports on the bioactive compounds of A. chinense leaves are still insufficient compared to the bulb; hence this study was carried out to understand the bioactive compounds present in A. chinense leaves using different solvents of varying polarity. Our investigation showed that the ethanol extract contained the highest saponin, flavonoid, phenol, and DPPH scavenging activity. Further, metabolite profiling revealed a total of forty-eight compounds, indicating a diverse range of phytochemicals present in the four extracts. The highest number of compounds were observed in ethanol extract (15) followed by chloroform extract (13), petroleum ether extract (11) and methanol extract (9). Some of the major compounds identified in the four solvents are octacosane (27.11%), heptadecane (19.66%), eicosane (18.51%), ethyl palmitate (18.50%), phytol (17.68%) and phytol acetate (17.30%). In conclusion, this study highlights that A. chinense leaf extracts contain high saponins, terpenes and alkanes which could be a potential source of a new beneficial drug.

Modeling, simulation, and optimization for producing ultra-low sulfur and high-octane number gasoline by separation and conversion of fluid catalytic cracking naphtha

Contradiction between the desulfurization and loss of octane number (ON) for fluid catalytic cracking (FCC) naphtha is the long-term problem of clean gasoline production. Moreover, ON loss is substantially aggravated during deep hydrodesulfurization because of the global limited supply of sulfur for gasoline. This paper introduced a novel process for ultra-clean gasoline production that solves the above problem by using a unique separation approach. The components were separated by the coupling of distillation and solvent extraction, which the separation efficiency depends on the relationship between solvent and feedstock components. However, the compositions of FCC naphtha are complicated and always changing due to different processing technologies. Therefore, changes in the material composition must be considered during production. In this study, ternary liquid–liquid equilibrium (LLE) was explored to investigate the interaction of olefin, sulfide, and sulfolane solvent. A universal quasi-chemical functional group activity coefficient (UNIFAC) group contribution model was selected to predict the product composition when the FCC naphtha was treated by this process. The lack and necessity of group interaction parameters for the prediction were obtained through the regressive calculation of LLE results. A simulation method was established by Aspen Plus, and the reliability was well illustrated. Finally, the high olefin content of FCC naphtha critical components was analyzed by this simulation method. The sulfur and olefin levels of the product were 9.0 mg/kg and 18.6 wt%, respectively. The operation conditions simulated using the proposed technique met the requirements for the latest commercial gasoline worldwide.

Bioaugmentation of Native Fungi, an Efficient Strategy for the Bioremediation of an Aged Industrially Polluted Soil With Heavy Hydrocarbons.

The concurrence of structurally complex petroleum-associated contaminants at relatively high concentrations, with diverse climatic conditions and textural soil characteristics, hinders conventional bioremediation processes. Recalcitrant compounds such as high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) and heavy alkanes commonly remain after standard soil bioremediation at concentrations above regulatory limits. The present study assessed the potential of native fungal bioaugmentation as a strategy to promote the bioremediation of an aged industrially polluted soil enriched with heavy hydrocarbon fractions. Microcosms assays were performed by means of biostimulation and bioaugmentation, by inoculating a defined consortium of six potentially hydrocarbonoclastic fungi belonging to the genera Penicillium, Ulocladium, Aspergillus, and Fusarium, which were isolated previously from the polluted soil. The biodegradation performance of fungal bioaugmentation was compared with soil biostimulation (water and nutrient addition) and with untreated soil as a control. Fungal bioaugmentation resulted in a higher biodegradation of total petroleum hydrocarbons (TPH) and of HMW-PAHs than with biostimulation. TPH (C14-C35) decreased by a 39.90 ± 1.99% in bioaugmented microcosms vs. a 24.17 ± 1.31% in biostimulated microcosms. As for the effect of fungal bioaugmentation on HMW-PAHs, the 5-ringed benzo(a)fluoranthene and benzo(a)pyrene were reduced by a 36% and 46%, respectively, while the 6-ringed benzoperylene decreased by a 28%, after 120 days of treatment. Biostimulated microcosm exhibited a significantly lower reduction of 5- and 6-ringed PAHs (8% and 5% respectively). Higher TPH and HMW-PAHs biodegradation levels in bioaugmented microcosms were also associated to a significant decrease in acute ecotoxicity (EC50) by Vibrio fischeri bioluminiscence inhibition assays. Molecular profiling and counting of viable hydrocarbon-degrading bacteria from soil microcosms revealed that fungal bioaugmentation promoted the growth of autochthonous active hydrocarbon-degrading bacteria. The implementation of such an approach to enhance hydrocarbon biodegradation should be considered as a novel bioremediation strategy for the treatment of the most recalcitrant and highly genotoxic hydrocarbons in aged industrially polluted soils.