Facile Polyolefin Plastics Hydrogenolysis Catalyzed by a Surface Electrophilic d0 Hydride

Polyolefins comprise a major fraction of single-use plastics and yet their catalytic deconstruction/recycling has proven challenging due to their inert hydrocarbon connectivities. Here an electrophilic earth-abundant single-site organozirconium catalyst chemisorbed on a highly Brønsted acidic support and characterized by a broad array of experimental and theoretical techniques, is shown to mediate the rapid hydrogenolytic cleavage of molecular and macromolecular saturated hydrocarbons under mild conditions. For n-hexadecane, hydrogenolysis to light hydrocarbons proceeds with an activity of 690 mol n-hexadecane · mol Zr-1 · h-1 at 150°C/2.5 atm H2 pressure. Under similar solventless conditions, polyethylene, polyethylene-co- 1-octene, isotactic polypropylene, and a post-consumer sandwich bag are rapidly hydrogenolyzed to low molecular mass hydrocarbons via a turnover-limiting C-C scission pathway involving ßalkyl transfer rather than more common σ-bond metathesis.

Effects of Adding Laccase to Bacterial Consortia Degrading Heavy Oil

High-efficiency bioremediation technology for heavy oil pollution has been a popular research topic in recent years. Laccase is very promising for the remediation of heavy oil pollution because it can not only convert bio-refractory hydrocarbons into less toxic or completely harmless compounds, but also accelerate the biodegradation efficiency of heavy oil. However, there are few reports on the use of laccase to enhance the biodegradation of heavy oil. In this study, we investigated the effect of laccase on the bacterial consortia degradation of heavy oil. The degradation efficiencies of bacterial consortia and the laccase-bacterial consortia were 60.6 ± 0.1% and 68.2 ± 0.6%, respectively, and the corresponding heavy oil degradation rate constants were 0.112 day−1 and 0.198 day−1, respectively. The addition of laccase increased the heavy oil biodegradation efficiency (p < 0.05) and biodegradation rate of the bacterial consortia. Moreover, gas chromatography–mass spectrometry analysis showed that the biodegradation efficiencies of the laccase-bacterial consortia for saturated hydrocarbons and aromatic hydrocarbons were 82.5 ± 0.7% and 76.2 ± 0.9%, respectively, which were 16.0 ± 0.3% and 13.0 ± 1.8% higher than those of the bacterial consortia, respectively. In addition, the degradation rate constants of the laccase-bacterial consortia for saturated hydrocarbons and aromatic hydrocarbons were 0.267 day−1 and 0.226 day−1, respectively, which were 1.07 and 1.15 times higher than those of the bacterial consortia, respectively. The degradation of C15 to C35 n-alkanes and 2 to 5-ring polycyclic aromatic hydrocarbons by laccase-bacterial consortia was higher than individual bacterial consortia. It is further seen that the addition of laccase significantly improved the biodegradation of long-chain n-alkanes of C22–C35 (p < 0.05). Overall, this study shows that the combination of laccase and bacterial consortia is an effective remediation technology for heavy oil pollution. Adding laccase can significantly improve the heavy oil biodegradation efficiency and biodegradation rate of the bacterial consortia.

Renewable Hydrocarbon Production via Rapeseed Oil Hydrotreatment Over Palladium Catalysts

The effect of SiO2-Al2O3 (Pd5%/SA), activated carbon (Pd5%/C) and Al2O3 (Pd5%/A) supported palladium (5%) catalysts on renewable hydrocarbon synthesis via rapeseed oil hydrotreatment was investigated. The hydrotreatment experiments were carried out in solvent free medium under initial H2 pressure 100 bar and at 340 °C temperature for 120 min using catalyst amount 5%. Gas chromatography-mass spectrometry (GC/MS) analysis were used for estimation of hydrocarbon content in the obtained samples. Pd5%/SA catalyst provided complete conversion of rapeseed oil into marketable liquid renewable hydrocarbons without presence of oxygen containing substances under studied hydrotreatment conditions. Moreover, all tested Pd catalysts gave narrow range of linear saturated hydrocarbons (n-C15-C19). Pd5%/C and Pd5%/A catalysts gave partial feedstock conversion into hydrocarbons even in long residence time. Overall liquid hydrocarbon yields were from 55.3% to 82.3%.

Trilobites, Biostratigraphy, and Geochemistry of the Middle Cambrian Kuonamka Formation (Northeastern Siberian Platform, Kyulenke River)

—We studied the middle Cambrian unit of the Kuonamka Formation section on the Kyulenke River (Siberian Platform) and performed its biostratigraphic subdivision based on trilobites. The middle Cambrian section has intervals corresponding to the regional zones of the Amginian Stage. Six levels with mass accumulation of fauna remains have been identified: Two levels are located within the Ovatoryctocara Zone; the third level is at the boundary between the Ovatoryctocara and Kounamkites zones; the fourth layer is confined to the roof of the Triplagnostus gibbus Zone; and the fifth and sixth levels are located within the Tomagnostus fissus–Paradoxides sacheri Zone. The composition of rocks and bitumens of their organic matter (OM) has been studied, including the geochemical specifics of the mineral components of rocks (iron, sulfur, and CO2) and of saturated hydrocarbons of bitumens as well as noncarbonate carbon isotopes in the OM. It has been established that the OM sedimentation took place under normal aeration of the sea basin waters, without hydrogen sulfide contamination of the bottom waters. The intensity of chemical and biochemical transformations of mineral and organic components during diagenesis was controlled by the contents of organic carbon and sulfate ion, the activity of the anaerobic prokaryote community, and the rate of sediment mineralization. We have also established relationships between the content of organic carbon in potentially oil source rocks and the contents of iron oxide, total sulfur, and sulfide and sulfate sulfur as well as the ratios of saturated hydrocarbons. The alternation of highly carbonaceous black shales and carbonaceous rocks is apparently due to a change in the composition of biologic communities of microorganisms (sources of hydrocarbon biomarkers) and in the intensity of OM transformation during diagenesis. We assume that the OM transformation included sulfate reduction and dealkylation of high-molecular steroids in the unconsolidated OM-enriched marine sediments with the participation of bacteria. The intensity of these processes depended on the mass of the primary OM, the amount of sulfate ion, and, hence, the pH and Eh of the medium.

Offline Solid-Phase Extraction and Separation of Mineral Oil Saturated Hydrocarbons and Mineral Oil Aromatic Hydrocarbons in Edible Oils, and Analysis via GC with a Flame Ionization Detector

A method was developed for the determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in edible oils, achieving similar limits of quantification than those obtained by online extraction methodologies, i.e., 0.5 mg/kg. The isolation of MOSH and MOAH was performed in a silver nitrated silica gel stationary phase prior to their analysis by gas chromatography–flame ionization detector (GC-FID). To improve the sensitivity, the simulated on-column injection method, using a suitable liner, was optimized. The method was validated at 0.5, 10.0 and 17.9 mg/kg, and recoveries ranged from 80 to 110%. Intra and inter-day precision were evaluated at the same levels, and relative standard deviation (RSD) was lower than 20%. The method was applied to a total of 27 samples of different types of oil previously analyzed in an accredited laboratory, detecting MOSH up to 79.2 mg/kg and MOAH up to 22.4 mg/kg.

A novel characteristic of a phytoplankton as a potential source of straight-chain alkanes

Biosynthesis of hydrocarbons is a promising approach for the production of alternative sources of energy because of the emerging need to reduce global consumption of fossil fuels. However, the suitability of biogenic hydrocarbons as fuels is limited because their range of the number of carbon atoms is small, and/or they contain unsaturated carbon bonds. Here, we report that a marine phytoplankton, Dicrateria rotunda, collected from the western Arctic Ocean, can synthesize a series of saturated hydrocarbons (n-alkanes) from C10H22 to C38H78, which are categorized as petrol (C10–C15), diesel oils (C16–C20), and fuel oils (C21–C38). The observation that these n-alkanes were also produced by ten other cultivated strains of Dicrateria collected from the Atlantic and Pacific oceans suggests that this capability is a common characteristic of Dicrateria. We also identified that the total contents of the n-alkanes in the Arctic D. rotunda strain increased under dark and nitrogen-deficient conditions. The unique characteristic of D. rotunda could contribute to the development of a new approach for the biosynthesis of n-alkanes.

Deep hydrocarbon cycle

Research subject. Experimental modelling of the transformation of complex hydrocarbon systems under extreme thermobaric conditions was carried out. The results obtained were compared with geological observations in the Urals, Kamchatka and other regions.Material and methods. The materials for the research were a model hydrocarbon system similar in composition to natural gas condensate and a system consisting of a mixture of saturated hydrocarbons and various iron-containing minerals enriched in 57Fe. Two types of high-pressure equipment were used: a diamond anvils cell and a Toroid-type high-pressure chamber. The experiments were carried out at pressures up to 8.8 GPa in the temperature range 593–1600 K.Results. According to the obtained results, hydrocarbon systems submerged in a subduction slab can maintain their stability down to a depth of 50 km. Upon further immersion, during contact of the hydrocarbon fluid with the surrounding iron-bearing minerals, iron hydrides and carbides are formed. When iron carbides react with water under the thermobaric conditions of the asthenosphere, a water-hydrocarbon fluid is formed. Geological observations, such as methane finds in olivines from ultramafic rocks unaffected by serpentinization, the presence of polycyclic aromatic and heavy saturated hydrocarbons in ophiolite allochthons and ultramafic rocks squeezed out from the paleo-subduction zone of the Urals, are in good agreement with the experimental data.Conclusion. The obtained experimental results and presented geological observations made it possible to propose a concept of deep hydrocarbon cycle. Upon the contact of hydrocarbon systems immersed in a subduction slab with iron-bearing minerals, iron hydrides and carbides are formed. Iron carbides carried in the asthenosphere by convective flows can react with hydrogen contained in the hydroxyl group of some minerals or with water present in the asthenosphere and form a water-hydrocarbon fluid. The mantle fluid can migrate along deep faults into the Earth’s crust and form multilayer oil and gas deposits in rocks of any lithological composition, genesis and age. In addition to iron carbide coming from the subduction slab, the asthenosphere contains other carbon donors. These donors can serve as a source of deep hydrocarbons, also participating in the deep hydrocarbon cycle, being an additional recharge of the total upward flow of a water-hydrocarbon fluid. The described deep hydrocarbon cycle appears to be part of a more general deep carbon cycle.