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It is well known that during biodegradation of oil in natural geological conditions, or oil pollutants in the environment, a degradation of hydrocarbons occurs according to the well defined sequence. For example, the major changes during the degradation process of n-alkanes occur in the second, slight and third, moderate level (on the biodegradation scale from 1 to 10). According to previous research, in the fourth, heavy level, when intensive changes of phenanthrene and its methyl isomers begin, n-alkanes have already been completely removed. In this paper, the ex situ natural bioremediation (unstimulated bioremediation, without addition of biomass, nutrient substances and biosurfactant) of soil contaminated with heavy residual fuel oil (mazut) was conducted during the period of 6 months. Low abundance of n-alkanes in the fraction of total saturated hydrocarbons in the initial sample (identification was possible only after concentration by urea adduction technique) showed that the investigated oil pollutant was at the boundary between the third and the fourth biodegradation level. During the experiment, an intense degradation of phenanthrene and its methyl-, dimethyl-and trimethyl-isomers was not followed by the removal of the remaining n-alkanes. The abundance of n-alkanes remained at the initial low level, even at end of the experiment when the pollutant reached one of the highest biodegradation levels. These results showed that the unstimulated biodegradation of some hydrocarbons, despite of their high biodegradability, do not proceed completely to the end, even at final degradation stages. In the condition of the reduced availability of some hydrocarbons, microorganisms tend to opt for less biodegradable but more accessible hydrocarbons. nema

Residual oils, high viscosity and large sulfur content petroleum products from the refining process of crude oil, are receiving increasing interest in pre-combustion carbon capture applications. Gasification is a promising technology to convert such complicated hydrocarbons into syngas. Pyrolysis and combustion are very important stages in the gasification process, and therefore a better understanding of these processes leads to higher efficiency and better development of such applications. In this work, pyrolysis and combustion of heavy fuel oil (HFO) and vacuum residual oil (VRO) were studied in a thermogravimetric analyzer (TGA). The HFO studied in this work is a blend of VRO and diesel, which provides insight into the performance of residual oils/diesel blends. The TGA experiments were conducted using nitrogen and mixtures of oxygen and nitrogen for pyrolysis and combustion studies, respectively, at different heating rates (5–20 °C min −1 ). The oxygen concentration was varied from 0 to 71.4% vol. to replicate oxygen concentration in applications ranging from pyrolysis (0% O 2 ) to combustion (21% O 2 ) and gasification (high O 2 %). The TGA experiments covered a temperature range from ambient to 1200 °C. The results show that pyrolysis is slightly slower than combustion at low temperatures for both oils. However, pyrolysis is significantly faster at high temperatures. The combustion of both oils resulted in minimal residue, while the residue remaining in the pyrolysis is 10–19%. The TGA was coupled with Fourier transform infrared spectroscopy (FTIR) to monitor the evolved volatiles from the pyrolysis and combustion processes. The results show more aromatics evolved from VRO than HFO. Apparent kinetic parameters were calculated using three model-free methods and a model-based method (Coats and Redfern).

Limiting fuel sulfur content (FSC) is a widely adopted approach for reducing ship emissions of sulfur dioxide (SO2) and particulate matter (PM), particularly in emission control areas (ECAs), but its impact on the emissions of volatile organic compounds (VOCs) is still not well understood. In this study, emissions from ships at berth in Guangzhou, southern China, were characterized before and after the implementation of the fuel switch policy (IFSP) with an FSC limit of 0.5 % in the Pearl River Delta ECA (ECA-PRD). After IFSP, the emission factors (EFs) of SO2 and PM2.5 for the coastal vessels decreased by 78 % and 56 % on average, respectively; however, the EFs of the VOCs were 1807±1746 mg kg−1, approximately 15 times that of 118±56.1 mg kg−1 before IFSP. This dramatic increase in the emissions of the VOCs might have been largely due to the replacement of high-sulfur residual fuel oil with low-sulfur diesel or heavy oils, which are typically richer in short-chain hydrocarbons. Moreover, reactive alkenes surpassed alkanes to become the dominant group among the VOCs, and low-carbon-number VOCs, such as ethylene, propene and isobutane, became the dominant species after IFSP. As a result of the largely elevated EFs of the reactive alkenes and aromatics after IFSP, the emitted VOCs per kilogram of fuel burned had nearly 29 times greater ozone formation potential (OFP) and approximately 2 times greater secondary organic aerosol formation potential (SOAFP) than those before IFSP. Unlike the coastal vessels, the river vessels in the region used diesel fuels consistently and were not affected by the fuel switch policy, but the EFs of their VOCs were 90 % greater than those of the coastal vessels after IFSP, with approximately 120 % greater fuel-based OFP and 70 %–140 % greater SOAFP. The results from this study suggest that while the fuel switch policy could effectively reduce SO2 and PM emissions, and thus help control PM2.5 pollution, it will also lead to greater emissions of reactive VOCs, which may threaten ozone pollution control in harbor cities. This change for coastal or ocean-going vessels, in addition to the large amounts of reactive VOCs from the river vessels, raises regulatory concerns for ship emissions of reactive VOCs.

We show that the oil market has become closer to “one great pool,” in the sense that price differentials between crude oils of different qualities have generally become smaller over time. We document, in particular, that many of these price differentials experienced a major structural break in or around 2008, after which there was a marked reduction in their means and volatilities. Differentials between residual fuel oil, a low-quality fuel, and higher-valued products, such as gasoline and diesel, experienced similar breaks during the same time period. A growing ability of the global refinery sector to process lower-quality crude oil and the U.S. shale boom, which has unexpectedly boosted the supply of high-quality crude oil, are two factors consistent with these changes. Differentials between crude oils of similar quality in general did not experience breaks in or around 2008, although we do find evidence of breaks at other times.

The production of very-low-sulfur residual fuel oil is a great challenge for modern petroleum refining because of the instability issues caused by blending incompatible relatively high-sulfur residual oils and ultra-low-sulfur light distillates. Another obstacle in the production of very-low-sulfur residual fuel oil using hydroprocessing technology is the contradiction of hydrodesulfurization with hydrodemetallization, as well as the hydrodeasphaltization functions of the catalytic system used. Therefore, the production of very-low-sulfur residual fuel oil by employing hydroprocessing could be achieved by finding an appropriate residual oil to be hydroprocessed and optimal operating conditions and by controlling catalyst system condition management. In the current study, data on the characteristics of 120 samples of heavy fuel oils produced regularly over a period of 10 years from a high-complexity refinery utilizing H–oil vacuum residue hydrocrackers in its processing scheme, the crude oils refined during their production, the recipes of the heavy fuel oils, and the level of H–oil vacuum residue conversion have been analyzed by using intercriteria and regression analyses. Artificial neural network models were developed to predict the characteristics of hydrocracked vacuum residues, the main component for the production of heavy fuel oil. It was found that stable very-low-sulfur residual fuel oil can be manufactured from crude oils whose sulfur content is no higher than 0.9 wt.% by using ebullated bed hydrocracking technology. The diluents used to reduce residue viscosity were highly aromatic FCC gas oils, and the hydrodemetallization rate was higher than 93%.

Engineered iron oxide (Fe3O4) nanoparticles (NPs) were synthesized with a silica shell using a modified alkylsilane approach with o-xylene, as a hydrocarbon media, and transmission electron microscopy (TEM) and single-particle inductively coupled plasma mass spectrometry (spICP-MS) were used to determine the particle size of the Fe3O4 core diameter. In contrast, mass concentrations of the Fe3O4 particles were determined using spICP-MS, using helium (He) as a collision gas to control spectral interferences from ArO and CaO on Fe at m/z 56. Different cell gas flow rates (3, 3.5, and 4 mL/min) and NP’s solution dilution factors from 1:20,000 up to 1:60,000 were investigated; He flow rate of 4 mL/min and a dilution factor of 1:20,000 were found as optimum. The spICP-MS method was calibrated by using gold nanospheres (polystyrene-coated) in toluene as reference material. For the engineered Fe3O4 nanoparticles, TEM. Results gave a (63 ± 6 nm) value for the Fe2O3 core diameter, while spICP-MS was 61.1 ± 4.5 nm (n = 36), demonstrating the excellent agreement among methods. The method was applied for the analysis Fe oxide NPs in petroluem hydrocarbon materials and data compared with TEM. Two standard reference materials (SRMs); NIST 2717a sulfur in residual fuel oil and NIST 8505 vanadium in crude oil were selected. spICP-MS results agreed pretty well among these techniques. These findings suggest that spICP-MS could be useful to characterize Fe-containing particles in complex solution media, such as petroleum hydrocarbons.Graphical abstract

The article reviews the main directions of development of vacuum units at oil refining plants. The indicators that are being subjected to updating because of growing quality requirements of the feedstock for production of fuel-lubricant materials are determined. Several types of vacuum creating system used at oil refineries and their merits and demerits are presented. The methods for separating wide vacuum distillates into narrower ones are analyzed. An improved fractionation scheme that ensures reliability of the process and less energy consumption is described.

PurposePropylene oxide (PO) is one of the useful chemicals that is predicted to experience a compound annual growth rate of 3.9% from 2020 through 2027. The environmental burdens of the current PO production process and its corresponding utility system including power generation system need to be determined quantitatively as a response to increasing demands for its environmentally sustainable production process in the energy transition period from fossil fuels towards renewable energy resources.MethodsA new methodology is proposed to study the PO production process called exergy-aided environmental life cycle assessment (EELCA), using the US National Renewable Energy Laboratory’s database known as life cycle inventory (LCI) database. EELCA is dedicated to LCA studies of processes in the energy transition period and is aided by Monte Carlo simulation (MCS) as a tool for discernibility analysis which brings another dimension to the EELCA because MCS was often used to assess uncertainty in LCA studies. EELCA impact categories are classified into two classes: (i) emission-dependent impact categories addressed by ReCiPe and (ii) resource-dependent impact categories covered by cumulative exergy demand (CExD). The alternative energy like bioenergy is evaluated through the stepwise scenarios assisted by MCS, which are employed in openLCA with 10,000 iterations.Results and discussionThe cumulative exergy depletion of the base scenario is 6.1898 MJ (CExD). The human health and ecosystem impacts are 3.65E-06 DALY and 1.58E-08 species.yr, respectively. Human health-total (2.7E-4 DALY) is the most important category, where the power generation system by residual fuel oil (33.19%) is on top of the list. By analysing statistically discernible scenarios using EELCA, it has been proven that natural gas is not a proper choice for energy mix in the energy transition period. This is because natural gas-based scenarios present more burden compared to residual fuel oil-based scenarios especially regarding human toxicity, freshwater ecotoxicity, marine ecotoxicity, terrestrial acidification, and particulate matter formation. This study shows that the reduction in environmental impacts without changes in the production process technology is feasible through implementing bioenergy scenarios.ConclusionsHaving applied successfully EELCA, this study shows that PO production in the present configuration is not sustainable at all. The statistically discernible scenarios regarding energy mix selection help to enhance sustainability of the PO production process. Moreover, by examining the application of CExD along with LCA analysis, it is proved that by using the concept of CExD, we were able to represent the environmental impacts of the entire system with one figure, which tremendously facilitates the calculations in MCS.

The environmental burdens of the ethylene oxide production processes are becoming more and more important due to the release of very harmful chemical components as well as its high-energy demand. One way to moderate its environmental burdens within the energy transition period is the natural gas/biomass-based scenarios. However, this Life Cycle Assessment (LCA) study reports that natural gas is not a right alternative for this special case, where natural gas-based scenarios are less sustainable than the residual fuel oil-based scenarios particularly concerning fossil depletion (93%), freshwater ecotoxicity (76%), marine ecotoxicity (59%), human ecotoxicity (53%), terrestrial acidification (51%) and particulate matter formation (40%). On the other hand, the LCA study shows that without revamping the heart of the process technology, the reduction in the environmental burdens is possible through biomass. The biomass-based scenarios reduce the burdens from 4.40 to 4.36 MJ (equivalent of non-renewables) according to Cumulative Exergy Demand or from 2.18E−04 to 1.85E−04 (dimensionless normalized results) in accordance with ReCiPe, preparing the way to a sustainable ethylene oxide process within the energy transition period where revamping the heart of the process technology is not desired.Graphic abstract

Photodegradation is a key process impacting the lifetime of oxalate in the atmosphere, but few studies investigated this process in the field due to the complex mixing and sources of oxalate. Oxalate-containing particles were measured via single-particle aerosol mass spectrometry at coastal and suburban sites in Qingdao, a coastal city in North China in the summer of 2016. The mixing state and influence of different ambient conditions on the source and photodegradation of oxalate were investigated. Generally, 6.3% and 12.3% of the total particles (by number) contained oxalate at coastal and suburban sites, respectively. Twelve major types of oxalate-containing particles were identified, and they were classified into three groups. Biomass burning (BB)-related oxalate–K and oxalate–carbonaceous particles were the dominant groups, respectively, accounting for 68.9% and 13.6% at the coastal site and 72.0% and 16.8% at the suburban site. Oxalate–Heavy metals (HM)-related particles represented 14.6% and 9.3% of the oxalate particles at coastal and suburban sites, respectively, which were mainly from industrial emissions (Cu-rich, Fe-rich, Pb-rich), BB (Zn-rich), and residual fuel oil combustion (V-rich). The peak area of oxalate at the coastal site decreased immediately after sunrise, while it increased during the daytime at the suburban site. However, the oxalate peak area of Fe-rich particles at both sites decreased after sunrise, indicating that iron plays an important role in oxalate degradation in both environments. The decay rates (k) of Fe-rich and BB-Fe particles at the coastal site (−0.978 and −0.859 h−1, respectively), were greater than those at the suburban site (−0.512 and −0.178 h−1, respectively), owing to the high-water content of particles and fewer oxalate precursors. The estimated k values of oxalate peak area for different ambient conditions were in the same order of magnitude, which can help establish or validate the future atmospheric models.