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The efficiency of spark ignition (SI) engines is usually limited by the occurrence of knock, which is linked to fuel octane number. If running the engine at its optimal efficiency requires a high octane number at high load, a lower octane number can be used at low load. Saudi Aramco, along with its long-term partner IFP Energies nouvelles, has been developing a synergistic fuel engine system where the engine is fed by fuel with an octane number adjusted in real time, on an as needed basis, while running at its optimal efficiency. Two major steps are identified to develop this “Octane on Demand” (OOD) concept: • First, characterize the octane requirement needed to run the engine at its optimal efficiency over the entire map. • Then, select the best dual fuel combination, including a base fuel and an octane booster to fit this concept. For this purpose, the behavior of different octane boosters, including ethanol, reformate and a blend of butanol isomers (SuperButol™), are studied on a CFR engine when blended with a very low RON naphtha-based fuel (RON 71). It is shown that the fuel combination [naphtha; ethanol] offers the most promising boosting effect. Dedicated tests on an up-to-date gasoline direct injection multicylinder engine reveal the opportunity to use a naphtha-based fuel of RON 71 over a significant area of the engine map. The advantage of using ethanol as an octane booster is then clearly demonstrated, linked both to its very high RON and its high latent heat of vaporization and favorable sensitivity. Finally, around two-thirds of the engine map can be run using a moderate ethanol rate within the range 0% to 40%, making this OOD concept compatible within the E10-E20 context. Finally, deeper analyses are also made to correlate the engine octane requirement with RON, MON, Octane Index, and heat of vaporization.

Heterogeneous photocatalysis is highlighted to treat volatile organic compound (VOC) emission. Then, this work analysed the influence of palladium (Pd) content loaded in TiO 2 on n-octane and iso-octane photodegradation. For this, TiO 2 was loaded with Pd in different contents: 0.4%, 0.7%, and 1.0%. The samples were characterized, and the photodegradation experiments were conducted by Pd/TiO 2 /UV process. The characterization analyses showed that the metal presence did not change the catalyst structure or its surface area; however, it reduced the bandgap energy. The photocatalytic results proved that palladium improved n-octane degradation from 62% (pure TiO 2 ) to 92.6% (0.4%Pd/TiO 2 ) and, iso-octane degradation enhanced from 59% (pure TiO 2 ) to 90.6% (0.7%Pd/TiO 2 ); all results were obtained in the space time of 39 s. Therefore, 0.4%Pd/TiO 2 and 0.7%Pd/TiO 2 showed better oxidation results to degradation n-octane and iso-octane, respectively. The kinetic model of pseudo-first order showed a good fit for the data of both VOCs. Heterogeneous photocatalysis with Pd/TiO 2 showed to be an adequate technique to reduce VOCs emission.

Renewable fuel additives were selected as a solution to address the depletion of petroleum fossil fuels and associated environmental issues. Sweet orange peel oil (SOP) has a strong potential to be used as a fuel additive due to its unique characteristics resembling fuel oil. SOP contains 92.06% of limonene which has octane hyper-boosting characteristics. Limonene can enhance the research octane number (RON) beyond the octane rating of the primary fuel. This study aimed to understand the reported octane hyper-boosting effect of limonene by measuring RON and exhaust emissions through SI engines. Limonene was added to n-heptane as a representative of a low octane hydrocarbon in eight distinct volumetric concentrations (1-80%). The engine was tested at three different engine speeds (2000, 2500, and 3000 rpm). The RON test showed that limonene increased the RON of n-heptane from 0 to 91.5 (exceeding the original RON of limonene). The presence of limonene increased the bond stability of the fuel blends, thus preventing detonation. Furthermore, the exhaust emission test confirmed that carbon monoxide (CO) and unburnt hydrocarbon (HC) emissions decreased across all fuel formulations and engine speeds. Limonene has a high sensitivity that can inhibit the reaction of n-heptane and stimulate complete combustion. However, the rise in NOx is detected with an increase in the limonene concentration in the fuel blends, but the value is still below the minimum requirements. Overall, experimental investigation demonstrated that limonene is an effective alternative octane booster to reduce exhaust gas emissions.

In this contribution, we study situations in which nanoparticles in a fluid are strongly heated, generating high heat fluxes. This situation is relevant to experiments in which a fluid is locally heated by using selective absorption of radiation by solid particles. We first study this situation for different types of molecular interactions, using models for gold particles suspended in octane and in water. As already reported in experiments, very high heat fluxes and temperature elevations (leading eventually to particle destruction) can be observed in such situations. We show that a very simple modeling based on Lennard-Jones (LJ) interactions captures the essential features of such experiments and that the results for various liquids can be mapped onto the LJ case, provided a physically justified (corresponding state) choice of parameters is made. Physically, the possibility of sustaining very high heat fluxes is related to the strong curvature of the interface that inhibits the formation of an insulating vapor film.

Covalent organic frameworks (COFs) have emerged as a kind of crystalline polymeric materials with high compositional and geometric tunability. Most COFs are currently designed and synthesized as mesoporous (2–50 nm) and microporous (1–2 nm) materials, while the development of ultramicroporous (<1 nm) COFs remains a daunting challenge. Here, we develop a pore partition strategy into COF chemistry, which allows for the segmentation of a mesopore into multiple uniform ultramicroporous domains. The pore partition is implemented by inserting an additional rigid building block with suitable symmetries and dimensions into a prebuilt parent framework, leading to the partitioning of one mesopore into six ultramicropores. The resulting framework features a wedge-shaped pore with a diameter down to 6.5 Å, which constitutes the smallest pore among COFs. The wedgy and ultramicroporous one-dimensional channels enable the COF to be highly efficient for the separation of five hexane isomers based on the sieving effect. The obtained average research octane number (RON) values of those isomer blends reach up to 99, which is among the highest records for zeolites and other porous materials. Therefore, this strategy constitutes an important step in the pore functional exploitation of COFs to implement pre-designed compositions, components, and functions. The development of ultramicroporous covalent organic frameworks (COFs) remains a daunting challenge. Here, the authors report a pore partition strategy, which allows for the segmentation of mesopores of COFs into multiple uniform ultramicroporous domains.

Although considerable progress has been made in carbon dioxide (CO 2 ) hydrogenation to various C 1 chemicals, it is still a great challenge to synthesize value-added products with two or more carbons, such as gasoline, directly from CO 2 because of the extreme inertness of CO 2 and a high C–C coupling barrier. Here we present a bifunctional catalyst composed of reducible indium oxides (In 2 O 3 ) and zeolites that yields a high selectivity to gasoline-range hydrocarbons (78.6%) with a very low methane selectivity (1%). The oxygen vacancies on the In 2 O 3 surfaces activate CO 2 and hydrogen to form methanol, and C−C coupling subsequently occurs inside zeolite pores to produce gasoline-range hydrocarbons with a high octane number. The proximity of these two components plays a crucial role in suppressing the undesired reverse water gas shift reaction and giving a high selectivity for gasoline-range hydrocarbons. Moreover, the pellet catalyst exhibits a much better performance during an industry-relevant test, which suggests promising prospects for industrial applications. It is still a great challenge to synthesize value-added products with two or more carbons directly from CO 2 . Now, a bifunctional catalyst composed of reducible metal oxides (In 2 O 3 ) and zeolites (HZSM-5) is prepared and yields high selectivity to gasoline-range hydrocarbons (78.6%) with a high octane number directly from CO 2 hydrogenation.

Recent studies demonstrating an in situ formation of methane (CH₄) within foliage and separate observations that soil-derived CH₄ can be released from the stems of trees have continued the debate about the role of vegetation in CH₄ emissions to the atmosphere. Here, a study of the role of ultraviolet (UV) radiation in the formation of CH₄ and other trace gases from plant pectins in vitro and from leaves of tobacco (Nicotiana tabacum) in planta is reported. Plant pectins were investigated for CH₄ production under UV irradiation before and after de-methylesterification and with and without the singlet oxygen scavenger 1,4-diazabicyclo[2.2.2]octane (DABCO). Leaves of tobacco were also investigated under UV irradiation and following leaf infiltration with the singlet oxygen generator rose bengal or the bacterial pathogen Pseudomonas syringae. Results demonstrated production of CH₄, ethane and ethylene from pectins and from tobacco leaves following all treatments, that methyl-ester groups of pectin are a source of CH₄, and that reactive oxygen species (ROS) arising from environmental stresses have a potential role in mechanisms of CH₄ formation. Rates of CH₄ production were lower than those previously reported for intact plants in sunlight but the results clearly show that foliage can emit CH₄ under aerobic conditions.

Perfluoro octane sulfonate (PFOS) and cadmium (Cd) are toxic elements in the environment. As a micronutrient trace element, selenium (Se) can mitigate the adverse effects induced by PFOS and Cd. However, few studies have examined the correlation between Se, PFOS and Cd in fish. The present study focused on the antagonistic effects of Se on PFOS+Cd-induced accumulation in the liver of zebrafish. The fish was exposed to PFOS (0.08mg/L), Cd (1mg/L), PFOS+ Cd (0.08 mg/L PFOS+1 mg/L Cd), L-Se (0.07mg/L Sodium selenite +0.08mg/L PFOS+1mg/L Cd), M-Se (0.35mg/L Sodium selenite + 0.08mg/L PFOS+ 1 mg/L Cd), H-Se (1.75 mg/L Sodium selenite + 0.08 mg/L PFOS+ 1mg/L Cd) for 14d. The addition of selenium to fish exposed to PFOS and Cd has been found to have significant positive effects. Specifically, selenium treatments can alleviate the adverse effects of PFOS and Cd on fish growth, with a 23.10% improvement observed with the addition of T6 compared to T4. In addition, selenium can alleviate the negative effects of PFOS and Cd on antioxidant enzymes in zebrafish liver, thus reducing the liver toxicity caused by PFOS and Cd. Overall, the supplementation of selenium can reduce the health risks to fish and mitigate the injuries caused by PFOS and Cd in zebrafish.

Understanding the complementary roles of surface energy and roughness on natural nonwetting surfaces has led to the development of a number of biomimetic superhydrophobic surfaces, which exhibit apparent contact angles with water greater than 150 degrees and low contact angle hysteresis. However, superoleophobic surfaces--those that display contact angles greater than 150 degrees with organic liquids having appreciably lower surface tensions than that of water--are extremely rare. Calculations suggest that creating such a surface would require a surface energy lower than that of any known material. We show how a third factor, re-entrant surface curvature, in conjunction with chemical composition and roughened texture, can be used to design surfaces that display extreme resistance to wetting from a number of liquids with low surface tension, including alkanes such as decane and octane.

As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr 6 O 4 (OH) 4 (bptc) 3 adsorbs a large amount of n -hexane but excluding branched isomers. The n -hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr 6 O 4 (OH) 8 (H 2 O) 4 (abtc) 2 , is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds. The separation of C6 alkane isomers is crucial to the petroleum refining industry, but the distillation methods in place are energy intensive. Here, the authors design a series of topologically-guided zirconium-based metal-organic frameworks with optimized pore structures for efficient C6 alkane isomer separations.