Fuel Processing Technology最新文献

In this study, hydrothermal conversion of passion fruit husk powder (PFHP) into levulinic acid (LA) was achieved using SO₃H-functionalized ionic liquids (ILs) as catalyst. The investigation focused on the impact of IL types and reaction conditions (temperature, time, water quantity and catalyst loading) on LA yield. Among the selected ILs, [C₄SO₃Hmim][HSO₄] exhibited the highest LA yield at 66.6%, achieved under specific conditions: 4 h of reaction time, 180 °C temperature, 0.2 g of PFHP, 1.5 g of IL, and 6.0 g of deionized water. Remarkably, [C₄SO₃Hmim][HSO₄] displayed consistent stability and catalytic efficiency throughout four recycling cycles. Comprehensive analyses, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), were conducted on the solid residues of passion fruit husk obtained at different reaction times. These analyses revealed significant alterations in surface morphology, functional groups, and crystallinity index of the solid residues with prolonged reaction times. Notably, hemicellulose and lignin removal occurred within the first 0.5–1 h of the reaction, leading to the formation of by-products after 3 h. This one-pot process for LA production from agricultural waste showcases a promising avenue for converting sustainable biomass resources into valuable chemicals, emphasizing the potential for future biomass utilization.

The boom of the biodiesel industry has led to an oversupply of by-product glycerol as a direct consequence, which has been detrimental to its market value. The chemical reactivity that this compound possesses makes it an exceptional building block from which many synthetic routes can originate. In the past two decades, as a way to upgrade glycerol, there have been great developments in experimental approaches to obtain different products with applications as fuel additives, green solvents or precursors to other materials. These works have focused mainly on the development of catalytic and biotechnological processes and optimization of operation conditions to obtain chemicals like glycerol carbonate, acetals, esters, ethers, 1,2- and 1,3-propanediol, acrolein, halogenated products and different organic acids. Throughout these years an increasing amount of articles have reported thermodynamic information and kinetic models for different reactions using glycerol of substrate, whose knowledge is essential for subsequent reactor and process design. For the first time, these aspects for transformation reactions from glycerol are compiled and presented in a systematic way in this comprehensive review that also touches on process intensification strategies to enhance glycerol conversion.

The effects of ammonia and hydrogen addition on soot formation characteristics in n-decane laminar diffusion flames were studied. The addition of argon was specifically considered to identify the chemical effect of ammonia. The flame temperature, particle morphology, and oxidation characteristics were analyzed. Results showed that both ammonia and hydrogen addition increase the flame height and suppress soot formation, while the suppression effect of ammonia is more pronounced. The addition of argon or ammonia reduces the temperature of flame upstream and yields the similar flame temperature, while hydrogen addition increases the flame temperature. Compared to the flame with argon, the addition of ammonia delays particle nucleation, indicating that the soot nucleation and growth process are chemically inhibited. In contrast, doping hydrogen leads to an earlier nucleation process and aggregation phenomenon. Further analysis on particle nanostructure indicated that the addition of ammonia yields shorter lattice fringes, larger interlayer spacings and amorphous carbon contents, demonstrating a looser and higher disorder internal structure. The addition of hydrogen yields longer fringes and smaller interlayer spacings, showing the particles have a more compact internal structure and higher degree of graphitization. This indicates hydrogen addition reduces the oxidation activity of the particles, which is confirmed by thermogravimetric analysis.

Pyrolysis is a promising way to treat the waste tires for high value carbon black production. However, the carbon black formation mechanism is still unclear due to the complex decomposition and polymerization reactions during the pyrolysis of tire components. In this study, the production behavior, characters, and mechanism of carbon black from pyrolysis of natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) were investigated. The yield of carbon black was increased from 20.8%–24.4% to 47.9%–56.7% with the increase of pyrolysis temperature from 1100 to 1300°C. Although the carbon black production yield from NR was lower than that of BR and SBR at 1300°C, the graphitization degree (I_D/I_G = 2.22), microcrystal length (3.17 nm) and mean particle diameter (90.3 nm) of the carbon black derived from NR were the highest. The volatile evolution, carbon black nucleation mechanisms were revealed by reactive force-field molecular dynamics simulations. The pyrolysis of BR and SBR generated more C₂H₂, C₂H₃⋅, long carbon-chains and cyclic molecules than NR, which probably resulted in a higher carbon black yield than NR. With few defect borders, regular stacking and wrapping of the aromatic layers, the carbon black from NR exhibited more ordered nucleation and high graphitization degree.

In liquid discharging furnace, crystallization can occur in slags during the cooling process. The presence of crystal changes the structure, flow, heat transfer, especially the viscosity with a sharp increase. A deep understanding of the crystal kinetics is significant to optimize the flow of liquid slag. Crystal kinetics varies significantly with different slags due to the complexity and variability of the multi components in slags. In this paper, a high-temperature microscopy with high-resolution is used to clearly observe the in situ precipitation of different crystals and the kinetic parameters of different crystals are analyzed. Microscopic structure analysis of both the melt and the precipitated crystal shows that the proportion of basic oxygen structure and the diffusion coefficient of the basic cation in the melt have a direct correlation with the growth of crystal. A structural parameter St of the melt is developed, which has a positive correlation with the crystal growth rate. This is a new discovery in bridging the gap between the melt and precipitated crystals and it provides a way to control the crystal growth during slag cooling.

Serious coking from the bio-oil polymerisation is a bottle-neck challenge for bio-oil thermal upgrading. Probing the mechanism of bio-oil coking is the first step to achieve high carbon conversion efficiency. In this study, in-situ electron paramagnetic resonance (EPR) spectroscopy was used to characterise the stable free radical generation during bio-oil pyrolysis at 250–350 °C with reaction time of 2–10 min, which identify the coking process of bio-oil. The liquid and solid products were characterised using gas chromatography-mass spectrometer (GC–MS), ultraviolet fluorescence (UV-F) and Raman spectroscopy. The results indicate that the coking of bio-oil in pyrolysis can be divided into three stages of varied characteristics. The coke formation precedes with an initial induction period that lasts for 2–8 min and shortens with increasing pyrolysis temperature. In the period, light components polymerise into heavy ones, including polycyclic aromatics as the essential coke precursors. After the induction period, significant amounts of stable free radicals are generated with coke formation, and the content increases from 0.2 to 1.6–7.8 μmol/g bio-oil in the early stage of coking. Meanwhile, the coke precursors, polycyclic aromatics, are rapidly depleted. Afterwards, in the late stage, the nascent coke gradually condenses and the stable free radical content increases slowly.

Liquefaction of lignocellulosic biomass through fast pyrolysis, to yield fast pyrolysis bio-oil (FPBO), is a technique that has been extensively researched in the quest for finding alternatives to fossil feedstocks to produce fuels, chemicals, etc. Properties such as high oxygen content, acidity, and poor storage stability greatly limit the direct use of this bio-oil. Furthermore, high coking tendencies make upgrading of the FPBO by hydrodeoxygenation in fixed-bed bed hydrotreaters challenging due to plugging and catalyst deactivation. This study investigates a novel two-step hydroprocessing concept; a continuous slurry-based process using a dispersed NiMo-catalyst, followed by a fixed bed process using a supported NiMo-catalyst. The oil product from the slurry-process, having a reduced oxygen content (15 wt%) compared to the FPBO and a comparatively low coking tendency (TGA residue of 1.4 wt%), was successfully processed in the downstream fixed bed process for 58 h without any noticeable decrease in catalyst activity, or increase in pressure drop. The overall process resulted in a 29 wt% yield of deoxygenated oil product (0.5 wt% oxygen) from FPBO with an overall carbon recovery of 68%.

In this study, the acid-base bifunctional magnetic ZrMg@Fe₃O₄ metallic oxide catalysts with remarkable structural properties were synthesized by the co-precipitation method for the catalytic transfer hydrogenation (CTH) of furfural (FF), ethyl levulinate (EL), and 5-methylfurfural (5-MF) to furfuryl alcohol (FFA), gamma-valerolactone (GVL), and 5-methyl-2-furanmethanol (5-MFA). Characterization results indicated that the ZrMg@Fe₃O₄ (7: 1:1) catalyst possesses a substantial pore volume, large specific surface area, and mesoporous properties, which play an important role in improving catalytic activity. The leaching experiment indicated that the catalyst was not prone to leaching, proving its structural stability. The yield of FFA, GVL, and 5-MFA could be as high as 92.50%, 95.00%, and 53.95% by optimization experiments. The Py-FTIR, CO₂-TPD, and poisoning experiments showed that Lewis acid-base sites significantly impact the catalytic activity. The catalyst can be readily isolated and retrieved from the liquid reaction mixture by applying the external magnetic field. The reaction mechanism and catalytic stability were also conducted by systematically studying the reaction experiments and physicochemical properties of the catalyst.

Reliable and stable ignition under lean conditions is essential for safe operation of the engine. Nanosecond pulsed discharge non-equilibrium plasma assisted ignition characteristics of premixed ethylene-air flow in an advective combustion chamber were investigated. The effects of the equivalence ratio, discharge gap distance, flow velocity, discharge frequency or inter-pulse time, and pulse number were quantified in terms of ignition probability. Shadow images of ignition kernel development were captured and used to extracted the averaged kernel projected area. The results indicated that increasing the equivalence ratio, a higher flow velocity, a wider discharge gap distance, and a larger number of pulses are all conducive to the increasing of ignition probability via inducing a larger initial kernel. Increasing inter-pulse time has a non-monotonic effect on ignition probability for multiple nanosecond pulsed discharges ignition. As the inter-pulse time decreases, when neighboring kernel boundaries happen to overlap each other, the partially-coupled regime shows a higher ignition probability. Longer or shorter inter-pulse time both cause the decrease in ignition probability. The shortest inter-pulse time shown as the fully-coupled regime is the most favorable for ignition with the highest ignition probability. A method is proposed to estimate the critical frequency at which partially-coupled regime transitions to fully-coupled regime by 95% of the asymptotic time of flame development time.

Sustainable production of jet fuel additives plays an essential role to decrease greenhouse gas emissions in the aviation industry. Acetone obtained from biomass fermentation is one of the platform molecules of the bio-refinery that can be used as raw material of newly developed sustainable processes. Mesitylene jet fuel additive can be obtained by acetone self-condensation reaction catalyzed by porous solids. In the present work, TiO₂ and Al-MCM-41 have been chosen, respectively, as basic and acid catalysts, because of having some tolerance to deactivation. The reaction was studied in a continuous fixed-bed reactor operated in the gas phase at space velocities of 7900 mol/kg h for TiO₂ and 5000 mol/kg h for Al-MCM-41. The influence of feed concentration (5–20% acetone and 0–5% mesityl oxide) and temperature (200–350 °C) was studied. First, the reaction scheme was assessed based on the product distribution. It was found that the acid catalyst Al-MCM-41 favors mesityl oxide decomposition to undesired isobutylene and acetic acid. Then, a mechanistic kinetic model of the different steps of the reaction scheme was developed and fitted the experimental results of each catalyst. This model constitutes a valuable tool for the scale-up of this process.