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• The thermal reaction of residue and SARA fractions at 250–400 °C was studied. • Resins and asphaltenes produced coke at 250 °C with no coke induction period. • Asphaltenes are the sole fraction that generated reactive radicals at 250 °C. • Coking at high temperature is strongly correlated with the radical evolution. • Maltenes could suppress asphaltenes coking, serving as the immunity system. In this study, the coking propensity and reactive radical evolution of heavy residue and SARA fractions at 250–400 °C were studied to gain an insight into the coke induction process. The interactions among fractions for thermal coking were discussed. Results showed that residue started to form coke (i.e. toluene-insoluble at room temperature) at 350 °C for longer times while resins and asphaltenes have already extensively produced coke at 250 °C with no coke induction period. This indicates that the coke induction depends on the solubility gap of reactant and coke. The coking process can be fitted with the second-order and autocatalytic kinetics for residue while second-order kinetics for heavy fractions with initial coke precursor amount varying with temperature. Asphaltenes are the sole fraction that generated reactive radicals at 250 °C and responsible for the radicals of thermal residue. The explosion of reactive radicals began when the temperature exceeded 350 °C and became steady as the thermal reaction proceeded. The coke at low temperatures mainly originated from the molecules aggregation with faint radical emergence while that at high temperatures is strongly correlated with the radical evolution. The maltene subfractions could suppress the coking of asphaltenes possibly because of the physical solvation and chemical hydrogen donating behavior to cap reactive radicals. It can serve as the intrinsic immunity for coke inhibition of heavy residue during thermal partial upgrading. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-stage pre-treatment method for food waste (FW) adapted to incineration was proposed, and resources were recovered along with energy. • The freshwater in FW was recovered by a freeze-drying process and its availability was detected and proven. • The negative effect of the presence of lipids on the fuel properties evolution of torrefaction products was investigated. • The fuel properties and combustion performance of coal-like torrefaction products from FW were well evaluated. As of 2020, the annual generation of municipal solid waste (MSW) in China has surged to 235.12 Mt, and food waste (FW) accounts for more than 60 %. The most common treatment method is incineration, which accounts for 62.13 %. This research proposes a three-stage pretreatment method for FW that is suitable for incineration while recovering by-products and energy from the pretreatment process. The first stage is dehydration; as compared to hot air drying (HAD) processes, freeze drying (FD) exhibits a higher dehydration and oil preservation rate, allowing for the preservation of organic matter content and the recovery of freshwater resources from FW. The second stage is oil recovery; the FW extracted oil (FWEO) can be used to produce biodiesel, and this stage also helps to improve the effectiveness of the subsequent torrefaction process. The third stage improves the energy and fuel characteristics of the organic residue of FW and enhances the combustion performance by optimizing the torrefaction temperature. The solid fuel obtained at a torrefaction temperature of 350 °C shows the best combustion performance, with a solid yield of 35.76 %, a torrefaction temperature of 300 °C might be chosen to further improve the solid yield. [ABSTRACT FROM AUTHOR]

Rigid polyurethane, a common insulation material, is difficult to degrade naturally and poses significant health and environmental risk. Consequently, the cost-effective and efficient reuse of these solid wastes is a great challenge. Herein, we report an in-situ construction of hexadecyltrimethoxysilane (HDTMS) hydrophobic films on rigid polyurethane waste particle (RPUWP) as an accumulated packing layer in the gas-liquid pre-separator for gas pre-dehydration. The RPUWP grafted with HDTMS (P-HDTMS) packing layer exhibits excellent hydrophobicity in the air, acid (pH = 1), alkali (pH = 14), and high-temperature (over 95 ℃) resistance. Also, the gas pre-dehydration performance of the accumulated P-HDTMS packing layer in the gas-liquid pre-separator was evaluated by the water dew point depression (ΔT d). It is worth mentioning that the accumulated packing layer can stabilize and greatly reduce the ΔT d by 17.8 ℃ in over 48-hour uninterrupted operation through the coalescence separation mechanism. Therefore, the low-cost accumulated P-HDTMS packing layer is expected to be an ideal candidate material for gas pre-dehydration in large-scale practical applications. This work not only provides a novel method for the resource utilization of plastic solid wastes but also provides a hitherto unexplored perspective for gas dehydration in industrial production. [Display omitted] • A waste-to-resource strategy of rigid polyurethane solid waste is introduced. • The mechanism of two steps in-situ grafting process is proposed. • The stacked P-HDTMS packing layer exhibits remarkable gas pre-dehydration performance. • The mechanism of gas-liquid coalescence separation is revealed. • The as-prepared material can withstand strong acid/alkali and high-temperature solutions. [ABSTRACT FROM AUTHOR]

The large-scale development of metal-loaded adsorbents is restricted due to complicated preparation methods, poor dispersion of metal particles, and small specific surface area. Pistia stratiotes (PS) has a unique biological vein structure; it can adsorb and fix nickel evenly in its organism. The prepared high-performance desulfurization adsorbent PSAC-Ni(X) and loaded Ni nanoparticles are more uniform and smaller in diameter. However, in the control experiment, the dispersion and diameter of Ni particles of PSLAC@Ni prepared by the impregnation method were all lesser than that of PSAC-Ni(X). PSLAC@Ni had an adsorption desulfurization capacity of only 53 mg g−1. PS was cultured in four different Ni concentration solutions since the Ni concentration gradually decreases with the absorption of Ni by PS. Then the leaves and roots of the corresponding plants were prepared into leaf-based adsorbents and root-based adsorbents, respectively. The adsorption desulfurization test showed that the adsorption desulfurization capacity of the leaf-based adsorbent and the root-based adsorbent of the plants cultivated in the four kinds of Ni concentration solutions were 113, 108, 111, and 111 mg g−1. This demonstrates that the desulfurization capacity of the adsorbent prepared by this method does not change significantly with varying Ni content in the solution. This method not only produces high-performance desulfurization adsorbent from PS, but it also degrades heavy metals in water, playing a double role in the development of a green and friendly environment. [Display omitted] • The PSAC-Ni(X) prepared by the phytoremediation method had excellent physical structure. • The decrease of Ni content in water did not affect the adsorptive desulfurization capacity of PSAC-Ni(X). • The adsorption capacity of PSAC-Ni(X) for DBT was up to 113 mg g−1. • This research integrates the degradation of heavy metals in water with the preparation of desulfurization adsorbents. [ABSTRACT FROM AUTHOR]

Carbon microspheres were synthesized using itaconic acid fermentation waste liquid as the raw material by the hydrothermal method. The sequential porous adsorbent was prepared (by chemical activation) using carbon microspheres as a carbonaceous framework. The adsorbent was characterized by SEM, BET, Raman, XRD, XPS, and elemental analysis. Also, the adsorption performance of the adsorbent was tested using the batch adsorption method. The effects of several parameters such as pH, adsorbent dose, and concentration of Cr(VI) on the sorption of Cr(VI) were investigated. The results indicate that an outstanding adsorbent with a specific surface area of 1802.16 m2 g−1 and a maximum adsorption capacity for Cr(VI) of 270.14 mg g−1 has been acquired. According to the adsorption isotherm model, the kinetic model, and the intra-particle diffusion model, it was found that the adsorption process of Cr(VI) by the adsorbent conforms to the Freundlich model and the quasi-second-order kinetic model. The evaluation of the thermodynamic parameters (ΔH > 0, ΔS > 0, and ΔG < 0) revealed that the adsorption process was endothermic and spontaneous. The mechanistic studies showed that the adsorption of Cr(VI) likely involved electrostatic attraction and a redox reaction. After 5 cycles of repeated usage, the adsorbent maintains good adsorption stability to Cr(VI), favoring its practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • The olefin distributions of thermally cracked products derived from VR was investigated. • The effect of olefinic-bond-containing aromatics (OAH) on coke formation was revealed. • Evolution characteristics of OAH during thermal reaction was studied. • OAHs can form larger molecules via non-free radical reaction. The distributions of olefinic-bond-containing aromatic hydrocarbon (OAH) and the effect of OAH on coke formation during heavy oil thermal cracking have been rarely studied in the past. Here, the information of olefins in thermally cracked products derived from vacuum residue (VR) was investigated first, and then the effect of OAH on coke formation was elaborated by revealing the evolution characteristics of self/co-addition systems participated by representative OAH model compounds. The results found that OAHs were generated during VR thermal cracking, and they could participate in further reactions to promote coke formation. During thermal reaction, OAHs were more reactive for addition reactions than alkenes, and the reactivity of OAH increased roughly with the number of aromatic rings. Meanwhile, the higher concentration of OAH or the longer thermal reaction time or the higher thermal reaction temperature, the higher conversion of addition products, and the greater condensation degree of reaction products. OAHs participating in the larger structure molecule formation involves free radical addition reactions, which could occur between different OAHs as well as between OAHs and conventional aromatic molecules. More importantly, OAHs could form larger structure molecules by direct addition reaction of unsaturated double bond via non-free radical addition reaction, thus promoting fast coke formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • V, Ni, and Fe in wastewater were decontaminated and crystallized into nanoparticles. • The formed V 2 O 3 , NiO, and Fe 3 O 4 could catalyze both WGSR and PAHs hydrogenation. • The WGSR was coupled into PAHs hydrogenation by providing in-situ H 2. • Metals in wastewater and PAHs in fuel could be reduced simultaneously. The developing chemical demetallization technologies of petroleum emit thousands of tons of V, Ni, and Fe into water bodies annually for just one oil refinery. For this reason, a metal-containing wastewater (MCW) treatment and reutilization technique is highly demanded to be integrated into petroleum processing. This work introduced an in-situ decontamination of V, Ni, and Fe-containing wastewater from oil refineries into catalytically active particles for polycyclic aromatic hydrocarbons (PAHs) disposal. The water–gas shift reaction (WGSR) was coupled into the reaction system by providing the in-situ H 2. In one step, 98.7 wt% of soluble metal ions were precipitated into metal oxides, and 89.6 wt% of anthracene was hydrogenated. It took only 1 h for V, Ni, and Fe ions to crystallize into nanoparticles of V 2 O 3 , NiO, and Fe 3 O 4 , which could promote both the PAHs hydrogenation and the WGSR. The hydrogenation efficiency via in-situ H 2 was 48.7 % higher than that via ex-situ H 2. With the increase of PAHs aromatic ring number, the PAHs hydrogenation via in-situ H 2 was enhanced. Therefore, this method could simultaneously effectuate the separation of heavy me tals from MCW and the disposal of noxious PAHs in fuel oils. [ABSTRACT FROM AUTHOR]

FCC decant oil was always used as the raw material for the preparation of high-value-added carbonaceous materials. There is little disagreement that the free radical mechanism induces thermal polymerization reactions between reactant molecules and intermediate species, which leads to the formation of carbonaceous mesophase in the early stage of carbonization. Olefinic hydrocarbons were recently found to be widely distributed in FCC decant oil in our previous research, and these chemically active compounds usually possess weak π-bonds in molecules and thus potentially form free radicals easily, which may impact the carbonization performance dramatically. This research investigated the effects of olefinic compounds on the preparation of needle coke from FCC decant oil, as well as the corresponding mechanism in depth combined with the evolution pattern of the intermediate species during liquid carbonization. ESR analyses were adopted to evaluate the variation of the concentration of stable free radicals. Stable free radical concentration varied greatly in diverse polymerizing systems along with the carbonization process. Olefin showed a significant effect on the stable free radical concentration during carbonization. The stable free radical concentration of the polymerizing system derived from FCC decant oil was 3.32 × 1020 spins/g when the reaction time was 4 h. But with 3 wt% addition of 2-vinylnaphthalene and squalene in FCC decant oil, the stable free radical concentration increased to 2.14 × 1021 spins/g and 1.33 × 1021 spins/g, respectively, with the same reaction time. Meanwhile, the olefins conjugated with aromatic rings shown more obvious effect on the generation of free radicals. Olefinic compounds can lead to a high generation rate of free radicals and significantly high stable free radical concentration in the polymerizing system which then promote the formation of disordered carbon materials. Besides, plenty of fine particles appeared between mesophase spheres with the addition of olefinic hydrocarbons, and then impeded the coalescence between mesophase spheres. Effect mechanism for olefin on the development of carbonaceous mesophase was proposed accordingly. In sum, the content of olefinic compounds in raw materials should be limited for reaching the requirements of the synthesis of carbon materials with superior structures, in which the content of olefinic compounds should be less than 1 wt% at least based on the research in this paper. [Display omitted] • Concentration of stable free radical varies greatly along with carbonization. • Effect of olefin on the free radical concentration is revealed for the first time. • Olefin shows great impacts on the intermediate species during carbonization. • Influence mechanism of olefin on carbonization process is proposed. • Olefin content in feedstock should be limited for high-value-added utilization. [ABSTRACT FROM AUTHOR]

More efficient treatments of FCC decant oil (FDO) were developed to convert this common by-product in refineries to high-value-added carbonaceous materials, such as needle coke. The performance of the produced needle coke was determined by the properties of raw materials and the carbonization process based on the theories of carbonaceous mesophase. The preparation of needle coke can generally be divided into two stages before calcination and graphitization: liquid carbonization and solidification stage. Pressure in both stages, especially the pressure in the solidification stage, showed great effects on the properties of the products. The microstructure of semi-coke can hardly be the preferred needle structure with carbonization without decompressing operation, although the raw material satisfies the preparation requirement of needle coke. A new method for evaluating the order degree of microstructure (ODM) of semi-cokes was developed, enabling semi-cokes with preferable axial orientation to be further efficiently distinguished. The ODM value can also be used as an index to evaluate whether a semi-coke can be used as a precursor for further preparation of high-quality needle coke. The evolution of product gases can provide external force to the orientation of mesophase into the preferred needle structure in the product. This improvement can be achieved through decompressing operations in the second stage of carbonization and optimized when the pressure is at 0.5 MPa. [Display omitted] • Decompressing carbonization was implemented to the needle coke preparation. • A new evaluation index to distinguish the high quality semi-coke was developed. • Semi-coke with superior needle structure was obtained by decompressing carbonization. [ABSTRACT FROM AUTHOR]

In response to the enormous market demand for high-value-added carbonaceous materials and the urgent requirement of energy conservation and emission reduction, FCC slurry oil (SO) has drawn widespread attention in the preparation of these kinds of carbonaceous materials due to its abundant aromatic hydrocarbon contents. Distillation can be utilized as a pretreatment to efficiently remove the quinoline insoluble and other undesirable components in SO before carbonization. However, the distillate depth and yield are greatly restricted by the conspicuous coking phenomenon during thermal effect in the distillation. Mild hydrogenation coupled with distillation were adopted as the pretreatments before carbonization and effects of the hydrogenation on the distillation process were studied. Besides, transform patterns for the properties of sub-fractions in specimen before and after hydrogenation and resulted variations in carbonization performances were then systematically analyzed. Through hydrogenation, the distillation depth of hydrotreated SO (HSO) could be greatly improved to 530 °C with no significant coking phenomenon and the distillation yield was increased dramatically (from 38.4 wt% to 68.1 wt%). Especially, partial super high-boiling (above 530 °C) components in SO could be transformed into naphthenoaromatic structures by hydrogenation and acquired through distillation for further utilizations. Using anthracene as chemical probe, the hydrogen-donating abilities (HDAs) of specimens were detected, and results indicated the amounts of transferable hydrogen in HSO low-boiling and high-boiling sub-fractions were greatly increased compared with that of SO, which would provide the specimen with stronger stability in the thermal treatment and restrain the rapid coking. The carbonization performance varied with the properties of sub-fractions and a section of high-boiling components in SO was discovered to be exploitable through hydrogenation and demonstrated to be beneficial in the preparation of needle coke. [Display omitted] • Efficient pretreatment of slurry oil for preparing carbon material was developed. • Effects of hydrogenation on distillation/properties were studied. • Carbonization performances before/after hydrogenation were analyzed. • High-boiling and super high-boiling components were obtained for carbonization. • Hydrotreated distillates may lead to higher or lower carbonization yields. [ABSTRACT FROM AUTHOR]

[Display omitted] • The occurrence of olefinic bonds in asphaltenes derived from VR during thermal cracking was revealed. • The effect of different cracking conditions on the nature of olefinic-bond-containing asphaltenes was discussed. • The hypothetical average molecular structure of olefinic-bond-containing asphaltenes was constructed. In this study, the occurrence of olefinic bonds in asphaltenes separated from vacuum residue (VR) during thermal cracking was explored. Also, the effect of various thermal cracking conditions on the nature of olefinic bonds was discussed. The results showed that olefinic bonds were formed in asphaltenes during VR thermal cracking. The olefinic structure of asphaltenes detected by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy was mainly in the type of R–CH = CH–R′. An in-depth investigation revealed that increasing the severity of thermal cracking promoted the formation of more olefinic-bond-containing asphaltenes; the percentage of olefinic hydrogen in asphaltenes peaked at cracking under 420 °C for 40 min, was 2.7%. Meanwhile, the olefinic-bond-containing asphaltenes of high concentration consequently became precursors for the formation of coke by increasing the instability of the liquid system. Consequently, further prolongation of the cracking time led to a drastic decline of olefins content accompanying a sharp leap of coke yield. Finally, the hypothetical average molecular structures of the olefinic-bond-containing asphaltenes during VR thermal cracking were proposed based on the modified Brown-Ladner empirical formulas with improvement. They serve as intuitive insights into the existing olefinic bonds in asphaltenes. [ABSTRACT FROM AUTHOR]

• The relationship between olefins and the coalescence of mesophase spheres was investigated. • During thermal polycondensation, the olefins contents of residual oil, HS and HI-TS decreased while that of TI increased. • The involvement of olefins caused sharp increase of the system viscosity. • The involvement of olefins caused the deformation of mesophase spheres. • Catalytic hydrotreatment can shield the deformation of mesophase spheres. Mesophase carbon microbeads (MCMBs) were synthesized by thermal polycondensation with fluidized catalytic cracking residue oil (FRO) as the feedstock. The evolution features of functional groups of the residual oils and the residual solid products from thermal polymerization were analyzed, and the effect of olefinic compounds on the coalescence between mesophase spheres was investigated in depth. The results showed that the olefin contents of residual oil, heptane-soluble, and heptane-insoluble/toluene-soluble decreased simultaneously as the reaction proceeded while that of toluene-insoluble increased, indicating that the olefins in the solvent phase could not only provide molecule sources for the development of carbonaceous mesophase but also directly assemble into the insoluble mesogens. More importantly, the involvement of olefins caused a sharp increase of the system viscosity, making it difficult for the mesophase spheres to completely coalesce into regular large ones after cohering, leading to the apparent deformation. In contrast, catalytic hydrotreatment can saturate olefinic species and enhance the hydrogen transfer ability of FRO to further avoid the induction effect of olefins, slow down the mesophase development, reduce the system viscosity, and consequently avoid the deformation of mesophase spheres. [ABSTRACT FROM AUTHOR]

• Sequential pretreatments were developed for the high-value utilization of slurry oil. • Comprehensive properties of feedstock were improved for the need of carbon materials. • Carbon materials, possessing better performance for application, were synthesized. FCC slurry oil (SO) is an important and yield-rich by-product of the FCC process, which can be regarded as the raw material of high-value-added carbonaceous products due to its abundant concentration of aromatic components, but essential pretreatments and purifications for SO are required before carbonization to eliminate the adverse factors. Appropriate sequential pretreatments aimed at achieving the high-value utilization of SO have been developed, and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR, 13C NMR) were implemented for the systematical properties analyses of SO and its derivatives after sequential pretreatments. Polarized-light microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to evaluate the microstructures and microcrystal parameters of intermediate species and final products during carbonization. Through the varying degrees of sequential pretreatments, the comprehensive properties of feedstocks were improved gradually which further led to the diverse development of carbonaceous mesophase at the early stage of carbonization. Furthermore, ordinary or superior needle coke can be synthesized from the obtained oil samples during sequential pretreatments. The synthesized needle coke had suitable performance for the application in anode material of lithium-ion batteries. [ABSTRACT FROM AUTHOR]