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In this paper, we report a kind of composite phase change materials (PCMs) fabricated by the vacuum impregnation method in which ER functions as the filter and graphite foams (GFs) serve as the supporting framework, which is fabricated from polyurethane (PU) foam. Polyvinyl alcohol (PVA) and multi-wall carbon nanotubes (MWCNTs) serve as modifiers. Compared with pure ER, the ER/GFs show an excellent performance improvement; the resulting supercooling degree was reduced by ∼59 °C and thermal conductivity was improved to 56.93 W m−1 K−1, more than 86-folds that of pure ER, resulting in a tremendous latent heat-releasing percentage enhancement of 77.09%. This demonstrates that such ER/GFs composites can be used for efficient solar-thermal energy conversion, and have a low supercooling degree, good leakage resistance, and high thermal conductivity, mitigating the severe issues of ER and presenting a new strategy for enhancing the solar energy storage performance. [Display omitted] • The MWCNTs modified GFs by the template method used in the solar-thermal conversion process. • The effects of MWCNTs modification with different mass fractions on the properties of GFs and ER/GFs were studied. • The template method was selected to prepare GFs to avoid the high-pressure foaming process traditionally. • The prepared ER/GF 0 has a high thermal conductivity of 56.93 W m−1 K−1. • The solar-thermal conversion and storage mechanism have been demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Needle coke was prepared by co-carbonization of ETR and DO. • Incompatibility and compatibility in the co-carbonization of blended feedstocks were revealed and analyzed. • Synergistic effects of co-carbonization feedstocks were explored in terms of feedstocks composition and carbonization behavior. • New blend feedstocks for high-quality needle coke with higher production than that from DO carbonization alone were developed from low cost heavy oils. In this study, ethylene tar (ET) and refined ethylene tar (ETR) were co-carbonized with fluid catalytic cracking decant oil (DO) to prepare needle coke. The compositions and functional group changes of the blended feedstocks were revealed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. Besides, the carbonization behavior of feedstocks was determined in terms of coke optical observation, carbonized gas composition, and escape rates. The morphology and performance of needle coke were evaluated by scanning electron microscopy and coefficient of thermal expansion. The results showed that the blending of DO to the feedstocks increases the H/C ratio and the content of alkyl and naphthenic structures, which improves the growth and development of the mesophase. However, the coke derived from co-carbonization of ET and DO exhibits a clear separation interface between different optical textures. Further investigation revealed that a large amount of asphaltenes in ET polymerized rapidly into mosaic texture, which hardens prematurely and cannot coalesce with the domain texture subsequently generated by DO. The compatibility of blending ETR and DO for co-carbonization improves significantly after ET is refined to remove asphaltenes. In addition, sufficient gas flow derived from DO promotes the optical microstructure of the resultant cokes by a transition from domain texture into acicular flow type. The synergistic effects between ETR and DO result in the actual CTE and yield of needle coke being lower than the theoretical ones. The CTE of NC-ETRDO50 is lowered to 1.62 × 10-6/°C, being almost the same as that of NC-DO, and the production growth of NC-ETRDO50 is even higher by 7.32% compared with that of NC-DO. Therefore, high-quality needle coke with high production was prepared from low-cost heavy oils. [ABSTRACT FROM AUTHOR]

Information on distribution of metals and metalloporphyrins can help to understand molecular interaction presented by metals and asphaltenes and possible participation of metals in aggregation of asphaltenes. Therefore, contents of metals and metalloporphyrins were determined in three asphaltene subfractions separated based on solubility. Compositions of the subfractions were confirmed by elemental analysis, vapor pressure osometry molecular weight, and1H NMR, and molecular structures were simulated. The correlation between distribution of metals and metalloporphyrins and molecular composition was discussed. It indicates that metals interacting loosely with asphaltenes tend to be preferentially extracted into lighter fractions and present as metalloporphyrins, while a great portion of metals concentrates into the heavier fraction and presents as metal-nonporphyrins apparently due to strong interaction with asphaltenes. This suggests that distribution of metals plays a key role in determining the polarity and solubility of subfractions, and thus affects aggregation of asphaltenes. [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 flexibility evaluation method framework of the WMCB power system is proposed. • The LOFP, LOFE, and FDS indices are introduced to measure the flexibility margin of the WMCB. • The appropriate capacity ratio of the wind-PV power to hydropower in the WMCB should be 1:1 ∼ 1.5:1. The widespread expansion of renewable energy, like wind and photovoltaic (PV), increases the importance of power system flexibility. Quantify the balance between the flexibility supply of hydropower and the flexibility demand of wind-PV power is the key to the planning and development of multi-energy complementary system. Based on the power system flexibility balance principle, a novel flexibility evaluation method is proposed for watershed-type wind-PV-hydro multi-energy complementary bases (WMCB) considering the complementary characteristics of cascade hydropower stations. First, the wind and PV power capacity ratio are determined by complementarity index, and the timing production simulation model are used to determine the wind-PV-hydro power output to calculate the flexible supply. And the flexibility demand is calculated by the combined bias distribution of the wind-PV power output states. Then, the flexibility margin distribution is calculated by the convolution difference, and loss of flexibility probability (LOFP), loss of flexibility expectation (LOFE), and flexibility demand shortage (FDS) indices are used to measure various aspects of the WMCB system flexibility margin. Finally, the relationship is established between the wind-PV power capacity and system flexibility margin indices, and the impact of wind-PV power capacity improvement on the system flexibility margin is analyzed. To verify the feasibility of the method, the WMCB of the downstream Yalong River basin is taken as a case study, and 21 wind-PV power capacity scenarios are set as the comparative schemes. The case study results indicate that the wind and PV power capacity rate should be 0.43:0.57. The suitable wind-PV power developing capacity of the WMCB should be 12.7 GW to 14.7 GW without other flexibility resources. And the developing development potential of wind-PV power capacity would reach about 22.0 GW with 1600 MW upward flexibility resources and 850 MW downward flexibility resources. This study provides a novel method framework for the flexibility analysis of the wind-PV-hydro power systems and provides a valuable reference for the planning and design of WMCBs. [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]

Highlights: [•] TPO has high sensitivity to variation in terms of carbon species and order. [•] Heat peaks representing different carbon species have been defined. [•] TPO is a convenient method to quantitatively study the morphology of coke. [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]

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]

• Study the spatiotemporal distribution structure of drought in the YRB. • There are different types of spatiotemporal distribution patterns in the YRB. • The interannual variation of drought has obvious spatial propagation characteristics. • There is a significant lagging correlation between the spatiotemporal distribution of drought and the Southern Oscillation. Drought disasters restrict economic and social development. Understanding the evolution of the spatiotemporal characteristics of drought plays a vital role in basin risk response and management. Complex empirical orthogonal function analysis is widely used in meteorological research and is an important tool for studying the spatial-temporal distribution structure of arid fields. This research aims to take the Yellow River Basin (YRB) as an example, separate the temporal and spatial distribution structure of drought based on the CEOF method, and explore the abrupt changes, trends, and periodic characteristics of different temporal and spatial distribution patterns. In addition, the cross-wavelet analysis reveals the lagging correlation relationship between the distribution pattern of the arid field in the basin and the Southern Oscillation factor. Results indicated that: (1) there are three typical spatial and temporal distribution patterns (full basin type, southeast-northwest reversed type and east-west reversed type) of the interannual scale drought in the YRB; (2) interannual drought evolution have obvious spatial propagation characteristics. (3) There are correlations between the three types and the Southern Oscillation on the temporal-frequency scale, and there is a time lag of 1-2a with the Southern Oscillation factor. [ABSTRACT FROM AUTHOR]

• China's drought risk, the severity and frequency have increased due to climate warming. • Droughts occurred year-round in China, but differed among years and regions. • Clarify the regional differences of drought disaster risk over the mainland of China. Drought is complex geographical elements, which endangers China's food security, with coexistence of spatial and temporal heterogeneity and similarity. Thus, the recent abnormal characteristics of Chinese droughts warrant further study. This paper proposes a three-step framework to identify the spatiotemporal evolution characteristics of drought events in China Mainland, using the standardized precipitation evapotranspiration index (SPEI) at different time scales (1, 6 and 12 months). And then the drought characteristics are separated using the run theory. Finally, the spatiotemporal evolution patterns of meteorological, agricultural and hydrological drought risk in distance are investigated based on the geographic statistics analysis method (i.e., global and local Moran's index). Results show that the drought trend is gradually increasing in some basins, especially the Yellow River Basin, the Hai River Basin and the Southwest River Basins. The multi-variate attributes of drought characteristics in spatiotemporal evolution patterns at different time scales have the characteristics of regularity and mutation, for example, the drought frequency in northwestern China shows a low values in a low value neighbourhood, but the drought duration and intensity shows a high values in a high value neighbourhood. This indicates that the hydrological drought disaster in the region is extremely prominent. In addition, the risk of drought in inland River basins is the highest, followed by the Hai River basin and the Yellow River basin; the Pearl River basin has the lowest. Our results offer insights into the development of drought in China and provide support for disaster risk assessment and response planning. [ABSTRACT FROM AUTHOR]

Efficient dehydrogenation of cycloalkanes under mild conditions is the key to large-scale application of cycloalkanes as a hydrogen storage medium. In this paper, a series of active metals loaded on nitrogen-doped carbon (M/CN, M = Pt, Pd, Ir, Rh, Au, Ru, Ag, Ni, Cu) were prepared to learn the role of active metals in cycloalkane dehydrogenation with cyclohexane as the model reactant. Only Pt/CN, Pd/CN, Rh/CN and Ir/CN can catalyze the dehydrogenation of cyclohexane under the set conditions. Among them, Pt/CN exhibited the best catalytic activity with the TOF value of 269.32 h−1 at 180 °C, followed by Pd/CN, Rh/CN and Ir/CN successively. More importantly, the difference of catalytic activity between these active metals diminishes with the increase in temperature. This implies that there is a thermodynamic effect of cyclohexane dehydrogenation with the synthetic catalysts, which was evidenced by the study on the activation energy. In addition, the effects of molecular structure on cycloalkane dehydrogenation catalyzed by Pt/CN were studied. The results reveal that cycloalkane dehydrogenation activity and hydrogen production rate can be enhanced by optimizing the type, quantity and position of alkyl substituents on cyclohexane. [ABSTRACT FROM AUTHOR]

Highlights: [•] The interaction upon the morphology and reactivity of coke has been studied. [•] The composition change of feeds has apparent influence upon the morphology. [ • ] Improving in coke quality could be fulfilled by proper selection of blending feeds. [ABSTRACT FROM AUTHOR]

Enthalpy of pyrolysis and its variation in the pyrolysis process of four heavy oils: Daqing vacuum residue (DQVR), Karamay vacuum residue (KRVR), Liaohe vacuum residue (LHVR), and Venezuela vacuum residue (VNVR), have been quantitatively studied by differential scanning calorimetry associated with thermogravimetry. The results indicate that overall enthalpies at different heating rates show a linear trend with respect to the final coke yields in the thermal analysis. Classical kinetic method (Friedman method) is used to further analyze pyrolysis enthalpy variation in the pyrolysis process and determine the thermokinetic parameters. The main stage of thermal reaction (conversion ranges from 0.1 to 0.9) could be described by 1.5 order reaction model for four heavy oils. The mean activation energies determined by Friedman method are 216.3, 194.9, 173.9, and 168.7 kJ mol for DQVR, KRVR, LHVR, and VNVR, respectively. It means that endothermic enthalpy of pyrolysis in the thermal process of VNVR is easier to change compared with other oil sample cases. For the sake of simplification of kinetic treatment, Sharp method is tentatively used to perform kinetic analysis. The comparison between results from two methods indicates that activation energies from Sharp method are valid to a certain degree under the condition that the mechanism of thermal process is properly chosen although isoconversional method (Friedman method) is recommended and thought to be the better way. [ABSTRACT FROM AUTHOR]

Abstract: The heat in heavy oil pyrolysis process is a quantity of interest in the design of thermal process equipments and the calculation of energy balance in refineries. Thus, enthalpy of reaction and enthalpy of vaporization in the pyrolysis of four heavy oils: DQVR (Daqing vacuum residue), KRVR (Karamay vacuum residue), LHVR (Liaohe vacuum residue) and VNVR (Venezuela vacuum residue), have been quantitatively studied by a combination of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), plus microreactor experiments. As sample became heavier, the temperature range of pyrolysis process increased from 172 to 200°C and enthalpies of reaction decreased, which were determined to be −1070, −570, −489 and −393J/g for DQVR, KRVR, LHVR and VNVR, respectively. The enthalpies of reaction at various conditions showed a linear trend with respect to the final coke yield in the thermal analysis. Enthalpies of vaporization in the thermal analysis process were calculated to be 188, 181, 161 and 128J/g, for DQVR, KRVR, LHVR and VNVR, respectively. The contribution of vaporization to the overall pyrolysis process varied between 0.12 and 0.19. A method to quantify the enthalpy of cracking and that of condensation was tentatively developed by using extrapolation. [Copyright &y& Elsevier]

As the two types of major impurities in FCC slurry oil (SLO), olefins and sulfur seriously deteriorate the preparation and quality of mesophase pitch or needle coke. The development of a hydrotreatment for SLO to remove olefins and sulfur selectively becomes imperative. This work presents the potentiality of dispersed Mo2C and MoS2 nanoparticles as selective hydrotreating catalysts of SLO. Mo2C was synthesized by the carbonization of citric acid, ammonium molybdate and KCl mixtures while MoS2 was prepared from the decomposition of precursors. These catalysts were characterized by XRD, HRTEM, XPS, BJH, BET, and applied to the hydrotreating of an SLO surrogate with defined components and real SLO. The conversion of olefins, dibenzothiophene and anthracene in the surrogate was detected by GC-MS. Elemental analysis, bromine number, diene value, 1H-NMR and spot test were used to characterize the changes of the real SLO. The results show that hydrotreating the SLO surrogate with a very small amount of Mo-based nanoparticles could selectively remove olefins and sulfur without the overhydrogenation of polyaromatics. Mo2C exhibited much better activity than MoS2, with 95% of olefins and dibenzothiophene in the surrogate removed while only 15% anthracene was hydrogenated. The stability of the real SLO was significantly improved. Its structural parameters changed subtly, proving the aromatic macromolecules had been preserved. [ABSTRACT FROM AUTHOR]

Two-stage hydrocracking of petroleum residue consisting of hydrogenation (at low temperature) and thermocracking (at high temperature) has been investigated. Compared with one-stage reaction, two-stage reaction seems to have the following advantages: lower coke formation, higher cracking and higher removal of heteroatoms. Anthracene had been regarded as the model compound of coke precursor. After two-stage hydrocracking, about 51% of anthracene was hydrogenated at a low temperature (416 °C), and about 10% of the hydrogenated compound (9,10-dihydroanthracene) released the activated hydrogen which could prevent the residue from coke formation and removed the heteroatoms (i.e. sulfur and nitrogen) at a high temperature (436 °C). Comparison of two kinds of reactions showed that the two-stage reaction was superior to the one-stage reaction. [Copyright &y& Elsevier]

• 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]

• Low LSR yield can be obtained under low temperature and long time. • Compared to N 2 /H 2 O/EtOH system, CO/H 2 O/EtOH system improved BC yield. • The addition of n-C 6 H 14 to methanol contributed to deep deoxygenation of BC. • The alkylation and hydrogenation were paramount for producing the LOBF. • The HHV of the LOBF was 40.92 MJ/kg with 7.80 wt% oxygen content. In this work, a two-stage liquefaction-hydrogenation approach was devised to produce low-oxygenated bio-fuel from lignocellulose. At the first stage, lignocellulose was liquefied in CO/H 2 O/EtOH system without catalyst at 250 °C and 12 h to produce bio-crude (BC). Around 55 wt% of bio-crude and approximately 1 wt% lignocellulose solid residue (LSR) could be obtained after liquefaction. It indicated that a low-LSR liquefaction of lignocellulose with acceptably high yield of bio-crude could be achieved under low temperature, as long as long reaction time served. It also suggested that water–gas shift reaction improved BC yield and suppressed LSR formation. At the second stage, the deoxygenation of the bio-crude was then employed in MeOH/CuZnAl-2 system at 330 °C and 6 h with the aid from n-C 6 H 14 and Ni/HZSM-5 to produce the low-oxygenated bio-fuel (LOBF). Notably, without coke formation, the overall yield of the LOBF reached 36.73 wt% with 7.80 wt% of oxygen content, while the HHV of the LOBF reached 40.92 MJ/kg. It was found that MeOH played a role as hydrogen donor for hydrogenation to directly decrease oxygen content and carbon source for alkylation to indirectly decrease oxygen content. Moreover, the n-C 6 H 14 added to methanol contributed to deep deoxygenation of bio-crude, although it had no ability of supplying hydrogen. GC × GC-TOF-MS analysis indicated that the dominant products of the LOBF were hydrocarbons and polymethylphenols. MALDI-TOF-MS analysis showed that there were no big fragments in the LOBF. [ABSTRACT FROM AUTHOR]

Partial hydrogenation of anthracene under CO-H2O, N2-H2O, and H2-H2O over Fe-based catalysts was studied at 400 °C and 10 MPa. Results show that the Fe-based catalysts display obvious catalytic activity for anthracene hydrogenation under CO-H2O instead of hydrogenation under N2-H2O and H2-H2O. The activity follows in the order of Fe(NO3)3·9H2O > Fe naphthenate > FeSO4·7H2O. Even though the amount of molecular hydrogen remains higher than that of in situ hydrogen, the anthracene conversion with in situ hydrogen is remarkably higher. It demonstrates that the in situ hydrogen is more active than molecular hydrogen for PAH hydrogenation. To further reveal the exact fate of these Fe-based catalysts, the decomposed products under CO-H2O, N2-H2O and H2-H2O were characterized by TG, XRD, and TEM. Results indicate that the Fe3O4 species play a key role in hydrogenation of anthracene under CO and H2O. Higher catalytic activity for Fe(NO3)3·9H2O is due to its complete decomposition at 350 °C to acquire higher concentration of active Fe3O4 species. The possible form of in situ hydrogen during this process is also discussed. Given that heavy oil contains abundant polyaromatics, these results are meaningful for enhancing hydrogen shuttling to heavy oil by producing natural hydrogen donors and, thus, benefiting the high-efficient upgrading. [ABSTRACT FROM AUTHOR]

Improving eco-efficiency in arid areas is the crucial to resolve the dual constraints of scarce water resources and the fragile carrying capacity of the ecological environment on agricultural production. This study investigated the eco-efficiency of seed maize production in Zhangye City, the largest seed maize producer in the arid northwestern region of China. The environmental impacts were assessed through a life cycle assessment and incorporated into a data envelopment analysis model, together with economic factors to evaluate ecological efficiency. A Tobit regression model was applied to identify the key elements affecting eco-efficiency and determine suggestions for further improvements. The results showed that the environmental acidification index of Zhangye was 1.2079–1.3978 times larger than the world per capita level, with the primary cause being the application of nitrogen fertilizer. Water consumption was lower than the world average level. The comprehensive environmental index was lower than the 2000 world per capita level but higher than that of other Chinese regions. A production eco-efficiency evaluation showed that 14.68% of households achieved relatively efficient production. Water was the most influential element. Each additional 100 units of water reduce eco-efficiency by 0.34%. A comparative study of small, medium and large farms was carried out to examine the effect of farm size. Small farms were the most eco-efficient, followed by medium-sized farms, with large farms having the lowest eco-efficiency. The results highlighted that certain targeted policy interventions may be inefficient, including interventions focusing on expansion of the production scale, and that restrictions on fertilizer use and improving water-saving facilities can improve eco-efficiency performance. Image 1 • Environmental impacts of NW China oasis are lower than 2000 world values per capita • 14.68% of oasis households achieved relatively eco-efficient production in NW China • Fertilizer and water are the main factors affecting eco-efficiency in NW China • Eco-efficiency is highest for small farms followed by medium-sized then large farms • Controlling fertilizer, water & farm size helps improve eco-efficiency in NW China [ABSTRACT FROM AUTHOR]

• A Nonlinear Joint Hydrological Drought Index (NJHDI) is constructed. • The non-linear relationship between surface water and groundwater is reflected. • Changes in underlying surface is considered when characterizing hydrological drought. • The most-often hydrological drought grades (MHC) in different parts of the YRB are found. • The potential influencing factors on the MHC are analyzed and quantified. It is critical important to accurately evaluate hydrological drought evolutions based on a composite index for the sustainable development of water resources. In this study, a Nonlinear Joint Hydrological Drought Index (NJHDI) is constructed by combining surface water and groundwater to better reflect the multivariate phenomenon in characterizing hydrological drought. The bi-dimensional copula function is applied to describe the complicated and nonlinear relationship between surface water and groundwater due to its dependence structure and flexibility. To reflect the changes in underlying surface, the time-varying parameters are applied in the Soil and Water Assessment Tool (SWAT) model to simulate the surface water and groundwater more accurately. Based on the NJHDI, the spatio-temporal hydrological drought evolutions as well as their potential influencing factors are analyzed in a case study of the Yellow River Basin (YRB). Results indicate that: 1) compared to the single hydrological index, the NJHDI is more sensitive and effective to capture historically droughts; 2) hydrological droughts became increasingly serious during the last few decades, especially in parts of the basin located in the Loess Plateau areas where the ecosystem is extremely fragile; 3) climate and LULC changes have both contributed to the changes in hydrological droughts but their contributions vary significantly spatially. In general, the NJHDI-based hydrological drought evolution can provide more reliable information in hydrological drought decision-making owing to considering changes in underlying land surface, and combining the surface water and groundwater with nonlinear combination method. [ABSTRACT FROM AUTHOR]