Study on Mechanism for Formation of Carbon Oxides During Catalytic Cracking of High Acidic Crude

Based on the basis of analysis and interpretation of the products distribution of catalytic cracking of high acidic crude, the mechanism for decarboxylation of petroleum acids during FCC process was discussed. The protons originated from the Bronsted acid sites can combine with oxygen of the carbonyl groups with more negative charges to form reaction intermediates that can be subjected to cleavage at the weak bonds, leading to breaking of carboxylic groups from the carboxylic acids followed by its decomposition to form alkyl three-coordinated carbenium ions, CO and H2O. The Lewis acid as an electrophilic reagent can abstract carboxylic groups from carboxylic acids to subsequently release CO2.

Mixed‑Dimensional Assembly Strategy to Construct Reduced Graphene Oxide/Carbon Foams Heterostructures for Microwave Absorption,Anti‑Corrosion and Thermal Insulation

Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges.Herein,reduced graphene oxide/carbon foams(RGO/CFs)with two-dimensional/three-dimensional(2D/3D)van der Waals(vdWs)heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying,immersing absorption,secondary freeze-drying,followed by carbonization treatment.Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching,the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances,achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of-50.58 dB with the low matching thicknesses.Furthermore,the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties,good corrosion resistance performances as well as outstanding thermal insulation capabilities,displaying the great potential in complex and variable environments.Accordingly,this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures,but also outlined a powerful mixeddimensional assembly strategy for engineering multifunctional foams for electromagnetic protection,aerospace and other complex conditions.

Correlation between catalytic activity of supported gold catalysts for carbon monoxide oxidation and metal–oxygen binding energy of the support metal oxides

The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.

Enhanced cycle performance of Li/S battery with the reduced graphene oxide/activated carbon functional interlayer

The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional(3D) reduced graphene oxide/activated carbon(RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 m Ah/g and a reversible capacity of 655 m Ah/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.

La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9) composite electrodes as anodes in LaGaO_(3)-based direct carbon solid oxide fuel cells

Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.

Diurnal variations of carbon dioxide,methane,and nitrous oxide fluxes from invasive Spartina alterniflora dominated coastal wetland in northern Jiangsu Province

The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas（GHG） emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide（CO_2）,methane（CH_4）,and nitrous oxide（N2O） from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer（June） and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season（1 536.5 mg CO_2 m^（–2） h^（–1） and 25.6 μg N_2O m^（–2） h^（–1）） compared with those measured in the non-growing season（379.1 mg CO_2 m^（–2） h^（–1） and 16.5 μg N_2O m^（–2） h^（–1））.The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes（prominent peaks were found in the morning of October and in the afternoon of April,respectively）.The highest diurnal variation in the N_2O fluxes took place at 15：00（86.4 μg N_2O m^（–2） h^（–1）） in June with an unimodal distribution.Water logging in October increased the emission of CO_2（especially at nighttime）,yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux（MF） and total daily flux（TDF） were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of CH_4 and N_2O were higher in June.In spite of the difference in the optimal sampling times throughout the observation period,our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands.

Poly(amide-6-b-ethylene oxide)/[Bmim][Tf2N] blend membranes for carbon dioxide separation

Poly（amide-6-b-ethylene oxide）（Pebax1657）/1-butyl-3-methylimidazo-lium bis[trifluoromethyl）sulfonyl]-imide（[Bmim][Tf2N]） blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO2, N2,CH4 and H2 were studied, and the physical properties were characterized by differential scanning calorimeter（DSC） and X-ray diffraction（XRD）. Results showed that [Bmim][Tf2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg（PE） and crystallinity（PA）. With the addition of [Bmim][Tf2N], the CO2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf2N], the increase of fractional free of volume（FFV） and plasticization effect. However, the CO2 permeability reduced firstly when the [Bmim][Tf2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf2N]decreased the content of EO units available for CO2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf2N] blend membranes, the permeabilities of N2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO2 permeability increased with the increase of feed pressure for that the CO2-induced plasticization effect was stronger than hydrostatic pressure effect.

Catalytic Performance of Carbon Materials Supported Pd Nanoparticles in Selective Hydrogenation of Acetylene

Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction.

Support effect of zinc tin oxide on gold catalyst for CO oxidation reaction

Nanostructured gold catalyst supported on metal oxide is highly active for the CO oxidation reac‐tion. In this work, a new type of oxide support, zinc tin oxide, has been used to deposit 0.7 wt%Au via a deposition‐precipitation method. The textural properties of Zn2SnO4 support have been tuned by varying the molar ratio between base （N2H4＆#183;H2O） and metal ion （Zn2＋） to be 4/1, 8/1 and 16/1. The catalytic tests for CO oxidation reaction revealed that the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ = 8/1 was the highest, while the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ =16/1 was almost identical to that of the pure support. Both fresh and used catalysts have been characterized by multiple techniques including nitrogen adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, high‐angle annular dark‐field scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray adsorption fine structure, and tempera‐ture‐programmed reduction by hydrogen. These demonstrated that the textural properties, espe‐cially pore volume and pore size distribution, of Zn2SnO4 play crucial roles in the averaged size of gold nanoparticles, and thus determine the catalytic activity of Au‐Zn2SnO4 for CO oxidation.

Oxidation of CO on Nanometer Metal Oxides at Low Temperatures

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Preparation and Microstructure of a Si-Mo Fused Slurry Coating on Carbon/Carbon Composites for Oxidation Protection

A coating of composition Si-40Mo (wt pct) was prepared by fused slurry coating method on the two-dimensional carbon/carbon (2D-C/C) composite to improve oxidation resistance. In the procedure of the fabrication, pure St slurry inner layer in the pre-coating was necessary to apply because of infiltration of liquid Si into the substrate during the sintering. The coating consists of Si continuous phase and MoSi2 particles. In addition, the infiltration of Si into the substrate and the SiC reaction layer between the coating and the C/C composite were observed. Oxidation behavior of coated and uncoated C/C composites was studied in cyclic mode. The oxidation resistance and the thermal shock resistance of the Si-Mo fused slurry coating were quite excellent at 1370℃.

Land use effects on soil organic carbon, nitrogen and salinity in saline-alkaline wetland

Land-use and soil management affects soil organic carbon （SOC） pools, nitrogen, salinity and the depth distribution. The objective of this study was to estimate land-use effects on the distribution of SOC, labile fractions C, nitrogen （N） and salinity in saline-alkaline wetlands in the middle reaches of the Heihe River Basin. Three land-use types were selected： intact saline-alkaline meadow wetland, artificial shrubbery （planting Tamarix） and farmland （cultivated for 18 years） of soils previously under meadow wetland. SOC, easily oxidized carbon, microbial biomass carbon, total N, NO3--N and salinity concentrations were measured. The results show that SOC and labile fraction carbon contents decreased significantly with increasing soil depth in the three land-use wetlands. The labile fraction carbon contents in the topsoil （0-20cm） in cultivated soils were significantly higher than that in intact meadow wetland and artificial shrubbery soil. The aboveground biomass and soil permeability were the primary influencing factors on the contents of SOC and the labile carbon in the intact meadow wetland and artificial shrubbery soil, however, the farming practice was a factor in cultivated soil. Agricultural measures can effectively reduce the salinity contents; however, it caused a significant increase of NO 3--N concentrations which posed a threat to groundwater quality in the study area.

Soil organic carbon pool along different altitudinal level in the Sygera Mountains, Tibetan Plateau

Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon（SOC）, total nitrogen（TN）, microbial biomass carbon（MBC）, microbial biomass nitrogen（MBN） and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site（3700 m to 4300 m area） in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon（SMBC） and soil microbial biomass nitrogen（SMBN）were positively correlated with SOC. The content of easily oxidized carbon（EOC）, particulate organic carbon（POC） and light fraction organic carbon（LFOC） decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth.The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents weredifferent with the changes of SOC（p＆lt;0.05）,meanwhile, both LFOC and POC were related to total SOC（p＆lt;0.05）. The physical and chemical properties of soil, including temperature, humidity, and altitude,were involved in the regulation of SOC, TN, MBC,MBN and LFOC contents in the Sygera Mountains,Tibetan Plateau.

Effects of Organic Manure Applications on Methane and Nitrous Oxide Emissions in Paddy Fields

This study was carried out in paddy fields to explore how organic manure applications would affect greenhouse emissions in South China. The results showed that the seasonal emission of CH4 under the chemical fertilizer （CF） treatment was 271.47 kg/hm^2. In comparison, the seasonal emissions of CH4 under the treatment of pig manure （PM）, chicken manure （CM） and rice straw （RS） increased by 50.61,260.22 and 602.82 kg/hm^2, respectively. N2O emission under the CF treatment was 1.22 kg/hm^2, while the N20 seasonal emissions under tile PM, CM and RS treatment decreased by 23.6% （P〈0.05）, 31.7% （P〈0.05） and 30.9% （P〈0.05）, respectively. Meanwhile, the readily oxidized organic carbon （which was oxidized by 167 mmol/L potassium permanganate, ROC167） of manure, paddy soil Eh value and temperature could also affect the CH4 emissions. The average yield of the organic fertilizer treatments increased by 6.8% compared with that of the CF treatment. Among all the organic fertilizer treatments, the PM treatment offered the lowest global warming potential and greenhouse gas intensity, in which the PM was of no significant difference from NF （no fertilizing） and CF. Therefore, the pig manure is capable of coordinating the relationship between environment and yield, and it also has a low ROC167 content, so the PM is considered worthy of recommendation.

NOVEL OXIDATION RESISTANT CARBON SILICON ALLOY FIBRES

Anovel silicon containing carbon precursor was synthesised by reacting a petroleum pitchfraction and polydimethylsilane. The precursor containing about 26wt% Si was meltspunintofibresand then oxidativelystabilised in airto renderthefibresinfusiblebefore pyrolysisat1200℃underinertatmospheretoproduceC Sialloy( CSA) fibres. Theextentofstabili sation wasfoundto becriticalto the development of mechanicalstrength of thefibres which varied with heattreatmenttemperature, showing a maximum at 1200 ℃when thestrength was 1 4 1 6 GPa. Thesestrengthsareremarkably goodconsideringthelow modulus whichis duetothe quite high failurestrains. Thefibrescanshow excellentresistanceto oxidation if given an initialshortexposureto oxygen athigh temperature duetotheformation of an im perceptiblelayer of silica. CSAfibreshavethe advantagesof both carbon fibresand SiCfi bres,thusextended application areascan beenvisaged .

Nutrients Available and Stable Carbon from Archaeological Black Earth

The present study aims affinity between available concentrations of phosphorus, micronutrients (Cu, Zn and Mn) and stable carbon (SC) in archaeological black earth (ABE) from area “Ilha de Terra”/Caxiuanã—Pará. The relevance of this study refers especially to the determination of carbon concentrations (total, oxidable and semi-labile carbon) directly associated with those of pyrogenic carbon, common in ABE, which should add their contributions to the understanding of soil organic matter recalcitrance. Chemical properties such as CEC and base saturation were determined for ABE and subjacent Latossoil. The available concentrations of nutrients were performed from sequential extraction F1 to F5 phases. Phosphorus was obtained by spectrophotometric method and micronutrients by MP-AES. TOC was determined by the combustion method;stable carbon was obtained from thermoxidation method CTO-375. The following results were obtained from ABE: CEC effective = 21 to 28 (cmolc·L-1);base saturation = 58% to 69%;Carbon concentrations (%): TOC = 2.95 to 3.94;SC = 0.25 to 0.88;semi-labile carbon = 1.75 to 3.63;oxidable = 2.11 to 3.65;inorganic carbon 0.01 to 0.38;P2O5 concentrations (mg·kg-1) in the ABE phases F3 (Fe-Mn oxides, F4 (organic ) and F5 (residual)) in the following order: 35 to 65;200 to 400;140 to 230. It was concluded that the chemical properties in ABE from Ilha de Terra site fall within the range of fertile and the high concentrations of phosphorus are biogenic origin. Phases F3 and F4 are those considered nutrient stocks from ABE studied area.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Oxidation Resistance of the Aluminide Coating Formed on Carbon Steels

Low and medium carbon steels were aluminized by the pack aluminizing technique using halideactivated pure-Al and Fe-Al packs. The effect of mixture composition, aluminizing temperatureand time and C content of the steel substrate on the structure and thickness of the aluminidelayer, and on the oxidation resistance was investigated. The optimum oxidation resistance canbe achieved with a low carbon steel substrate when the intermetallic phases Fe3Al and FeAlform the surface of the aluminide layer. In this case, the Al concentration at the surface of thealuminide coating is at least ≥15 wt pct. Formation of high Al concentration phases (FeAl3 andFe2Al5) during aluminizing should be avoided as they tend to embrittle the aluminide layer andreduce its oxidation resistance.

Recent progress in CO oxidation over Pt-group-metal catalysts at low temperatures

CO oxidation is probably the most studied reaction in heterogeneous catalysis.This reaction has become a hot topic with the discovery of nanogold catalysts,which are active at low temperatures（at or below room temperature）.Au catalysts are the benchmark for judging the activities of other metals in CO oxidation.Pt-group metals（PGMs） that give comparable performances are of particular interest.In this mini-review,we summarize the advances in various PGM（Pt,Pd,Ir,Rh,Ru）catalysts that have high catalytic activities in low-temperature CO oxidation arising from reducible supports or the presence of OH species.The effects of the size of the metal species and the importance of the interface between the metal and the reducible support are covered and discussed in terms of their promotional role in CO oxidation at low temperatures.

Low temperature molten salt synthesis of porous La_(1-x)Sr_xMn_(0.8)Fe_(0.2)O_3(0≤x≤0.6) microspheres with high catalytic activity for CO oxidation

A molten salt method was developed to prepare porous La1‐xSrxMn0.8Fe0.2O3 （0≤ x ≤ 0.6） micro‐spheres using hierarchical porous δ‐MnO2 microspheres as a template in eutectic NaNO3‐KNO3. X‐ray diffraction patterns showed that single phase LaMn0.8Fe0.2O3 with good crystallinity was syn‐thesized at 450℃ after 4 h. Transmission electron microscope images exhibited that the LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h possessed a porous spherical morphology com‐posed of aggregated nanocrystallites. Field emission scanning electron microscope images indicated that the growth of the porous LaMn0.8Fe0.2O3 microspheres has two stages. SEM pictures showed that a higher calcination temperature than 450？？ had an adverse effect on the formation of a po‐rous spherical structure. The LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h displayed a high BET surface area of 55.73 m2/g with a pore size of 9.38 nm. Fourier transform infrared spectra suggested that Sr2＋ions entered the A sites and induced a decrease of the binding energy between Mn and O. The CO conversion with the La1‐xSrxMn0.8Fe0.2O3 （0≤x≤0.6） samples indicated that the La0.4Sr0.6Mn0.8Fe0.2O3 sample had the best catalytic activity and stability. Further analysis by X‐ray photoelectron spectroscopy demonstrated that Sr2＋doping altered the content of Mn4＋ions, oxygen vacancies and adsorbed oxygen species on the surface, which affected the catalytic performance for CO oxidation.