Heavy oil millisecond gas-phase in-line catalytic dehydrogenation over bifunctional catalysts was adopted to produce low-carbon olefins. In this study, the effect of the uncatalyzed reaction composition and distribution of atmosphere residue (AR) pyrolysis vapor at 650 degrees C was investigated for the first time. In the pyrolysis vapor, the yield of low-carbon olefins was only 15.2%. The yield of 1-olefin and n-alkanes, which are the primary products of rapid heavy oil pyrolysis, reached approximately 54.0%. To achieve further catalytic dehydrogenation, AR pyrolysis volatiles were catalyzed over single calcium aluminate (C(12)A(7)), ZSM-5, and C(12)A(7)-ZSM-5 (CZ) catalysts at 650 degrees C, which possess different pore structures, and acid-base properties. The ZSM-5 catalyst obtained the highest low-carbon olefin yield after catalytic dehydrogenation of pyrolysis volatiles. Finally, the C(12)A(7 )and CZ stepwise coupling bifunctional catalysts increased the catalytic activity, and thus increased the higher low-carbon olefin yield but reduced the yields of alkanes and aromatics fraction. Notably, the yields of propylene and butane were important sources of the low-carbon olefins. Thus, heavy oil millisecond gas-phase in-line catalytic dehydrogenation could achieve the maximum conversion of these residues to produce low-carbon olefins.
By evaluating the SEM images,specific surface area,and the catalytic synthesis reaction conditions of an activated carbon-supported p-toluenesulfonic acid catalyst,and comparing the physical and chemical properties,infrared spectra,nuclear magnetic resonance spectra,oxidation stability,thermal stability,hydrolytic stability,and extreme pressure anti-wear performance of the synthesized trihydroxymethylpropyl trioleate with imported reference esters,the feasibility of its application as a substitute was investigated.The results indicated that the activated carbon-supported p-toluenesulfonic acid catalyst exhibited loose porosity,high specific surface area,and high esterification efficiency.When synthesized under optimal conditions,the yield rate of trihydroxymethylpropyl trioleate reached 99.3％,with a simple separation process that did not require additional steps such as neutralization and washing and generated minimal wastewater.The physical and chemical properties of the synthesized trihydroxymethylpropyl trioleate were comparable to those of the reference ester in terms of color,viscosity,viscosity index,flash point,and pour point.Moreover,the peak position and peak height in the infrared and nuclear magnetic carbon spectra were essentially the same.Through comprehensive evaluations and comparisons of various properties,it was determined that the performance of trihydroxymethylpropyl trioleate was comparable to that of the imported reference esters.
Due to increasingly stricter emissions on particulate matter(PM)emissions,diesel particulate filter(DPF)regeneration has become the most widely used and effective technology to reduce PM emissions.However,using in-cylinder post-injection-based active DPF regeneration can increase engine oil dilution,thus affecting engine lubrication.Using a 4-cylinder turbocharged direct-injection diesel engine,this study analyzed the effect of lubricating oil on the formation and properties of turbocharger compressor soot deposits associated with engine oil dilution.Three diesel engine lubricating oils(CJ-4,CK-4,and CJ-4*)were selected,with each subjected to 200 hours of engine bench testing at 8％oil dilution.The composition of CJ-4* was the same as that of CJ-4 but with reduced amount of additives.Soot deposits were collected and analyzed.A merit calculation method was established to rate turbocharger deposits.Transmission electron microscopy,Raman spectroscopy,Fourier transform infrared spectroscopy,and thermogravimetric analysis(TGA)were used to characterize the morphology and composition of soot samples.The results showed that turbocharger deposits from CJ-4 and CK-4 were less than that from CJ-4*.The deposits from CJ-4* showed a more disordered morphology,whereas those from CJ-4 and CK-4 exhibited a higher degree of order.TGA results showed that the soluble organic fraction content in the deposit derived from CJ-4*was much higher than that obtained from CJ-4 and CK-4.
Fe-Al catalysts with hollow nano-spherical structures were synthesized following the hard template method using self-made carbon spheres as templates.The catalytic performance of these catalysts in the production of carbon nanotubes(CNTs)was evaluated through ethane catalytic cracking on a fixed bed reactor.Furthermore,the influence of these hollow nanospheres on the yield and quality of CNTs was investigated.The results showed that compared to the irregular-shaped catalyst synthesized by coprecipitation and the catalyst with micro-spherical structures prepared by the impregnation method,the Fe-Al hollow nano-spherical catalysts exhibited significantly enhanced specific surface area and pore volume,reaching 236 m2/g and 0.77 cm3/g,respectively.At a reaction temperature of 700 ℃ and an ethane feed rate of 90 mL/min,the CNTs yield of Fe-Al hollow nano-spherical catalyst reached as high as 48.6 gCNT/gcat,which was 1.8 and 4.6 times higher than the yield of irregular-shaped(27.7 gCNT/gcat)and micro-spherical(10.5 gCNT/gcat)catalysts,respectively.This was mainly attributed to the hollow cavity structure of Fe-Al catalyst providing sufficient space for the CNTs growth.As a result,the blockage of catalyst internal pores was prevented by the formed CNTs,which isolated ethane molecules from the active sites and lead to catalyst deactivation.Furthermore,the CNTs synthesized by Fe-Al hollow nano-spherical catalyst exhibited a uniform diameter distribution and a higher degree of graphitization.
This study investigates the simultaneous accumulation of S-0 and NO2- during short-cut sulfur autotrophic denitrification (SSADN) in response to 0-35 mg/L hydroxylamine (NH2OH) addition. At a dosage of 15 mg/L NH2OH, the accumulation of NO2--N peaked at 32.49 +/- 1.33 mg/L, which is 1.65 times higher than that of the control. The addition of NH2OH facilitates the retention of S-0 in the system. Enzyme assays indicated significant discrepancies in the enhanced NO3--N reductase (NAR) and NO2--N reductase (NIR) activities induced by NH2OH are responsible for the excellent NO2--N production. These results are supported by the corresponding NO3--N reduction genes (napA, narG) and NO2--N reduction genes (nirS, nirK). In addition, the abundance of sulfur oxidation genes (soxB) decreases with increasing NH2OH dosage, inhibiting further oxidation of S-0 to SO42-. The accumulation of NO2---N and S-0 increases from 45.8% and 36.8% to 70.04% and 52.52%, respectively, with the addition of 2 mg/L NH2OH in the continuous-flow up-flow anaerobic sludge blanket (UASB) reactor.
As a new type of semiconductor, Bi-based photocatalysts have attracted widespread attention in the field of environmental pollution control. In this study, a ternary BiPO4/BiOIO3/PI composite was prepared using a facile hydrothermal process and ultrasonic-assisted deposition method. The Fourier transform infrared spectra (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffused reflection spectra (UV-Vis DRS) were employed to determine the morphology and structure of the as-obtained BiPO4/BiOIO3/PI composite. The photocatalytic performance of the as-prepared BiPO4/BiOIO3/PI was evaluated via the degradation of dyes such as rhodamine B (RhB), methyl orange (MO), and methylene blue (MB) in aqueous solution. It was found that 99.6% of RhB, 92.7% of MO, and 87.5% of MB were degraded, within 15 min of simulated solar irradiation over the BiPO4/BiOIO3/PI composite, showing the remarkably high photocatalytic activity of the BiPO4/BiOIO3/PI ternary photocatalyst. The results of trapping experiments displayed that photogenerated holes and superoxide radicals were the main active species in the photocatalytic process. The obvious enhancement of photocatalytic activity could be mainly ascribed to enhancing the separation and migration of photogenerated charge carriers in the BiPO4/BiOIO3/PI composite.
Dioctyl sebacate(DOS)is an organic ester compound,mainly used as a low-temperature plasticizer and synthetic antirust and cold-resistant ester lubricant base oil.This study discusses the use of synthesized molybdenum disulfide/C60(MoS2/C60)composite particles as catalysts to synthesize a new type of DOS endowed with high lubricity.This was achieved through a catalytic esterification reaction between sebacic acid and 1-octanol.After the reaction,MoS2/C60 was dispersed in situ in this novel DOS to form a suspension(MoS2/C60/DOS).The tribological properties of MoS2/C60/DOS were examined through high-frequency reciprocating friction and wear experiments,and the friction and wear mechanisms were analyzed.The results show that MoS2/C60/DOS can significantly enhance the antiwear and friction reduction performance compared to commercial DOS by 91％and 95％,respectively,achieving an ultra-low friction state with an average friction coefficient of 0.006.A friction film containing elements such as Fe,O,C,Mo,and S forms on the friction surface,significantly improving the lubrication state of the friction interface and achieving low friction.
Catalytic dehydrogenation represents one of the most effective methods for converting low-carbon hydrocarbons into monoolefins and hydrogen with identical carbon numbers. In this study, microporous (HZSMi) and meso-microporous molecular sieves (HZSMu) with a Si/Al atomic ratio of 150, synthesized in the laboratory, were prepared via hydrothermal synthesis. These supports were impregnated with 2.4%Co using the incipient wetness impregnation method and subsequently modified by introducing the metal additives Zr and Sn. Notably, the Co-Sn/HZSMu catalyst exhibited the highest stability, achieving a propylene selectivity of 95.3%within 400 min while maintaining robust activity. A series of characterization analyses reveal that the HZSMu molecular sieve possesses distinctive weaving properties. The synergistic effect between mesopores facilitates the adsorption and activation of reactants while preventing pore blockage, thus promoting the rapid diffusion of reactants on its surface. The incorporation of the metal additive Sn promotes the uniform dispersion of Co, mitigating the occurrence of side reactions and enhancing the catalytic performance and reaction stability of the catalyst.
The effect of combining different organic friction modifiers(OFMs)with ashless dispersants on the dispersion performance of lubricant oils in sludge was investigated using molecular dynamics(MD)simulations.polyisobutylsuccinimide(PIBSI)was mixed with either glycerol monooleate(GMO)or oleamide(OAM)in a poly-α-olefin(PAO)base oil.The distribution and interaction energy of sludge precursors were analyzed both with and without these additive mixtures.The results show that both the OFMs and dispersants can form hydrogen bonds with sludge precursor molecules,preventing further aggregation.Adding OFMs to lubricant oil-containing dispersants enhances the dispersion of the lubricant.Compared to OAM,GMO forms more hydrogen bonds with sludge precursors,which favors improved dispersion.However,there is strong competition and interaction between GMO and PIBSI,which reduces the dispersant's effectiveness in mitigating sludge precursor aggregation.The interactions among additives and their impact on performance should be considered when designing high-performance lubricant formulations.
NH2-MIL-125 is one of the most promising metal-organic frameworks(MOFs)for use as an adsorbent to remove nitrogen-containing compounds(NCCs)from fuels.In this study,NH2-MIL-125 was further modified by loading the highly electronegative F and the heteropoly acid phosphomolybdic acid hydrate(PMA).Hydrogen bonds are suggested to form between F and PMA.X-ray diffraction(XRD)and scanning electron microscopy(SEM)showed that the addition of these elements altered the morphology of NH2-MIL-125,resulting in the growth of sectional octahedrons and cubes.The adsorptive denitrogenation(ADN)activity of 10％PMA@M125 was 1.7 times greater than that of NH2-MIL-125 without F and PMA.The synergistic effect of F and PMA on the morphology and structure of NH2-MIL-125 was examined,with a focus on different PMA contents.This study provides a simple method for modifying the morphology and structure of NH2-MIL-125 by adding the required elements.
Ansa rac-MeSi(2-Me-4-Ar-Ind)ZrCl2(Ar=Ph,Ind=indenyl,7a)is an industrial metallocene catalyst commonly used for propylene polymerization.This study investigated the effects of substituents at the para position of the Ar group on catalyst performance.Four derivatives of 7b(p-MePh),7c(p-OMe),7d(p-tBuPh),7e(p-F-Ph)were successfully synthesized through three methods.The influence of these substitutions on catalyst activity was evaluated in 1-hexene polymerization with 7a-e in toluene using solid methylaluminoxane as a co-catalyst.Derivative 7c exhibited the highest catalytic activity and stereoselectivity,achieving an isotacticity of 94％,indicating that electron-donating substituent enhancing catalytic reactivity.
The oxidation characteristics of n-hexadecane with O-2 were investigated by reaction force field molecular dynamics (ReaxFF MD) from 2200 to 3200 K at intervals of 200 K. As the temperature increased, the consumption of n-hexadecane and the generation of the main products (H2O, CO, and CO2) accelerated. The peak number of intermediate CH2O was reached more quickly, initially increasing and then decreasing until stabilizing at 90-120. Free radical OH also appeared earlier, with higher average concentrations of 3.41-36.58 at different temperatures. The temperature 3000 K was selected to analyze the reaction pathways of the intermediate and main products, based on which a high-temperature general oxidation mechanism of n-hexadecane was developed. Differences in the initial reaction step between the oxidation and pyrolysis models of n-hexadecane were also examined. The presence of O-2 promoted C-H bond cleavage, leading to significantly fewer molecular fragments (e.g., C2H4, CH3, and CH4) generated during oxidation.
The number of independent reactions in the methanol aromatization system using a Zn/ZSM-5 molecular sieve as a catalyst is first determined by the atomic matrix method.Then,the thermodynamic network structure of the methanol aromatization system is proposed based on the double-cycle mechanism and independent reaction equations.Thermodynamic analysis is performed to determine the reaction enthalpy change,equilibrium constant,and Gibbs free energy at different temperatures for each reaction.The effects of temperature and pressure on the equilibrium composition are also investigated.The results indicated that the entire system is a process that generates a considerable amount of heat.Increasing the temperature is not conducive to forming olefins,alkanes,and aromatics,except for methanol decomposition.The equilibrium composition of aromatics tends to increase and then decrease with the temperature rise.The equilibrium molar fraction of aromatics at pressures below 1.5 MPa,except benzene,increases significantly with increasing pressure.Simulation analysis of equilibrium components at varying temperatures and pressures is conducted to narrow the range for selecting the appropriate reaction temperature and pressure.
Photocatalysis has emerged as a promising alternative for converting and utilizing CO2. Polymeric carbon nitride (PCN), typically synthesized through the one-step thermal polycondensation of nitrogen-rich precursors, has shown considerable promise due to its adjustable band structure and inherent safety. Over the past five years, significant literature in this field has identified and heterojunction construction. A detailed discussion on how each modification method influences light absorption, charge separation, and surface reaction efficiencies in photocatalysis is provided. Based on these findings, several future directions for the development of PCN-based materials are proposed, such as designing tailored PCN structures for specific photocatalytic reactions and using theoretical calculations to verify and correct results from current characterization methods. Despite the challenges associated with the large-scale synthesis of PCN materials with controllable structures and satisfactory performance, this work offers valuable insights for advancing photocatalytic PCN-based systems for large-scale solar fuel production.
A series of Lewis-acid deep eutectic solvents (DESs) were synthesized by stirring phosphoric acid and zinc chloride as raw materials at 80 degrees C to form H3PO4/nZnCl(2) (n = 0.1, 0.25, 0.5, 0.75, 1). The DESs were characterized by Fourier transform infrared spectrophotometry (FT-IR), thermogravimetry/differential thermogravimetry (TG/DTG), and electron spray ionization mass spectrometry (ESI-MS). The DESs were used as both extractants and catalysts to remove dibenzothiophene from fuels via oxidative desulfurization (ODS). Experiments were performed to investigated the inffuence of factors such as composition of DES, temperature, oxidant dosage (molar ratio of O:S), DES dosage (volume ratio of DES:oil), and number of cycles on desulfurization rate. The results indicated that the removal rate of dibenzothiophene (DBT) was affected by the Lewis acidic DESs, with that of H3PO4/0.25 center dot ZnCl(2)reaching 96.4% under optimal conditions (V-oil =5 mL, V-DES=1 mL, an oxidant dosage of 6, T=50 degree celsius). After six cycles, the desulfurization rate of H3PO4/0.25 center dot ZnCl2 remained above 94.1%. The apparent activation energy of dibenzothiophene (DBT) removal reaction was determined by a pseudo-ffrst order kinetic equation according to the Arrhenius equation to be 32.34 kJ/mol, as estimated. A reaction mechanism is proposed based on the experimental data and characterization results.
Hydrate-based CO2 sequestration is an effective method for reducing the greenhouse effect, and the presence of porous media and NaCl can impact the formation characteristics of hydrates. This study uses the constant volume temperature search method to investigate the effects of quartz sand particle size (0.006-0.03 mm), water saturation (30%- 90%), and NaCl concentration (1%-9%) on the phase equilibrium and kinetics of CO2 hydrates within a temperature range of 273-285 K and pressure range of 1.0-3.5 MPa. The results indicate that a decrease in quartz sand particle size or an increase in NaCl concentration shifts the hydrate phase equilibrium curve towards lower temperatures and higher pressures, making hydrate generation conditions more demanding. In different particle size systems, there are no significant changes in the rate of CO2 hydrate formation or conversion rate. The highest hydrate conversion rate of 71.1% is observed in a 0.015 mm particle size system. With increasing water saturation, both the generation rate and conversion rate of CO2 hydrates show a trend of first increasing and then decreasing. Meanwhile, low concentrations of NaCl (1%-3%) are found to enhance the formation and conversion rates of CO2 hydrates. However, as NaCl concentration increases, the rate of CO2 hydrate formation and conversion rate decrease.
Rice husk powder was used as a carbon source in a high-temperature carbonization reaction for the production of rice husk ash(RHA).Under the catalysis of ferric nitrate,onion-like carbon(OLC)nanomaterial with a particle size of approximately 200 nm was successfully prepared and incorporated into waterborne polyurethane(WPU).The tribological properties of the coatings were determined using a controlled-atmosphere tribometer(WMT-2E)under dry-friction conditions.Following the friction test,the friction mechanism was investigated by characterizing the abrasive spot surfaces of the test samples using 3D laser microscopy and scanning electron microscopy/energy dispersive spectrometer.The final results demonstrated that the thermal stability of WPU composite coatings containing various concentrations of OLC nanoparticles was significantly enhanced,binding forces between coatings and steel sheets increased,and hardness improved compared to pure WPU coatings.Tribological tests revealed a notable enhancement in the anti-wear properties of WPU coatings due to the presence of OLC particles.Specifically,the wear rate of the 1.5%OLC/WPU coating was reduced by 45.3%.The coating's anti-wear mechanism was attributed to the improvement in the mechanical properties of WPU due to OLC,as well as OLC's participation in the formation of a transfer film under induced friction,which protected the matrix.
Utilizing solvent extraction to separate alkanes and olefins from catalytic light gasoline is an effective method for maximizing the utility of gasoline fractions. This study presents the determination of liquid-liquid equilibrium data for the ternary system of 1-hexene-n-hexane-3-methylsulfolane at 30 degrees C,40 degrees C, and 50 degrees C under atmospheric pressure. The obtained data facilitated the construction of a ternary phase diagram for the system. The results showed that the extraction selectivity of 1-hexene/n-hexane exceeded 1.5 when using 3-methylsulfolane as the extraction solvent. Furthermore, the thermodynamic consistency of the experimental data was examined using Hand's equation and the Othmer-Tobias method. The correlation coefficient, R2 >= 0.9578, indicated the acceptable reliability of the phase equilibrium data. Subsequently, the NRTL (non-random two liquid) model was used to correlate the liquid-liquid phase equilibrium data and derive the binary interaction parameter. Notably, the results demonstrated that the root mean square deviation of the NRTL model correlation values from the experimental values did not exceed 2.5%.
The Cu/ZnO catalyst formed upon the calcination of aurichalcite has a uniform distribution of ZnO, which can delay the sintering of Cu species at high temperatures. In this study, aurichalcite possessing a nearly pure phase was prepared using the ammonium complex dissociation precipitation method, and the effect of calcination temperature on the structure and surface properties of the derived Cu/ZnO catalyst was studied. The results show that the calcination temperature determines the particle size and crystallization degree of the Cu/ZnO catalyst and the surface properties of the corresponding copper oxide and reduced copper. Low-temperature calcination is more conducive to reducing the particle size of the Cu/ZnO catalyst, increasing the specific surface area, and generating abundant defect characteristics on the surface, which is key to obtaining highly dispersed copper and copper-specific surface area catalysts by subsequent reduction. Additionally, the Cu/ZnO catalyst derived using a 300 degrees C or 400 degrees C calcination proved to have a higher specific activity per gram of copper than a commercial Cu/Zn/Al catalyst. The discovery in this study opens up a new method for the convenient preparation of a high-temperature resistant Cu/Zn methanol reforming catalyst.
Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al2O3 and their performance in methylcyclohexane(MCH)dehydrogenation.The results demonstrated that the addition of Fe to Pt/Al2O3 enhanced the electron density of Pt and improved catalytic activity,while exhibiting negligible influence on the catalytic selectivity for toluene.When the Fe content was 0.057％,the catalyst exhibited the highest MCH consumption rate,which was approximately two times higher than that of the catalyst without Fe.Additionally,the incorporation of Fe inhibited the formation of coke and reduced the quantity of coke deposits on the catalyst,thereby improving its catalytic durability.Overall,Fe shows promise as a prospective secondary element for Pt/Al2O3 to enhance the MCH dehydrogenation performance.
