Ultrasonic-assisted Impregnation Research Articles

Effect of silane hydrolysis on the interfacial adhesion of carbon nanotubes/glass fiber fabric-reinforced multiscale composites

Three types of multiwall carbon nanotubes (MCNTs)/glass fiber fabrics (MGf) were prepared by dispersing industrial-grade MCNTs onto commercial E-glass fiber fabrics (GFfs) through an ultrasonic-assisted impregnation deposition method. The multiscale MGf-reinforced composites were fabricated by the vacuum infusion process. The effect of γ-aminopropyltrimethoxysilane (APS) or APS hydrolysis on the MCNT dispersion and the interfacial bonding between MCNTs and glass fiber were investigated by Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy and their flexural stiffness, respectively. The interfacial adhesion of MGf composites was evaluated by interlaminar shear strength (ILSS) and dynamic mechanical thermal analysis. The results indicated that MCNTs on the MGf surface could form an interpenetrating network and act as anchors to interlock glass fiber with epoxy. The initial storage modulus and glass transition temperature of the MGf composites clearly increased, while the first loss factor of the MGf composites decreased by 30.0–45.0% compared with that of the GFf composite. Whether or not APS was hydrolyzed, it helped the MCNTs disperse on the GFf surface by chemical bonds. The ILSS of the multiscale composite with APS-treated MCNTs was enhanced significantly, while that with hydrolyzed APS-treated MCNTs (MGf-h) had a slight increase. APS hydrolysis increased the flexural rigidity of the MGf-h.

Photocatalytic degradation of diazinon under visible light using TiO 2 /Fe 2 O 3 nanocomposite synthesized by ultrasonic-assisted impregnation method

Abstract Diazinon is one of the organophosphorus pesticides. It can threaten human and animal health, if stays in water and soil resources. Herein, the photocatalytic degradation of Diazinon under visible light was accomplished using TiO 2 /Fe 2 O 3 nanocomposite, which has been never employed for diazinon degradation. Firstly, TiO 2 /Fe 2 O 3 nanopowder was synthesized via ultrasonic-assisted impregnation method. To achieve this goal, TiO 2 nanoparticles were effectively dispersed in the solution. Then, Fe 3+ was impregnated on TiO 2 nanopowder under sonication process and calcined at 300 °C. The prepared photocatalyst was authenticated by XRD, EDX, FESEM, TEM, PL, and DRS analysis methods yielding following results: Anatase and maghemite crystalline structure of TiO 2 /Fe 2 O 3 nanoparticles, successful impregnation of Fe 2 O 3 on the surface of TiO 2 nanopowder, mean diameter size of 17 nm, extended absorption spectra of Fe 2 O 3 /TiO 2 nanocomposite in the visible region, and the better inhibition of electron and electron-hole recombination. Secondly, Kinetics of degradation was systematically optimized by multi variable central composite design based on response surface method. Degradation efficiency was highly affected by Diazinon dosage. The maximum experimental degradation efficiency was 95.07%. Optimum condition which was determined by software, included 0.1 g/L catalyst, 10 ppm Diazinon dosage, 45 min reaction time and 14 W/cm 2 light intensity and predicted 88.93% degradation efficiency with desirability of 0.873.

Enhancing the photocatalytic oxidation of dibenzothiophene using visible light responsive Fe and N co-doped TiO2 nanoparticles

Fe and N co-doped TiO2 nanoparticles were synthesized by an ultrasonic assisted impregnation reaction method. The prepared samples were characterized using XRD, BET, FE-SEM, XPS, FT-IR, and UV–vis DRS techniques. Fe and N co-doping resulted in a decrease in the crystallite size and an increase in the specific surface area. Photocatalytic oxidation of dibenzothiophene (DBT) in diesel model fuel was investigated using Fe and N co-doped TiO2 nanocatalyst under visible light irradiation and air bubbling. The photocatalytic activity of the Fe and N co-doped TiO2 nanoparticles was found to be considerably higher than that of the mono-doped counterparts. The differences in the photocatalytic activity of the prepared samples were discussed. It can be inferred that the visible light absorption alone is not a sufficient criterion for the photocatalyst activity. The efficient photocatalytic activity of the Fe and N co-doped TiO2 can be attributed to the co-operation of the Fe and N dopants. The presence of nitrogen and iron resulted in extending the absorption to the visible region. Under aerated conditions, Fe ions can considerably promote the photogenerated charge separation and consequently decrease the recombination rate of electron-hole pairs. The optimum iron content for Fe and N co-doped TiO2 was determined as 0.5wt%. Photocatalyst loading of 3gL−1 and air flow rate of 200mL/min were identified as optimum reaction conditions for photocatalytic desulfurization of the model fuel.

Sulfidation and regeneration of iron-based sorbents supported on activated-chars prepared by pressurized impregnation for coke oven gas desulfurization

The sulfidation and regeneration properties of lignite char-supported iron-based sorbent for coke oven gas (COG) desulfurization prepared by mechanical stirring (MS), ultrasonic assisted impregnation (UAI), and high pressure impregnation (HPI) were investigated in a fixed-bed reactor. During desulfurization, the effects of process parameters on sulfidation properties were studied systematically. The physical and chemical properties of the sorbents were analyzed by X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared (FTIR) and BET surface area analysis. The results of desulfurization experiments showed that high pressure impregnation (HPI) enhanced the sulfidation properties of the sorbents at the breakthrough time for char-supported iron sorbents. HPI method also increased the surface area and pore volume of sorbents. Sulfur capacity of sorbents was enhanced with increasing sulfidation temperatures and reached its maximum value at 400 °C. It was observed that the presence of steam in coke oven gas can inhibit the desulfurization performance of sorbent. SO2 regeneration of sorbent resulted in formation of elemental sulfur. HPIF10 sorbent showed good stability during sulfide-regeneration cycles without changing its performance significantly.

Comparative sonochemically synthesis of CeO 2 -doped Pd/clinoptilolite and Pd/Al 2 O 3 nanocatalysts used in total oxidation of toluene at low temperatures for polluted air treatment

Abstract A series of palladium based nanocatalysts which were loaded on CeO 2 doped alumina or clinoptilolite supports were synthesized by the ultrasonic assisted impregnation method. The influence of different ceria doped supports via total oxidation of toluene was investigated. Therefore, physiochemical properties of prepared nanocatalysts were evaluated by XRD, FESEM, BET and FTIR analyses. The FESEM images stated that synthesized naocatalysts had nanometric particles. The average size of catalyst particle was obtained to be 34.5 nm. BET analysis introduced a considerable rise in clinoptilolite surface area after treatment and demonstrated large surface area for Al 2 O 3 and its composites. CeO 2 acts not only as a fine support due to its stability and surface area, but also had catalytic role because of its reducibility properties. Among synthesized catalysts, Pd/Al 2 O 3 –CeO 2 sample resulted the lowest particle size, highest surface area and consequently highest oxidation performance and stability.

Synthesis and characterization of N-doped TiO2 nanoparticles and their application in photocatalytic oxidation of dibenzothiophene under visible light

Abstracts N-doped TiO 2 nanoparticles, as a novel photocatalyst for the photocatalytic oxidative desulfurization, were synthesized via an ultrasonic assisted impregnation reaction method using urea as nitrogen source. The prepared sample was characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and X-ray photoelectron spectroscopy (XPS). Nitrogen doping caused a decrease in the crystallite size and an increase in the specific surface area. XPS and FT-IR results showed that N was successfully incorporated into the TiO 2 lattice as substitutional and interstitial forms. The light absorption extended to the visible region with a red shift in absorption edge for the N–TiO 2 nanoparticles, which resulted in the enhancement of the visible light absorption. More surface hydroxyl groups were observed in the N-doped TiO 2 . Photocatalytic oxidative desulfurization of dibenzothiophene (DBT) in diesel model fuel under visible light irradiation and air bubbling was investigated using the N-doped TiO 2 nanocatalyst for the first time. N–TiO 2 exhibited efficient and significant photocatalytic activity for DBT oxidation under visible light illumination in organic phase. The photo-oxidation products were determined using GC–MS analysis. A possible mechanism for the role of N-doped TiO 2 in DBT oxidation under visible light irradiation was proposed. In addition, the kinetic studies revealed that the photocatalytic oxidation kinetics of DBT would follow a pseudo first order reaction. Finally, the stability and cyclic efficiency of the N–TiO 2 photocatalyst were investigated.

CuCl2 promoted low-gold-content Au/C catalyst for acetylene hydrochlorination prepared by ultrasonic-assisted impregnation

A detailed study of low-gold-content Au(0.25%)/C and Au(0.25%)Cu(4%)/C catalysts prepared via ultrasonic-assisted impregnation method is described and discussed. The addition of 4wt% Cu to Au/C increases the initial activity and the Au loading is decreased to 0.25wt%. Au(0.25%)Cu(4%)/C exhibits best catalytic performance with an acetylene conversion of 97.4% and the selectivity to VCM of more than 99% at a space velocity of 720h−1 and 150°C. The observations are rationalized in terms: (i) Au(0.25%)Cu(4%)/C exhibits relative larger specific surface area (562m2/g) than Cu(4%)/C (385m2/g), which provides more active sites for acetylene hydrochlorination; (ii) the reduction activation energy of Au3+→Au0 in Au(0.25%)Cu(4%)/C (45.5kJ/mol) is much higher than that of Au(0.25%)/C (35.6kJ/mol), which indicates that the Au3+ species in Au(0.25%)Cu(4%)/C catalyst is more difficult to be reduced, the reduction activation energy of Cu+→Cu0 in Au(0.25%)Cu(4%)/C (48.9kJ/mol) is higher than that of Cu(4%)/C (43.1kJ/mol) as a result of the electronic interaction between Au and Cu atoms; (iii) Au(0.25%)Cu(4%)/C possesses more Au3+ species (28%) than Au(0.25%)/C (16%) determined by XPS. Free-mercury low-gold-content Au(0.25%)Cu(4%)/C catalyst is environmental-friendly, making it a potentially green catalyst for acetylene hydrochlorination.

Effect of calcination temperature on desulfurization performance over Mn x O y supported on MCM-41 at low temperatures

Adsorbents consisting of Mn x O y supported on MCM-41 have been prepared at different calcination temperatures by the ultrasonic assisted impregnation method. The physical properties of these adsorbents have been characterized by thermogravimetric and differential thermal gravimetry, X-ray diffraction, Fourier-transform infrared spectroscopy, temperature-programmed reduction, and nitrogen sorption analysis. The results showed that the adsorbent calcined at 550 °C exhibited the best desulfurization performance. The saturated H2S capacity reached 28.65 mg/g at an adsorption temperature of 25 °C. The saturated H2S capacities of the different adsorbents decreased in the order of their calcination temperatures as follows: 550 > 450 > 350 > 650 °C.

Effects of pore sizes and oxygen-containing functional groups on desulfurization activity of Fe/NAC prepared by ultrasonic-assisted impregnation

A series of Fe-loaded activated carbons treated by HNO3 (Fe/NAC) were prepared by incipient impregnation method with or without ultrasonic assistance and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy disperse spectroscope (SEM-EDS), transmission electron microscopy (TEM) and N2 adsorption/desorption. The desulfurization activities were evaluated at a fixed bed reactor under a mixed gas simulated from flue gas. The results showed that desulfurization activity from excellent to poor is as follows: Fe/NAC-60>Fe/NAC-80>Fe/NAC-30>Fe/NAC-15>Fe/NAC-0>Fe/NAC-100>NAC. Fe/NAC-60 exhibits the best desulfurization activity and has breakthrough sulfur capacity of 319mg/g and breakthrough time of 540min. The introduction of ultrasonic oscillation does not change the form of Fe oxides on activated carbon but can change the dispersion and relative contents of Fe3O4. The types of oxygen-containing functional groups have no obvious change for all samples but the texture properties show some differences when they are oscillated for different times. The fresh Fe/NAC-60 has a surface area of 1045m2/g and total pore volume of 0.961cm3/g with micropore volume of 0.437cm3/g and is larger than Fe/NAC-0 (823m2/g, 0.733 and 0.342cm3/g). After desulfurization, surface area and pore volume of all samples decrease significantly, and those of the exhausted Fe/NAC-60 decrease to 233m2/g and 0.481cm3/g, indicating that some byproducts deposit on surface to cover pores. Pore size distribution influences SO2 adsorption, and fresh Fe/NAC-60 has more pore widths centralized at about 0.7nm and 1.0⿿2.0nm and corresponds to an excellent desulfurization activity, showing that micropore is conducive to the removal of SO2.

Liquid Fuels From Ethylene Tar by Two-stage Catalytic Hydroprocessing

Two-stage hydroprocessing of ethylene tar was performed on bench-scale equipment under typical reaction conditions of hydrogen pressure of 6 MPa, liquid hourly space velocity of 0.8 h–1, H2/oil volume ratio of 1,600, first-stage temperature of 360°C, and second-stage temperature of 380°C. Alumina-supported molybdenum-nickel (Mo-Ni) and tungsten-nickel (W-Ni) catalysts, which were prepared through combinational technologies of ultrasonic-assisted impregnation and temperature-programming, were filled in the first and second stages, respectively. Gasoline (≤180°C) and diesel (180–360°C) fractions separated from the produced oil were analyzed. Results showed that the ethylene tar can be considerably upgraded through two-stage catalytic hydroprocessing, and fuels with sulfur and nitrogen contents of less than 10 and 2 ppm, respectively, were obtained.

Enhanced stability of hydrochlorination of acetylene using polyaniline-modified Pd/HY catalysts

ABSTRACT A polyaniline (PANI)-modified zeolite Y supported Pd catalyst (Pd/PANI-HY) for acetylene hydrochlorination was successfully synthesized by ultrasonic-assisted impregnation. The catalyst exhibited excellent stability, and acetylene conversion was maintained at > 95% more than 300 h. The excellent stability of the Pd/PANI-HY catalyst was attributed to the presence of the polyaniline that partly weakens the occurrence of carbon deposition and also inhibited the reduction of the Pd 2 + active component on the catalyst surface.

Synthesis and characterization of Ag nanoparticles decorated mesoporous sintered activated carbon with antibacterial and adsorptive properties

In this study, the sliver nanoparticles (AgNPs) immobilized on the sintered activated carbon (Ag/SAC) were synthesized by the ultrasonic-assisted impregnation method and were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption. SEM showed that the AgNPs were well embedded in the SAC and immersion time had an important influence on final morphologies of AgNPs. Longer immersing duration caused significant aggregation of the AgNPs. The XRD data revealed that the successful synthesis of AgNPs on the SAC and immobilizing AgNPs on sintered active carbon did not change the crystalline degree of SAC. Texture characteristics were determined by analysis of the N2/77 K isotherms. The minimum inhibitory concentration (MIC) of Ag/SAC against Escherichia coli (DH5α) and Staphyloccocus aureus (ATCC 29213) was evaluated by a broth dilution method. MICs such as 5 mg/L (against E. coli) and 10 mg/L (against S. aureus) suggest that Ag/SAC have predominant antibacterial activity compared to active carbon.

Catalytic properties of Pd/HY catalysts modified with NH4F for acetylene hydrochlorination

Ammonium fluoride (NH4F) modified HY zeolite catalysts were prepared by ultrasonic-assisted impregnation and their efficient catalytic behavior in acetylene hydrochlorination reaction was investigated (the conversion of acetylene and the selectivity to vinyl chloride were all achieved above 99%). The results indicate that the presence of NH4F in Pd/HY catalysts can partially enhance the surface acidity of catalysts, and weaken the occurrence of carbon deposition and the loss of Pd active component on the catalyst surface, thus improving the catalytic performance of catalysts.

Ultrasonic-assisted preparation of highly reactive Fe–Zn sorbents supported on activated-char for desulfurization of COG

The desulfurization properties of Fe–Zn sorbent prepared by impregnating Fe and Zn into lignite char via ultrasonic-assisted impregnation (UAI) were investigated in comparison with the mechanical stirring (MS) method. The sulfidation experiments were carried out using a fixed-bed quartz reactor under ambient pressure. The amounts of metals loaded into char were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline phases and chemical structure of sorbents before and after sulfidation were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. The morphology of sorbents was analyzed by using scanning electron microscope (SEM) with an energy dispersive X-ray (EDX) auxiliary. The experimental results showed that metal oxides as the active components were evenly dispersed on char as nanoparticles. The impregnation of active components was significantly improved by the ultrasonic-assisted impregnation method. When sorbents were prepared by ultrasonic-assisted impregnation, the metal oxide particles became smaller and more evenly dispersed on the char matrix which resulted in higher desulfurization efficiency and sulfur uptake capacity of the sorbents. The BET results showed that the physical properties of sorbents (surface area and pore volume) significantly improved when prepared by UAI method compared to MS method. The sulfidation temperature had a significant effect on desulfurization performance of char supported sorbents. The Fe:Zn molar ratio of 2:1, and impregnation time of 9h were suggested as the optimal preparation conditions during ultrasonic-assisted impregnation.

Bamboo shaped carbon nanotube supported platinum electrocatalyst synthesized by high power ultrasonic-assisted impregnation method for methanol electrooxidation and related density functional theory calculations

Carbon nanotubes (CNTs) with special forms may exhibit novel properties, which are different compared to conventional carbon nanotubes and may open a way for future applications. The nanotubes with a bamboo-like structure due to nitrogen doping have been well studied because of the increased attention for their bamboo shaped structure associated properties. In this work, bamboo shaped carbon nanotubes (BCNTs), synthesized by chemical vapor deposition (CVD) method, were investigated for direct methanol fuel cells (DMFC). Small sized platinum nanoparticles (Pt NPs) were dispersed onto BCNT surface through a high power ultrasonic-assisted impregnation method in a short time. The structure and nature of the resulting Pt NP coated BCNT composites (Pt/BCNTs) were characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Energy dispersive spectroscopy (EDS). Density functional theory (DFT) calculations of Pt NPs coated on different structural CNTs showed that inclusion of nitrogen improved the catalytic performance of carbon nanotubes toward methanol electrooxidation. High electrochemical activity of BCNTs supported Pt NPs was demonstrated by the electrochemical studies.

Visible-light photocatalytic denitrogenation of nitrogen-containing compound in petroleum by metastable Bi20TiO32

Exploration of new system which selectively removes nitrogen-containing organic compounds in petroleum by photocatalytic catalysts is of great value on enriching the foundation of photocatalytic science as well as developing photocatalytic technologies in their practical applications in gasoline fuel. In this paper, tetrabutyl titanate was used as titanium source and bismuth nitrate was utilized as the source of bismuth, and Bi20TiO32 was synthesized using ultrasonic assisted impregnation method. The samples were characterized by X-ray diffraction (XRD), N2 adsorption–desorption (BET), and X-ray photoelectron spectroscopy (XPS). To evaluate its photocatalytic denitrogenation performance, simulated gasoline feed containing a certain concentration of pyridine was used as a reference. The analysis results showed that the synthesized Bi20TiO32 was a type of tetragonal crystal system of Bi–Ti oxide in metastable phase with nanosheet at a size of about 15 nm and band gap of 2.9 eV. This system can absorb the light ranging from UV to 500 nm wavelength. Under the irradiation of visible light above 420 nm wavelength for 150 min, the conversion of pyridine by photocatalytic degradation in 50 mL simulated feed (pyridine containing 100 μg/g) using 0.05 mg the photocatalyst was up to 86.0%. The visible light removal efficiency of pyridine was directly proportional with the illumination time, and there was no noticeable oxidation degradation of the solvent.

Desulfurization Activity of Ni/NAC Catalysts Prepared by Ultrasonic-Assisted Impregnation

Desulfurization Activity of Ni/NAC Catalysts Prepared by Ultrasonic-Assisted Impregnation

Catalytic Pyrolysis of Coffee Grounds Using NiCu-Impregnated Catalysts

NiCu/γ-Al2O3 catalysts with different Cu loadings were prepared using an ultrasonic-assisted impregnation method. The effect of the Cu content in the catalyst on the mass loss behavior of coffee grounds and the evolution of gaseous products during pyrolysis were investigated. The effect of two different heating rates of 10 and 60 °C/min on the catalytic pyrolysis was also studied. The mass loss and evolution of the main pyrolytic volatiles were analyzed with a thermogravimetric (TG) analyzer connected to a Fourier transform infrared (FTIR) spectrometer. The bio-oils collected from non-catalytic and catalytic pyrolyses of coffee grounds were subjected to gas chromatography–mass spectrometry (GC–MS) analysis. Gram–Schmidt curves obtained by TG–FTIR indicated that the addition of NiCu/γ-Al2O3 catalysts and the increase in the Cu content in the catalysts increased the concentrations of CO2 and CO in the produced gas evolved during coffee grounds pyrolysis. In comparison to the slow heating rate of 10 °C/min, ...

Effect of impregnation methods on sorbents made from lignite for desulfurization at middle temperature

With lignite after vacuum drying as the raw material, a series of Zn-based sorbents were prepared by static impregnation, ultrasonic-assisted impregnation, bubbling-assisted impregnation and high-pressure impregnation. The physical properties and the desulfurization performances of Zn-based sorbents were studied systematically by XRD, BET, AAS characterization techniques and the fixed-bed desulfurization evaluation apparatus. The sorbents obtained by high-pressure impregnation method have a larger specific surface area, pore volume and pore diameter comparing with other methods, which is conducive to the sulfidation reaction of hydrogen sulfide gas in the sorbent. The effects of pressure during the high-pressure impregnation and concentration of Zn(NO3)2 precursor solution on the sorbents properties and desulfurization behavior were investigated. The higher the impregnation pressure and the concentration of impregnation solution are, the greater the amount of the active components are uploaded. However, overhigh impregnation pressure can cause collapse and blocking of the carrier pore. The optimal operating condition of high-pressure impregnation method for preparing the sorbents was the impregnation pressure of 20 atm and the solution concentration of 41%. Under that condition, the sorbent had the best desulfurization ability with a sulfur capacity of 13.94 gS/100 gsorbent and a breakthrough time of 54 h. Its desulfurization precision and efficiency of removing H2S before sorbent breakthrough from the middle temperature gases of 400 °C can reach <5 ppm and >99%, respectively. Sorbents could be regenerated under the condition of 1 vol% O2, 20 vol% H2O, 0.5 vol%NH3, and N2 balance gas. The regenerated sorbent could be used for repeated absorption of H2S with a slight decrease in desulfurization effect.

Adsorption of Benzothiophene on Activated Carbon Supported Copper and Palladium

Deep desulfurization via π-complexation adsorption is a promising method for the purification of diesel. Activated carbon (AC) with copper and palladium deposited on their surfaces were investigated as adsorbents to remove benzothiophene (BT) from model diesel fuel. The adsorbents were prepared by ultrasonic-assisted impregnation and characterized using X-ray diffraction (XRD) and Scanning Electron Microscopy with Energy-dispersive X-ray Spectroscopy (SEM/EDS). The adsorption isotherms of BT were also investigated.