Xiaodong Wang

Study on composition, structure and formation process of nanotube Na2Ti2O4(OH)2

A nanotube material is obtained by the reaction of polycrystalline TiO2 with concentrated NaOH solution for 20 h at 110 °C. From the contents of Na, Ti and the structural water determined, it is concluded that the nanotube material is Na2Ti2O4(OH)2, rather than TiO2, TiOx or H2TiO3. After treating with an HCl solution of pH 1, nanotube Na2Ti2O4(OH)2 can be converted to nanotube H2Ti2O4(OH)2. The crystalline structure of such nanotube materials belongs to an orthorhombic crystalline system. TEM results indicate that nanotube Na2Ti2O4(OH)2 is formed in the reaction stage of TiO2 with concentrated NaOH solution. The formation process is discussed.

Self-organized vanadium and nitrogen co-doped titania nanotube arrays with enhanced photocatalytic reduction of CO2 into CH4

Self-organized V-N co-doped TiO2 nanotube arrays (TNAs) with various doping amount were synthesized by anodizing in association with hydrothermal treatment. Impacts of V-N co-doping on the morphologies, phase structures, and photoelectrochemical properties of the TNAs films were thoroughly investigated. The co-doped TiO2 photocatalysts show remarkably enhanced photocatalytic activity for the CO2 photoreduction to methane under ultraviolet illumination. The mechanism of the enhanced photocatalytic activity is discussed in detail.

AgBr modified TiO2 nanotube films: highly efficient photo-degradation of methyl orange under visible light irradiation

Anatase TiO2 nanotube film was prepared by calcination of the orthorhombic titanic acid nanotube at 400 °C. To expand the light absorption, AgBr nanoparticles were sensitized on TiO2 film. The AgBr–TiO2 nanotube film showed a high activity for MO photo-degradation under visible light irradiation. Moreover, the photocatalytic activity was further improved a lot after annealing of the AgBr–TiO2 nanotube film.

Photocatalytic oxidation of propylene on La and N codoped TiO 2 nanoparticles

Lanthanum- and nitrogen-codoped TiO2 photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO2 were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectra. The La-/N-codoped TiO2 showed excellent photoactivity of propylene oxidation compared with the single-doped TiO2 and La-/N-codoped P25 TiO2 nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

Fe0/Graphene Nanocomposite as a Catalyst for the Viscosity Reduction of Heavy Crude Oil

Fe0/graphene nanocomposites were prepared via a thermal polymerization method and used as a catalyst to reduce the viscosity of heavy crude oil. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms and thermal analysis. Their performance on the aquathermolysis of heavy crude oil was assessed in an autoclave. Under the reaction conditions of 200°C and 24 h, the viscosity of the oil was remarkably reduced when the catalysts were added.

Enhanced Heavy Oil Recovery in Mild Conditions by /- Solid Superacid Prepared by Different Methods

The important key of heavy oil efficient exploring is to decrease the viscosity and increase the flowability. Solid acid catalyst is one of the commonly used catalysts to reducing the viscosity of heavy oil, but good dispersion in oil phase and better catalytic activity are difficult to achieve. Herein, ZrO2-TiO2 was selected as the fundamental catalyst because of its superior solid superacid properties, and CTAB was selected as the surfactant package coat to help enhance catalytic activity. The as-prepared catalysts were characterized systematically by TEM, XRD, FTIR, and N2 adsorption-desorption isotherms measurement. The reduction efficiency of the heavy oil viscosity achieved as high as 66.3% at 180°C. At the same time, the portion of asphaltenes and resins slipped down by 4.93% and 3.78%, respectively, while saturated and aromatic hydrocarbon component increased by 5.37% and 3.26%, respectively, indicating that our catalyst showed a good activity for reducing the viscosity and improving the quality of heavy crude oil.

Preparation of Cerium Modified Titanium Dioxide Nanoparticles and Investigation of Their Visible Light Photocatalytic Performance

Mesoporous Ce/TiO2 nanoparticles have been successfully synthesized using titanate nanotubes as precursor through the hydrothermal-calcination method. The as-prepared materials were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), UV-vis diffuse reflectance spectra and nitrogen adsorption-desorption isotherm analysis. All the obtained Ce/TiO2 materials exhibit anatase phase. Ce element existed in two valance states of Ce3

Effect of reaction temperature and hydrogen donor on the Ni0@graphene-catalyzed viscosity reduction of extra heavy crude oil

ABSTRACT Ni0@graphene nanocomposites were prepared via a solvothermal method and used as the catalysts for the viscosity reduction of extra heavy crude oil. Higher graphene content in Ni0@graphene nanocomposite has an adverse effect on its catalytic activity. The addition of tetralin and higher reaction temperature can obviously promote the catalytic activity. The catalyst accompanied by hydrogen donor can attain a viscosity reduction rate of 84.3% after the catalytic reaction under 280°C for 24 h and reduce the viscosity of crude oil from 174,219 to 27,352 mPa s (measured at 50°C).

Aquathermolysis of heavy crude oil with ferric oleate catalyst

Oil-soluble catalysts could be of special significance for reducing the viscosity of heavy crude oil, because of their good dispersion in crude oil and high catalytic efficiency toward aquathermolysis. Ferric oleate was synthesized and applied as catalyst in the aquathermolysis reaction of Shengli heavy oil. It was found that ferric oleate was more efficient for heavy oil cracking than Co and Ni oleates. Besides, it was superior to oleic acid and inorganic ferric nitrate and achieved the highest viscosity reduction rate of up to 86.1%. In addition, the changes in the components of Shengli heavy oil before and after aquathermolysis were investigated by elemental analysis, Fourier transform infrared spectrometry, and 1H nuclear magnetic resonance spectroscopy. Results indicated that ferric oleate contributed to a significant increase in the content of light components and decrease in the content of resin, N and S. The as-prepared ferric oleate showed good activity for reducing the viscosity and improving the quality of the heavy crude oil, showing promising application potential in aquathermolysis of heavy crude oil.

Synthesis of SO 4 2− /Zr-silicalite-1 zeolite catalysts for upgrading and visbreaking of heavy oil

AbstractCatalyst is crucially important to reduce the viscosity of heavy oil during the catalytic aquathermolysis. SO42−-modified ZrO2-based nanoparticle catalyst is a commonly used catalyst. But less acid sites and poor hydrothermal stability limited further improving its catalytic performance and practical application. In this study, the Zr-doped silicalite zeolite catalysts with large surface area were prepared as a support matrix, and SO42−-modified Zr-doped silicalite zeolite (denoted as SO42−/Zr-silicalite-1 zeolite) was used as a solid superacid catalyst to crack the heavy oil. A reference catalyst of SO42−/Zr-SiO2 nanoparticles (NPs) was also prepared, which has the same composition with the SO42−/Zr-silicalite-1 zeolite catalyst. Compared with the SO42−/Zr-SiO2 NP catalyst, the amount of acid sites for the SO42−/Zr-silicalite-1 zeolite catalyst is significantly increased and the viscosity reduction efficiency is also enhanced by 40%. More importantly, the SO42−/Zr-silicalite-1 zeolite catalyst exhibits a high hydrothermal stability. After catalytic aquathermolysis, the quality of the heavy oil was also ameliorated. The heavy resins and asphaltenes reduced, while the light saturated and aromatic hydrocarbon increased. The results suggest metal element-doped silicalite zeolite catalyst is a potential useful way to solving the less acid sites and poor hydrothermal stability for the SO42−-modified nanoparticle catalyst. Graphical abstractCompared with the SO42−/Zr-SiO2 nanoparticle catalyst, the viscosity reduction ratio of the heavy oil is increased by 40% for the SO42−/Zr-silicalite-1(1:1) zeolite catalyst.