Jingchang Zhang

Study on the deactivation and regeneration of the ZSM-5 catalyst used in methanol to olefins

Abstract ZSM-5 zeolite catalyst modified by a trace of metal cations shows high activity and high selectivity for the reaction of methanol to olefins (MTO), but it inclines to deactivate during the reaction. In this paper, the mechanism of the catalyst deactivation and the regeneration method were studied by X-ray diffraction (XRD), N 2 adsorption-desorption, infrared spectra (IR), and infrared spectra coupled with NH 3 molecular probes (IR-NH 3 ). These characterizations indicated that coke formation was the main reason for the catalyst deactivation. To regenerate the deactivated catalyst, two methods, i.e., calcination and methanol leaching, were used. N 2 adsorption-desorption, IR and IR-NH 3 characterizations showed that both methods can eliminate coke deposited on the catalyst and make the catalyst reactivated. XRD showed that the structure of the catalyst did not change after regeneration. Interestingly, the regenerated catalyst even showed better catalytic performance of the MTO reaction than the fresh one. Besides, the calcination regeneration can eliminate coke more completely, however, the methanol leaching method can be more easily carried out in situ in the reactor.

Pt-Au/CNT@TiO2 as a High-Performance Anode Catalyst for Direct Methanol Fuel Cells

Multi-walled carbon nanotubes (CNT) modified using TiO2 nanoparticles (CNT@TiO2) were prepared. Then, Pt-Au/CNT@TiO2 catalysts were prepared by a deposition-UV-photoreduction method for direct methanol fuel cells. The physico-chemical properties of the catalysts were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic performance was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The Pt-Au nanoparticles were found to be uniformly deposited onto the CNT@TiO2 support and had diameters of 2–3 nm. Compared with the Pt-Au/CNT catalyst that was made using a general chemical method, Pt-Au/CNT@TiO2 exhibits higher CO-tolerance for the following reasons. Firstly, the strong interaction between the Pt-Au alloy and TiO2 leads to an increase in electron density on the metallic Pt-Au, which transfers electrons to the ϕ

Synthesis of Ti-Ce-Si Binary and Ternary Nanocomposite Photocatalyst by Supercritical Fluid Drying Technology

CO* orbital of CO and weakens C–O binding while the oxidation overpotential is lowered. Secondly, the high-valence Ti ions dissociate water to form OHad (ad: adsorbed) species, which then reacts with the strongly bound COad on the Pt surface to form CO2.

Enhanced luminescence of novel rare earth complexes Eu(3,5-DNBA)3Phen in nano-TiO2

Abstract Ti-Ce, Ti-Si binary and Ti-Ce-Si ternary novel nanocomposite oxide photocatalysts were prepared with cheap in organic salts TiCl4, Na2SiO3·9H2O and Ce(NO3)3·6H2O as precursors by supercritical fluid drying (SCFD) technology. The catalysts were characterized by means of XRD and TEM. The particle size of nanocomposite oxide photocatalysts synthesized by SCFD method is about 6 ∼ 11 nm, which is smaller than those obtained by common drying method (CD). The phase transformation from anatase to rutile was inhibited by SCFD technology. The peaks of SiO2 and CeO2 in XRD patterns indicate that a SiO2 amorphorous phase exists in all the samples and CeO2 is well dispersed on the surface of TiO2. The orthogonal test was designed to optimize the preparing conditions. It is found that ceria doping enhances the photocatalytic activity markedly, and the optimum doping of CeO2 is 0. 1 %. The thermal stability of photocatalyst can be improved; the growth of particle-size and the decrease of surface area can be prohibited by doping of SiO2. Heat-tieatment is a necessary factor to induce chemistry change of Ti-Si surface. The optimum heat-treating temperature is 600 °C. A novel and efficient Ti-Ce-Si ternary nanocomposite was prepared by SCFD method with strong thermal stability and high photoactivity in the photodegratation of phenol.

In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering

Eu(3+) (or Tb(3+)) of 3,5-dinitrobenzoic acid and 1,10-phenanthroline ternary rare earth complexes were synthesized and characterized by thermal analysis, infrared spectroscopy, elemental analysis and fluorescence spectroscopy. In this study an organic-inorganic combined device indium tin oxide/poly(N-vinylcar-bazole):RE(3,5-DNBA)(3)Phen:TiO(2)/Al was fabricated. The nano-TiO(2) has been used in the luminescence layer to change the electroluminescence property of RE(3,5-DNBA)(3) Phen (RE=Eu(3+)or Tb(3+)).

Electronic structure effect of polythiophene derivatives and nano N-Zn-Ag/TiO 2 on performance of organic thin film solar cell

Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing.

Development of multifunctional nanoparticles towards applications in non-invasive magnetic resonance imaging and axonal tracing

Nanocrystal N-Zn-Ag/TiO2 powders were prepared with N-Zn/TiO2 by photo deposition method. A series of pure polymers P3HT[poly(3-hexylthiophene)], P3OT[poly(3-octylthiophene)], P3DT[poly(3-decylthiophene)] and P3DDT[poly(3-dodecylthiophene)], was synthesized, which were used to synthesize p-n type semiconductor materials P3HT/N-Zn-Ag-TiO2, P3OT/N-Zn-Ag-TiO2, P3DT/N-Zn-Ag-TiO2 and P3DDT/N-Zn-Ag-TiO2 by in situ chemical method. X-Ray diffraction(XRD) and infrared(IR) spectroscopy showed the structure of the polymers and complexes. Ultraviolet-visible(UV-Vis) spectra and cyclic voltammograms(CV) showed the optical and electronic performance of the polymers and complexes. Two new single and double organic thin film heterojunction solar cells were prepared with the above mentioned synthesized powders as raw materials. Current-voltage(I–V) measurements indicate that the conversion efficiency of the single organic thin film heterojunction solar cell is higher than that of the double organic thin film heterojunction solar cells. Single organic thin film heterojunction solar cells based on P3DT/N-Zn-Ag-TiO2 can get a photoelectric conversion efficiency of 0.0408%. The performance of electronic transform between electron donor and acceptor on organic thin film solar cells was researched.

Study on Luminescence Properties of a Novel Rare Earth Complex Eu(TTA)2 (N-HPA)Phen

A multifunctional nanobiomaterial has been developed by deliberately combining functions of superparamagnetism, fluorescence, and axonal tracing into one material. Superparamagnetic iron oxide nanoparticles were first synthesized and coated with a silica layer to prevent emission quenching through core–dye interactions; a fluorescent molecule, fluorescein isothiocyanate, was doped inside second layer of silica shell to improve photo-stability and to enable further thiol functionalization. Subsequently, biotinylated dextran amine, a sensitive axonal tracing reagent, was immobilized on the thiol-functionalized nanoparticle surfaces. The resulting nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis spectroscopy, magnetic resonance imaging and fluorescence confocal microscopy. In vitro cell experiments using both undifferentiated and differentiated Neuro-2a cells showed that the cells were able to take up the nanoparticles intracellularly and that the nanoparticles showed good biocompatibilities. In summary, this new material demonstrated promising performances for both optical and magnetic resonance imaging modalities, suggesting its promising potentials in applications such as in non-invasive imaging, particularly in neuronal tracing.Graphical abstract

Developing a non-fouling hybrid microfluidic device for applications in circulating tumour cell detections

Abstract A novel rare earth complex Eu (TTA) 2 (N-HPA) Phen (TTA = thenoyltrifluoroacetone, N-HPA = N-pheny-lanthranilic acid, and phen = 1, 10-phenathroline), which contains three different ligands, was synthesized. The Eu complex was blended with poly N-vinylcarbazole (PVK) in different weight ratios and spin coated into films. The luminescence properties of films were investigated and energy transfer between PVK and the complex was discussed. Multilayer structural devices consisting of ITO/PVK: Eu(TTA) 2 (N-HPA) phen/BCP/Alq 3 /Al were fabricated with PVK: Eu (TTA) 2 (N-HPA) as light-emitting layer. Increasing the concentration of Eu in the PVK thin film would inhibit the emission of PVK to different degrees. Finally, the pure red luminescence of europium (III) was observed when the doping weight ratio was approximately 1:5, which indicated an effective energy transfer from PVK to rare earth complex.

12-tungstophosphoric acid supported on MCM-41 for esterification of fatty acid under solvent-free condition

Non-specific cell adsorption is a challenge in sensitive detections using microfluidic systems, such as detecting circulating tumour cells from blood samples. In this report, we present a new strategy to study the combined effects of surface hydrophilicity/hydrophobicity, electric charges and roughness on surface non-fouling properties of a PDMS/SU-8 microfluidic system. To achieve this, microchannel surfaces were modified by poly(amidoamine) generation 4 and generation 7, dendrimers that rendered surfaces negatively and positively charged at pH 7.4, respectively. Water contact angle, atomic force microscopy (AFM) and microscopy were used to characterize and confirm surface modifications, and the non-fouling performance of the resulting surfaces was tested using both live and dead CCRM-CEM cancer cells. Our results show that for live cells, electric charges of a surface is the most important factor affecting the non-fouling features of the surface in microfluidic systems; in contrast, for dead cells, surface hydrophilicity is the most important factor affecting surface non-fouling properties. However, surface roughness does not seem to be as important for both live and dead cells under the experimental conditions used in this study. These results also highlight the importance of different considerations when designing a lab-on-a-chip microfluidic system for high sensitivity biosensing and detection applications.