Research on KOH/La-Ba-Al2O3 catalysts for biodiesel production via transesterification from microalgae oil

Alumina supports modified by lanthanum(La)and barium(Ba)were prepared by peptization.Catalysts with different KOH contents supported on modified alumina were prepared by impregnation method.Various techniques,including N2 adsorption-desorption(Brunauer-Emmet-Teller method,BET),X-ray diffraction(XRD),scanning electron microscopy(SEM),and fourier transform infrared absorption spectroscopy(FT-IR). Catalytic activity for microalgae oil conversion to methyl ester via transesterification was evaluated and analyzed by GC-MS and GC.BET results showed that the support possessed high specific surface area,suitable pore volume and pore size distribution.Activity results indicated that the catalyst with 25 wt%KOH showed the best activity for microalgae oil conversion.XRD and SEM results revealed that Al-O-K compound was the active phase for microalgae oil conversion.The agglomeration and changing of pore structure should be the main reasons for the catalyst deactivation when KOH content was higher than 30 wt%.     

Ni/MgO catalyst prepared using atmospheric high-frequency discharge plasma for CO2 reforming of methane

A new type of Ni/MgO catalyst was prepared using atmospheric high-frequency discharge cold plasma. The influences of conventional method, plasma method, and plasma plus calcination method on the catalytic activity were studied and the CO2 reforming of methane was chosen as the probe reaction. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy, and CO2 temperature-programmed surface reaction techniques. The results suggested that the nickel-based catalyst prepared by plasma plus calcination method possessed a smaller particle size and a higher dispersion of active component, better low-temperature activity and enhanced anti-coking ability. The conversion of CO2 and CH4 was 90.70% and 89.37%, respectively, and the reaction lasted for 36 h without obvious deactivation under 101.325 kPa and 750°C with CO2/CH4 = 1/1.     

苝染料敏化Pt/TiO2光催化分解水制氢

The photocatalyst (DPPBI/Pt/TiO2)was prepared using N,N’-di(4-pyridyl)-3,4,9,10-perylene tetracarboxylic acid bisimide (DPPBI) sensitized Pt/TiO2 and characterized by infrared spectroscopy(IR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), and X-ray diffraction (XRD). The results of characterizationshowedthat the crystal form of TiO2was anatase, Ptwas highly dispersed on the surface of TiO2 and DPPBI was adsorbed on the surface of Pt/TiO2 in DPPBI/Pt/TiO2. Hydrogen production from water splitting using photocatalyst (DPPBI/Pt/TiO2) was studied. It has been found that the rate of hydrogen evolution reaches 6.69 滋 mol·h-1·g-1 under visible light irradiation for 8 h with 300 W Xe-lamp cold light source when 250 mL reactive liquid contains 0.8 g·L-1 photocatalyst (0.1%DPPBI/0.4%Pt/TiO2) and 0.2 mol·L-1 KI.     

Effects of CeO_2 preparation methods on the catalytic performance of MoO_3/CeO_2 toward sulfur-resistant methanation

CeO_2 supports were prepared by calcination or precipitation method and 5% MoO_3/CeO_2 catalysts were prepared by incipient-wetness impregnation method. The catalytic performance of the 5% MoO_3/CeO_2 catalysts toward sulfur-resistant methanation was investigated. The results showed that the Mo/Ce-1 catalysts with CeO_2 support prepared by calcination method exhibited the best sulfur-resistant methanation activity and stability with CO conversion as high as 75% while the Mo/Ce-3 catalysts the poorest. The supports and catalysts were characterized by N_2-adsorption–desorption, temperature-programmed reduction(TPR), X-ray diffraction(XRD), Raman spectroscopy(RS) and scanning electron microscope(SEM). The results indicated that the saturated monolayer loading MoO_3 on Ce-3 support was lower than 5% and there were some crystalline MoO_3 particles on the surface of the Mo/Ce-3. The preparation method of CeO_2 had a big influence on the specific surface area, the crystalline of CeO_2, and the catalytic performance of the corresponding Mo-based catalyst for sulfur-resistant methanation.     

纳米 Ce1MgxZr1-xO2 固体多相催化剂的制备、表征及催化合成四氢苯并[b]吡喃衍生物的性能

 A series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, temperature-pro- grammed desorption of CO2, and N2 adsorption techniques. The prepared materials were tested for catalytic activity by the synthesis of tet-rahydrobenzo[b]pyran derivatives using a three component reaction (aromatic aldehydes, malononitrile, and dimedone) in an ethanol me-dium. The best catalytic activity was obtained with Ce1Mg0.6Zr0.4O2. The particle size or crystallite size was estimated using the De-bye-Scherrer equation. The addition of magnesium oxide into the ceria-zirconia lattice resulted in the formation of nanosized particles rang-ing from 5.41 to 9.78 nm. This work describes the catalytic behavior of magnesium oxide in mixed metal oxide systems.     

PREPARATION OF Au/SULFONATED POLYSTYRENE CATALYSTS FOR LOW-TEMPERATURE CO OXIDATION*

Supported An catalysts for low-temperature CO oxidation were prepared by solvated motal atom impregnation(SMAI) and conventional impregnation (CI). X-ray photoelectron spectroscopy (XPS) investigations indicated that theelemental gold in all the samples was in the metallic state. XRD measurements showed that the mean diameters of Auparticles prepared by SMAI were smaller than those prepared by CI with the same gold content. Catalytic tests showed thatthe SMAI catalyst had higher CO oxidation activity than the CI catalyst with the same compositions. Both SMAI and CIcatalysts exhibited high activity in low temperature CO oxidation. Full CO conversion was obtained at 323--383K.     

In-situ hydrothermal synthesized γ-Al_2O_3/O-g-C_3N_4 heterojunctions with enhanced visible-light photocatalytic activity in water splitting for hydrogen

In this work,γ-Al_2O_3 and hydrogen peroxide treated g-C_3N_4(O-g-C_3N_4) were combined through a novel in-situ hydrothermal method to form heterojunction structured photocatalysts.These photocatalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy(PL).FT-IR results indicate that oxygen functional groups can be grafted on the surface of O-g-C_3N_4 by hydrogen peroxide treatment.The visible light photocatalytic hydrogen evolution rate was investigated in 10 vol% TEOA aqueous solution.The optimal Al_2O_3 mass content is set to be 20 wt% and the corresponding hydrogen evolution rate is 1288 μmol/h/g which is approximately 6,3 folds that of pristine g-C_3N_4 and O-g-C_3N_4 respectively and 1.6 folds that of mechanical mixed composite with the same Al_2O_3 mass content.The photocurrent density–time curves were carried out under visible light illumination for four on–off cycles.The electrochemical impedance spectroscopy(EIS) measurements verified the enhanced separation efficiency of electron–hole pairs.This work raised a new method to form the heterojunction structured photocatalysts and achieved a remarkable improvement of the photocatalytic activity in water splitting for hydrogen under visible light irradiation.     

BiIO_4 Nanoflakes for the Degradation of Phenol under Simulated Solar Light Irradiation

BiIO_4 nanoflakes were successfully prepared through a facile hydrothermal method. The as-prepared BiIO_4 was characterized by scanning electron microscope(SEM), high-resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), energy-dispersive spectroscopy(EDS) and ultraviolet visible diffuse reflectance spectroscopy. BiIO_4 nanoflakes showed excellent photocatalytic activity for the degradation of phenol solution under simulated solar irradiation. The influence of synthesis temperature on the morphology, size and photocatalytic performance of BiIO_4 was investigated. BiIO_4 prepared under 140 ℃ exhibited the highest removal rate of phenol under simulated solar light irradiation. In addition, the parametric studies such as the effect of catalyst loading and phenol solution pH were carried out to optimize the reaction conditions. The active species trapping experiment demonstrated that h~+ and ·OH are the major active species during the photocatalytic process.     

水热法合成多孔Ag_2S敏化二氧化钛催化剂及其可见光催化活性(英文)

Porous Ag2S sensitized TiO2 catalysts were synthesized by the hydrothermal process.The crystallization and porous structure of the Ag2S/TiO2 composite photocatalysts were investigated by X-ray diffraction,scanning electron microscopy with energy dispersive X-ray analysis,UV-Vis diffuse reflectance spectroscopy,and N2 adsorption.The Ag2S/TiO2 composites were mainly composed of anatase TiO2 and acanthite Ag2S.The absorption edge wavelengths of TiO2 and the Ag2S/TiO2 composite prepared with 3 mmol Na2S.5H2O were 400 and 800 nm,respectively,that is,the absorption edge of the composite had a pronounced red shift.The photocatalytic activity under visible light was investigated by the degradation of methylene blue with a UV-Vis spectrophotometer.The photocatalytic activities under visible light of the Ag2S/TiO2 photocatalysts were much higher than that of TiO2.     

Synthesis of KNiF3 with Lower Oxygen Content by Refluxing Method

The complex fluoride,KNiF3,with perovskite structure was synthesized by refluxing KF and Ni(NO3)2·6H2O in ethanediol.The samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),and ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS).The results indicate that the mean diameter of KNiF3 particles is about 30―60 nm and the oxygen content in the samples is≤5%.The prepared KNiF3 shows obvious absorption peaks at 400―830 nm.     

Coordination mechanism,characterization, and photoluminescence properties of spinel ZnAl<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles prepared by a modified polyacrylamide gel route

Single-phase ZnAl₂O₄ nanoparticles with the spinel structure were successfully synthesized using a modified polyacrylamide gel method according to the atomic ratio of Zn to Al = 1: 1.8. The as-prepared samples were characterized by means of X-ray powder diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry analysis (DSC), field-emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) spectra. XRD patterns show that the pure phase of ZnAl₂O₄ is obtained after heating the xerogel at 900°C for 5 h in air. The SEM images reveal that the ZnAl₂O₄ nanoparticles have a narrow particle size distribution and the average particle size is around 45 nm. Photoluminescence (PL) spectra demonstrate the single phase ZnAl₂O₄ nanoparticles have an emission peak located at 469 nm when excited by 350 nm light. The phase structure, coordination mechanism, and luminescence properties have been discussed on the basis of the experimental results.     

Shape controlled synthesis of CaMoO4 thin films and their photoluminescence property

CaMoO₄ (CMO) disordered and ordered thin films were prepared by the complex polymerization method (CPM). The films were annealed at different temperatures and time in a conventional resistive furnace (RF) and in a microwave (MW) oven. The microstructure and surface morphology of the structure were monitored by atomic force microscopy (AFM) and high-resolution scanning electron microscopy (HRSEM). Order and disorder were characterized by X-ray diffraction (XRD) and optical reflectance. A strong photoluminescence (PL) emission was observed in the disordered thin films and was attributed to complex cluster vacancies. The experimental results were compared with density functional and Hartree-Fock calculations.     

Characterization of nanosized ZnAl<Subscript>2</Subscript>O<Subscript>4</Subscript> spinel synthesized by the sol–gel method

Single-phase zinc aluminate (ZnAl₂O₄) nanoparticles with the spinel structure was successfully obtained by the sol–gel method. The nanoparticles are crystalline with no impurities related to ZnO or Al₂O₃ residues. The microstructural environment of aluminum ions changes with heat treatment temperature, as observed by FT-IR and also by ²⁷Al solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. The photoluminescence spectra show that the emission of pristine ZnAl₂O₄ may change depending on the calcining temperature due to the quantum size effect.     

一锅法制备Co3O4/g-C3N4复合光催化剂及其光催化性能

以三聚氰胺和六水合氯化钴为原料,一锅法制备Co_3O_4负载的多孔石墨相氮化碳(Co_3O_4/g-C_3N_4)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)等手段对其结构和光学特性进行表征。以盐酸四环素(TC)为目标污染物,评价了不同负载量Co_3O_4/g-C_3N_4复合光催化剂的可见光催化性能。结果表明,所制备的Co_3O_4/g-C_3N_4复合光催化剂为多孔结构,其比表面积较大,并在可见光区域具有显著的吸收。利用原位生成的Co_3O_4纳米粒子在氮化碳表面形成异质结构,可有效转移光生载流子,降低光生电子-空穴的再结合率,从而提高光催化活性。并且存在最佳Co_3O_4复合量,当六水合氯化钴加入量为三聚氰胺的8%(w/w)时,所制备的复合光催化剂CoCN-8具有最佳的光催化性能。在可见光的照射下,60 min内可降解85%的TC,而同样条件下,纯g-C_3N_4仅降解23%的TC。     

Sol-gel preparation and spectroscopic study of the pyrophanite MnTiO<Subscript>3</Subscript> nanoparticles

The nanosized xerogel of titanium dioxide (TiO₂) and manganese oxides (MnO₂, Mn₂O₃, Mn₃O₄) was prepared by the sol-gel method using manganese chloride (MnCl₂·4H₂O) and titanium isopropoxide (Ti(O-iPr)₄) as precursors in cetyltrimethylammonium bromide (CTAB)/ ethanol/H₂O/HCl micelle solutions, following the calcinations of the produced powders at difference temperatures. The nanostructure and phase composition of these nanoparticles were characterized with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The spectroscopic characterizations of these nanoparticles were also done with UV-Vis spectroscopy and laser Raman spectroscopy (LRS). XRD patterns show that the pyrophanite MnTiO₃ phase was formed at the calcinations temperature of 900°C. The TEM images show that the nanoparticles are almost spherical or slight ellipose and the sizes are 50 nm on average. The UV-Vis spectra show that the nanosized MnTiO₃ have significant absorption bands in the visible region. There are new absorption peaks of MnTiO₃ nanoparticles in LRS compared with the pure TiO₂ powder.     

氯掺杂二氧化钛柱撑蒙脱土的合成及光催化性能

采用溶胶 凝胶法制备了氯掺杂二氧化钛柱撑蒙脱土催化剂。 利用XRD、SEM、UV-Vis-DRS、光致发光谱(PLS)、N2吸附-脱附和XPS等测试技术对其进行了表征。 结果表明,该催化剂具有明显的锐钛矿相结构,且氯掺杂与二氧化钛柱撑后,蒙脱土的层间结构没有完全被破坏;氯掺杂拓宽了其光吸收范围,在可见光区吸收增强;其带隙能由3.19 eV减小至3.14 eV;氯以阴离子形式存在于TiO2晶格中。 对硝基苯胺降解实验表明,氯掺杂可显著提高二氧化钛柱撑蒙脱土的光催化活性,氯掺杂量为6%(与钛的摩尔比)的催化剂具有较好光催化活性。     

Synthesis and characterization of Eu-doped hydroxyapatite through a microwave assisted microemulsion process

Europium doped hydroxyapatite (Eu:HAp) nanosized particles with multiform morphologies have been successfully prepared via a simple microemulsion-mediated process assisted with microwave heating. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and the kinetic decays, respectively. The results reveal that the obtained Eu:HAp particles are well assigned to the hexagonal lattice structure of the hydroxyapatite phase. Additionally, it is found that samples exhibit uniform morphologies which can be controlled by altering the pH values. Furthermore, the samples show the characteristic ⁵D₀–⁷F_1–4 emission lines of Eu³⁺ excited by UV radiation.     

偏硼酸锶催化剂光催化还原CO2合成CH4

采用溶胶-凝胶法制备出偏硼酸锶(SrB₂O₄)光催化剂. 紫外光催化还原CO₂合成CH₄(在液相水中)的实验证明: SrB₂O₄催化剂的光催化活性略高于TiO₂(P25). 利用X射线电子衍射谱(XRD)、傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、荧光(PL)光谱和紫外-可见(UV-Vis)漫反射吸收光谱等技术, 研究了SrB₂O₄ 催化剂的晶体结构、形貌和能带结构. 结果表明: SrB₂O₄ 的价带为2.07 V (vs normalhydrogen electrode (NHE)), 低于(H₂O/H⁺)的氧化还原电位E_redox^o (0.82 V (vs NHE)); 而导带为-1.47 V (vsNHE), 高于(CO₂/CH₄)的氧化还原电位E_redox^o (-0.24 V (vs NHE)). 因此, SrB₂O₄催化剂可以有效地光催化还原CO₂生成CH₄. 与TiO₂(P25)相比, SrB₂O₄催化剂具有相对较高导带, 光生电子的还原能力强于TiO₂(P25), 更有利于CH₄的生成, 从而决定了SrB₂O₄催化剂光催化还原CO₂合成CH₄具有较高的光催化活性.     

Effects of Cobalt Doping on the Microstructure and Optical Properties of ZnAl2O4 Nanoparticles

Co-doped ZnAl₂O₄ nanoparticles were prepared by hydrothermal method. The samples were characterized by XRD, HRTEM, EDX, FT-IR, XPS, PL, and UV–Vis, and the effects of cobalt doping on the microstructure and optical property of the samples were studied. The experimental results showed that Co-doped ZnAl₂O₄ nanoparticles synthesized by this method are single phase with cubic crystal structure, no other impurity phases were observed. Furthermore, with increasing the Co²⁺ concentration, the average crystallite size of the Co-doped samples became smaller. The absorption bands in FT-IR spectra are broadened in the low frequency region, the PL spectra had the red-shift and the UV–Vis peaks intensity gradually enhanced.

     

Structural,optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl₂O₄:Ce³⁺) increased the photocatalytic activity of zinc aluminate.