Structure and Catalytic Performance of Mg‐SBA‐15‐Supported Nickel Catalysts for CO2 Reforming of Methane to Syngas

A series of Mg‐modified SBA‐15 mesoporous silicas with different MgO contents were successfully synthesized by a simple one‐pot synthesis method and further impregnated with Ni. The Mg‐modified SBA‐15 materials and supported Ni catalysts were characterized by N₂ physisorption (BET), X‐ray diffraction (XRD), temperature‐programmed desorption of CO₂ (CO₂‐TPD), temperature‐programmed H₂ reduction (H₂‐TPR), and temperature‐programmed hydrogenation (TPH) techniques and used for methane dry reforming with CO₂. CO₂‐TPD results proved that the addition of Mg increased the total amount of basic sites which was responsible for the enhanced catalytic activity over the Mg‐modified Ni catalyst. The excellent catalytic stability of Ni/8Mg‐SBA‐15 was ascribed to less coking and higher stability of the Ni particle size due to the introduction of Mg.     

Removal of methylene blue from coloured effluents by adsorption onto SBA‐15

Adsorption has been proven to be the most efficient method for quickly lowering the concentration of dissolved dyes in an effluent. In this regard, activated carbon is the most widely used adsorbent for removal of dyes from aqueous solution. However, the high cost of production and regeneration make it uneconomical. Therefore, inorganic adsorbents (e.g. zeolites) with high surface areas have been used as alternatives to carbon adsorbents. Microporous zeolites ZSM‐5, NH₄‐Beta, MCM‐22 and mesoporous materials MCM‐41 have been investigated for the removal of dyes from aqueous solutions and they show effective adsorption performance. SBA‐15 possesses a larger pore size and pore wall thickness than MCM‐41. As a result, SBA‐15 has greater potential for the adsorption of methylene blue with larger molecule size and higher hydrothermal stability than the M41S family. SBA‐15 is an excellent adsorbent for methylene blue (MB), exhibiting 280 mg g^?1 adsorption capacity and about 100% fading rate for MB. The adsorptive process is so fast that adsorption equilibrium is achieved in 5 min. In addition, SBA‐15 can be effectively recovered by calcination and reused 10 times without significant loss in removal of MB from aqueous solution. The efficient adsorption of MB molecules onto SBA‐15 was ascribed to MB adsorbed into the pore channels of SBA‐15, which was confirmed by nitrogen physisorption analysis of the adsorbent before and after adsorption. The long reuse life of the adsorbent suggests a high potential for application in industry. Copyright © 2010 Society of Chemical Industry     

Synergistic effect of mesoporous silica SBA‐15 on intumescent flame‐retardant polypropylene

Mesoporous silica SBA‐15 synthesized from Pluronic P123 and tetraethoxysilane was used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame‐retardant (IFR) system. Limiting oxygen index (LOI), UL‐94 rating and thermogravimetric analysis were used to evaluate the synergistic effect of SBA‐15 on PP/IFR system. It showed that PP/IFR system could reach V‐0 with loading of SBA‐15 ranging from 0.5 to 3 wt%, while without SBA‐15 it had no rating at UL‐94 test. The LOI value increased from 25.5 to 32.2 when the loading of SBA‐15 was 1 wt%. The thermal stability of PP/IFR was improved in the presence of SBA‐15 and the amount of the char residue at 600° C was increased from 8.96 to 16.42 wt% when loading of SBA‐15 varied from 0.5 to 5 wt%. Laser Raman spectroscopy (LRS) and scanning electron microscopy were employed to study the morphology of the char residue of PP/IFR system with and without SBA‐15. Copyright © 2010 John Wiley & Sons, Ltd.     

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

Directed isomerisation of safflower oil under very low hydrogen partial pressure of 7 psi over a novel bifunctional highly structured rhodium‐based catalyst (Rh/SBA‐15), having narrow pore size distribution ranging from 4 to 8 nm, and BET‐specific surface of ≈1,000 m² g^?1, was investigated as a new chemocatalytic approach for vegetable oil hardening and simultaneously producing health‐beneficial conjugated linoleic acids (CLA). Time course profiles of (cis‐9, trans‐11)‐; (cis‐10, trans‐12)‐; (trans‐10, cis‐12)‐; (cis,cis)‐ and (trans, trans)‐octadecadienoic isomers (CLAs) as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed under selected process conditions. Preliminary results show that it is possible to tailor characteristics of the hydrogenation catalyst in such way to confer its bi‐functional activity: hydrogenation and conjugation isomerisation. © 2011 Canadian Society for Chemical Engineering     

Removal of ammonium cations from aqueous solution using arene‐sulphonic acid functionalised SBA‐15 as adsorbent

Removal of ammonium cations from aqueous solution was investigated using an arene‐sulphonic acid functionalised mesostructured SBA‐15 material as adsorbent. Arene‐sulphonic acid‐SBA‐15 (AS‐SBA‐15) was prepared via a co‐condensation strategy using tetraethylorthosilicate (TEOS) and 2‐(4‐chlorosulphonylphenyl)ethyltrimethoxysilane (CSPTMS) as framework precursors under acidic conditions. The material exhibited high surface area (680 m²/g) and total pore volume (0.84 mL/g). The effects of adsorbent loading, initial ammonium concentration, temperature, pH and the presence of competitive ions on the adsorption performances were investigated. The ammonium removal increased with the increase of the adsorbent loading and the decrease of the initial concentration. The adsorption capacity decreased with increasing the temperature. Maximum adsorption capacity obtained at 5°C was ca. 19 mg NH/g adsorbent. The isotherms data were studied using different adsorption models and thermodynamic parameters were calculated. Competitive ions such K⁺ and Na⁺ slightly affected the ammonium adsorption. After six adsorption–desorption cycles, the adsorbent retained its adsorption capacity.     

Humidity sensitivity of polypyrrole and polypyrrole/SBA‐15 host–guest composite materials

Polypyrrole (PPY) and PPY/SBA‐15 host–guest composite materials have been prepared using chemical synthesis route and characterized by XRD, IR, N₂ adsorption–desorption isotherms, and SEM. The humidity sensitive properties (HSP) of this kind of materials have been studied by analyzing the variation curve of impedance as a function of relative humidity. It was found that the PPY/SBA‐15 host–guest composites materials exhibit better HSP than that of the corresponding pure PPY. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3301–3305, 2006     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Synthesis of TPA impregnated SBA‐15 catalysts and their performance in polyethylene degradation reaction

Tungstophosphoric acid (TPA)‐containing mesoporous santa barbara amorphous (SBA)‐15 materials were synthesized by impregnation of TPA into hydrothermally synthesized SBA‐15. TPA was incorporated to the porous framework of silica with different W/Si ratios, using TPA hydrate as the acid source. The synthesized materials had a surface area range of 212–825 m² g^?1, depending on the TPA loading and exhibited Type IV adsorption–desorption isotherms. Energy dispersive spectrometry and X‐ray photoelectron spectroscopy (XPS) analyses showed that TPA was successfully penetrated into mesopores of the SBA‐15 material. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of the pyridine adsorbed synthesized materials revealed the existence of Lewis and Brønsted acid sites in the synthesized materials. Their performances were tested in the degradation of polyethylene by thermogravimetric analysis. An increase in TPA content significantly lowered the degradation temperature and activation energy of the polyethylene degradation reaction. In the presence of TPA‐incorporated SBA‐15 catalyst, activation energy was reduced to approximately half‐value of the value found in the absence of the catalyst. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2466–2472, 2012     

Adsorptive removal of nitrate and phosphate anions from aqueous solutions using functionalised SBA‐15: Effects of the organic functional group

Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering     

催化湿式氧化3-甲基吡啶农药废水的研究

以过渡金属Cu为主要活性组分,与过渡金属Mn复合,研制出催化湿式氧化法(CWO)处理含3-甲基吡啶农药废水的复合金属氧化物催化剂。结果表明,新制备的复合催化剂氧化活性显著提高,并有效地抑制铜的溶出。通过对氧气分压、反应温度和废水pH 等工艺条件的考察,催化湿式氧化法处理含3-甲基吡啶农药废水的适宜工艺条件为：190 ℃,氧分压1.60 MPa,pH＝8.28。在此条件下,用自制催化剂处理初始质量浓度为15 430 mg·L^－1的废水,在120 min 内,废水COD去除率达到92%,说明可生化性能良好。     

直接合成Nb-SBA-15催化氧化苯乙烯

用直接合成法制备Nb-SBA-15介孔分子筛,并用XRD、BET、FT-IR和DTA测试手段对其进行分析。结果表明,Nb-SBA-15仍保留高度有序的介孔结构。以质量分数30%的H2O2为氧化剂,丙酮为溶剂,对Nb-SBA-15催化氧化苯乙烯反应进行了研究,试验得到较适宜工艺条件为:反应温度为70℃,反应时间为10 h,催化剂用量为原料质量的10.0%,n(苯乙烯)∶n(H2O2)∶n(丙酮)=1∶2∶2,苯乙烯的转化率可达43.21%,苯甲醛的选择性为94.32%。     

筛板塔Fe/Cu湿式催化氧化脱除H2S气体制硫磺的实验

阐述了筛板塔Fe/Cu湿式催化氧化脱除H₂S气体制硫磺流程,考察了操作空塔气速、液气比、起始pH值和H₂S入口浓度对H₂S脱除效率的影响及鼓风量、液柱高度对Fe^3＋氧化再生的影响;并进行了综合实验。结果表明,含120g/L的Cu²⁺、70g/L的Fe²⁺及70g/L的Fe³⁺的吸收体系即能对体积分数为1000×10^－6的H₂S废气近100％稳定脱硫,流程简短、能耗低,体系除消耗O₂外,过程不消耗原料,不产生二次污染,体系无降解问题。     

Catalytic Oxidative Dehydrogenation of n‐Butane on Gallium Nitride‐Containing Titanosilicate Catalyst

GaN‐containing titanosilicate catalysts were used for the first time for the oxidative dehydrogenation (ODH) of n‐butane at a relatively low reaction temperature (460 °C). Commercially available GaN powder with a wurtzite crystal structure showed superior reactivity and stability for the ODH of n‐butane. The catalytic property of GaN catalyst for ODH strongly depends on the GaN particle size. The effects of the GaN weight percentage and GaN particle size on the catalytic performance are investigated in a fixed bed reactor. Based on the physicochemical properties of the catalyst characterized via TEM, DLS, N₂ adsorption‐desorption, XRF, O₂‐TPD, XRD, XPS, and in‐situ FTIR, the textural and structural properties of catalyst were obtained. The catalytic results reveal that the presence of GaN increases the activity of the catalysts, indicating that GaN can be used as a new active phase for the ODH of n‐butane. XRD, XPS, O₂‐TPD, DLS, TEM, and in‐situ FTIR results show that activated O species exist on the surface of the GaN catalyst and enhance the catalytic performance with a decreasing GaN particle size, suggesting that smaller GaN particles possess a remarkable capability to activate O species in O₂ and C‐H bonds in light alkanes.     

Synthesis,Oxygenation and Catalytic Oxidation Performance of Crown Ether‐Containing Schiff Base‐Transition Metal Complexes

Mono‐Schiff bases containing a crown ether ring ( HL ¹ , HL ² , HL ³ and HL ⁴ ) and their transition metal complexes were synthesized and characterized by ¹H NMR, IR, and mass spectroscopy as well as elemental analysis. The oxygenation constants (K) of Schiff base‐Co(II) complexes were measured over the range of −5 to +25 °C, and the values of ΔH° and ΔS° were calculated based on these K values. Using Mn(III)‐Schiff base complexes, the biomimetic catalytic oxidation of styrene to benzaldehyde was carried out with 100% selectivity. Comparison of this complex with analogues not containing a crown ether moiety clearly demonstrated the influence of crown ether ring on the dioxygen affinities and biomimetic catalytic oxidation performance of the Schiff base complexes.     

High Oxygen‐Reduction‐Activity and Methanol‐Tolerance Cathode Catalyst Cu/PtFe/CNTs for Direct Methanol Fuel Cells

A novel nanocomposite Cu/PtFe/carbon nanotubes (CNTs) was designed, prepared and examined as a cathode catalyst for direct methanol fuel cells (DMFCs). The effects of Fe and Cu on oxygen reduction reaction (ORR) activity and methanol tolerance were investigated by varying their amounts or their configurations in the nanocomposite. The experimental results show that PtFe alloy on CNTs could not enhance methanol tolerance, but could improve the ORR activity. Cu was deposited on PtFe/CNTs to obtain better methanol tolerance. The optimum molar ratio of Cu/Pt/Fe in Cu/PtFe/CNTs is 2.1:1:0.7. After 500 cycles in 1 M HClO₄ solution, the Cu/PtFe/CNTs catalyst is fairly stable with 92% of its original ORR activity and 89.6% of its original electrochemical active surface areas (EAS) maintained.