Catalytic decomposition of 1,2-dichlorobenzene using Pt-loaded nanoporous zeolite MFI catalyst

Nanoporous zeolite MFI was prepared by using HClO4 as a promoter. A significant proportion of the synthesized zeolite MFI nanoparticles exhibited nanoporous characteristics. Although the synthesis of the zeolite MFI was completed within 6 h, the crystallinity of all the zeolite MFI was shown to be high. The synthesis time of approximately 6 h used in this study was much shorter than the conventional hydrothermal method. The feasibility of the new nanoporous zeolite MFI towards the gas phase catalytic oxidation of a model for dioxin, 1,2-dichlorobenzene, was tested by comparing the catalytic activity of Pt/nanoporous zeolite MFI with that of a Pt/gamma-Al2O3 catalyst. The catalytic activity of the Pt/nanoporous zeolite MFI was higher than that of the Pt/gamma-Al2O3 catalyst. The internal surface area and acidity appears to be a major factor for the decomposition of 1,2-dichlorobenzene.     

Catalytic pyrolysis of oil fractions separated from food waste leachate over nanoporous acid catalysts

Oil fractions, separated from food waste leachate, can be used as an energy source. Especially, high quality oil can be obtained by catalytic cracking. In this study, nanoporous catalysts such as Al-MCM-41 and mesoporous MFI type zeolite were applied to the catalytic cracking of oil fractions using the pyrolysis gas chromatography/mass spectrometry. Mesoporous MFI type zeolite showed better textural porosity than Al-MCM-41. In addition, mesoporous MFI type zeolite had strong Br?nsted acidity while Al-MCM-41 had weak acidity. Significant amount of acid components in the food waste oil fractions were converted to mainly oxygenates and aromatics. As a result of its well-defined nanopores and strong acidity, the use of a mesoporous MFI type zeolite produced large amounts of gaseous and aromatic compounds. High yields of hydrocarbons within the gasoline range were also obtained in the case of mesoporous MFI type zeolite, whereas the use of Al-MCM-41, which exhibits relatively weak acidity, resulted in high yields of oxygenates and diesel range hydrocarbons.     

Catalytic conversion of waste particle board to bio-oil using nanoporous catalyst

The catalytic pyrolysis of waste wood including the particle board was examined by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to produce bio-oil. Three different catalysts with a nanoporous structure, Al-MCM-48, Meso-MFI, and Pt-Meso-MFI, were used and their performances were compared. When MCM-48 was used, the quality of the bio-oil product was better than that prepared by non-catalytic pyrolysis but the improvement was limited due to its weak acid sites. On the other hand, Meso-MFI, which has both an MFI structure and strong acid sites, exhibited much better cracking ability and higher selectivity for aromatics. Moreover, Pt-impregnation on Meso-MFI resulted in an even higher selectivity for aromatics and phenolics, which are important raw materials in various petroleum chemical processes. Keywords: Catalytic Pyrolysis, Py-GC/MS, Waste Particle Board, AI-MCM-48, Meso-MFI,     

Numerical investigation of influence of treatment of the coke component on hydrodynamic and catalytic cracking reactions in an industrial riser

A three dimensional gas-solid reactive flow model based on the Eulerian-Eulerian approach was used to simulate the hydrodynamic, heat transfer and catalytic cracking reaction within in a conventional Fluid Catalytic cracking (FCC) riser. A 12-lump kinetic model was used to represent the catalytic cracking reaction network. It was proposed a catalyst deactivation model as a function of the weight percentage of coke amount on the catalyst to replace the deactivation model dependent of the residence time. It was compared the effects of novel treatment for coke component (coke produced in the solid phase) with common treatment (coke produced in the gas phase) on the fluid dynamic and catalytic cracking. The results showed that the treatment for coke component affects radial distribution of coke mass flow. It also showed that the treatment for coke plays an important role in simulation with catalyst deactivation as a function of coke amount on catalyst.     

Scalable synthesis of nanoporous boron for high efficiency ammonia electrosynthesis

Three-dimensional bicontinuous nanoporosity fabricated by dealloying can provide unique chemical properties in catalytic materials, which conventional nanoparticulate catalysts do not have. Although many solid elements in the periodic table have been fabricated as nanoporous materials by dealloying, technically important nanoporous boron has not been realized because of the poor diffusivity and high chemical stability of boron. Here we report a scalable top–down method to produce three-dimensional nanoporous boron by selectively leaching a less stable metal compound phase from rapidly solidified two-phase metal–boron alloys. The metalloid boron phase with relatively high chemical stability remains as the skeleton of a nanoporous structure. The resultant nanoporous boron with tunable pore sizes, and porosities, shows superior catalytic activities towards ammonia electrosynthesis. This work provides a new approach to fabricate nanoporous metalloids for a wide range of functional applications and brings boron, an important functional material, to the family of dealloyed nanoporous materials.     

A novel pilot-scale production of fuel gas by allothermal biomass gasification using biomass micron fuel (BMF) as external heat source

A novel pilot-scale allothermal biomass gasification system integrating steam gasification, thermal cracking, and catalytic reforming aiming at fuel gas production was developed. Biomass micron fuel (BMF) was used as external heat source by combusting with air in the combustor. Biomass feedstock was gasified with steam, and then, tar in the produced gas was decomposed by thermal cracking and catalytic reforming. The waste heat of high-temperature flue gas and fuel gas was recovered and used for biomass feedstock pre-heating and steam generation, respectively. The fuel gas yield is 1.36 Nm³/kg with lower heating value of 11.61 MJ/Nm³. An overall energy analysis of the system was also investigated. The results showed that the cold gas efficiency and energy conversion efficiency in this system are 88.11 and 63.59 %, respectively. Meanwhile, combustion of BMF accounts for 25.66 % of the total energy input.     

纳米多孔Pd-Cu/Pd-Ag催化剂的制备及其电催化性能EI北大核心CSCD

针对直接甲醇燃料电池(direct methanol fuel cell,DMFE)对高效阳极催化剂的需求,设计研发Ca-Mg-Pd-M(M=Cu,Ag)非晶合金前躯体体系,并采用去合金化制备系带-孔道双连续结构的纳米多孔Pd-Cu/Pd-Ag合金。通过设计前驱体合金比例可调节多孔结构的元素比例和尺寸,Pd元素可与Cu,Ag元素形成连续固溶体,在去合金化过程中可以降低Cu,Ag元素的扩散,进而细化纳米多孔的系带尺寸(由100 nm减小到10 nm)。相较于纳米多孔Pd,纳米多孔Pd-Cu/Pd-Ag合金表现出更优异的甲醇催化活性(催化电流强度:45 mA/mg)和抗毒化能力(J f/J b值为1.56),还具有低成本的优点,在直接甲醇燃料电池阳极催化剂方面有着良好的应用前景。     

Fracture of nanoporous thin-film glasses

Fracture of nanoporous thin-film glasses is a significant challenge for the integration of these mechanically fragile materials in emerging microelectronic and biological technologies. In particular, the integration of these materials has been limited by accelerated cracking rates in moist environments leading to premature failure. Here, we demonstrate how cracking is affected by aqueous solution chemistry, and reveal anomalously high crack-growth rates in hydrogen peroxide solutions frequently encountered during device processing or when in use. Kinetic mechanisms involving the transport and steric hindrance of reactive hydrogen peroxide molecules at the crack tip are proposed. Thin-film design strategies that involve energy dissipation by local plasticity in thin ductile layers on increasing the resistance to cracking of nanoporous glass layers is demonstrated. Understanding how aqueous solutions influence cracking and associated device reliability is a fundamental challenge for these promising materials to be viable candidates for new technologies.     

Ultrasmall Metal Nanoparticles Confined within Crystalline Nanoporous Materials: A Fascinating Class of Nanocatalysts

Crystalline nanoporous materials with uniform porous structures, such as zeolites and metal–organic frameworks (MOFs), have proven to be ideal supports to encapsulate ultrasmall metal nanoparticles (MNPs) inside their void nanospaces to generate high‐efficiency nanocatalysts. The nanopore‐encaged metal catalysts exhibit superior catalytic performance as well as high stability and catalytic shape selectivity endowed by the nanoporous matrix. In addition, the synergistic effect of confined MNPs and nanoporous frameworks with active sites can further promote the catalytic activities of the composite catalysts. Herein, recent progress in nanopore‐encaged metal nanocatalysts is reviewed, with a special focus on advances in synthetic strategies for ultrasmall MNPs (<5 nm), clusters, and even single atoms confined within zeolites and MOFs for various heterogeneous catalytic reactions. In addition, some advanced characterization methods to elucidate the atomic‐scale structures of the nanocatalysts are presented, and the current limitations of and future opportunities for these fantastic nanocatalysts are also highlighted and discussed. The aim is to provide some guidance for the rational synthesis of nanopore‐encaged metal catalysts and to inspire their further applications to meet the emerging demands in catalytic fields.     

Effect of ultraviolet illumination and ambient gases on the photoluminescence and electrical properties of nanoporous silicon layer for organic vapor sensor

The purpose of this research, the nanoporous silicon layer were fabricated and investigated the physical properties such as photoluminescence and the electrical properties in order to develop organic vapor sensor by using nanoporous silicon. The Changes in the photoluminescence intensity of nanoporous silicon samples are studied during ultraviolet illumination in various ambient gases such as nitrogen, oxigen and vacuum. In this paper, the nanoporous silicon layer was used as organic vapor adsorption and sensing element. The advantage of this device are simple process compatible in silicon technology and usable in room temperature. The structure of this device consists of nanoporous silicon layer which is formed by anodization of silicon wafer in hydrofluoric acid solution and aluminum electrode which deposited on the top of nanoporous silicon layer by evaporator. The nanoporous silicon sensors were placed in a gas chamber with various organic vapor such as ethanol, methanol and isopropyl alcohol. From studying on electrical characteristics of this device, it is found that the nanoporous silicon layer can detect the different organic vapor. Therefore, the nanoporous silicon is important material for organic vapor sensor and it can develop to other applications about gas sensors in the future.     

In2O3纳米孔材料的制备及其甲醛气敏性能研究

以In(NO3)3·4.5H2O为主要原料,采用溶剂热法成功地制备出In2O3纳米孔材料.采用X射线粉末衍射、透射电子显微镜等对样品的物相和形貌进行了表征和分析,并系统研究了其气敏性能.结果表明,成功合成的六方相In2O3纳米孔材料,其孔径小于17nm,孔道形状复杂且相互连通,以该材料制成的气敏元件对甲醛有很好的气敏性能,对50×10-6甲醛的灵敏度高达23.6.     

Catalytic oxidation of benzene with ozone over nanoporous Mn/MCM-48 catalyst

The catalytic oxidation of a representative volatile organic compound, benzene, with ozone at a low temperature was investigated. A nanoporous MCM-48 material with a high specific surface area was used as the support for the catalytic oxidation for the first time. Mn, which has high activity at a low temperature, was used as the metal catalyst. To examine the effect of the Mn precursor, MCM-48 was impregnated with two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were analyzed by Brunauer Emmett Teller surface area, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. MCM-48 impregnated with Mn acetate showed higher catalytic activity than MCM-48 impregnated with Mn nitrate. This result was attributed to the better dispersion within nanoporous MCM-48 and higher oxygen mobility of Mn oxides produced by Mn acetate. The catalytic activity was also shown to depend closely on the ozone concentration.     

Tuning Surface Structure of 3D Nanoporous Gold by Surfactant‐Free Electrochemical Potential Cycling

3D dealloyed nanoporous metals have emerged as a new class of catalysts for various chemical and electrochemical reactions. Similar to other heterogeneous catalysts, the surface atomic structure of the nanoporous metal catalysts plays a crucial role in catalytic activity and selectivity. Through surfactant‐assisted bottom‐up synthesis, the surface‐structure modification has been successfully realized in low‐dimensional particulate catalysts. However, the surface modification by top‐down dealloying has not been well explored for nanoporous metal catalysts. Here, a surfactant‐free approach to tailor the surface structure of nanoporous gold by surface relaxation via electrochemical redox cycling is reported. By controlling the scan rates, nanoporous gold with abundant {111} facets or {100} facets can be designed and fabricated with dramatically improved electrocatalysis toward the ethanol oxidation reaction.     

Dealloying by metallic melt

Dealloying, which commonly involves corrosion processes in aqueous solutions, is a promising technique for preparing functional nanoporous metals. While this technique is ideal for preparing nanoporous noble metals such as of Au, it is not readily applicable to less-noble metals. Here, we propose a novel dealloying method employing a metallic melt, instead of an aqueous solution, as the dealloying liquid for a preparing of nanoporous metals. An atomic interaction among alloy components and metallic melt causes specific component to dissolve out from the alloy solid into the melt with self-organizing nanoporous structure by the remaining component. The dealloying method can be applied for preparation of nanoporous less-noble metal such as of Ti for the development of functional materials such as fluid filters, gas absorption media, and biomaterials.     

A thermogravimetry-capillary gas chromatography/mass spectrometry interface

An interface and gas chromatograph oven are described that couple a thermogravimetric analyzer with a mass spectrometer and permit multiple capillary gas chromatographic separations of volatile thermal decomposition products generated during a single thermogravimetric analysis. Examples of the use of this apparatus for identifying the volatile products generated during poly(vinyl butyral) thermal decomposition in the presence of γ-alumina and catalytic cracking of poly(styrene) and poly(ethylene) are described. TG-GC/MS analyses employing isothermal, temperature programmed, and subambient temperature ramp gas chromatography separations are described. The apparatus permits repetitive temperature-programmed capillary gas chromatographic analyses of thermogravimetric effluent containing more than 25 constituents in 3-min intervals.     

Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.     

Self-supporting nanoporous Ni/metallic glass composites with hierarchically porous structure for efficient hydrogen evolution reaction

Searching for free-standing and cost-efficient hydrogen evolution reaction (HER) electrocatalysts with high efficiency and excellent durability remains a great challenge for the hydrogen-based energy industry.Here,we report fabrication of a unique hierarchically porous structure,i.e.,nanoporous Ni (NPN)/metallic glass (MG) composite,through surface dealloying of the specially designed Ni40Zr40Ti20 MG wire.This porous composite is composed of micrometer slits staggered with nanometer pores,which not only enlarges effective surface areas for the catalytic reaction,but also facilitates the release of H2 gas.As a result,the NPN/MG hybrid electrode exhibited the prominent HER performance with a low overpotential of 78 mV at 10 mAcm-2 and Tafel slope of 42.4 mV dec-1,along with outstanding stability in alkaline solutions.Outstanding catalytic properties,combining with their free-standing capability and cost efficiency,make the current composite electrode viable for HER applications.     

General Synthesis of Nanoporous 2D Metal Compounds with 3D Bicontinous Structure

Although 2D layered metal compounds are widely exploited using various techniques such as exfoliation and vapor-phase-assisted growth, it is still challenging to construct the 2D materials in a 3D configuration with preservation of the unique physicochemical properties of the metal compounds. Herein, a general synthetic strategy is reported for a wide variety of 2D (atomic-scale thickness) metal compounds with 3D bicontinous nanoporous structure. 19 binary compounds including sulfides, selenides, tellurides, carbides, and nitrides, and five alloyed compounds, are successfully prepared via a surface alloy strategy, which are readily created by using a recyclable nanoporous gold assisted chemical vapor deposition process. These 3D nanoporous metal compounds with preserved 2D physicochemical properties, tunable pore sizes, and compositions for electrocatalytic applications, show excellent catalytic performance in the electrochemical N₂ reduction reaction. This work opens up a promising avenue for fundamental studies and potential applications of a wide variety of nanoporous metal compounds.     

Study on the structural formation of new useful multiporous material ‘nano–meso ZSM-5’ and its application in producing biofuel

New ‘nano–meso ZSM-5’ (NM-ZSM-5) material was successfully synthesised by hydrothermal treatment using silica derived from rice husk. The synthesis of the material involves two steps of crystallisation, including the formation of ZSM-5 zeolite seed and mesoporous structure. The effect of crystallisation time on the formation of mesoporous structure was studied in the range 0–40?h. Samples were characterised by X-ray diffraction, infrared spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller and ²⁷Al-NMR methods. The results show that the best time for crystallisation is 14?h. The synthesised material has a multiporous structure, including micropore system of ZSM-5 zeolite, mesopore system of MCM-41 and another pore system which has a diameter in the range 10–50?nm (mesoporous system) due to the burning of organic compounds that remain in the material during the calcination process. In addition, the synthesised NM-ZSM-5 achieves crystallinity of approximately 100%. The catalytic performance of NM-ZSM-5 material was evaluated by the catalytic cracking reaction to produce biofuel from vegetable oil sludge. The research proved that NM-ZSM-5 is one of the most suitable catalysts for this process. The catalytic cracking reaction over NM-ZSM-5 yields products that are similar to those of the petroleum cracking process, such as dry gases, liquefied petroleum gas, gasoline, light cycle oil and heavy cycle oil.     

Progress in the Physisorption Characterization of Nanoporous Gas Storage Materials

Assessing the adsorption properties of nanoporous materials and determining their structural characterization is critical for progressing the use of such materials for many applications, including gas storage. Gas adsorption can be used for this characterization because it assesses a broad range of pore sizes, from micropore to mesopore. In the past 20 years, key developments have been achieved both in the knowledge of the adsorption and phase behavior of fluids in ordered nanoporous materials and in the creation and advancement of state-of-the-art approaches based on statistical mechanics, such as molecular simulation and density functional theory. Together with high-resolution experimental procedures for the adsorption of subcritical and supercritical fluids, this has led to significant advances in physical adsorption textural characterization. In this short, selective review paper, we discuss a few important and central features of the underlying adsorption mechanisms of fluids in a variety of nanoporous materials with well-defined pore structure. The significance of these features for advancing physical adsorption characterization and gas storage applications is also discussed.