Zeolites are crystalline aluminosilicates possessing a regular microporous channel network. Unique properties of zeolites such as the presence of framework cations, acid sites, and their well-defined porous structure-with pore sizes similar to those of small molecules-account for their traditional utilization in ion exchange, catalysis, and separation. in addition, zeolites are being investigated for novel emerging applications in a diversity of areas including optoelectronic devices and reactive membranes because they provide for discrimination, recognition, and organization of molecules with a precision of less 1 Å. However, their applications are limited by the relatively small pore openings; therefore, pore enlargement was one of the main aspects in zeolite chemistry. A new class of porous materials, which contain large uniform spaces in the mesopore size regimen (15-100 Å), was reported. These so-called mesoporous materials have two different characters, disorder at the atomic scale but long range order at the atomic scale but long range order at the mesoscopic scale.

Cerium dioxide (ceria) is known for its excellent oxygen storage capacity (OSC) and redox properties. Addition of the transition metal oxide CuOx, improves the low-temperature oxidation activity of ceria by a synergistic mechanism. It has been shown that copper oxide on the high energy CeO2{001}surface, is exceedingly more efficient than on the statistically dominating lowenergy {111} surface for obtaining a high catalytic conversion rate of CO to CO2.:To investigate morphology and composition effects, in a situation which is closer to an industrial catalyst, we have produced nanocomposite particles in the CuOx/CeO2 system with different composition, size, and nanostructured morphology (Fig. la-d) utilizing the inert gas condensation (IGC) technique.

The samples were characterized in a JEM 4000EX HRTEM, and a JSM-840A SEM, interfaced with a Link AN 10000 EDS system. The specific surface area was measured using the adsorption of N2 (BET method).

In combinatorial chemistry, miniaturization and automation are used to carry out many experiments in a simultaneous array, as opposed to doing single experiments in sequence. This high throughput approach is widely used in the drug industry, and is now finding application in the development of novel materials for catalysis. Successful implementation of combinatorial methodology to speed discovery and commercialization of new materials requires that these techniques be applied to every step of the experimental process, from combination of reagents for synthesis through characterization and performance testing.

Arrays of catalyst precursors and molecular sieves synthesized by combinatorial methods must be rapidly screened for particle size distribution and morphology. Optimization of these characteristics is crucial for successful manufacture of formed products such as beads or extrudates on a commercial scale, and has traditionally been done by manual examination of dispersed powder samples in an SEM

For supported bimetallic catalysts it is important to know if the metal components are present in the form of ordered alloys or metal mixtures. For metals with similar crystal structure, Vegard's law predicts a simple relationship between alloy composition and lattice dimensions [1]. It is therefore possible to use high-resolution electron microscopy (HREM) to provide both structural and compositional information. in nanometer sized particles, accurate determination of the lattice spacing from fringes in an HREM image is difficult because of errors due to signal-to-noise, particle tilt and edge effects [2,3]. However, statistical distributions of fringe spacing can be used to determine the lattice spacing of particle ensembles to within 1.5% when measurements are carried out on at least 100 particles [2]. We extend this technique with model AuPd bimetallic catalysts and show that Vegard's law applies to nanometer-sized particles.

Model bimetallic catalysts were prepared by sputtering metal from AuPd alloy targets and/or a Pd target onto thin amorphous carbon substrates.

The focus of this work is on processes that lead to loss of active metal surface area during high temperature operation of automotive catalysts. As under-floor catalytic converters are moved closer to the engine to achieve faster light off, the catalyst is subjected to higher operating temperatures during the normal driving cycle. Sintering of the active metal phase leading to loss of surface area represents one of the most important factors limiting the long-term durability of automotive catalysts. Despite its obvious technological importance, fundamental understanding of sintering is still lacking.

In this research, we have prepared a series of Pd metal catalysts on a θ alumina support. The metal loading was varied from 1.1 wt% to 7 wt%. The catalysts were subjected to sintering at 900 °C for up to 192 hours. To ensure relevance to automotive catalysts, the sintering was performed in a gas atmosphere that contained 10 mol % H2O in flowing N2 or in air.

Organofunctional silanes are the key intermediates for production of silicon polymeric chemicals. Traditionally, platinum catalysts on carbon support materials have been used for these hydrosilylation reactions. The efficiency of the current commercial Pt/C catalyst is not very satisfactory, so a catalyst of platinum on aluminum oxide support was developed to accelerate the reactions. The Pt/Al2O3catalyst greatly increases both reaction and conversion rates. However, the acidic nature of the supporting material is sometimes undesirable. Recently, a new class of platinum-copper bimetallic catalysts has been developed at Dow Corning, using co-deposition techniques with platinum chloride and copper chloride precursors. The bimetallic catalysts have also demonstrated significantly improved on hydrosilylation reaction efficiency and rates. The activity, selectivity, and stability of the catalysts are related to their structural properties, including catalyst particle size, size distribution, and particle composition. The knowledge of catalyst structures are, therefore, very important for understanding the performance of the catalysts and for optimizing production processes.

Characterization of nanometer-sized particles dispersed onto a porous support is critical for understanding performance of heterogenous catalysts. The electron microscope offers a unique capability for measuring the cluster size and chemistry of these nanometer-sized metal clusters. Cluster size and size distribution can be readily determined by using high angle annular darkfield or z-contrast microscopy. However, as catalysts become more complex with additional components that modify the metal activity, determination of the chemistry of individual clusters could be interesting. Conducting such studies is not straightforward and some of the problems associated with making such measurements will be discussed using model catalysts and a VG HB 601UX dedicated STEM.

Problems associated with this type of measurement can include the instability of the small metal particle under the intense, focused electron beam as well as spurious signals from the area surrounding the region of interest.

In the fluidized catalytic cracking (FCC) unit of oil refinery, the attrition resistance of FCC catalysts is affected by particle shape. Although some sophisticated methods, such as Fractal dimension and Fourier analysis, have been introduced to particle shape analysis, most of them are used to assess the shape of individual particle. It is difficult to be used as a means of powder quality control in the course of application and production of FCC catalysts. So three shape factors, i.e. Short/long ratio (S), Roundness (R) and Concavity (C), are applied to characterize them in three different aspects.

A small quantity of FCC catalyst powders were spread on a glass slide M and a thin layer of glue was spread on another glass slide N, then all the particles on slide M were sprinkled on slide N by vibrating manually up and down, in the meantime moving back and forth more than 10 times.

Introduction

Conventional methods to determine polymerization kinetics rely on a measurement of the monomer consumption or on calorimetric measurements. All these methods are integral methods and they are not appropriate to determine the kinetic of individual catalyst particles. Reichert and coworkers have invented video microscopy as a tool that allows the direct determination of polymer growth in gas-phase butadiene polymerization with heterogeneous catalysts.

Results

We present the direct measurement of polymer growth in gas-phase propene polymerization under industrial process conditions by means of video microscopy.The key-element of our equipment is a window autoclave that allows working with pressures up to 150 bar in the temperature range of 0 °C to 120°C. to insure inert atmosphere the reaction chamber is heated under high vacuum conditions before it is loaded with catalyst in a glove box. The reaction temperature is controlled by means of a temperature fluid slope inside the autoclave wall. to start the polymerization monomer gas is introduced to the reactor. We use a black eloxed aluminum disk as support for the catalyst grains.

Supported transition metal particles are often used as heterogeneous catalysts. Elemental mapping with energy-filtered transmission electron microscopy (EFTEM) offers distinct advantages over conventional TEM and x-ray analysis for these systems. Thickness maps, metal identification, support identification, and direct imaging of oxide layers all represent key new information made possible with EFTEM. Energy-filtered transmission electron microscopy with an omega filter has been used to show Ni, Cu and Cr distributions in an alumina-supported catalyst. in this paper we look at analogous cobalt particles from a colloidal suspension supported on a carbon film.

Energy-filtered TEM maps were obtained using a Gatan Image Filter at 200 kV integrated with an FEI CM200FEG microscope. The colloidal cobalt particles have a nominal diameter of 10 nm, providing an excellent model system when supported on thin amorphous carbon supports. Figures 1 - 3 show cobalt L23, oxygen K and elastic micrographs of partially oxidized cobalt particles (native oxide present after drying).

The heterogeneous catalytic system Pt/SiO2 is widely used in “three-way” catalysts, because of its highly selective catalytic reduction of NO by hydrocarbons at low operating temperatures. Although used effectively for more than a decade, in recent years it has become clear that the core phenomena of heterogeneous catalysis can occur at interfaces. in the work presented here, we seek to better understand the role of the atomic and electronic structure of interfaces in making particular reactions facile and moderating the stability and selectivity of a catalytic system.

We investigate model supported platinum catalysts by atomic resolution Z-contrast imaging and EELS using a 200 kV STEM/TEM JEOL2010F with a post column GIF. The combination of these techniques allows us to obtain direct images of the metal particle and its interface with the supporting SiO2, and to correlate that with the modulation of the Si L-edge fine structure.

Antimony-doped tin oxide (ATO) catalysts are used for the oxidation of propylene to acrolein, the ammoxidation of propylene to acrylonitrile and the oxidative dehydrogenation of butanes to 1,3- butadiene. The distribution and valence states of Sb in ATOs are key in determining their catalytic activities. While these materials have been subjects of intensive studies for more than 20 years, X-ray photoelectron spectroscopy, Mössbauer spectrometry, and X-ray absorption spectroscopy4 have so far provided only indirect data for the distribution of Sb and its valence states. in particular, while has been hypothesized that the tin (IV) oxide contains Sb (V) within the bulk lattice and Sb (III) located at surface sites, no direct experimental evidence for this has been provided.

Here we use electron energy loss spectroscopy (EELS) combined with Z-contrast imaging in a JEOL 2010F field emission STEM/TEM operating at 200 KV to analyze ATO catalysts.

Many catalytic materials, especially the maximum valence transition metal oxides, are particularly susceptible to electron beam irradiation and thus undergo structural changes. Hence knowledge about the behaviour of catalytic materials under the electron beam is of importance for all TEM investigations of such materials. On the other hand, this effect can be utilised for an in-situ study of the reductive property, phase transition and/or phase stability of various transition metal oxides in an inert, simple ambient high-vacuum. The knowledge so obtained is needed for understanding the reduction mechanism of catalysts in more complicated chemical environments. in the present work, we study the electron beam induced change in MoO3 and TiO2 (anatase) by means of electron energy-loss spectroscopy (EELS), electron diffraction and high-resolution electron microscopy (HREM).

Molybdenum trioxide, MoO3, important as catalyst in the selective oxidation of hydrocarbons, forms an orthorhombic crystal layer structure. Fig. 1 shows oxygen AT-edges recorded at various irradiation periods in a Philips 200 FEG electron microscope.

Industrial catalysts are often chemically and physically complex systems resulting from many years of technology, science, and art. Successful development of commercial catalysts requires talents of many disciplines including chemistry, chemical engineering, surface science, materials science, and physics. A better understanding of the relationship between catalyst structure and activity can provide a scientific prediction of catalytic properties. The insight gained from catalyst characterization can provide guidance for designing and synthesizing better commercial catalysts. Characterization of industrial catalysts is challenging and expensive; however, it can be highly rewarding in developing commercial catalysts used for manufacturing multibillion-dollar products.

The ultimate goal of catalyst characterization is to correlate the physical, chemical, mechanical, and electronic properties of a catalyst to its activity, selectivity, and stability. in industrial practice, however, because of the complexity of the catalysts, the time limit, and the available resources, the goal of characterizing industrial catalysts is often to elucidate the key performance indicators of a catalyst; these key performance indicators, such as the size and spatial distribution and the composition of the active components and promoters, can then be used to provide guidance for manufacturing better catalysts with desired properties.

The field of catalysis is one of the most important areas of the nano-sciences for many years. in deed the goal of having a catalyst, with the maximum active area exposed to a chemical reaction, has produced enormous amount of research in nanoparticles. Particularly, the metal nanoparticles study is a very important field in catalysis. Electron Microscopy is one of the techniques that have played a mayor role on studding nanoparticles. Since bright field images, dark field techniques, to the high-resolution atomic images of nanoparticles and more recently the High Angle Annular dark field images or Z-contrast. However this technique provides only indirect evidence of the atomic arrangements on the particles. High Resolution Electron Microscopy (HREM) still appears as a very powerful technique to study nanoparticles and their internal structure. Among the most interesting metals to study is the palladium, which acts for instance as excellent catalyst for hydrogenation of unsaturated hydrocarbons and has many other applications such as environmental catalysts.

A vital component to nanoparticle science will be the three dimensional (3-D) characterization of both structure and chemistry of these nanoparticles on their supports at the nanometer scale and below. to achieve this goal, quantitative Z-contrast and atomic resolution will provide essential information about their structure. Z-contrast imaging is ideal for imaging these large Z nanoparticles on low Z supports. in this proceedings, we present a quantitative Z-contrast method to determine number of atoms and a few examples of a combination of electron microscopy methods to gain structural insights into supported nanoparticle, such as Pt on different support materials, PtRu5 on C and Pt-Sn on SiO2.

A relatively new and powerful method is to determine the number of atoms in a nanoparticle, by very high angle annular dark-field (HAADF) imaging or Z-contrast technique [1, 2]. We have shown that quantification of the absolute image intensity from very HAADF microscopy will provide the number of atoms in very small particles of high atomic number to ±2 atoms for Re6 nanoparticles supported on carbon [3].

Progress in the design of catalysts based on nanoparticles supported within a mesoporous silica framework requires structural analysis at high spatial resolution. While bulk analysis by X-ray diffraction and EXAFS can give the structure of active sites they are unable to determine their relative positions and local physical structure. Some success has been achieved using a combination of STEM ADF imaging and EDX mapping to elucidate such structures but these results are limited to giving 2D projections of 3D arrangements. The need exists therefore to analyse specimens in full 3D. A suitable approach is electron tomography where the 3D structure is reconstructed from a tilt series of 2D projections. in conventional electron tomography a tilt series is acquired using bright field (BF) TEM. However the large beam current means such an approach generally cannot be used on specimens based on a mesoporous silica framework as beam damage can develop rapidly.

A large number of papers have been published on using HREM to characterize the crystal structure and defects of catalysts. While such work is important to advance the scientific understanding of catalysis, the bulk of daily analytical work of an industrial catalyst microscopist focuses on analyzing the morphological features of the catalysts. That is, to find out the shape, the size, and the distribution of various phases. in the case of heterogeneous catalysts, the same information is needed for the catalytic metal particles. Ultimately, the goals are to correlate the performance of the catalyst with the size and morphology of the phases or particles. These types of information are often critical element in a patent.

Unfortunately, very little attention has been paid to properly and quantitatively describe crystal shapi crystal size, and size distribution. It is common to find in the literature, statements such as “the crystal size of this sample was 0.5 microns” or “the sample contains elongated crystals of 0.5 microns”.

Antimony compounds play a major role in commercial polyester catalysis. Antimony complexes are used in ppm quantities, not only to catalyze melt-phase reactions in which oligomers are converted to high molecular weight polymers, such as poly(ethyleneterephthalate) (PET), but to further increase chain length through a high temperature solidphase polymerization process. During the course of the melt-phase reaction the initial, clear and colorless, Sb+3 compounds are transformed to a gray product that has been linked with the reduction of Sb+3 complexes to metallic antimony (Sb°). The presence of oxygen during the solid-phase process also increases clarity and reduces color of gray polymers. to further our understanding of antimony catalysis, a field emission-based scanning electron microscope (FEGSEM) was used to study antimony transformations during melt-phase polymerization and after treatments at high temperature in oxidizing and reducing environments.

Antimony metal powder from Fisher Scientific was used in redox studies.

Transition metal oxides have been studied extensively over the last few decades, due to their electro optical and catalytic properties.The overall properties of these oxides and the heterostructures that can be built on them depend upon the surface structure, composition and morphology. However, the available information on the surface structures of transition metal oxides is scarce and often contradictory. Knowledge of the atomic structure of the catalytically active surfaces and of the adsorbed reactants and intermediates under in-situ reaction conditions is crucial for an understanding of catalytic oxidation at the molecular level, and will subsequently create possibilities for faster development of new catalysts, improve their performance on industrial level, and lower the costs associated with processing. The objective of the current work is to develop and apply the available experimental (UHV chambers, UHV-HREM, catalytic treatment chamber) and computational techniques (Direct Methods analysis and multislice simulations of electron diffraction data) to improve understanding of catalytic phenomena under various environmental conditions.