In 1999 Thermo NORAN completed licensing agreements with NIST for the microcalorimeter x-ray spectrometer technology developed by Martinis, Irwin, Hilton and Wollman.Steady progress has been made to commercialize this technology.

Briefly, the NIST microcalorimeter consists of a Transition Edge Sensor (TES) which measures the temperature rise in an absorber due to an incident photon. The sensor must be operated at temperatures below 100 milliKelvin, which is provided by an Adiabatic Demagnetization Refrigerator (ADR), coupled with a traditional liquid helium cryostat. Additional enabling technology includes a Superconducting Quantum Interference Device (SQUID) and a SQUID Array for device readout and low temperature signal amplification. All of this technology has been widely used in cryogenic research facilities for many years, but is not readily available for commercial purchase and use.

Initial work focused on adapting the NIST design to a modern FESEM. The available ports in an FESEM required scaling the heat shields, and cold extension diameters by 68%.

The high performance of single-pixel microcalorimeter EDS (μ,cal EDS) has been shown to be very useful for a variety of microanalysis cases. The primary advantage of jxcal EDS over conventional EDS is the factor of 25 improvement in energy resolution (∽3 eV in real-time). This level of energy resolution is particularly important for applications such as nanoscale contaminant analysis where it is necessary to resolve peak overlaps at low x-ray energies. Because μcal EDS offers practical solutions to many microanalysis problems, several companies are proceeding with commercialization of single-pixel μal EDS technology. Two drawbacks limiting the application of uxal EDS are its low count rate (∽500 s−1) and small area (∽0.04 mm for a bare single pixel, ∽5 mm2 with a polycapillary optic). We are developing a 32x32 pixel array with a total area of 40 mm2 and with a total count rate between 105 s−1 and 106 s−1.

The concept utilized in charge coupled devices (CCD’s) for detection and imaging of light signals involving lateral movement of charges and extremely low capacitance of the detector and readout electronics has spawned a variety of new ideas in the design of nuclear detectors. Initially, silicon drift detectors (SDD’s) were developed for high energy physics applications. More recently, a vigorous effort to develop new structures for x-ray spectroscopy and light detection has started. Drift structures have been designed in a variety of topologies and materials (such as Si, CdZnTe, and HgI2) to satisfy the requirements of many different applications. The most interesting features that can be achieved with drift structures include: a) Large active area devices with low capacitance and low electronic noise, b) Very high signal throughput, c) Operation at or near room temperature, d) High sensitivity over the large entrance electrode to low energy xrays and short wavelength light, f) Single carrier charge collection allowing for elimination of hole contribution to the spectral broadening in compound semiconductor detectors such as HgI2, CdTe, and CdZnTe, f) 2D resolution of few tens of micrometer in both directions over few cm2 active areas, and g) Possibility of using more sophisticated schemes of charge collection by switching between integration and drift mode.

The analysis of samples with a scanning electron microscope often requires element distribution images. Until recently, element mapping was strongly limited by the count rate that could be processed with conventional EDS systems using Si(Li) or Ge crystal diode detectors. The enhancement of secondary and backscattered SEM images can now be achieved through the addition of rapid color imaging. Using a new methodology for color enhancement, features as small as 1 micrometer can be colored and easily distinguished. The addition of color to SEM images enables easy visualization of element distributions and allows the microstructural features and compositional variations of different materials to be more readily identified. Persons unfamiliar with electron microscopy can more readily interpret color images than black and white or gray scale images. This new technology for imaging elements has great potential to revolutionize electron microscopy.

The detector technology behind this new methodology is the silicon drift diode (SDD).

As scientists look to determine elemental composition of smaller and smaller particles using a scanning electron microscope, the usefulness of conventional EDS detectors (Si(Li)) becomes limited. to obtain analytical information from the SEM on extremely small particles the analyst can reduce the excitation energy of the electron beam; excitation energies of around 3kV are regularly used for the analysis of these particles. with only low energies (up 3keV) to work with, the scientists have to use L, or in some cases M, spectra to determine the chemical composition of the particle. A standard Si (Li) with a resolution of ≈100eV @3keV (130eV at 6keV) will be unable to adequately resolve spectra for confident characterization work to be carried out for these low energy lines. A new generation of EDS detectors for microanalysis is required to fulfill the scientists requirements for fast, simultaneous chemical determination of these small particles.

Low temperature heterogeneous catalytic routes for polymers are of considerable interest in the chemical sciences and technology because they are economical and environmentally beneficial. However such routes have been difficult because of an incomplete understanding of process control and low yields. Currently, hydrogenation of aliphatic dintriles in solvents is used in the chemical industry to manufacture the corresponding diamenes which are subsequently reacted with adipic acid solutions and polymerized to produce the polyamide, nylon (6,6).

Here we report an alternative, low temperature heterogeneous catalytic process for the polymerization reactions using novel environmental-HRTEM (EHREM) in liquid environments. EHREM under simulated reaction conditions provides direct, in situ real-time information on the dynamic structural and chemical changes and reaction modes of operation. We prepared high surface area heterogeneous catalysts including cobalt-ruthenium nanoclusters supported on rutile titania using a single step sol-gel technique, (shown in Fig. 1).

The crystallographic orientation and atomic termination layer of oxide catalysts are known to influence their reactivity. The objective of this work was to measure how the relative photochemical reactivities of two ternary titanates vary with surface orientation and composition. The surface structure property relationships derived from these observations can be used to define optimized photocatalyst microstructures.

To measure the relative reactivity of surfaces with different orientations, crystallites (∽ 20 μm in diameter) in a polycrystalline ceramic were examined individually. First, polycrystalline specimens of BaTiO3 and SrTiO3 were synthesized using conventional ceramic processing. Surfaces for analysis were prepared by polishing and thermal etching in air. The surface orientations of selected grains in the sample were then determined from backscattered electron diffraction patterns recorded in a scanning electron microscope. to make a local measurement of the photochemical activity of each grain, we used a well established probe reaction (the reduction of aqueous Ag+ to Ag0) that deposits metallic silver on the surface as a reaction product.

Combustion of natural gas for power generation leads to NOx formation due to the high temperatures encountered. Catalytic combustion allows the entire combustion process to be completed at temperatures where NOx formation can be avoided. The catalyst of choice is supported PdO. As temperature is increased, PdO decomposes to Pd metal with profound effects on catalyst reactivity. Persistent hysteresis in reaction rates have been related to the decomposition of PdO into Pd and its reformation.

Understanding and controlling the phase transformations, and the resulting activity variations, is of enormous importance for high temperature combustion catalysts where predictable catalyst activity is necessary for stable operation. Farrauto et al. studied the phase transformations of PdO to Pd using thermogravimetric analysis (TGA). They concluded that while PdO decomposes to Pd at high temperatures during the heating cycle, upon cooling the Pd does not transform to PdO till the temperature drops by several hundred degrees.

New EPA regulations limiting the emissions of NOx from diesel engines will require a reduction by 70% in the amount of NOx leaving the tailpipe of diesel powered vehicles by the year 2004. Some form of exhaust aftertreatment will need to be applied to diesel engines to meet the new stricter requirements. One option is to develop a “lean-NOx” catalyst that uses a hydrocarbon reductant (e.g. diesel fuel) to convert NOx into N2 and O2. Two of many constraints on such a catalyst are that it achieve a high degree of conversion over a fairly broad temperature range and that the amount of reductant necessary to reach the 70% goal is sufficiently small as to be cost effective. A number of promising systems comprise either platinum group metals or base metals on oxide supports. Such catalyst systems typically involve near-atomic dispersions, or ultra-fine clusters, of the heavy metal species on the oxide support.

Recently a number of reports have been made in which direct methods (DM) were used to solve bulk inorganic crystal structures with electron diffraction (ED) data, either ab initio or in a combined approach using phase information from images. This paper reports ab initio application of DM to experimental ED data from the zeolite mordenite. Data from mordenite [001] were taken using a JEOL 3010 TEM at 300 kV. For collecting data, a small condenser and spot size were used to obtain a defocused probe 50 nm in size positioned over the edge of a thin area. Patterns were recorded with a CCD camera. Fig. 1 compares experiment with modeled kinematical data based on a published structure. Phase determination by DM was performed with the minimum relative entropy approach. As a test, ab initio DM was performed on modeled kinematical data.The result, shown in Fig. 2, is not distinguishable from a picture of the projected potential.

Heterogeneous catalysts are extremely important to the chemical industry. The goal of much current research is to develop predictive models for real world catalysts in order to optimize and exploit new processes. The first step in any predictive modeling is to understand the systems that are currently in use. A key question regarding these materials is the distribution of atoms within the catalyst particle, i.e., are the materials equally distributed within the particle or is there clustering or shelling of the constituents. This is a more general question than just catalytic systems and has applicability to many small cluster problems where normally immiscible systems can be forced to mix or order when confined to small volumes.

EXAFS analysis has provided useful information for these systems; due to the small scattering cross-section and large beam sizes of x-rays, the systems have only been studied as ensemble averages.

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.