Acidity Characterization of Catalyst Libraries by High-Throughput Testing

The development of acid and bi-functional catalysts with controlled properties is a matter of high interest for refinery applications. The issues of characterization and quantification of catalyst acidity in the frame of high throughput (HT) screening are outlined. The present study deals with the development of a HT method for the characterization of the Brønsted acidity of 80 bifunctional catalysts library by means of isomerization of 3,3-dimethylbutene testing. Catalytic results are validated with literature data. The choice of probe molecules, the operating conditions and deactivation issues upon testing are addressed. This method allows quantifying very accurately the acid strength. Catalyst ranking from large library can be achieved an acidity scale in conditions similar to the practical applications. The pros and cons of the use of model reactions for HT quantitative characterization are discussed.     

Non-Catalyzed and Pt/γ-Al2O3 Catalyzed Hydrothermal Cellulose Dissolution-Conversion: Influence of the Reaction Parameters

The dissolution of cellulose under 5 MPa of H₂ in the absence of catalyst is temperature and time dependant. The presence of Pt/γ-Al₂O₃ increases the initial rate of dissolution. The presence of H₂/Pt is essential although its exact role has not been well elucidated.     

3D Visualization of Morphological Evolution of Large Defects during Spark Plasma Sintering of Alumina Granules

The mechanical reliability of products must be assured for scaling up and production of complex-shaped components by spark plasma sintering (SPS) of spray-dried granules. The evolution of morphologies of pores and defects, which control the mechanical strength, is investigated by using synchrotron X-ray multiscale tomography during SPS of alumina granules at 1300 °C. While large defects arising from the hierarchical granule packing structure cannot be removed by pressureless sintering, crack-like defects and branched rodlike defects are almost eliminated by SPS at stresses higher than 30 and 50 MPa, respectively. But, small ellipsoidal porous regions, which may arise from aggregates or dimples of granules, cannot be removed even at a pressure of 50 MPa. A very large defect is also found by using micro-CT. It is supposed that this defect is formed from a large void in loosely packed granules. The shrinkage of large voids and the elimination of crack-like defects are explained by the theoretical prediction based on the continuum theory of sintering.     

New experimental results of millimetre-wave whispering gallery modedielectric resonators excited by microstrip lines

Presents an experimental investigation of planar millimetre-wave dielectric resonators acting on whispering gallery modes and excited by microstrip lines. Experimental results including measured resonant frequencies and loaded quality factors obtained in both Ka bands (26.5-40 GHz and 90-100 GHz) are presented     

Dielectric resonator dual modes filter

In a shielded cylindrical dielectric resonator a number of degenerate modes with identical natural frequencies can be found. These degenerate modes can be coupled together to form coupled circuits by perturbating the geometrical configuration of the structure. The letter presents both TE01p mode resonant frequency perturbation by a tuning screw and a two modes dielectric filter using two perpendicularly polarised HE111 modes of the resonator.     

Un combineur de puissance à résonateur diélectrique dans la bande 75–110 GHz

This paper presents the utilisation of planar millimeter wavelength whispering gallery dielectric resonators modes for the realization of directional filters and for application to power combination. The different advantages of these resonator modes allow their utilisation in the millimeter wavelength range. The electrical study based on the ring resonator theory permits to predict the theoretical responses of several circuits realised. Finally, experimental results obtained from power combiners in W band will be presented.