Optimisation of anode characteristics of calcium thionyl chloride cells

In the field of high performance primary battery systems lithium anoded cells have been shown to have an excellent performance and extremely good shelf life. The major drawback with the lithium technology is one of safety, whereby abuse conditions (such as charging of the cell) lead to an unstable system with the very real possibility of a cell explosion. For a commercially available cell consideration of safety issues would preclude the marketing of a high performance lithium cell for general use, rather, it will be reserved for specialist e.g. Military use where the personnel having contact with the power source can be trained in its safe operation. The work described in this thesis is concerned with the development of a high performance battery system utilising calcium as the anode material. Calcium has received attention as an anode material for a high performance battery system because it removes many of the safety problems associated with lithium. The major disadvantages of calcium have been addressed namely the shelf life and discharge performance. The electrochemical techniques of cyclic voltammetry and a.c. impedance have been used in conjunction with physical methods such as scanning electron microscopy to define the mode of operation of these cells

Can Palladium Acetate Lose Its “Saltiness”? Catalytic Activities of the Impurities in Palladium Acetate

Commercially available palladium acetate often contains two major impurities, whose presence can impact the overall catalytic efficacy. This systematic study provides a comparison of the differences in catalytic activity of pure palladium acetate, Pd₃(OAc)₆, with the two impurities: Pd₃(OAc)₅(NO₂) and polymeric [Pd­(OAc)₂]_<i>n</i> in a variety of cross-coupling reactions. The solid state ¹³C NMR spectra of all three compounds in conjunction with DFT calculations confirm their reported geometries

Synthetic Control of the Defect Structure and Hierarchical Extra-Large-/Small-Pore Microporosity in Aluminosilicate Zeolite SWY

The SWY-type aluminosilicate zeolite, STA-30, has been synthesized via different routes to understand its defect chemistry and solid acidity. The synthetic parameters varied were the gel aging, the Al source, and the organic structure directing agent. All syntheses give crystalline materials with similar Si/Al ratios (6–7) that are stable in the activated K,H-form and closely similar by powder X-ray diffraction. However, they exhibit major differences in the crystal morphology and in their intracrystalline porosity and silanol concentrations. The diDABCO-C82+ (1,1′-(octane-1,8-diyl)bis(1,4-diazabicyclo[2.2.2]octan)-1-ium)-templated STA-30 samples (but not those templated by bisquinuclidinium octane, diQuin-C82+) possess hierarchical microporosity, consisting of noncrystallographic extra-large micropores (13 Å) that connect with the characteristic swy and gme cages of the SWY structure. This results in pore volumes up to 30% greater than those measured in activated diQuin-C8_STA-30 as well as higher concentrations of silanols and fewer Brønsted acid sites (BASs). The hierarchical porosity is demonstrated by isopentane adsorption and the FTIR of adsorbed pyridine, which shows that up to 77% of the BASs are accessible (remarkable for a zeolite that has a small-pore crystal structure). A structural model of single can/d6r column vacancies is proposed for the extra-large micropores, which is revealed unambiguously by high-resolution scanning transmission electron microscopy. STA-30 can therefore be prepared as a hierarchically porous zeolite via direct synthesis. The additional noncrystallographic porosity and, subsequently, the amount of SiOHs in the zeolites can be enhanced or strongly reduced by the choice of crystallization conditions