Optimise carrier material

Thus, optimisation of the carrier material as well as of the composition and dispersion and manufacturing of the catalysts still is going on. 

O.lmg/cm was found to be optimal due to the use of an optimised carbon carrier material and improved preparation process leading to a finer dispersion of the coagulated ionomer. 

These experiments confirmed once again that pure noble metal surfaces are not suitable catalysts, even at reaction temperatures exceeding 1000 °C. Even though low surface area carrier materials such as a-alumina probably provide insufficient surface area to achieve satisfactory catalyst selectivity, fine dispersion of noble metals on carrier materials of substantial surface area improves the catalytic performance of noble metals considerably. In Section 4.2.5 results of catalyst optimisation for partial oxidation of propane performed by Pennemann et al. [59] were discussed, which always revealed full propane conversion over rhodium catalysts above a reaction temperature of 750 °C and short contact time, because catalysts of sufficient surface area were applied. 

The evaluation of carriers and catalyst compositions showed that significantly higher SO2 oxidation activity could be achieved with Cs as a promoter under the operating conditions downstream the intermediate absorption tower as demonstrated by the results in Table 1, where the activity compared to the standard product is increased by more than a factor 2. This was clearly sufficient for the introduction of VK69 to the market as a new sulphuric acid catalyst. The activity results for different melt compositions were used to optimise the vanadium content and the molar ratios of K/V, Na/V. and Cs/V. However, the choice of Cs/V was not only a question of maximum activity, because of the significant influence of the Cs content on the raw material costs (the price of caesium is 50-100 times the price of potassium on a molar basis). Here, the economic benefits obtained by the sulphuric acid producer by the marginal activity improvement at high Cs content also had to be taken into account. 

In addition, charge carrier mobilities larger than 1 cm A/ s for processable semiconductors are needed. These values have to be achieved in the final device using high volume processes. Charge carrier mobility in the order of 5-10 cmWs would be a major advance since it enables more complex devices. As a result, the existing materials have to be optimised or new material classes have to be developed. In addition to polymers, this includes small molecule and inorganic semiconductor materials as well as nanomaterials and new hybrid systems that can be processed from solution. 

Many techniques have been applied in attempts to optimise the performance of organic LEDs. Electron and hole transporting films have been deposited between the cathode and the emitting layer and the anode and the emitting layer, respectively, to improve and balance the injection of carriers [5]. The use of low work function cathode materials such as calcium [6] or Mg/Ag [7] has led to high efficiency devices. These metals are unstable on exposure to air, however. 

One of the major tasks for the development of thermoelectric materials is to find and optimise the thermoelectric properties of both n- and p-type legs. As explained in the Introduction, in the case of oxides, the ZT of n-type materials are always smaller, and it is therefore important to find new ways to generate n-type materials. From the simple Heikes formula, with only the x dependence, and no spin and orbital degeneracy term, it can be shown that n- and p-type materials should be symmetrically obtained by doping an insulator with a small amount of carriers or holes (Figure 4.12). 

There are also advantages with glass fibre-reinforced materials. For example, the typical processing temperature with 30% glass fibre-reinforced PEI (360-380 °C) blended with 21% PPO can be reduced to 310-340 °C. This flow-optimised technology can find applications in, for example, automotive headlamp reflectors, lamp bases, throttles, chip carriers and aerials. 

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