Metal supported, multi technique

Co-precipitation. - The preparation of supported catalysts by the coprecipitation of metal ions with the support ions usually produces an intimate mixing of catalysts and support. An example of this technique is the coprecipitation of metal ions with aluminium ions to produce a precipitated alumina gel containing the metal hydroxide. This precipitate when calcined produces a refractory support with active component dispersed throughout the bulk as well as at the surface. However, in the preparation of multi-component catalysts, it is possible under improper conditions to obtain a heterogeneous product because of the different solubility products of the constituents. Care should be taken therefore to avoid this undesirable situation by appropriate forethought. 

ICP-OES continues to dominate the market because of its ease of use and relatively low maintenance cost. Inductively coupled plasma mass spectrometry (ICP-MS) is a very powerful state-of-the-art technique used for metal analysis of all kinds of samples but requires highly skilled operators. A vast amount of information is received that is not necessarily required as part of problem-solving or routine support. The cost difference and relative freedom from maintenance problems would favour ICP-OES. This book is aimed at practitioners requiring multi-elemental analysis in industrial, environmental, pharmaceutical and research laboratories, where information on identification and quantification is required on a regular basis. The main focus of this book will be on sample preparation, a topic overlooked in most books on atomic spectroscopy. It is aimed at most ICP-OES and ICP-MS users to show that the instrument is useless unless the sample is prepared in a suitable state that can be used to accurately and precisely quantify the metals present. 

In order to reduce the thermal mismatch between the Pd alloy film and the porous substrate, metal porous supports (stainless steel, nickel, etc.) are used with an intermediate layer to reduce the intermetallic diffusion (with consequent poisoning) between the metal porous support and the Pd/Ag layer. The intermediate layer can be a ceramic or a porous Pd/Ag layer prepared by the bi-metal multi-layer deposition technique [17]. The resulting membranes demonstrate high operating temperature (over 500°C) and long-term durability. 

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