Industrial catalysis

Precipitation processes are not only relevant for catalysis, but also for other industries, as for instance the production of pigments. However, in spite of the tre- [Pg.35]

In order for a solid to precipitate from homogenous solution, first a nucleus has to form. The formation of a particle is governed by the free energy of agglomerates of the constituents of the solution. The total free energy change due to agglomeration, AG, is determined by [Pg.35]

Another way to induce precipitation without needing a homogeneous nucleation step is the seeding of the solution. Best results are usually obtained if seeding is done with the desired phase. If the solution is seeded, usually no nucleation takes place, since the precursor concentration never exceeds a critical threshold. The precipitation rates in seeded systems normally follow Arrhenius-type rate laws. Precipitation of Al(OH)3 in the Bayer process is described by [7] [Pg.37]

If catalysts are prepared by coprecipitation, the relative solubilities of the precipitates and the possibility for the formation of defined mixed phases are essential. If one of the components is much more soluble than the other, there is a possibility that sequential precipitation occurs. This leads to concentration gradients in the product and less intimate mixing of the components. If this effect is not compensated by adsorption or occlusion of the more soluble component, the precipitation should be carried out at high supersaturation in order to exceed the solubility product for both components simultaneously. Precipitation of the less soluble product will proceed slightly faster, and the initially formed particles can act as nucleation sites for the more soluble precipitate which forms by heterogeneous precipitation. The problem is less crucial if both components form a defined, insoluble species. This is for instance the case for the coprecipitation of nickel and aluminum which can form defined compounds of the hydrotalcite type (see the extensive review by Cavani et al. [9] and the summary by Andrew [10]). [Pg.37]

In many cases it has been found advantageous to work at low and relatively constant supersaturation which is achieved homogeneously in the whole solution (precipitation from homogeneous solution, PFHS). This can also be employed for deposition-precipitation processes, see Section A.2.2.1.5. This can be reached by using a precipitating agent which slowly decomposes to form the species active in the precipitation. The most commonly employed precursor for the liberation of [Pg.37]

Recently, in situ studies of catalytic surface chemical reactions at high pressures have been undertaken [46, 47]. These studies employed sum frequency generation (SFG) and STM in order to probe the surfaces as the reactions are occurring under conditions similar to those employed for industrial catalysis (SFG is a laser-based teclmique that is described in section A 1.7.5.5 and section BT22). These studies have shown that the highly stable adsorbate sites that are probed under vacuum conditions are not necessarily tlie same sites that are active in high-pressure catalysis. Instead, less stable sites that are only occupied at high pressures are often responsible for catalysis. Because the active... [Pg.302]

R. K. Obedander ia B. E. Leach, A., Aluminas for Catalysis Their Preparation and Properties, Vol. 3, Applied Industrial Catalysis, Academic Press, New York, 1984, pp. 98-102. [Pg.157]

Catalysis is a broad, complex subject that is documented in many and varied sources. The field is rich in opportunity, in part because there is so much information that it is possible to find nuggets that competitors miss. Industrial catalysis is a competitive field, and much practical knowledge is proprietary. [Pg.183]

This catalytic cycle is related to some stereoselective industrial catalysis. [Pg.170]

Berty, Laboratoty reactors for catalytic studies , in Leach, ed.. Applied Industrial Catalysis, vol. 1, Academic, 1983, pp. 41-57. [Pg.708]

Vinyl chloride is made from ethylene and chlorine with Cu and K chlorides. The Stauffer process employs 3 multitubular reactors in series with 25 mm (0.082 ft) ID tubes (Naworski and Velez, in Leach, ed.. Applied Industrial Catalysis, vol. 1, Academic Press, 1983, p. 251). [Pg.2104]

Berty, J.M., 1983, Laboratory Reactors for Catal34ic Studies, chapter 3 in J. Applied Industrial Catalysis 1, B.E. Leach, ed., pp. 41-67, Academic Press, New York. [Pg.210]

Volume 79 Catalysis An Integrated Approach to Homogeneous, Heterogeneous and Industrial Catalysis... [Pg.265]

Volume 113 Recent Advances in Basic and Applied Aspects of Industrial Catalysis. [Pg.267]

Activated Carbon for Process Water Treatment Activated Carbon from CPL Carbon Link - Activated carbon from CPL Carbon Link for liquid and gas phase purification by adsorption. Activated carbons for all applications including chemical, water, air, solvent recovery, gold recovery, food, automotive, industrial, catalysis.. http //www.activated-carbon.com. [Pg.442]

Manzer, L. E. (1993). Toward Catalysis in the 21st Century Chemical Industry. Catalysis Today 18,199-207. [Pg.142]

Since then Electrochemical Promotion of Catalysis has been proven to be a general phenomenon at the interface of Catalysis and Electrochemistry. More than seventeen groups around the world have made important contributions in this area and this number is reasonably expected to grow further as the phenomenon of electrochemical promotion has very recently been found, as analyzed in this book, to be intimately related not only to chemical (classical) promotion and spillover, but also to the heart of industrial catalysis, i.e. metal-support interactions of classical supported catalysts. [Pg.584]

R.J. Wijnggaarden, A. Kronberg and K.R. Westerterp, Industrial Catalysis, Wesley-VCH, Weinheim, 1988. [Pg.708]

J.A. Moulijn, P.N.W.M. van Leeuwen, R.A. van Santen (Eds.), Catalysis an Integrated Approach to Homogeneous, Heterogeneous and Industrial Catalysis (1993), Elsevier, Amsterdam. [Pg.22]

What are the aims of catalyst characterization in the context of (a) industrial catalysis and (b) fundamental research ... [Pg.405]

Binary systems of ruthenium sulfide or selenide nanoparticles (RujcSy, RujcSey) are considered as the state-of-the-art ORR electrocatalysts in the class of non-Chevrel amorphous transition metal chalcogenides. Notably, in contrast to pyrite-type MS2 varieties (typically RUS2) utilized in industrial catalysis as effective cathodes for the molecular oxygen reduction in acid medium, these Ru-based cluster materials exhibit a fairly robust activity even in high methanol content environments of fuel cells. [Pg.314]

Department of Chemical Process Technology, Section Industrial Catalysis Department of Organic Chemistry and Catalysis... [Pg.369]

Industrial Catalysis, Department of Chemical Engineering, Delft University of Technology,... [Pg.641]

B. E. Leach 1983, Applied Industrial Catalysis, Academic Press, New York. [Pg.283]

Wijngaarden R.J, Kronberg A and Westerterp K.R (1998) Industrial Catalysis - Optimizing Catalysts and Processes, Wiley-VCH. [Pg.140]

Volume 113 Recent Advances in Basic and Applied Aspects of Industrial Catalysis. Proceedings of the 13th National Symposium and Silver Jubilee Symposium of Catalysis of India, Dehradun, India, April 2-4, 1997 edited by T.S.R. Prasada Rao and G. Murali Dhar... [Pg.414]

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