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The background and theoretical and experimental requirements of powder compaction equations have been briefly reviewed. There have been many equations proposed. However, the equations most commonly used today are the Heckel and Kawakita ones, because they alone have claimed to be able to relate to the physical properties of the materials being compacted. There has been much discussion about their relative merits, and in their form, they appear very different. The two equations are discussed in detail and examples are given, and their relative merits are discussed. However, it is first shown for applied pressures, which are low compared to the yield strength of the particles, that they are identical in form. It is then shown mathematically that if a pressure dependent term is used in the Heckel equation then the resulting modified equation is very similar to the Kawakita one and, in fact, becomes identical in form for a particular, likely value of the pressure dependency term. It is concluded that the Kawakita equation is a special case of the more general, modified Heckel equation. It is further concluded that compaction equations need further development to take into account the anisotropy in compacts made by uniaxial compaction. It is shown that the Poisson's ratio of compacts will also increase with applied pressure, and this must be considered.

The addition of14CO or14CO2 tracers to CO2/CO/H2 reactant mixtures for methanol synthesis over a commercial copper/zinc oxide/alumina catalyst was used to determine the origin of the carbon in the product. For PCO2/PCO ratios from 0.02 to 1 the fraction of methanol made from carbon dioxide rises from ∼0.7 to ∼1, so carbon dioxide is the major reactant under industrial conditions. There is no carbon-containing surface intermediate common to methanol synthesis and the water-gas shift reaction.

Summary The application of a type of porous ceramic coating, typically 80 to 400 microns thick to metal, is described. These coatings were developed for mild steel self-clean oven liners to assist removal of fat splatters during cooking operations at normal oven temperatures. The coatings are based upon specially developed “self-matting” vitreous enamels, which, unlike conventional ones, show controllable fusion characteristics during firing in the temperature range 750-850°C. Thus high porosity, hardness, and good adhesion can be achieved simultaneously. Catalysts or catalyst support material can be incorporated in the coatings before firing as with oven liner catalyst or preferably after firing by eg an impregnation step. Uses of the coatings or coating materials for reactions other than fat removal are possible. Coatings can be made having a wide range of pore size distributions and their surface areas can be up to over 100 m 2 /gm.

The factors limiting catalyst performance and life are discussed in terms of all the basic requirements of industrial catalyst systems. (change-para-here) Catalyst life can be limited by deterioration in any of these requirements rather than just by loss of catalytic activity. This is illustrated by examples from many of the more important industrial gas phase catalytic processes, which have catalyst lives varying over a wide range. Considerable information about the processes shortening catalyst bed life can be obtained by monitoring performance during plant use, and examining catalyst after discharge. Additional information and clarification must come from laboratory studies. The difficulties in relating the results of such studies to plant conditions are discussed, and the general areas requiring further work are highlighted.