Industrial Catalytic materials, types

In view of catalytic potential applications, there is a need for a convenient means of characterization of the porosity of new catalyst materials in order to quickly target the potential industrial catalytic applications of the studied catalysts. The use of model test reactions is a characterization tool of first choice, since this method has been very successful with zeolites where it precisely reflects shape-selectivity effects imposed by the porous structure of tested materials. Adsorption of probe molecules is another attractive approach. Both types of approaches will be presented in this work. The methodology developed in this work on zeolites Beta, USY and silica-alumina may be appropriate for determination of accessible mesoporosity in other types of dealuminated zeolites as well as in hierarchical materials presenting combinations of various types of pores. 

Catalysts are so important in chemical industry that combinatorial-type approaches will certainly be utilized as tools in the identification and optimization of both heterogeneous and homogeneous catalysts. These are, in many cases, high value-added, commercially important materials. In any research activity it makes sense to remove any choke points that impede progress. However, many engineering considerations are important in producing commercial catalytic processes thus, combinatorial-type approaches are unlikely to be a panacea. Still, a variety of unanticipated discoveries may result from various efforts that are under way. 

There are many difficulties involved in the application of pure nanozeolites as catalytic materials, such as the aggregation of nanozeolites, their low thermal and hydrothermal stabilities, and the difficulties in regeneration, filtration, and recycling. Hence, how to develop nanozeolites into new catalytic materials with application values in industry is of particular interest. Here, we use /i-type (BEA) nanozeolite catalytic material as an example to introduce this topic. 

The physical and chemical properties discussed above are influenced by every step of the preparation process as well as the choice of raw materials. In addition, several preparation routes may be available to obtain a catalyst with specific properties. On developing a catalyst for industrial applications, the influence of the preparation procedure on these properties must be taken into consideration as well as economical production of a material. Examples of industrial catalytic processes and the method of manufacture of the catalysts are shown in Table 1. This table illustrates the many different types of catalysts as well as preparation methods used in industry. 

The great majority of catalytic reactions which have been applied technically as industrial processes are those where solid catalytic material acts on gaseous material. They, therefore, represent one type of hetcro-qeneous catalvsis. In such cases, theoretical considerations, especially those based upon the laws of mass action, do not apply in the same way as in cases where the system is homogeneous, i.e. where the catalyst together with all of the components of the reaction are in the same state of aggregation as, for example, when all are either liquids or gases. 

Acidic micro- and mesoporous materials, and in particular USY type zeolites, are widely used in petroleum refinery and petrochemical industry. Dealumination treatment of Y type zeolites referred to as ultrastabilisation is carried out to tune acidity, porosity and stability of these materials [1]. Dealumination by high temperature treatment in presence of steam creates a secondary mesoporous network inside individual zeolite crystals. In view of catalytic applications, it is essential to characterize those mesopores and to distinguish mesopores connected to the external surface of the zeolite crystal from mesopores present as cavities accessible via micropores only [2]. Externally accessible mesopores increase catalytic effectiveness by lifting diffusion limitation and facilitating desorption of reaction products [3], The aim of this paper is to characterize those mesopores by means of catalytic test reaction and liquid phase breakthrough experiments. 

Many books, reviews and treatises have been pubUshed on related subjects [1-7]. Thus the objective of this chapter is the deUneation of the key features of the catalytic surface and the process conditions which enable better control of the reaction pathways for more efficient and environmentally friendly processes and minimal utiHzation of precious natural resources. As it stands today, hundreds of known framework types have been synthesized and scaled-up [8], but only a handful have found significant application in the hydrocarbon processing industries. They are zeolite Y and its many variants, ZSM-5, Mordenite and zeohte Beta. Other very important crystalline materials (including aluminophosphates (ALPOs),... 

The separation of organic mixtures into groups of components of similar chemical type was one of the earliest applications of solvent extraction. In this chapter the term solvent is used to define the extractant phase that may contain either an extractant in a diluent or an organic compound that can itself act as an extractant. Using this technique, a solvent that preferentially dissolves aromatic compounds can be used to remove aromatics from kerosene to produce a better quality fuel. In the same way, solvent extraction can be used to produce high-purity aromatic extracts from catalytic reformates, aromatics that are essentially raw materials in the production of products such as polystyrene, nylon, and Terylene. These features have made solvent extraction a standard technique in the oil-refining and petrochemical industries. The extraction of organic compounds, however, is not confined to these industries. Other examples in this chapter include the production of pharmaceuticals and environmental processes. 

In addition to a large catalytically active surface and good capacity for adsorption, an efficient catalyst requires selectivity, that is, preferential affinity for the appropriate reactants. Nonselectivity is a source of significant problems in catalysis, particularly in the petrochemical industry, which has to deal with hydrocarbons of various types and isomers in a single stream. This situation has provided a strong incentive for the development of artificial (man-made) catalysts that offer the type of selectivity unthinkable on metal surfaces discussed in the last section of Chapter 9 (see, for example, Ball 1994) and illustrates another example of molecular design (or molecular engineering ) of advanced materials for use in science and industry. 

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