New Catalysts and Catalytic Processes

The field of chemical kinetics and reaction engineering has grown over the years. New experimental techniques have been developed to follow the progress of chemical reactions and these have aided study of the fundamentals and mechanisms of chemical reactions. The availability of personal computers has enhanced the simulation of complex chemical reactions and reactor stability analysis. These activities have resulted in improved designs of industrial reactors. An increased number of industrial patents now relate to new catalysts and catalytic processes, synthetic polymers, and novel reactor designs. Lin [1] has given a comprehensive review of chemical reactions involving kinetics and mechanisms. 

Sittig, M., Catalysts and Catalytic Processes, Chem. Process Rev. No. 7. Noyes Develop. Co., Park Ridge, New Jersey, 1967. 

Metal oxide-based materials are widely employed as catalysts for a wide number of applications, particularly in processes such as dehydrogenation and oxidation, where redox chemistry is important The structure of metal oxides facilitates these reactions through the transfer of oxygen, or the removal of hydrogen. In order to fully understand the structural dependence of these processes, and hence to refine existing catalysts and catalytic processes and to develop new active materials, it is... 

The control of reactivity to achieve specific syntheses is one of the overarching goals of organic chemistry. In the decade since the publication of the third edition, major advances have been made in the development of efficient new methods, particularly catalytic processes, and in means for control of reaction stereochemistry. For example, the scope and efficiency of palladium- catalyzed cross coupling have been greatly improved by optimization of catalysts by ligand modification. Among the developments in stereocontrol are catalysts for enantioselective reduction of ketones, improved methods for control of the... 

With the financial and technical help of those two oil companies, extensive development work on the catalytic cracking process was carried out on a laboratory and semiplant scale. This included the study of catalysts and the process variables, as well as the development of new engineering concepts which led to the first commercial application of this process in 1936. 

The zeolites are also known as molecular sieves because of their capacity to discriminate between molecules they find numerous uses in separation and catalytic processes. Although they appear to be solid particles to the naked eye, they are highly porous, with a typical specific surface area of about 1000 m2/g. Catalysis is discussed in Chapter 9, but the scope of that chapter does not permit detailed discussions of the various types of catalysts and the role of physisorption and chemisorption in catalysis this vignette provides a glimpse of the rationale used in the molecular design of new materials of interest in surface chemistry and how the concepts introduced in Chapter 1 and Chapter 9 fit into the larger scheme. 

The heterogeneous reactors with supported porous catalysts are one of the driving forces of experimental research and simulations of chemically reactive systems in porous media. It is believed that the combination of theoretical methods and surface science approaches can shorten the time required for the development of a new catalyst and optimization of reaction conditions (Keil, 1996). The multiscale picture of heterogeneous catalytic processes has to be considered, with hydrodynamics and heat transfer playing an important role on the reactor (macro-)scale, significant mass transport resistances on the catalyst particle (meso-)scale and with reaction events restricted within the (micro-)scale on nanometer and sub-nanometer level (Lakatos, 2001 Mann, 1993 Tian et al., 2004). 

As an extension of our earlier work, studies of new transition metal and noble metal oxide systems have been undertaken. The systems selected for study are widely used as both catalysts and catalytic supports in industrial processes. Particular emphasis has been on establishing structure reactivity relationships and elucidating the molecular level mechanisms of oxygen transfer reactions that are not well understood. A discussion of several of our most recent studies follows. A detailed review of our earlier work may be found in the literature [41]. 

It is known that the adsorption processes play an important role in numerous fields of modern technique, in medicine, analytical chemistry etc. In the initial period mainly carbon adsorbents and silica gels were used. Later the metal oxides mainly AI2O3, mixed oxides prepared on the basis of AI2O3 as well as zeolites became to be more and more widely used as adsorbents and catalysts. These are not obviously all materials needed for carrying out different adsorption and catalytic processes. There exists constant the need for new materials. Such materials should be characterized by high efficiency in different adsorption and catalytic processes as well as by high mechanical resistance especially to oxidizing media. 

There are still many developments in selective hydrogenation, both in terms of new catalysts and process operations. An example of the first is the discovery that Sn-substituted zeolite beta is the most active heterogeneous catalyst for the Meer-wein-Pondorff-Verley reduction of aldehydes and ketones to the corresponding alcohols, with high cis-selectivity (99-100%) in the reduction of 4-alkylcyclohexa-nones [301]. An example of process development is in the heterogeneous catalytic hydrogenation of organic compounds in supercritical fluids (SCFs) [302]. 

Great advances have been made in the field of catalytic epoxidation in the last 10 years, and continue to be made as new catalysts and reactions are discovered and new processes are developed. Of particular interest has been the subject of mechanism, which has played an important role not only in improving... 

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