Industrial fine chemicals catalyst developments

High throughput screening is one of the hot topics in heterogeneous catalysis. Advanced experimental techniques have been developed to screen and develop solid catalysts for gas-phase systems. However, for catalytic three-phase systems, rapid screening has got much less attention [1-6]. Three-phase catalysis is applied in numerous industrial processes, from synthesis of fine chemicals to refining of crade oil. 

One of the most common heterogeneous organic reactions in the fine chemicals and the specialty chemicals industries is the hydrogenation of carbon-carbon multiple bonds. It is so common that an entire array of specialty catalysts has been developed to accomplish specific hydrogenation reactions. An important goal in this field is selectivity. However, when relatively large quantities of chemicals are produced, concerns also embrace economy, yield, and... 

Among the wide variety of organic reactions in which zeolites have been employed as catalysts, may be emphasized the transformations of aromatic hydrocarbons of importance in petrochemistry, and in the synthesis of intermediates for pharmaceutical or fragrance products.5 In particular, Friede 1-Crafts acylation and alkylation over zeolites have been widely used for the synthesis of fine chemicals.6 Insights into the mechanism of aromatic acylation over zeolites have been disclosed.7 The production of ethylbenzene from benzene and ethylene, catalyzed by HZSM-5 zeolite and developed by the Mobil-Badger Company, was the first commercialized industrial process for aromatic alkylation over zeolites.8 Other typical examples of zeolite-mediated Friedel-Crafts reactions are the regioselective formation of p-xylene by alkylation of toluene with methanol over HZSM-5,9 or the regioselective p-acylation of toluene with acetic anhydride over HBEA zeolites.10 In both transformations, the p-isomers are obtained in nearly quantitative yield. 

The development of chiral phosphorus ligands has made undoubtedly significant impact on the asymmetric hydrogenation. Transition metal catalysts with efficient chiral phosphorus ligands have enabled the synthesis of a variety of chiral products from prochiral olefins, ketones, and imines in a very efficient manner, and many practical hydrogenation processes have been exploited in industry for the synthesis of chiral drugs and fine chemicals. 

The further optimization and development concerning stability and selectivity of the organometallic catalyst in these kinds of media and the application of isolation methodologies similar to CESS (catalysis and extraction using supercritical solutions [43]) together with the physical and chemical advantages of supercritical fluids can lead to high potential catalyst matrices that fulfil the requirements of industrial processes both for bulk and fine chemicals. 

In the 1970s and 1980s, however, it was believed that the key to wider use of solid-phase supported reagents and catalysts is their adoption in industry for fine chemical and pharmaceutical manufacturing on a large scale. In fact, this restricted view hampered their wide use [7]. The dramatic developments in the need for compound library preparation in pharmaceutical and agrochemical industries have finally removed functionalized supports from their academic corner and helped reinvent them for industrial purposes and applications. 

In order to understand the challenges facing the application of catalysts in the fine chemicals industry, one has to understand not only the essential industrial requirements but also how process development is carried out, and which criteria determine the suitability of a catalyst. 

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