Catalyst tailoring

This chapter will consider some of the most interesting of current approaches to the evolution of enzyme mimics, in the context of continuing dramatic progress in protein and nucleotide engineering. There are excellent practical as well as intellectual reasons for the broad interest in this topic. Catalysis is a major preoccupation of the chemical industry if the application of the principles of biocatalysis can lead to robust and efficient catalysts tailor-made for reactions of economic importance the area will become even more a focus of intense activity and investment. 

Pd- and Pt-nanoparticles protected by PS-b-PMAA were used to perform catalytic hydrogenations of cyclohexene in ethanol as solvent It could be shown that such colloids are catalytically active and thus interesting for the development of catalysts tailored for special reactions. 

NOx reduction conversions met in the DOC are quite low. Excess of air in burned lean fuel mixture results in excess of oxygen in the exhaust. Under such conditions, the reducing components naturally present in diesel exhaust (CO, H2 and HC) are readily oxidized by the excessive oxygen and NOx remains unreduced. However, the unburned hydrocarbons still exhibit a certain activity for NO reduction on NM/y-Al203 and NM/zeolites catalysts under lean conditions (HC-SCR). Many efforts have been put into the investigation of different NM-based or alternative catalysts tailored for the HC-SCR reaction and the development of reliable reaction mechanisms—cf., e.g., Joubert et al. 

Worthy of mention are the numerous catalyzed reactions utilizing highly selective zeolite catalysts tailored to the particular process. However, significantly lower quantities of catalyst are utilized compared with those used in petrochemical processes. 

A bimetallic hydrotreating catalyst, tailored for this kind of feedstock, has been developed and tested under different conditions and the main results are summarized here. 

Clays or modified clays are commercially available at reasonable prices and a broad spectrum of their applications already exists, and even more applications will be found in the future in unexpected areas, due to the possibilities of designing catalysts tailored for specific reactions and/or substrates. In particular, the key role that they can play in the production of fine chemicals should be emphasized. Furthermore, montmorillonite, as such or modified, was the clay used in most of the applications reported in this paper yet it is just one among the many smectites and there are many other, very different families of clays. 

The demonstration of extended butene conversion (80%) and Cg selectivity (-74%, with the alkylates constituting approximately 40% of the total Cg compounds) at a relatively mild pressure (80 bar at 568 K), low I/O ratio (5) and reasonable CO2 dilution (70%) is a significant advance over previous efforts. Our results clearly indicate that with rational design of catalyst, tailoring parameters such as acidity and pore structure, it should be possible to further enhance the Cg alkylates selectivity. Thus, C02-based supercritical... 

Wan, K.T. and B.L. Crynes. Catalyst Tailoring for Coal-Derived Liquids. cited in Shah, Y.T. and D.C. Cronauer. Oxygen, Nitrogen and Sulfur Removal Reactions in Donor Solvent Coal Liquefaction. Catalysis Reviews Science and Eng. 20(2) (1979) 209. 

The two reaction steps can occur over a single ammoxidation catalyst tailored for propylene ammoxidation, or the two steps can be separated in two reactors. In the case of the latter, the first reactor uses an acidic alcohol dehydration catalyst with the resulting propylene containing product sent to a second reactor containing a conventional propylene ammoxidation catalyst (104). 

Weiser, M.S., Wesolek, M., and Mulhaupt, R. (2006b) The synthesis and X-ray structure of a phenoxyimine catalyst tailored for living olefin polymerization and the synthesis of ultra-high molecular weight polyethylene and atactic polypropylene. Journal of Organometallic Chemistry, 691,2945-2952. 

Designer acids are acid catalysts tailored through creative imagination, and optimized through careful engineering, which are expected to show high reactivity, selectivity, versatility, and robustness for various synthetic applications [1,2]. 

Foam-supported catalysts tailored for industrial steam reforming processes... 

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