Amination zeolite supported catalysts

N-Arylamines.Arylation of secondary amines in good regioselectivity is observed when the catalyst is supported on NaY zeolite. Such catalysts are easily separated after the reaction by filtration. 

Three papers have appeared in the past two years on catalysts that are either supported on polymers or are heterogeneous. Djakovitch first reported animation reactions catalyzed by palladium particles immobilized on metal oxide supports, as well as by palladium complexes contained in NaY zeolites [172]. In most cases, these reactions were conducted at high temperatures, generally 135 °C. When NaOtBu was used as the base, competing amination through a benzyne intermediate was observed. Thus, para meta regioselectivity was not high, and reaction yields were modest. 

Carbon monoxide is hydrogenated over ruthenium zeolites in both methanation and Fischer-Tropsch conditions. is exchanged in the zeolite as the amine complex. The zeolites used are Linde A, X, Y, and L, natural chabazitey and synthetic mordenite from Norton. The zeolites as a support for ruthenium were compared with alumina. The influence of the nature of the zeolite, the ruthenium metal dispersion and the reaction conditions upon activity and product distribution were investigated. These zeolites are stable methanation catalysts and under the conditions used show a narrow product distribution. The zeolites are less active than other supports. Sintering of ruthenium metal in the zeolite supercages shows only minor effects on methanation activity, although under our Fischer-Tropsch conditions more C2 and C3 are formed. 

Whereas the appropriate forms of zeolites and related solids are widely used in acid-catalysed industrial processes, microporous solids are not currently of importance in commercial base-catalysed conversions. Instead, high-surface-area forms of alkali metal and alkaline earth metal oxides and hydroxides, often supported on alumina, fulfil the need for solid base catalysts. Nevertheless, interest remains in characterising basic sites in cationic zeolites and in developing routes to more strongly basic sites in microporous solids." Routes to the latter include the introduction of metallic forms of alkali metals or nanoparticles of metal oxides and the partial replacement of amine groups at the sites of framework oxygen atoms. Porous solid bases have been shown to exhibit a varied catalytic chemistry, particularly for reactions such as dehydrogenations,... 

Zeolites have also known as efficient catalysts for a wide variety of acid-promoted cyclization reactions. Most of them involves the formation of N-heterocycles through the intramolecular amination reaction pathway [48-50]. See examples are shown in Figure 11.13. Pyridines are also being produced by the reaction of ammonia over solid support acid catalyst with various aldehydes [50]. 

The most widely used catalysts for acid-catalyzed aldol condensations are the molecular sieve zeolites, for example, crystalline aluminosilicates of group I and II elements, in which the latter have been replaced by protons. The surface protons confer Br0nsted acidity. Among the acidic zeolites we can mention HZSM-5 (pentasil zeolite), HY (faujasite), or HM (mordenite). Recently, polystyrene-supported sulfonic acids such as those of the macroreticular strongly acidic cation-exchange resins (59) and acid-base functionalized mesoporous materials such as amine and sulfonic acid-containing SBA-15 (60) have been shown to promote the acid-catalyzed aldol condensation of aldehydes with ketones at low temperatures. 

For the selective nitrogenation of benzene with ammonia, Hodlerich et al. investigated the catalytic effect of a series of Group Vlll metals (e.g., Ru, Rh, Pd, Pt, Cu, and Ni) as the catalyst supported on carriers such as alumina, silica and zeolite in a plug slow reactor or in a continuously stirred tank reactor. Oxygen or carbon monoxide was employed respectively to shift the reaction equilibrium towards aniline formation [69]. Durante et al. developed a process for catalytic oxidative amination of aromatic hydrocarbons in which aromatic feedstock contacts with oxygen under suitable reaction conditions in the presence of a catalyst... 

---