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Catalysis on Bifunctional Pt Acid Zeolites. A Route to Cleaner Processes

Guisnet M.

Polish Journal of Chemistry

2003

Vol. 77 / nr 5

637-656

The large benefit brought by the association of hydrogenating sites (Pt or Pd) with the protonic acid sites of a zeolite is shown here on three examples of reactions related to Refining, Petrochemicals and Specialty Chemicals processes: n-alkane hydroisomerization and hydrocracking, ethylbenzene (EB) isomerization, synthesis of methylisobutylketone (MIBK) from acetone. Whatever the reaction, the bifunctional catalysts are more stable than the purely acidic catalysts. They are able to catalyze certain reactions, which cannot occur through acid catalysis (e.g. EB isomerization). They allow the synthesis in one apparent step of products, which requires several successive steps catalyzed by metallic and acidic sites (e.g. synthesis of MIBK). Their selectivity can be directed to the desired products (e.g. monobranched alkanes in isodewaxing, xylenes in EB isomerization). Moreover, the semi-quantitative relations, which were established between their physicochemical properties, especially the balance between hydrogenating and acid functions and the zeolite pore structure, and their catalytic properties constitute guidelines for a scientific design of optimal catalysts and for the development of economic and environmentally friendly processes.

Zeolite catalysts for fine chemicals synthesis. Acetylation of 2-methoxynaphtalene

Guisnet M., Moreau V., Magnoux P.

Bulletin of the Polish Academy of Sciences. Chemistry

2002

Vol. 50, No. 2

203-218

Acetylation of 1-methoxynaphthalene into 2-acetyl-6-methoxynaphthalene, which is a precursor of the anti-inflammatory S-Naproxen, was chosen as an example to show the great potentialities of zeolite catalysts for substituting polluting and corrosive Friedel-Crafts catalysts. A selective and clean process can be developed using acetic anhydride, as acylating agent, and a HBEA zeolite with a Si/Al ratio between 20 and 40 and without extraframework aluminum species, as catalyst. Adsorption experiments demonstrate that all the acetyl-methoxynaphthalene isomers can enter the BEA micro-pores hence can be formed within these pores. The strong interactions between the polar molecules of reactants and products and the micropore walls were shown to determine both the reaction scheme and the mechanisms. These interactions play a more important role than product shape selectivity in the kinetically limiting desorption of products.