Two mesoporous SBA-15 materials with different morphologies (spherical and fiber-shaped) were synthesized and evaluated as supports for nickel-based catalysts for polymerization reactions. The supports were pretreated with trimethylaluminum (TMA), and the catalyst dibromo-bis(4-amino-2,3,5,6-tetramethylimino)acenaphthene nickel(II) was attached to the supports and activated with TMA or MAO (methylaluminoxane). Characterization showed that the insertion of cetyltrimethylammonium bromide (CTABr) as a cosurfactant led to spherical SBA-15 with a decrease in particle and pore sizes to 4.8 nm compared to 6.5 nm in traditional fiber-shaped SBA-15. The spherical SBA-15 showed thicker walls than the fiber-shaped SBA-15, attributed to the increase in functional groups of the cosurfactant. The different spherical and fiber-shaped morphologies did not show any significant difference in the productivity of polyethylene. The catalyst supported on spherical SBA-15 materials showed 58% productivity compared to its homogeneous analogue using TMA as a cocatalyst.

In this work, the catalysis area in Brazil is analyzed from several perspectives between 1977 and 2017. The conceptual aspects and the area at world level are briefly introduced. A history of the main organizational initiatives of the area is also presented, highlighting the activities of the Catalysis Division of the Brazilian Chemical Society. An overview of the industry situation related to the area, as well as the evolution of scientific production in Brazil, are also discussed.

<p>Homogeneous polymerization catalysts require large amounts of solvent and cannot control the polymer morphology. In order to solve this issue, a narrow-shaped spherical ZSM-5 zeolite was used in ethylene polymerization as a support for zirconocene (Cp₂ZrCl₂). Several heterogeneous catalytic precursors were prepared and used in ethylene polymerization reactions, which showed yields (between 980-8019 kg PE mol^-1 h^-1) and were efficient at promoting morphological replication of the support. So, a well-established protocol for slurry polymerization reaction was found, yielding well-defined polymer particles in an advantageous polymerization process.</p>

A oligomerização do propeno foi realizada utilizando o complexo dibromo-bis(N,N'- difenilpentano-2,4-diimina)niquel(II) como precursor catalítico combinado ao sesquicloreto de etilalumínio (Al2Et3Cl3, EASC) como co-catalisador. A 10 ºC, usando o tolueno como solvente, altas frequências de rotação foram obtidas (até 57000 h–1) com alta seletividade em produtos C6 (até > 99%) e seletividade moderada em C6 linear (até 29%). Observou-se que nas condições experimentais empregadas o propeno reagiu com tolueno por reação de Friedel-Crafts. O aumento da concentração de precursor catalítico, mantendo constante a relação precursor/co-catalisador, teve por efeito de aumentar a selectividade para os produtos de oligomerização em relação aos produtos de alquilação por reação de Friedel-Crafts.

Propylene oligomerization was performed using dibromo-bis(N,N'-diphenylpentane-2,4- diimine)nickel(II) complex as catalytic precursor combined with ethyl aluminum sesquichloride (Al2Et3Cl3, EASC) as co-catalyst. At 10 ºC, using toluene as solvent, high turnover frequencies (up to 57,000 h–1) with high selectivities to C6 products (up to > 99%) and moderate linear C6 selectivity (up to 29%) were obtained. Under our reaction conditions propylene reacted with toluene through Friedel-Crafts reaction. Increasing the concentration of catalyst precursor keeping the nickel complex/co-catalyst ratio constant increased the selectivity of the oligomerization products vs. Friedel-Craft products.