Anderson Joel Schwanke

Dandelion-Like Microspherical MCM-22 Zeolite Using BP 2000 as a Hard Template

The chemistry between layered MWW zeolite and carbon black pearls (BP 2000) as an inexpensive hard template was investigated to develop a rational one-pot synthesis of MCM-22 microspheres. The characterization results showed that the insertion of BP 2000 in the gel synthesis did not substantially compromise the crystallinity and microporosity, and the microscopic analyses showed that BP 2000 played a key role in controlling the final morphology of the MCM-22 zeolite, creating beautiful dandelion-like microspherical particles. The morphology obtained is due to the tortuous shape of the hard template, the particular MWW particle crystals, the interaction with the external surface of the MWW zeolitic precursor, and the synthesis conditions. The stacking of MWW crystals with edge-to-face orientations generates meso-/macrovoids, allowing access to the interiors of the microspheres. The microspheres were homogeneous with sizes ranging from 6 to 8 μm with an increase of the external surface and a macroporous size distribution centered at 200 nm, which is two times that of the traditional MCM-22 zeolite.

Gallium-Containing Mesoporous Silica: Supported Catalysts with High Catalytic Activity for Oxidation of Benzene, Toluene and o-Xylene

Benzene, toluene and xylene (BTX) are a particular class of volatile organic compounds, which are highly toxic pollutants. In this study, samples of gallium-containing mesoporous silica (MS-Ga7% and MS-Ga11%) were synthesized and their catalytic activity in the oxidation of BTX was investigated. The physicochemical characterization shows that the inclusion of gallium in the mesoporous silica structure leads to an increase in the number of oxygen vacancies in the structure of the MS-Ga system, which can result in an increase in the total and surface oxygen mobility. The results show the highest conversion for benzene (65%), with > 40% for toluene and > 28% for o-xylene. The high catalytic activity observed was attributed to a combination of several factors including a higher number of active sites (gallium and gallium oxide) being exposed, with a greater mobility of the active oxygen species on the surface of the catalyst promoting the catalytic activity.

SBA-15 as a Support for Nickel-Based Catalysts for Polymerization Reactions

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.