Candida antarctica lipase B (CALB) is an enzyme able to catalyze chemical reaction, however when it is used as a free enzyme, it cannot be recovered from reaction medium. One of the alternatives is to immobilize the enzymes on a support which allows the maintenance of their catalytic activities. The purpose of this paper was to immobilize the CALB on MCM-48 using the ionic solid [C16MI]Cl as structure director. 22 CCRD (Central Composite Rotational Design) was proposed to analyze the influence of the variables like enzyme mass (0.059 to 0.341 g) and ionic solid concentration (0.59 to 3.41%) in the enzyme immobilization process to obtain the maximum esterification activity in order to optimize the process. After immobilization, the study results showed that the enzymes exhibited improvement of thermal (40, 60 and 80 ºC) and storage stability (90 days), besides the possibility to reuse of the enzyme up to 10 times, showing residual activity of 50%.
<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 (Cp<sub>2</sub>ZrCl<sub>2</sub>). Several heterogeneous catalytic precursors were prepared and used in ethylene polymerization reactions, which showed yields (between 980-8019 kg PE mol<sup>-1</sup> h<sup>-1</sup>) 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 new kind of material, denominated MCM-71, was synthesized and characterized by several complementary techniques: X Ray Diffractometry, textural analysis by nitrogen adsorption, Scanning electronic microscopy and infrared spectroscopy. MCM-71 zeolite was successfully synthesized by hydrothermal synthesis in the presence of triethanolamine. Mordenite phase as impurity was not detected, otherwise quartz was observed. The MCM-71 sample obtained presented a BET surface area of 20 m²/g in the as synthesized form and of 85 m²/g in protonic form. By SEM was observed crystals with rectangular shape with average size of 2 x 0,2 x 0,05 µm and this crystals were agglomerated in spherical particles with average diameter between 14 and 24 µm.
This paper deals with an adosrption of sulphur compounds employing zeolites containing zinc. The zeolites employed were commercial NaY and Beta. The zinc was incorporated in three levels: 0.5; 1.0 and 5%. The sulphur compounds studied were benzothiophene and dibenzothiofene. The results showed that both zeolites can be employed for adsorption of benzothiophene and dibenzothiophene. The Zn incorporation (0.5%) promotes an increase in zeolites adsorption ability. The DBT adsorbs more than BT, probably because it strongly interacts with zeolite structure. The BT adsorbs more in NaY than in beta probably because the NaY zeolite has a high intern volume. This is not observed for DBT.
The synthesis of ZSM-5 zeolite was studied by three synthesis methods: standard synthesis, three day synthesis and synthesis employing clays (kaolin and montmorillonite). The raw materials and prepared materials were characterized by Chemical Analysis by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD). The results show that it is possible to synthesized ZSM-5 zeolite using clays as raw materials. Kaolin gives phases of higher crystalinity than montmorillonite.