Estudo da síntese de zeólitas com estruturas ferrieritas (FER) e sua aplicação em pirólise de biomassa
Zeolites are microporous crystalline materials with a well-defined porous structure belonging to the group of materials called molecular sieves. Among these materials, there is the Ferrierite zeolite that has high stability to thermal / hydrothermal and chemical treatments and has a two-dimensional...
Tallennettuna:
| Päätekijä: | |
|---|---|
| Muut tekijät: | |
| Aineistotyyppi: | doctoralThesis |
| Kieli: | pt_BR |
| Julkaistu: |
Universidade Federal do Rio Grande do Norte
|
| Aiheet: | |
| Linkit: | https://repositorio.ufrn.br/handle/123456789/46633 |
| Tagit: |
Lisää tagi
Ei tageja, Lisää ensimmäinen tagi!
|
| Yhteenveto: | Zeolites are microporous crystalline materials with a well-defined porous
structure belonging to the group of materials called molecular sieves. Among
these materials, there is the Ferrierite zeolite that has high stability to thermal /
hydrothermal and chemical treatments and has a two-dimensional microporous
structure that provides a remarkable performance as an acid catalyst in
hydrocarbon conversion reactions. In view of its characteristics, this material has
been extensively studied in recent years and was the object of study in this work.
Another zeolite that was also studied here was a ZSM-5 that has been widely
exploited in various industrial processes such as hydrocracking, isomerization,
alkylation and deprotonization of benzene. Thus, the FER structure and
commercial ZSM-5 zeolites were characterized and tested in biomass catalysis
reactions in the present study. The FER-type zeolite syntheses were studied in
the bulletin by the method described in IZA, and later some parameters were
modified, such as silicon and aluminum sources, the Si/Al ratio and the addition
of the cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). The
use of alternative sources of silicon and aluminum, which are easily sources in
nature, brings a great cost-benefit to the process. The study of the Si / Al ratio
and the addition of surfactant was carried out to observe the growth of crystals
and dispersion of particles, promoting a greater external area, which could lead
to better applicability of these materials. The ZSM-5 zeolite was altered by
zirconium impregnation to improve the acidity of the catalyst. For the
characterization of these materials, X-ray diffraction (XRD), X-ray fluorescence
(FRX), scanning electron microscopy (SEM), thermogravimetric analysis (TG),
and textural analysis by N2 adsorption (BET method). The FER-type zeolite was
successfully obtained in the syntheses following the IZA method, in the use of
different sources of silicon and aluminum and in Si/Al ratios of 7.6 with and
without the use of surfactant. In the syntheses with increment of silicon, a
structure of the FER-type zeolite was directed to a ZSM-5 zeolite. However, the
surfactant drove a structure to a ZSM-5 at a faster rate than syntheses without
surfactants. After the step of studying the syntheses, it was followed by their
applications as catalysts for biomass pyrolysis. Cellulose, lignocellulose and hemicellulose were the tested biomasses for the production of bio-oil by rapid
pyrolysis. In the characterization of the products obtained in the reactions, the
techniques of gas chromatography, elemental analysis CHNS-O,
thermogravimetric analysis and moisture analysis (Karl Fisher) were used. It was
observed that the use of catalysts, FER and ZrO2/n-ZSM-5 in the reaction, led to
a drastic reduction in bio-oil, but led to a greater production of CO and CO2, which
are molecules that reduce the oxygen content. in bio-oil. These preliminary
results showed that the studied catalysts are promising for biomass catalysis
reactions, which may indicate the use of these reactions to obtain solid, liquid and
gaseous products that can later be used as a fuel source, among other uses.
Obtaining these products implies a possible replacement of fossil fuels by fuels
from alternative sources, which is extremely important for the environment. |
|---|