Tiago Pinheiro Braga

CO2 mitigation by carbon nanotube formation during dry reforming of methane analyzed by factorial design combined with response surface methodology

Abstract A factorial experimental design was combined with response surface methodology (RSM) to optimize the catalyzed CO2 consumption by coke deposition and syngas production during the dry reforming of CH4. The CH4/CO2 feed ratio and the reaction temperature were chosen as the variables, and the selected responses were CH4 and CO2 conversion, the H2/CO ratio, and coke deposition. The optimal reaction conditions were found to be a CH4/CO2 feed ratio of approximately 3 at 700 °C, producing a large quantity of coke and realizing high CO2 conversion. Furthermore, Raman results showed that the CH4/CO2 ratio and reaction temperature affect the systems response, particularly the characteristics of the coke produced, which indicates the formation of carbon nanotubes and amorphous carbon.

Catalytic properties of cobalt and nickel ferrites dispersed in mesoporous silicon oxide for ethylbenzene dehydrogenation with CO2

A polymeric precursor method was applied to synthesize catalysts of the general formula MFe2O4 (M = Co and Ni) in order to contribute to studies on ethylbenzene dehydrogenation in the presence of CO2. The catalysts were characterized by TG, H2-TPR, XRD, Mossbauer spectroscopy (MS), N2 adsorption/desorption isotherms and TPD-CO2. Investigations using XRD and MS revealed that the spinel structures of CoFe2O4 and NiFe2O4 phases were formed. The catalytic results suggested that materials with a spinel structure are particularly interesting for ethylbenzene dehydrogenation. Compared to the other catalysts synthesized the sample containing cobalt ferrite showed higher conversion and good styrene selectivity. The analysis of the spent catalyst (DRX) showed that the CoFe2O4 phase was stable under the reaction conditions and that a coke (TG) deposit was more pronounced for the NiFeSi.

Co2 na desidrogenação oxidativa do etilbenzeno utilizando catalisadores compostos de óxido de ferro e óxido de alumínio

Materials containing aluminum and iron oxide were synthesized through the preparation of hybrid spheres and tested in the dehydrogenation of ethylbenzene in the presence of CO2. The catalytic results suggest that the high initial ethylbenzene conversion is due to the contribution of basic sites. These results also point to a competitive process between CO2 adsorption and the oxidative dehydrogenation of ethylbenzene for the basic sites (lattice oxygen). In spite of the coke deposition is originating from ethylbenzene and CO2, the amount of carbonaceous deposits was smaller with the presence of CO2, if compared with the dehydrogenation in the absence of CO2.