Utilização de substâncias húmicas na obtenção de materiais catalíticos do tipo metal-suportado, Ni/Al2O3, para a produção de carbono via decomposição do metano

Abstract

Humic Substances (SH) consist of 70% to 80% of organic matter and one of their main characteristics is the high complexation with metallic ions. Thus, this work proposes the use of SH as complexing agents in the production of alumina catalytic supports and nickel catalysts anchored in alumina (Al2O3), conceptualized as supported metal. Initially, the catalytic supports were synthesized in mass ratios of 0.5, 1 and 2 of SH:Al, calcined at 700 °C and named XSH/Al2O3Y. Subsequently, catalysts were synthesized via wet impregnation in the presence and absence of SH and in for comparison purposes, with 5, 10 and 15% Ni (m/m), calcined at 700 °C and named XNi/Al2O3(SH)Y. The obtained materials were characterized by thermogravimetry (TG), X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), liquid N2 adsorption/desorption at 77K and temperature programmed reduction (TPR) and tested in the decomposition reaction catalysis of methane at 500 °C for 30 min. The catalytic performance was evaluated from the yield on carbonaceous materials. The use of SH in the alumina synthesis process and supported metal catalysts was effective. The insertion of SH in obtaining these materials provided alteration of the crystalline phase of alumina and Ni oxide, promoted an increase of 50% in the surface area of the catalysts and porosity. The catalysts synthesized in the presence of SH, depending on the reaction conditions of methane decomposition, showed a higher carbon yield than those catalysts synthesized without the presence of SH.