Abstract This paper discussed the synthesis of LTA zeolite from Pinheiro clay (PIN) aiming for adsorption of CO2. To obtain the LTA-PIN zeolite, the PIN was submitted to acid treatment, followed by calcination and hydrothermal treatment. These treatments promoted the reorganization of the crystalline structure of the PIN, leading to the LTA-PIN zeolite with 95.79% purity confirmed by XRD, SEM, XRF, and FTIR results. The performance of the LTA-PIN zeolite was similar to the one of the standard LTA zeolite. The CO2 adsorption by the zeolites could be properly described by the pseudo-second-order kinetic and Freundlich isotherm models, suggesting that physisorption was the main mechanism responsible for the deposition of CO2 at the surface of the zeolites. According to regeneration results, LTA-PIN zeolite can be reused five times without significant loss of CO2 adsorption capacity, contrary to the 12% reduction in CO2 adsorption capacity presented by the LTA-standard zeolite.

Abstract The synthesis of SSZ-13 was studied by evaluating the influence of two types of crystallization seeds with CHA structure (S1 seeds prepared in fluoride medium and S2 seeds by the conversion of zeolite Y), SiO2/Al2O3 (28, 40, 60 and 100) and OH/SiO2 (0.6 and 0.8) ratios. Choline chloride was used as the structure-directing agent and the crystallizations occurred at 140 ºC from 24 to 96 h. S1 seeds led to the coexistence of zeolites SSZ-13 and P, while S2 seeds promoted in all SiO2/Al2O3 ratios and OH/SiO2 = 0.8, the formation of pure SSZ-13 after 24 h. The SSZ-13 samples are formed by clusters of crystals with cuboid-like morphology and exhibited textural properties typical of CHA framework. SSZ-13 zeolite led to a decrease in the temperature and the activation energy required for the degradation of ultra-high molecular weight polyethylene polymer, demonstrating its efficiency as catalyst in this process.

Resumo A degradação termocatalítica do polietileno (PE) e do polietileno de ultra alto peso molecular (UHMWPE) foi estudada na presença de zeólitas (ZSM-5, ZSM-22 e ferrierita) com diferentes sistemas de poros e propriedades texturais. As zeólitas foram misturadas fisicamente aos polímeros na proporção de 30% em massa e submetidas à análise termogravimétrica nas taxas de aquecimento de 5, 10, 20 e 30 °C.min-1. A energia de ativação do processo de degradação foi determinada pelo método de Flynn-Wall-Ozawa. A adição das zeólitas aos polímeros reduziu consideravelmente a temperatura de degradação. A ZSM-22 demonstrou maior eficiência na degradação do PE por apresentar menor tamanho de cristalito, promovendo um caminho difusional mais curto para os fragmentos de polímero provenientes da superfície. A ferrierita apresentou menor nível de energia na degradação do UHMWPE, mostrando a necessidade da sinergia entre a acessibilidade da estrutura e a acidez do catalisador para promover a quebra desse polímero.

Abstract The thermo-catalytic degradation of polyethylene (PE) and ultra-high molecular weight polyethylene (UHMWPE) was studied in the presence of zeolites (ZSM-5, ZSM-22, and ferrierite) with different pore systems and textural properties. The zeolites were physically mixed with polymers in the proportion of 30 wt% and submitted to thermogravimetric analysis at heating rates of 5, 10, 20, and 30 °C.min-1. The activation energy of the degradation process was determined using the Flynn-Wall-Ozawa method. The addition of zeolites to polymers has considerably reduced the temperature of degradation. ZSM-22 demonstrated greater efficiency in the degradation of PE because it has a smaller crystallite size, promoting a shorter diffusional path for the polymer fragments coming from the surface. Ferrierite showed a lower energy level in the degradation of UHMWPE, showing the need for synergy between the accessibility of the structure and acidity of the catalyst to promote the cracking of this polymer.