Uso da diatomita como suporte de catalisadores de Ni e Co na reação de reforma a seco do metano

摘要

Due to environmental requirements and to the development of the chemical industry,the demand for hydrogen has been getting an important focus in the energy, input andenvironmental sectors. Since the two major methods used in obtaining hydrogen are steamand dry methane reforming reactions. The greatest challenge faced by hydrogen productionreactions is to find long-term stable catalysts that are also resistant to carbon accumulationand selective to the formation of hydrogen gas. Besides lowering the cost, the utilization ofcatalytic supports has important role for the reforming reactions, increasing the chemical andthermal resistance during the processes, besides, it provides good dispersion of the activephase, avoiding avoiding the sinterization of the active phase, influencing positively theactivity and stability of the catalyst. In this context, this work aims to use diatomite ascatalytic support to disperse the metallic phases of Ni and Co, evaluating the catalystsobtained for the methane dry reforming process, as well as evaluating the effects of additionof Ce and La as promoters to the most effective catalysts. Monometallic and bimetallic Ni andCo catalysts were prepared with different active phase concentrations using the wetimpregnation methodology. The support and the active phases were evaluated according tothe following characterization methods: X-ray diffraction (XRD), adsorption and desorptionof N2, thermogravimetric analysis (TGA), X-ray fluorescence (XRF), programmed reductiontemperature (TPR) and scanning electron microscopy (SEM). The catalytic tests wereperformed in a quartz fixed bed differential reactor at 700°C. The products formed during areaction were analyzed by gas chromatography. The results showed that the mono andbimetallic Ni and Co were formed. The catalyst with 8% of Ni and 2% of Co concentrationssupported on diatomite showed good interaction with the support, low reduction temperatureprofile and and good stability over the 10h test. The catalyst containing 10% Ni had thegreatest activity during this reaction. The use Ce or O promoters had no influence to thecatalytic properties and led to a higher formation of coke. In all cases studied, the diatomitewas shown to be chemical and thermally stable during the preparation of the catalysts and thecatalytic test, being considered, therefore, an excellent support for the dry reforming reactionof methane.