Desenvolvimento de um sistema catalítico em meio pressurizado para conversão da γ-butirolactona em produtos de alto valor agregado

Abstract

The unsustainability of the use of fossil materials generates the search for alternative components capable of producing chemical products and energy from clean, renewable and economically viable processes. In the context of chemical product production, biomass is considered a source of platform molecules capable of synthesizing high value-added chemicals. γ-Butyrolactone (GBL), for example, is an important platform molecule for the production of 1,4-butanediol (BDO) and tetrahydrofuran (THF), these substances having several industrial applications. Thus, the present work aimed to study the processes of catalytic hydrogenation of γ-butyrolactone, employing bimetallic nanostructured catalysts based on palladium and rhenium and supported on silica (PdRe/SiO2). The PdRe/SiO2 catalysts were synthesized by the successive impregnation method and characterized in terms of their surface and pore volume, quantity of metals, reduction temperature, crystalline structure and morphology. The reactions were evaluated for the effect of temperature and pressure, from a central rotational composite design, water effect (solvent) and supercritical CO2 (reaction medium). The catalysts were characterized as mesoporous materials with narrow and uniform pores. From the XRD of the catalyst, the Pd peaks were identified in different planes, only a peak of Re and a characteristic peak of amorphous materials referring to silica. TEM images showed agglomerated metal structures, but well distributed on the support. For the reactions, only the linear temperature effect was significant for the GBL conversion, while for the BDO selectivity, the quadratic effects of temperature and pressure were statistically significant. Dimers of BDO and GBL were identified as products of the reactions and water had a great influence on their formations. The effects of SC-CO2 were more expressive in increasing the selectivity of THF.