Investigação do potencial catalítico do α-MoO3 combinado com resíduo de rochas ornamentais para a produção de biodiesel: uma tecnologia promissora

Abstract

The improper handling and disposal of industrial waste, such as ornamental rock waste, causes serious environmental problems, contributing to the accumulation and dissemination of harmful pollutants in the air, water and soil. Studies related to the use of waste have been gaining strength in the scientific community, in the use of these pollutants as support for catalysts in the production of biodiesel. On the other hand, molybdenum trioxide (α-MoO3) is widely recognized as an excellent catalyst in several industrial processes and especially biodiesel due to its mechanical, thermal and electrical properties. Therefore, the objective of this work was to add value to ornamental rock waste by using it as support for α-MoO3 produced on a pilot scale by combustion reaction as a new α-MoO3/Res catalytic system, aiming at application in simultaneous transesterification/esterification reactions of residual frying oil for biodiesel production. The catalysts were obtained by incorporating the residue and α-MoO3 using an Attritor mill in the proportions of 30, 40 and 50% by mass of α-MoO3/Res. The catalytic tests were performed in the PARR reactor (4848) by the ethyl/methyl route using the molar ratio (alcohol/oil) of 15:1 with 3% and 6%. The results showed the presence of crystalline phases of mica, quartz, feldspar and iron-tschermakite related to the residue and characteristic peaks of the orthorhombic phase of α-MoO3 in all incorporated catalysts (X%α-MoO3/Res). The FTIR spectra exhibited vibrational bands characteristic of Si-O T bonds (T=Si). Its morphology is formed by clusters of small particles in the form of plates and rods characteristic of the residue and α-MoO3. EDX analysis identified the majority presence of oxides (SiO2, Al2O3 and Fe2O3). Analysis by the Brunauer-Emmet Teller (BET) method showed porous structures in the mesopore range, with monomodal and bimodal particle size distribution as molybdenum was added. Analysis of the determination of acid sites by TPD-NH3 indicated that the addition of α-MoO3 to the residue increased the acidity. The incorporated catalysts proved to be effective in the transesterification/simultaneous esterification (TES) reactions, reaching conversions into biodiesel between 57.3% - 78.6% in the ethyl route and 75.1% - 84.3% in the methyl route. According to the results, it is possible to produce catalysts supported with ornamental rocks, thus reducing the environmental impact.