Avaliação de minérios e rejeitos industriais à base de ferro como transportadores de oxigênio e do resíduo do algodão colorido para o processo Biomass Chemical Looping Gasification – BCLG

Abstract

The reduction of anthropogenic greenhouse gas (GHG) emissions has become one of the main environmental concerns of this century. Limiting global warming to 1.5°C by 2100, as established in the Paris Agreement, requires minimizing cumulative emissions of CO2 and other GHGs such as methane (CH4). In this context, the use of biofuels (biomass) combined with Carbon Capture and Storage (CCS) processes presents an attractive solution to achieve zero carbon dioxide emissions in industrial processes. Biomass Chemical Looping Gaseification (BCLG) has emerged as an innovative and advantageous option compared to conventional gasification, as it produces high-purity synthesis gas, undiluted with N2, and with lower energy and economic penalties. A fundamental criterion in the development of the BCLG process is the appropriate selection of an oxygen carrier (OC). Iron-based ores and waste materials are attractive in industrial Chemical Looping (CL) applications due to their low cost, abundance, and heterogeneous composition. Therefore, this doctoral thesis aims to assess the potential of four iron-based oxygen carriers: Brazilian iron ore (Carajás - CRJ), iron industry waste (Derramamento – DRM) and (Carepa - CRP), as well as a physical mixture of DRM with eggshell waste (DRM-RCO), for subsequent application in the BCLG process. The energy potential of colored cotton residue (BRAC) was analyzed through characterization techniques such as apparent density, proximate analysis, calorific value, and elemental chemical analysis. The oxygen carriers were evaluated using techniques such as X-ray Fluorescence (XRF), X-ray Diffraction (XRD), laser granulometry, picnometry, Field Emission Scanning Electron Microscopy (FE-SEM) with Energy Dispersive X-ray Spectroscopy (EDX), Temperature Programmed Reduction (TPR), mechanical resistance, frictional loss (Air Jate Index), and reactivity assessment by thermogravimetry. Following the characterizations, it was found that BRAC biomass is a potential fuel due to its promising compositional and energetic characteristics for the BCLG process. Additionally, the CRJ oxygen carrier exhibited suitable physico-chemical properties to be evaluated in the discontinuous fluidized bed reactor – Batch Reactor, under conditions similar to CLC, using H2, CO, and CH4 as different fuel gases at temperatures of 850 °C, 900 °C, and 950 °C. The CRJ particles post-Batch were assessed by characterization techniques: mechanical resistance, AJI, XRD, FE-SEM, and reactivity analysis with H2 and CH4. It was possible to conclude that the CRJ carrier showed good fuel conversion and reactivity with H2, followed by CO fuel, and finally, with CH4. Furthermore, it did not exhibit carbon deposition, and minimal frictional loss was observed during 12 hours of operation, resulting in a service life of 12.030 hours. After tests in the Batch Reactor, the CRJ oxygen carrier did not experience agglomeration or defluidization issues and maintained its reactivity under hydrogen gas.