Demineralization of Brazilian Coals for Use in Gasification and Oxy-Fuel Combustion Processes, Aiming to Reduce CO₂ Emissions

Abstract

Mineral matter in coal has an environmentally negative effect, as it is responsible for the generation of soot and slag. Technically, the mineral matter causes corrosion of equipment and reduces the combustion rate of coal, as well as influencing the sizing of equipment. Therefore, removal of this unwanted portion of the carbon matrix would reduce the need for importing high-quality coals and minimize transportation costs. This work aims to study the effects of the removal of mineral matter on the structure of southern Brazilian coal at the temperature of gasification and considering the kinetic parameters of the oxy-fuel combustion reaction. The demineralization process was conducted using solutions of HF, HCl, and HNO 3 with concentrations of 20% (v/v). The samples were characterized by elemental analysis, proximate analysis, SEM, FT-IR spectroscopy, petrographic analysis, XRD, and XRF. The removal of the mineral portion introduced major changes in the structure of coal, reflecting an increase in the start temperature of the Boudouard reaction to 160 K. The oxy-fuel reaction was performed at temperatures of 873, 973, 1073, and 1173 K with O 2 /CO 2 concentration ratios ranging from 10% to 30% (v/v). Before the demineralization process, the activation energy for the oxy-fuel reaction was 10.8 kJ•mol −1 . The value obtained with demineralized char was 56.46 kJ•mol −1 .

Emerging Single-Atom Catalysts and Nanomaterials for Photoelectrochemical Reduction of Carbon Dioxide to Value-Added Products: A Review of the Current State-of-the-Art and Future Perspectives

“…Almost 64.2% share of the Earth's total energy is profoundly dependent on fossil fuels (Figure 1). 2 Excessive use in the form of fossil fuel combustion has led to higher carbon dioxide (CO 2 ) emissions, which is a major greenhouse gas responsible for climate change. 3,4 There are various adverse effects of increasing CO 2 emissions, such as acid rain, smog, and global warming, potentially leading to climate change.…”

“…Almost 64.2% share of the Earth’s total energy is profoundly dependent on fossil fuels (Figure ). Excessive use in the form of fossil fuel combustion has led to higher carbon dioxide (CO 2 ) emissions, which is a major greenhouse gas responsible for climate change. , There are various adverse effects of increasing CO 2 emissions, such as acid rain, smog, and global warming, potentially leading to climate change . Many anthropogenic activities from humans also increase CO 2 emissions, leading to global warming, which can cause temperature elevation of the near-surface air resulting in heat waves across regions of the Earth. , Global warming is also causing the elevation in the temperature of the polar regions, which could be 3-fold greater than that of the other regions, resulting in the melting of ice caps, thereby leading to widespread floods in low-lying areas .…”