Na-Containing Mineral Transformation Behaviors during Na₂CO₃-Catalyzed CO₂ Gasification of High-Alumina Coal

Abstract

Interactions between alkali metals in catalysts and silicon or aluminum minerals in coal are closely related to gasification reactivity, deactivation, and recovery of alkali catalysts during coal catalytic gasification, and alkali-containing minerals and their transformation behaviors are key issues for understanding these interactions. In this paper, Na-containing mineral transformation behaviors and their influences on the catalytic performance during Na 2 CO 3 -catalyzed CO 2 gasification of highalumina coal were comprehensively investigated by thermogravimetry, inductively coupled plasma, X-ray diffraction, and Fourier transform infrared spectroscopy. Moreover, to have a better understanding of the mineral transformation during catalytic gasification, model compounds, i.e., kaolinite (Al 2 O 3 •2SiO 2 •2H 2 O) and boehmite (AlOOH), the main Al-containing minerals in high-alumina coal, were chosen as model compounds to investigate the mineral transformation behaviors. The results show that Na 2 CO 3 first deactivates to generate inert sodium aluminum silicate (Na 1.55 Al 1.55 Si 0.45 O 4 ) at 700 °C, which contributes to the deactivation of catalysts, and then various kinds of sodium aluminum silicates are formed with increasing temperature and Na 2 CO 3 addition. Among them, sodium aluminum silicate [(Na 2 O) 0.33 NaAlSiO 4 ] has been testified as the most stable mineral during gasification. In addition, Na-containing mineral transformation and its resulting products are helpful to the recovery of Al from the ash of catalytic gasification, and 94% recovery rate can be obtained, which is considered to be a method to extract Al from gasification ash. Model kaolinite and boehmite can well explain the mineral transformation during Na 2 CO 3 -catalyzed CO 2 gasification of high-alumina coal.

Effect of Na2CO3 on the Microstructure and Macroscopic Properties and Mechanism Analysis of PVA/CMC Composite Film

“…Two absorption peaks that appeared in the region of 1417 cm −1 and 1325 cm −1 corresponded to scissoring CH2 and bending OH, respectively [27]. For Na2CO3, the peaks at 1426 cm −1 , 878 cm −1 , and 700 cm −1 were carbonate bands [28]. For P/C/N and P/N composite films, the absorption peaks at 878 cm −1 and 700 cm −1 indicated the presence of Na2CO3.…”

Catalytic effect of alkali and alkaline earth metals in different occurrence modes in Zhundong coals

“…XRD analysis was employed to elucidate the fundamental compositions of the AAEMs. XRD determines the major crystalline compounds present in a sample, but some information about amorphous materials and poorly crystalline materials cannot be obtained by XRD . The variation of some crystalline phases identified by powder XRD in the Zhundong coals and treated samples is shown in Figures and .…”

Acid-Leaching and Silanization of Catalytic Gasification Ash Enhance the Mechanical Properties of Polyurethane/Ash Composites

“…It shows that the main crystalline compounds of Raw-Ash are lazurite, sodium aluminum silicate, zeolite, and nosean, while the XRD spectra of H-Ash only presents a broad peak at 2θ = 23°. This bulge is the peak of amorphous SiO 2 . , Many studies indicated that sodium aluminosilicate is soluble in acid. ,− The Si–Al bond of sodium aluminosilicate in the coal ash is first split by sulfuric acid leaching . SiO 2 is mainly concentrated in the residue because it is insoluble in acid, but the compounds containing aluminum and sodium remain are mainly dissolved in the solution because they are soluble in acid.…”

“…At present, extraction of aluminum − from coal ash has attracted more attention, and alkali activation then acid leaching is the most common method to achieve this goal. However, in terms of catalyzed gasification, Ding et al found that Na and K, which act as catalysts, can react with the minerals in the coal to form aluminosilicates and nepheline.…”