Thermal decomposition of solid sodium sesquicarbonate, Na₂CO₃·NaHCO₃·2H₂O

Abstract

The thermal decomposition of solid sodium sesquicarbonate has been studied at temperatures between 350 and 487 K in nitrogen and carbon dioxide atmospheres. In nitrogen, a single-stage decomposition to sodium carbonate occurs, following Avrami-Erofeyev kinetics (n = 2), with an inflexion at ca. 390 K. The activation energies are 24 kJ mol-' for the high-temperature region and 58 kJ mol-' for the low-temperature region. In carbon dioxide above 435 K, the single-stage reaction follows contracting disc kinetics with an activation energy of 29 kJ mol-'. In carbon dioxide at low temperatures, wegscheiderite (Na2C0, .3NaHCO,) and sodium carbonate monohydrate (Na2C0, * H20) are formed, and this reaction follows first-order kinetics, with an activation energy of 67 kJ mot -' . Microscopic evidence is also presented. Relationships between the decomposition of sesquicarbonate and other related compounds are discussed.

Operando DRIFTS-MS Study of WGS and rWGS Reaction on Biochar-Based Pt Catalysts: The Promotional Effect of Na

“…As shown in Figure 3b, a heterogeneous dispersion of the platinum was observed apart from the appearance of anhydrous sodium carbonate with laminar morphology. This morphology is characteristic of the thermal decomposition of sodium sesquicarbonate into CO2 and H2O under an inert atmosphere at 350 °C [34].…”

Study of formation conditions of sodium sesquicarbonate in H3PO4–Na2CO3–H2O system

“…2, a gradual decrease in the sample mass is observed at 40°C, which corresponds to removal of 7 mol of water. No elimination of H 2 O contained in crystal hydrates of carbonate-containing compounds occurs at the given temperature [10]. Thus, water introduced into the H 3 PO 4 -Na 2 CO 3 -H 2 O system with the solution of orthophosphoric acid is mostly (~60-80%) expended for formation of crystal hydrates of phosphate-and carbonate-containing compounds, and just this circumstance is responsible for the formation of a friable powder-like product with moisture content not exceeding 8-9 wt %.…”

Crystallographic and Morphological Transformation of Natrite and Nahcolite in the Dry Carbonate Process for CO2Capture

“…For the temperature of 120 °C, decomposition takes approximately 80 min for all NaHCO 3 to be transformed into Na 2 CO 3 , while it takes 30 min for 135 °C, 12 min for 150 °C, and only 6 min are needed at 165 °C for the reaction to be completed. A number of studies have been reported on the decomposition of trona to obtain natrite in the presence of CO 2 and humidity, 21,32,42 but the mechanisms of formation of trona from natrite in the range of temperatures used in this work have not been previously analyzed. In the same way, the nahcolite phase is also present at all three temperatures coexisting with trona.…”