Decomposition of Potassium Hydrogen Carbonate: Thermochemistry, Kinetics, and Textural Changes in Solids

Abstract

To determine unbiased rates of the decomposition of KHCO 3 , slowly increasing-and constant-temperature TGA methods were employed with small, finely ground samples. Such reaction provides a novel, porous, and highly reactive sorbent for noxious and/or malodorous gases. The bicarbonate commences decomposing at 364 K, and the maximum rate of reaction, attained at 421.9 K, amounts to 5.73 × 10 −4 1/s. Taking advantage of the Schlomilch function, an Arrhenius-type relationship is developed by an integral method: the activation energy is as large as 141.3 kJ/mol and the order of reaction amounts to 1.145. While the pore volume made by calcination (0.2309 cm 3 /g) is not affected by temperature at 403−503 K, the mean pore diameter and the grain size augment with increasing temperature. The diagram presented makes it possible to conveniently predict the conditions to attain near-complete conversion of the bicarbonate and minimize undesirable sintering of the nascent carbonate.

New Approach to Improve Ionic Conductivity at Low Temperature by the Decomposition of KHCO3 in the Nanocomposite Electrolyte @

“…The previously‐mentioned results are quite different from those obtained by M. Hartman et al., [16] who showed that the transformation of into occurred in a single step at 91 °C, proved the strong interaction between and . The small sharp endothermic peak is indicated by a blue circle around 910 °C without gain or loss of mass in TG plot corresponding to the beginning melting of [16] . Based on DTA/TG investigations, the precipitate LCDC@KHC was calcined at temperature below 120 °C and the sintering procedure was restricted to<900 °C.…”

Turning Waste into Value: Potassium‐Promoted Red Mud as an Effective Catalyst for the Hydrogenation of CO2

“…Thereafter, temperature‐programmed reduction (TPR) was carried out on red mud and 2 wt % K‐promoted red mud (Figure S10). Several differences could be observed upon comparing both samples: i) peaks below 120 °C for the K‐promoted sample, which arise from the decomposition of KHCO 3 that starts at 67 °C; ii) peaks in the region of approximately 370–730 °C, which come from the reduction of iron species: hematite (Fe 2 O 3 ) into magnetite (Fe 3 O 4 ) at 420 °C (vs. 450 °C for the promoted sample), broad reduction of magnetite to iron monoxide at 510–720 °C (vs. 530–730 °C for the promoted sample), and reduction to metallic Fe at 750 °C . In accordance with previously reported results, the addition of K shifts the reduction temperature of iron oxide species to higher temperatures .…”

Limitation of K2CO3 as a Chemical Agent for Upgrading Activated Carbon

“…Nevertheless, the large differences in the specific surface areas of the upgraded ACs impregnated with KOH and K 2 CO 3 , as shown in Figure 3, are difficult to explain. Because KHCO 3 also transforms into K 2 CO 3 at temperatures greater than 140 • C (2KHCO 3(s) K 2 CO 3(s) + H 2 O (g) + CO 2(g) ) [25], the amounts of K 2 CO 3 formed on the carbon precursors would adversely affect the degree of activation. Given that the peaks of K 4 H 2 (CO 3 ) 3 and KHCO 3 are more intense for the carbon precursor impregnated with K 2 CO 3 that for that impregnated with KOH, the K 2 CO 3 -impregnated sample would favor the formation of K 2 CO 3 during activation.…”