Kinetic calculations for the thermal decomposition of calcium propionate under non-isothermal conditions

Abstract

Calcium propionate (CP) is shown to be useful for simultaneous SO 2 /NO reduction in coal-fired power plants and its thermal decomposition characteristics are measured by thermogravimetric analysis in a feasibility study into more complete reduction of these hazardous gases. Calcium carbonate (CC), which has been used primarily for in-furnace desulfuration, was used for comparison. The thermal decomposition of this organic calcium-based sorbent began at low temperature, i.e. the carboxylic radical was evaporated from 565 K to 759 K for CP and the corresponding mass loss percentage was 47.79%. The residual was subsequently decomposed to release carbon dioxide between 843 K and 1012 K. The latter phase of the process occurred more readily than with CC because of the loose structure of CP resulting from evaporation of the carboxylic radical in the low temperature zone, which could be seen directly by scanning electron microscope. The maximum mass loss rates of this phase occurred at temperatures of 972 K and 1012 K for CP and CC, respectively. The Ozawa-Flynn-Wall method was used to calculate the activation energy during the thermal decomposition process at heating rates of 5, 7.5, 10 and 15 K/min. The result further confirmed the multistage characteristic of CP thermal decomposition, which could be seen in differential thermogravimetry curves. The reaction orders of CP in the conversion range 20%−80%, calculated using the Avrami theory were from 0.061 to 0.608, smaller than those of CC, which were 1.647 to 2.084. Sulfur dioxide (SO 2 ) and nitric oxide (NO) emitted from coal-fired power plants cause serious environmental problems and therefore many technologies for the reduction of these two hazardous gases have been explored [1,2]. Among these technologies, the wet-spray of organic calcium-based sorbents has the potential for simultaneous SO 2 and NO abatement. Calcium-based sorbents [3,4], such as calcium magnesium acetate (CMA), calcium acetate (CA), calcium formate (CF), calcium benzoate (CB) and calcium propionate (CP), can produce hydrocarbon fragments (CH i ) and Ca-based compounds during pyrolysis and so can combine the reburning process for NO reduction and impregnation of Ca-based compounds into the furnace for SO 2 capture. Thus, *Corresponding author (email: cml@sdu.edu.cn) investment and the running costs could be significantly reduced if this technology could be extended to coal fired power plants. conducted laboratoryscale experiments with a down-fired pulverized coal combustor operated at 80 kW to investigate the performance of the above organic sorbents for control of air-pollutant gases under a number of conditions, obtaining satisfactory results. CMA and CP have been used as the deicing agent and food preservative, respectively, and the recent researches showed these compounds could reduce both SO 2 and NO. Increasing interest is being shown in these environment-friendly calcium salts. They achieved 70%-80% NO and SO 2 reduction efficiencies using wet-spray injection at a calcium-to-sulfur m...

Calcination Thermokinetics of Carbon Capture Using Coal Fly Ash Stabilized Sorbent

“…This was estimated to be of second-order reaction and is in agreement with reported data. 5,33 This graph as such could not be used to estimate kinetic parameters for nonisothermal sorbent regeneration reaction due to the absence of a temperature dependent term.…”

“…This indicates the uniform thermal decomposition process of CaCO 3 which was in agreement with the reported order of reaction that varied in the range of 0.5−2.084 for sorbent regeneration. 5,33 The overall intrinsic reaction resistance energy, limited by the formation and rupture of chemical bonds, results in the form of calculated activation energy. 27,36,37 Calcination reaction rate depends on calcination temperature and CO 2 partial pressure, but it does not depend on CaCO 3 content and particle lifetime.…”

Solubility Study and Thermal Stability Analysis of Calcium Propionate

“…A second drastic mass loss started from around 342 °C, causing a mass loss of around 27 % until the final measurement was accomplished. The decomposition process of calcium propionate has been studied by Gobert‐Ranchoux and Niu , . During this process, the gaseous product 3‐pentanone C 2 H 5 COC 2 H 5 was emitted and calcium carbonate (CaCO 3 ) was left.…”

“…In order to evaluate the solid‐phase behavior at higher temperatures and also to obtain information on the occurrence of further solid phases, the thermal behavior and solid‐phase identity of a substance should be analyzed. The thermal properties of calcium propionate were studied by thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) . However, the solid‐phase behavior of calcium propionate with respect to temperature is not clear and the identity of the solid phases is still missing.…”

Synthesis of calcium propionate from indigenous limestone from Swat area in Pakistan

“…Figure 7 illustrates the calcium propionate TGA curve, where in the first stage a gradual weight loss occurred followed by an abrupt decrease in mass resulting in a total weight loss of 46.33% till 545 ° C due to the decomposition of calcium propionate into CaCO3. During this phase, an organic compound pentanone (C5H10O) is emitted from calcium propionate according to the following equation, since the observed mass loss is very close to the ideal value of 46.24% for this thermal decomposition reaction [21].…”