Characterization of the SO₂−N-Formylmorpholine Complex:  Application to a Regenerative Process for Waste Gas Scrubbing

Abstract

This paper presents the results of fundamental investigations on physical and chemical interactions between sulfur dioxide and N-formylmorpholine (NFM), with a view to the development of a regenerative process for waste gas scrubbing. This solvent is a promising medium for such processes because of its high absorption capacity, its low-to-moderate vapor pressure for temperatures below 100 °C, and its reduced toxicity. The existence of a chemical interaction between SO2 and NFM, with the formation of a 1:1 complex, was demonstrated by absorption tests, melting curve measurements, and the determination of vapor−liquid equilibrium from 25 to 80 °C. Further characterization was carried out by IR spectrometry. The formation of a solid complex with a melting point at 5.7 °C allows for the transport of absorbed sulfur dioxide under a convenient solid state; in addition, its stability was shown to decrease with temperature, which enables the solvent to be regenerated at high temperatures. The existence of a second complex with a 2:1 stoichiometry was suggested by modeling the gas−liquid equilibrium using the Harris and Prausnitz approach but could not be put into evidence by the other techniques. The parameters deduced by the above-mentioned model were successfully used for the prediction of the melting curve of an SO2−NFM system.

Thermodynamic properties and spectral investigation of dilute sulfur dioxide in binary system N,N-dimethylformamide+diethylene glycol

“…[ 1 _ T D $ D I F F ] 6, it was also found that the stretching vibrational bands of carbonyl in DMF [26] shifts to lower frequency from (1676 to 1662) cm À1 , and stretching vibrational band of -[ 1 0 4 _ T D $ D I F F ] N-CH 3 in DMF [27] locates at 1256 cm À1 did not obviously change with the increasing DMF concentration. The stretching vibrational band of carbon hydrogen H-[ 1 0 5 _ T D $ D I F F ] C¼O in DMF shifts from (2858 to 2876) cm À1 [28][29][30][31]. The bending vibrational band of ether oxygen -[ 1 0 6 _ T D $ D I F F ] C-O-C-in DEG locates at 1128 cm À1 and 1059 cm À1 did not obviously change with the increasing DMF concentration.…”

Absorption of dilute sulfur dioxide in aqueous poly-ethylene glycol 400 solutions at T=308.15K and p=122.60kPa

“…Liquid temperatures were controlled at 308.15 K using the thermostatic bath (3) and registered on a standard thermometer (7) at different points, and the temperatures do not vary more than 0.02 K for about 30 min. Total pressures were recorded on pressure meter (8). SO 2 concentrations in gas phase were determined by GC (5) with FPD detector.…”

“…There is considerable interest in the solubility of SO 2 because of its importance in industrial applications and in pollution control [1][2][3][4][5]. Among the many procedures employed to desulfurize exhaust gases, organic solvents used as absorbents have been identified as an option among the regenerative processes [6][7][8][9][10] because regeneration can be done by pressure reduction, by temperature increase, and by use of a carrier gas. Therefore, our research group has paid great attention to the (alcohol + water) system for SO 2 removal for several years [11][12][13][14].…”

Computational Studies on the Sulfur Dioxide Absorption by Organic Lewis Bases

“…As this process gives a large amount of solid waste cakes as by-products as well, the new absorption methods using organic solvents as SO 2 -removal agents have been explored because the absorbing agents can be regenerated repeatedly. [1][2][3][4][5] The SO 2 removal method by organic solvents is generally composed of two steps; 1) a fixation of SO 2 from the flue gas by the formation of a absorbent-SO 2 complex, and 2) thermal regeneration of absorbing agents and SO 2 stripping at the same time. The working process looks similar to that of an amine-CO 2 reaction which is an important CO 2 removal method from the flue gas.…”

“…Only chemical engineers have been interested in this issue, and studied the SO 2 removal process experimentally. [1][2][3][4][5] In this regard we have conducted quantum mechanical computations to trace the reaction between amines and SO 2 , and to calculate binding energies of the stable Lewis acid-base complexes in both a gas phase and an aqueous environment. Lewis bases dealt with in this work were trimethylamine (TMA), triethylamine (TEA), monoethanolamine (MEA), pyridine, and methylpyrolidone (NMP), where NMP did not form an SO 2 complex via an N-S bond but reacts with SO 2 by forming a O(carbonyl)-S bond (Figure 1e).…”