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![Kinetic curves of catalytic oxidation of Na 2 S (A) and of the change in stilbenequinone concentration (B): [Na2S] = 0.7 mol L −1 , t = 90°C, [stilbenequinone] = 0.052 mol L −1 , the oxygen-supply rate = 13 L h −1 .](profile/Renat-Akhmadullin/publication/329380669/figure/fig8/AS:840196895559685@1577329958767/Kinetic-curves-of-catalytic-oxidation-of-Na-2-S-A-and-of-the-change-in-stilbenequinone.png)
Kinetic curves of catalytic oxidation of Na 2 S (A) and of the change in stilbenequinone concentration (B): [Na2S] = 0.7 mol L −1 , t = 90°C, [stilbenequinone] = 0.052 mol L −1 , the oxygen-supply rate = 13 L h −1 .
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The aim of this study is to monitor the kinetics and mechanism of liquid-phase oxidation of inorganic sulfide by oxygen in the presence of a catalyst based on 3,3’,5,5'-tetra-tert-butyl-4,4'-stilbenequinone. The research results point out that this reaction has a first order with respect to each reactant. The effects of temperature, initial sulfide...
Context in source publication
Context 1
... forms may promote oxidizing sulphide sulfur to the maximum oxidation degree (SO 4 2− ). While studying the catalyst concentration change in the oxygen-saturated solution (Figure 5), the most interesting finding was that during the reaction course the concentration of stilbenequinone decreases to a certain minimum value, and then increases solely after sulphide has reached the point of complete exhaustion. This implies that the rate of sulphide oxidation by stilbenequinone exceeds that of catalyst regeneration. ...
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Citations
... The sulfur concentration of mercaptide was determined by a potentiometric titration method (Hoang et al., 2018;Zhan et al., 2019) and can be calculated by ...
Catalytic oxidation of mercaptide is a significant way to eliminate waste emission of spent caustic and recycle the resource of caustic. However, the kinetics of mercaptide oxidation for spent caustic regeneration is still unclear, which hinders the reactor design. In this work, mechanism analyses and kinetics experiments were conducted to investigate the kinetics of homogeneous catalytic oxidation of sodium ethyl mercaptide. Ultraviolet visual spectra show that mercaptide ion is superior to oxygen molecule adsorbed on the catalyst, which is in accord with the simulations. Reaction mechanism of two-layer adsorption structure was proposed by density functional theory calculations. By applying the method of decoupling macroscopic kinetics and making pseudo-first-order fast reaction hypothesis, the rate expression of the intrinsic kinetics for the oxidation reaction of sodium ethyl mercaptide was proposed as -dCAdt=6.84×1010exp(-29584RT)CACB. A statistical test was carried out to verify the intrinsic kinetics data, showing that the kinetics data were overall reasonable.
... During the experimental running, the inorganic sulfur (NaSR) concentration was determined with a method of potentiometric titration, (Hoang et al., 2018) temperature, a sessile drop method was adopted to measure contact angle on the flat surface via the same surface modification procedure as wire mesh packing. Zhang et al., 2017)Aiming to estimate the stability of the different surface-modified packings, they were immersed in the simulated spent caustic (10 wt.% NaOH solution) during 96 h, and the contact angle was measured in every 24 h. ...
Spent caustic from the desulfurization of liquefied petroleum gas has been proved to be effectively regenerated in a rotating packed bed (RPB) with classic wire mesh packing. However, the influence of the packing’s surface wettability on regeneration performance in the RPB was not clear with this oil-water two-phase system. In this work, the surface-modified packing was proposed to be used in the RPB to estimate the regeneration performance, including oxidation and separation efficiency. Three different surface-modified packings of hydrophilic surface-modified wire mesh packing (ISP), non-surface-modified wire mesh packing (NSP), and hydrophobic surface-modified wire mesh packing (OSP) were prepared and employed in the RPB for regeneration experiments. Results show that regeneration performance is in order of ISP＞NSP＞OSP. Compared with OSP, the NaSR conversion, RSSR removal efficiency, and number of transfer units of ISP increased nearly by 34%, 13%, and 21% at 1000 r/min rotational speed and 25 mm packing thickness, respectively. For the view of different packing combination, not only in the inner layer but also in the outer layer, ISP had noticeable superior regeneration performance, which displays the bright future of advanced surface-modified packing used in the RPB for process intensification of reaction and separation.
Regeneration of spent caustic from liquefied petroleum gas sweetening in refineries is significant to save resources and reduce solid waste emissions. Conventional regeneration technologies have been widely used, but usually having a reactor and a separator in series with large space occupied. In this work, simultaneous reaction and separation processes were proposed to be conducted in a rotating packed bed (RPB), aiming for the process intensification of spent caustic regeneration. Experimental results of laboratory test show that the regeneration processes of mercaptide oxidation and disulfide separation were efficiently enhanced in the RPB. The side-line test, treating the actual spent caustic from a refinery, could achieve good performance for a long-time running. An artificial neural network model was applied for parameters analysis and prediction of the regeneration performance. This work demonstrated the feasibility of spent caustic regeneration in only one RPB unit, which displays bright prospects for industrial application.
