CO 2 capture from flue gas using the amine-based postcombustion technique is costly because of the high energy requirement for solvent regeneration. The addition of catalyst to the regeneration step can overcome this drawback. In this study, we investigate the regeneration performance of CO 2 -rich MEA solution without and with two solid metal oxide catalystsZrO 2 and ZnOwithin a temperature range of 40−86 °C. The solvent regeneration performance was evaluated in terms of CO 2 desorption rate, total amount of desorbed CO 2 , solvent cyclic capacity, and CO 2 -lean loadings achieved from the catalytic solutions in comparison with the noncatalytic MEA solution.To understand and support the obtained results BET, NH 3 −TPD, pyridine−FTIR, and 13 C NMR characterization techniques are performed. The obtained results suggest that both catalysts are capable of optimizing the solvent regeneration by desorbing up to 32% greater amounts of CO 2 , improving the CO 2 desorption rate up to 54%, and increasing the solvent cyclic capacity up to 56%. On the basis of the obtained experimental and characterization results, a possible mechanism for metal oxide catalyst-aided MEA regeneration process is proposed. The stabilities of both catalysts are confirmed by 5 cyclic solvent regeneration experiments. Additionally, by studying the CO 2 absorption in MEA in the presence of catalyst, it has been investigated if the catalysts induce any undesired activity in the CO 2 absorption step. Catalytic regeneration of amine solvent can pace up the construction of largescale CO 2 capture plants by economizing the process.
The purpose of this study is to investigate the removal of dimethyl disulfide (DMDS) in the olefin rich Fluid Catalytic Cracking (FCC) C4 hydrocarbon mixture with the ion-exchanged β-zeolite. Effects of Si/Al ratio, metal cations, and the ion exchange level on the removal efficiency have been accessed by performing the breakthrough experiment with a model C4 mixture of 20 ppm DMDS in 40% n-Butane/60%1-Butene. The metal ions used for the preparation of ion exchanged zeolite are Ag(I), Cu(II), Ni(II), Fe(III), and Cu(I). The adsorption characteristics of 1-Butene and DMDS on the adsorbent have been studied through the temperature programmed desorption (TPD).
Aqueous amine solutions have been widely used for the absorption of carbon dioxide (CO 2 ) from the gas mixtures. An understanding of the physical and chemical properties of aqueous amine solutions is important for the successful design and operation of CO 2 absorption processes. Particularly, the absorption capacity, absorption rate, and heat of absorption of CO 2 are major factors that affect the CO 2 absorption and stripping performance. A comparison study of the aqueous piperazine (PZ), 2-methylpiperazine (2-MPZ), homopiperazine (HomoPZ), and hexamethylenediamine (HMDA) solutions was conducted in this study. Absorption capacities and heats of absorption of these diamine solutions were measured using a semibatch-type reactor and a differential reaction calorimeter (DRC). The species distributions of the absorbents were investigated using a nuclear magnetic resonance spectroscopy (NMR), and the CO 2 absorption mechanism was also discussed. Aqueous PZ and PZ derivative solutions (2-MPZ and HomoPZ) displayed excellent characteristics as CO 2 absorbents. Aqueous 10 wt % PZ and PZ derivative solutions had higher absorption capacities and lower heats of absorption than that of aqueous 10 wt % monoethanolamine (MEA) at 313 K (−ΔH abs of the CO 2 -saturated PZ, 2-MPZ, HomoPZ, and MEA solutions: 62, 58, 68, and 80 kJ/mol CO 2 ).
The worldwide large-scale deployment
of the state-of-the-art CO2 capture technique is being
delayed due to the overwhelmingly
high energy consumption in the stripper. Here, we reveal an efficient
Ag2O–Ag2CO3 catalytic cycle
and analyze its activity in the amine solvent regeneration step which
is capable of greatly minimizing the energy requirement by desorbing
greater amounts of CO2 at up to 1000% higher desorption
rate, at low temperature, e.g. 80 °C. After substantially improving
the CO2 desorption, the Ag2O converts into Ag2CO3 which is even more efficient. The Ag2CO3 ultimately decomposes into Ag2O in the
amine regeneration step, and this cycle continues. The validity of
the cyclic catalytic behavior was tested for ten cycles. Furthermore,
the mechanism of Ag2O/Ag2CO3 facilitated
CO2 desorption was elucidated using 1H and 13C nuclear magnetic resonance spectroscopy.
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