Zain Ali Saleh Bairq,Hongxia Gao,Yufei Huang,Haiyan Zhang,Zhiwu Liang
A significant impediment to the widespread adoption of amine-based post-combustion technique for CO 2 capture from flue gas is the huge energy demand for amine solvent regeneration. In this study, five novel bifunctional heterogeneous catalysts e.g., SO 4 2− /ZrO 2 /SiO 2 with different molar ratios of zirconia and SO 4 2− /ZrO 2 as a parent catalyst were synthesized and applied to evaluate their effectiveness in enhancing the CO 2 desorption and solvent regeneration of 5M monoethanolamine solution with CO 2 loading of 0.5 ± 0.01 mol CO 2 /mol monoethanolamine at 97 °C. The catalysts were characterized by Fourier transform-infrared spectrometry, pyridine-infrared spectroscopy, X-ray diffraction, N 2 -adsorption-desorption, and ammonia-temperature programmed desorption. The results demonstrated that these catalysts can significantly reduce the heat duty for CO 2 desorption by 36.48% compared to without catalyst and enhance desorption rate by 35.1%. The results also showed that SO 4 2− /ZrO 2 /SiO 2 15% presented the highest efficiency compared to the other SO 4 2− /ZrO 2 /SiO 2 ratios and the super solid acid catalyst SO 4 2− /ZrO 2 . Additionally, to investigate if the catalysts induce any unfavorable effects on the amine, the absorption of CO 2 by regenerated amine solvent was studied. Finally, a reaction mechanism for the amine solvent regeneration with the synthesized catalyst e.g., SO 4 2− /ZrO 2 /SiO 2 was suggested.
Xiaodi Li,Shan Ren,Lian Liu,Xiangdong Xing,Lin Chen,Jiangling Li,Jian Yang,Qingcai Liu
The serious deactivation of denitration catalysts caused by heavy metals still a thorny issue in the practical application of selective catalytic reduction of NO x with NH 3 . Herein, we proposed a novel anti-poisoning strategy by designing SO 4 2− /ZrO 2 superacid supported CeO 2 /ZrO 2 catalyst, and the effect of SO 4 2− /ZrO 2 supported CeO 2 /ZrO 2 for PbO-resistance NO x catalytic reduction was investigated. It was worthy to note that the introduction of solid superacid SO 4 2− /ZrO 2 significantly enhanced catalytic performance over the entire temperature range, with an exceptionally high NO x removal efficiency over 98 % during 250–500 °C. When 2 wt% PbO was deposited on the fresh catalyst, the catalytic activity of CeO 2 /ZrO 2 catalyst decreased obviously, while CeO 2 /ZrO 2 -S catalyst can still maintain a higher NO x conversion over 90 % from 275 to 500 °C. The characterization results confirmed that the introduction of solid superacid SO 4 2− /ZrO 2 enhanced the surface acidity and promoted the transformation from Ce 4+ to Ce 3+ . The results of in situ DRIFTS implied that the Eley-Rideal (E-R) mechanism was obeyed over CeO 2 /ZrO 2 catalyst, and both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms were followed over CeO 2 /ZrO 2 -S catalyst in the SCR process. With regard to poisoned catalysts, the NH 3 adsorption was inhibited to some extent, while the reaction mechanism wasn’t changed by PbO poisoning.
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