High heat duty is an urgent challenge for industrial applications of amine-based CO 2 capture. The temperature (>110°C) of carbamate breakdown in amine regeneration requires large energy consumption. In this work, we report a novel, stable, efficient, and inexpensive Ni-HZSM-5 catalyst to improve the CO 2 desorption rate and reduce the heat duty. The impregnation method was applied for varying nickel content in the catalysts from 2.16 to 9.80 wt% in HZSM-5. The catalysts were characterized by scanning electron microscope, X-ray powder diffraction, N 2 adsorption–desorption, inductively coupled plasma-optical emission spectrometry, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, NH 3 -temperature programmed desorption (TPD), Infrared spectroscopy of pyridine adsorption, and Fourier transform infrared spectroscopy. The catalytic performance was evaluated by CO 2 desorption of rich amine solvent at 90°C. It was found that the introduction of nickel increased the acid sites of catalysts compared with parent HZSM-5. This phenomenon plays a key role on improving the CO 2 desorption rate. The density functional theory (DFT) calculations successfully explain the catalytic performance. The catalytic activity associates with the combined properties of MSA × B/L × Ni 2+ . The 7.85-Ni-HZ catalyst presents an excellent catalytic activity for the CO 2 desorption: it increases the amount of desorbed CO 2 up to 36%, reduces the relative heat duty by 27.07% with the same reaction time, and possesses high stability during five cyclic tests. A possible catalytic mechanism for the Ni-HZSM-5 catalysts through assisting carbamate breakdown and promoting CO 2 desorption is proposed based on experimental results and theoretical calculations. Therefore, the results present that the 7.85-Ni-HZ catalyst significantly accelerates the protons transfer in CO 2 desorption and can potentially apply in industrial CO 2 capture.
Xitong Yang,Ruifeng Zhou,Guowei Liu,Sajjad Hussain,Qiuye Li
Catalytic regeneration has become one of the most promising technologies to solve the high energy consumption problem of CO 2 capture in organic amine solutions. As the most mainstream type of catalyst, the instability of acidic catalysts in alkaline solutions attracts increasing attention from researchers. Herein, we proposed a composite catalyst of MnOOH loaded HZSM-5 to weaken the adsorption of alkaline substances and improve the catalytic stability of the catalytic material. The optimized catalytic effect is obtained when the mass ratio of MnOOH is 20% The CO 2 desorption efficiency is increased by 68.2%, and the energy consumption is reduced by 31.8% when the dosage of the catalyst is only dosage of 0.2 wt% amine solution. Through materials characterization and DFT calculations, it was found that the surface O and hydroxyl groups on MnOOH are the key factors for proton cycling, and HZSM-5 has an important impact on improving proton transfer rate. This work provides a valuable approach to solving the stability problem of acidic catalysts.
Weihong Wang,Fei Li,Jie Liu,Yingying Zhao,Xiaofu Guo,Shizhao Wang,Zhiyong Ji
The treatment of wastewater and exhaust gas is the main issues in the environment protection field. A bipolar membrane electrodialysis metathesis (BP-EDM) process was proposed for the regeneration of MDEA and resourcelization of NH 4 Cl wastewater in the rare earth ores industry. The operating voltage had a favorable impact on augmenting both the MDEA regeneration rate and the desalination rate, accompanied by an increase in energy consumption. The increase in C(S):C(N) could reduce system energy consumption and enhance current efficiency when the ratio of C(S):C(N) was lower than 1:3.5. The increase of concentration of SO 4 2− in spent MDEA solution was advantageous for elevating the concentrations of (NH 4 ) 2 SO 4 and HCl solution, but accompanied by a decline in both the regeneration rate of MDEA and the desalination rate. The regeneration rate of MDEA and removal rate of HSS could reach 94.57 % and 93.11 %, respectively. Meanwhile, 43.83 g/L (NH 4 ) 2 SO 4 and 22.77 g/L HCl solutions could be produced. The energy consumption was only 0.33 kWh/kg MDEA, and the product cost was only 0.22 $/kg MDEA. The BP-EDM has shown great prospects as a cost-effective method for treatment and reclamation of wastewater and exhaust gas, and will play a pivotal role in the stable, efficient, and low-consumption operation of the absorption process by the regeneration and utilization of the MDEA absorbent.
危险品化学品经营许可证（带存储）