Efficient nickel-based catalysts for amine regeneration of CO2 capture: From experimental to calculations verifications

High heat duty is an urgent challenge for industrial applications of amine-based CO2 capture. The temperature (>110 degrees 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 CO2 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, NH3-temperature programmed desorption (TPD), Infrared spectroscopy of pyridine adsorption, and Fourier transform infrared spectroscopy. The catalytic performance was evaluated by CO2 desorption of rich amine solvent at 90 degrees 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 CO2 desorption rate. The density functional theory (DFT) calculations successfully explain the catalytic performance. The catalytic activity associates with the combined properties of MSA x B/L x Ni2+. The 7.85-Ni-HZ catalyst presents an excellent catalytic activity for the CO2 desorption: it increases the amount of desorbed CO2 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 CO2 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 CO2 desorption and can potentially apply in industrial CO2 capture.

Automated summary

In this study, a novel Ni-HZSM-5 catalyst was developed to improve CO2 desorption rate and reduce heat duty. The introduction of nickel increased the acid sites of the catalyst, leading to higher CO2 desorption rate. Both computational and experimental results support the potential application of this catalyst in industrial CO2 capture.