Effect of High-Pressure Impregnation on Structure Variation and Desulfurization Property of a Zn-Based Sorbent Prepared Using Lignite as a Support

摘要

In this study, a series of zinc (Zn)-based sorbents were prepared by high-pressure impregnation under different conditions of time and pressure, followed by fixed-bed pyrolysis using lignite as a precursor of support and zinc nitrate [Zn(NO_3)_2] as an active component precursor. The desulfurization performances of lignite and sorbents were measured. Moreover, they were characterized by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), N_2 adsorption, transmission electron microscopy-energy-dispersive X-ray (TEM-EDX), and scanning electron microscopy-energy-dispersive X-ray (SEM-EDX) techniques. The ambient conditions involved in hydrothermal synthesis are favorable for the efficient uploading of Zn(NO_3)_2 and the improvement of lignite texture during high-pressure impregnation. The content of Zn in prepared sorbent and the utilization rate of the active component can reach over 20 and 90%, respectively. The impregnation pressure and time are the main factors influencing the desulfurization performance and textural property of the sorbent through improving the content and distribution of the active component and specific surface area of sorbent. A sorbent prepared using Zn(NO_3)_2 solution (34 mL, 36 wt %) at 20 atm impregnation pressure and 5 h impregnation time exhibited the best desulfurization performance. The sulfur capacity and utilization rate of the active component were 10.05 g of S/100 g of sorbent and 93.40%, respectively.