Performance of Na2CO3-CaO sorbent in sorption-enhanced steam methane reforming

NaNO3-Promoted MgO-Based Adsorbents Prepared from Bischofite for CO2 Capture: Experimental and Density Functional Theory Study

MgO has broad application potential in CO2 capture at intermedium temperatures. In this paper, the effects of NaNO3 doping on the properties of MgO prepared by using waste bischofite as the raw material were investigated to improve the performance of the CO2 capture. MgO-doped NaNO3 exhibited excellent CO2 capture performance at 320 °C with a maximum adsorption capacity of 36.62 wt %. MgO-doped NaNO3 has good cycling stability after 10 adsorption-desorption cycle experiments. In addition, CO2 adsorption on pure MgO and MgO-NaNO3 surfaces was investigated in accordance with density functional theory. Calculation results show that doping with NaNO3 allows more electrons to be transferred from the MgO substrate to the CO2 molecule. MgO-doped NaNO3 can lead to an increase in adsorption energy, resulting in a more stable structure after adsorption and thereby promoting adsorption. The result of this study provides an effective method for the comprehensive utilization of salt lake resources.

Hydrogen Production with In Situ CO2 Capture at High and Medium Temperatures Using Solid Sorbents

Hydrogen is a versatile vector for heat and power, mobility, and stationary applications. Steam methane reforming and coal gasification have been, until now, the main technologies for H2 production, and in the shorter term may remain due to the current costs of green H2. To minimize the carbon footprint of these technologies, the capture of CO2 emitted is a priority. The in situ capture of CO2 during the reforming and gasification processes, or even during the syngas upgrade by water–gas shift (WGS) reaction, is especially profitable since it contributes to an additional production of H2. This includes biomass gasification processes, where CO2 capture can also contribute to negative emissions. In the sorption-enhanced processes, the WGS reaction and the CO2 capture occur simultaneously, the selection of suitable CO2 sorbents, i.e., with high activity and stability, being a crucial aspect for their success. This review identifies and describes the solid sorbents with more potential for in situ CO2 capture at high and medium temperatures, i.e., Ca- or alkali-based sorbents, and Mg-based sorbents, respectively. The effects of temperature, steam and pressure on sorbents’ performance and H2 production during the sorption-enhanced processes are discussed, as well as the influence of catalyst–sorbent arrangement, i.e., hybrid/mixed or sequential configuration.