Enhanced Carbon Storage Process from Flue Gas Streams Using Rice Husk Silica Nanoparticles: An Approach in Shallow Coal Bed Methane Reservoirs

Carbon capture and storage (CCS) is considered a key process to reach net-zero emission by the 2050 aim of limiting global warming. Coal bed methane (CBM) is considered potential geological reservoirs for underground CCS due to the CO2-CH4 exchange feasibility by adsorptive phenomena. Global implementation has been focused only on deep reservoirs to provide methane recovery. Thus, this work proposes a modified CCS process based on silica nanoparticle inclusion for shallow CBM reservoirs (< 300 m). The nanomaterials were evaluated at high pressure in two main stages including i) CO2 sorption on a single CO2 stream and ii) CO2 selectivity on a flue gas stream (N-2-CO2 mixture). This work includes silica nanomaterial synthesized from rice husk as agro-waste sources with better technical-economic feasibility framed in a circular economy to reduce costs and maximize the use of available resources. Rice husk silica (RSi) nanoparticles were doped with 1.0, 3.0, and 5.0 wt % of urea (Si-U), diethylamine (Si-DE), triethylamine (Si-TE), and ethylenediamine (Si-EM) to enhance the CO2 sorption. First, CO2 sorption was evaluated at 30 degrees C and between 0.084 and 3 MPa using a CO2 stream to determine the best-doped amount of each N-source. Then, the best nanoparticles were used to impregnate CBM at 10 and 20 wt %, and the subsequent CO2 storage on the flue gas stream (70% v/v N-2 and 30% v/v CO2) was done. The results showed that CO2 sorption on RSi increases with the N -group coating in the order RSi-DE < RSi-TE < RSi-U < RSi-EM. Also, the best-doped amount for each N-source was 3 wt %. For CBM impregnation, the nanofluid containing 20 wt % of RSi-EM3 presented the best yield increasing the CO2 sorption from 0.05 to 0.75 mmol g(-1), meaning an increase of more than 1000% in the sorption capacity.

Automated summary

This study proposes a modified CCS process using silica nanoparticle inclusion for shallow CBM reservoirs. The experiment verifies that the addition of nanofluids, particularly QSi-EM3 particles, significantly increases the CO2 sorption capacity by more than 1000%.