Comparative Study on Ni/γ-Al₂O₃ Prepared via Ultrasonic Irradiation and Impregnation Approaches as an Oxygen Carrier in Chemical Looping Combustion

Abstract

With the recent advancement of the chemical looping combustion (CLC) industry, the development of materials with high stability, high oxidation and reduction rate, and high oxygen transport capacity (OTC) has become a research hotspot. In this paper, the behavior of nickel oxide (NiO) as an oxygen carrier (OC) has been analyzed using thermogravimetric analysis. The influences of the preparation methods and Ni composition have been evaluated to develop Ni-based carriers with high reduction and oxidation rates over 10 redox cycles without changes in the chemical and structural properties. It has been observed that the carriers prepared by the ultrasound irradiation method showed excellent stability and higher reduction and oxidation rate (less than 1–3 min) during multiple redox cycles. However, their OTC values were lower than those of impregnated carriers. It was found that, in the ultrasound irradiation method, the 15NA (15 wt % Ni loading supported with gamma alumina) OC exhibited the highest OTC (3.17%) while 5NA (5 wt % nickel loading supported with gamma alumina) exhibited the lowest OTC (1.34%). A similar trend was observed for the impregnated OC, where 15NA exhibited the highest OTC value (3.67%), whereas 5NA exhibited the lowest OTC value (1.38%). Overall, the carriers prepared via the impregnation method possessed a high value of OTC at approximately 3.67% while the carriers prepared by ultrasound irradiation possessed an OTC value of 3.17%. In terms of physicochemical properties, the carriers prepared using the ultrasound irradiation approach possessed comparatively lower oxidation and reduction temperatures, smaller particle size, higher specific surface area, and more uniform metal distribution on the support. These findings suggested that the Ni-based OC prepared by ultrasound irradiation is a good candidate for CLC reactions.

Investigation on the Redox Properties of a Novel Cu-Based Pr-Modified Oxygen Carrier for Chemical Looping Combustion

“…For reduction and oxidation processes, 5% CH 4 /N 2 (for 3 min) and air (for 10 min) were used at a flow rate of 80 mL/min, respectively. However, the temperature of the furnace is kept constant at 800 °C. , Between methane and air, nitrogen gas was purged for 3 min to avoid mixing between methane and air. The OTC of OCs during 10 redox cycles was calculated using eq . OTC = m ox − m red m ox where, m ox is the mass of fully oxidized OC and m red is the mass of fully reduced OC.…”

“…However, the temperature of the furnace is kept constant at 800 °C. 14 , 18 Between methane and air, nitrogen gas was purged for 3 min to avoid mixing between methane and air. The OTC of OCs during 10 redox cycles was calculated using eq 1 .…”

“…A number of materials have been studied as OCs for the CLC process in recent years . For this purpose, transition metal oxides, such as CuO, , Fe 2 O 3 , , NiO, , Mn 3 O 4 , , and Co 2 O 3 , have been investigated as OCs. Across all monometallic oxide-based OCs, NiO and CuO exhibited the highest OTCs, 21 and 20 wt %, respectively.…”

Chemical Looping Combustion and Gasification: A Review and a Focus on European Research Projects

“…Five biomasses with different volatile and alkali contents were tested (including residual biomasses), and 21 h of fueled operation were achieved: carbon capture efficiencies were close to 100% (for biomass with high content of volatile matter) and anyway >94% (biomass with low-volatiles content); the choice of ilmenite helped to control the alkali release in outlet gases (96% of fuel's alkali captured by ilmenite). Regarding OC development, Ghazali et al 102 studied two synthesis methods for Ni-γ-Al 2 O 3 (ultrasonic irradiation vs impregnation) and compared related CLC performances by 10 redox cycles monitored by thermogravimetric-analysis (TGA). OCs prepared by the ultrasound irradiation method showed excellent stability and higher reduction and oxidation rate, but slightly lower oxygen transport capacity (section 5.1.1) than those of impregnated OCs.…”

“…Regarding OC development, Ghazali et al studied two synthesis methods for Ni-γ-Al 2 O 3 (ultrasonic irradiation vs impregnation) and compared related CLC performances by 10 redox cycles monitored by thermogravimetric-analysis (TGA). OCs prepared by the ultrasound irradiation method showed excellent stability and higher reduction and oxidation rate, but slightly lower oxygen transport capacity (section ) than those of impregnated OCs.…”