Abstract

Chemical looping combustion (CLC) is known as a low-cost strategy for the capture of carbon dioxide for fuel combustion. In CLC process, oxygen carriers (OCs) are the cornerstone and play a vital role in defining reaction process. The aim of the present work was to investigate the potential of niobium (Nb) as a promoter on the -Al2O3 and its behavior as an oxygen carrier for chemical looping combustion process. In this work, the Nb loading was varied between 5 – 15 wt. %. Their behavior in CLC was analyzed by TPR, TPO, SEM and TGA. From the TPR results, the reduction temperature for 5 wt.%, 10 wt.% and 15 wt.% Nb loading were 560 ℃, 529 ℃ and 545 ℃, respectively which indicated that reduction reaction occurs around 500 ℃ and above. SEM analysis showed that increasing of Nb loading resulted in some agglomeration and thus lowering the ability of metal oxide to gain and release oxygen. The redox characteristics were carried out using TGA with 5% CH4/N2 was used as the reducing gas, while air was used as oxidizing gas. The highest oxygen transfer capacity was 3.0% which is presented by 5 wt.% of Nb loading. Since the addition of Nb successfully improved the oxygen transport capacity, it can be concluded that Nb is the potential candidate for oxygen carrier in CLC.

Highlights

  • Climate change caused by greenhouse gases, and it can have a detrimental effect on its structure when gases such as carbon dioxide (CO2), nitrous oxide (NOx), methane (CH4), etc. are in abundance in the ozone

  • The oxygen carriers (OCs), Nb/alumina were prepared by wet impregnation according to the method proposed by [11] using Nb2O5 as the Nb promoter

  • The effect of Nbloading (5, 10 and 15 wt.%) on the physical properties and oxygen transfer capacity of the Nb/alumina OCs prepared by wet impregnation method was investigated

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Summary

Introduction

Climate change caused by greenhouse gases, and it can have a detrimental effect on its structure when gases such as carbon dioxide (CO2), nitrous oxide (NOx), methane (CH4), etc. are in abundance in the ozone. CCS is a method where CO2 is segregated from power generation, shipped under high pressure to the storage site and subsequently stored in the deep ground in a way to reach zero carbon emissions in using fossil energy [1]. Chemical looping combustion (CLC) is a great carbon sequestration practice where it uses metal oxides, defined as the oxygen carrier (OC), rather than air to supply oxygen for the combustion process [5]. The fuel in the gaseous process is oxidized by a chemical reaction using an oxygen carrier. The OCs, Nb/alumina were prepared by wet impregnation according to the method proposed by [11] using Nb2O5 as the Nb promoter. The OCs were coated by sputtering (Emitech Quorum SC7620) at 20mA for 60s with gold using a coating machine

Chemical looping combustion
Temperature-programmed reduction and oxidation analysis
Conclusion
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