Structure and Reactivity of Brazilian Iron Ores as Low-Cost Oxygen Carriers for Chemical Looping Combustion

Development of multimode gas-fired combined-cycle chemical-looping combustion-based power plant layouts

Operation of power plants with carbon dioxide capture and sequestration (CCS) and without carbon dioxide capture and storage modes and energy penalty or energy utilization in such operations is of great significance. This work reports on two gas-fired pressurized chemical-looping combustion (CLC) power plant layouts with two inbuilt modes of flue gas exit, namely, one with carbon dioxide capture mode and the second mode is letting flue gas (consists of carbon dioxide and water) without capturing carbon dioxide. Without CCS mode, the higher thermal efficiencies of 54.06 and 52.63% are obtained for natural gas and syngas, respectively. In carbon capture mode, a net thermal efficiency of 52.13% is obtained with natural gas and 48.78% with syngas. The operating pressure of the air reactor is taken to be 13 bar for realistic operational considerations, and that of the fuel reactor is 11.5 bar. Two power plant layouts were developed based on combined-cycle chemical-looping combustion (CC CLC) for natural gas and syngas fuels. A single layout is developed for two fuels with a possible retrofit for dual fuel operation. The CLC power plants can be operated with two modes of flue gas exit options, and these operational options make them higher thermal efficient power plants.

Prospects and Technical Challenges in Hydrogen Production through Dry Reforming of Methane

Environmental issues related to greenhouse gases (GHG) emissions have pushed the development of new technologies that will allow the economic production of low-carbon energy vectors, such as hydrogen (H2), methane (CH4) and liquid fuels. Dry reforming of methane (DRM) has gained increased attention since it uses CH4 and carbon dioxide (CO2), which are two main greenhouse gases (GHG), as feedstock for the production of syngas, which is a mixture of H2 and carbon monoxide (CO) and can be used as a building block for the production of fuels. Since H2 has been identified as a key enabler of the energy transition, a lot of studies have aimed to benefit from the environmental advantages of DRM and to use it as a pathway for a sustainable H2 production. However, there are several challenges related to this process and to its use for H2 production, such as catalyst deactivation and the low H2/CO ratio of the syngas produced, which is usually below 1.0. This paper presents the recent advances in the catalyst development for H2 production via DRM, the processes that could be combined with DRM to overcome these challenges and the current industrial processes using DRM. The objective is to assess in which conditions DRM could be used for H2 production and the gaps in literature data preventing better evaluation of the environmental and economic potential of this process.