Hydrogen production via chemical looping dry reforming of methane: Process modeling and systems analysis

Abstract

The present study presents and analyses a family of "chemical looping dry reforming" (CLDR) processes that produce inherently separated syngas (H 2 and CO) streams via a combination of methane cracking in a "cracker reactor" and the Boudouard reaction (i.e., conversion of the formed carbon with CO 2 to CO) in a "CO 2 reactor," and then further maximize the H 2 yield via conversion of the produced CO via water-gas-shift.Remaining CO 2 emissions are minimized via CO 2 capture and sequestration. Four different configurations are evaluated which differ in how the heat required for the highly endothermic dry reforming reaction is supplied: (i) combustion of additional CH 4 feed (CLDR-CH 4 ); (ii) combustion of some of the CO produced in the CO 2 reactor (CLDR-CO); and combustion of some of the carbon produced in the cracker reactor with (iii) pure oxygen (CLDR-C-oxy); or (iv) with air (CLDR-C-air). Process models are developed to comparatively analyze the mass and energy balances of these configurations, and benchmark them against H 2 -production via conventional dry reforming and steam reforming of methane. Our results show that CLDR-C-oxy is the most promising H 2 -production pathway among the chemical looping and conventional technologies both in terms of chemical energy efficiency and in terms CO 2 emissions. Thus, the unique flexibility offered by the production of inherently separated syngas streams in CLDR enables overcoming the disadvantage of the strongly endothermic dry reforming reaction by combusting carbon internally in the reactor and thus achieving highly effective heat integration. Overall, the results support the technical viability and demonstrate the promise for strong process intensification of CLDR compared to conventional dry reforming and even steam reforming, the most widely used H 2 -production pathway to-date.

Effect of Supports on the Performance of La-Modified CoFe2O4 Oxygen Carriers in Chemical Looping Hydrogen Generation from Hydrogen-Rich Syngas

“…The Fe 2p spectrum exhibits two contributions, Fe 2p 3/2 and Fe 2p 1/2 , located at approximately 710.5 and 724.2 eV, respectively, accompanied by the satellite peaks at about 718.0 and 733.1 eV. ,, Furthermore, the Fe 2p 3/2 spectra can be divided into the peaks at around 710.0 and 712.1 eV, corresponding to the Fe 2+ 2p 3/2 and Fe 3+ 2p 3/2 , respectively. Similarly, the peaks at around 723.7 and 725.8 eV can be ascribed to Fe 2+ 2p 1/2 and Fe 3+ 2p 1/2 , respectively, in the Fe 2p 1/2 spectra . As shown in Table , based on the peak fitting results, the relative content of Fe 2+ is about 45%, with the remaining Fe in the form of Fe 3+ .…”

Implications of CO2 Sourcing on the Life-Cycle Greenhouse Gas Emissions and Costs of Algae Biofuels

“…Several analyses have found that future energy for CO 2 capture (in terms of the parasitic load (MJ/kg-CO 2 ) for the power plant) is related to the developments in capture technologies. IECM currently allows simulation of chemical looping capture, which is widely considered as a benchmark for an improved technology. , IECM models chemical looping capture based on the design provided by their publications, which involves a heat recovery steam generator. These processes are found to be thermodynamically much more efficient than postcombustion incumbents.…”

Carbon‐negative syngas production: A comprehensive assessment of biomass pyrolysis coupling chemical looping reforming

“…The syngas is purified using a monoethanolamine (MEA)-based CO 2 capture process that separates H 2 O and CO 2 in raw syngas. 15 The waste heat from raw syngas and flue gas is recovered to preheat air and generate steam. Any remaining low-grade heat is utilized in generating electricity through a steam turbine.…”

“…12,13 Chemical looping gasification (CLG) has emerged as a promising gasification technology, garnering significant attention from researchers. 14,15 A schematic of a typical CLG process is illustrated in Figure 1, where two interconnected fluidized bed reactors serve as an air reactor (AR) and a fuel reactor (FR). The fuel is mixed with an oxygen carrier that provides the necessary lattice oxygen for fuel gasification in the FR.…”