Sorbent enhanced steam reforming (SESR) of methane using dolomite as internal carbon dioxide absorbent: Limitations due to Ca(OH)2 formation

Hildenbrand, Nicolas; Readman, Jennifer E.; Dahl, Ivar M.; Blom, Richard

doi:10.1016/j.apcata.2006.02.015

Cited by 69 publications

(37 citation statements)

References 17 publications

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“…CaO-based sorbents combine well with bio-oil steam reforming because of their high capacity and fast kinetics at the temperatures of maximum hydrogen yield (500-700°C), when temperatures in excess of 600°C have been shown necessary to ensure significant bio-oils conversion in practice [17]. The inexpensive dolomite was chosen over limestone in many studies on the basis that it gives better multicycle performance [32][33][34][35]. The methane SESR experiment by Lopez-Ortiz and…”

Section: Solids Characterisationmentioning

confidence: 99%

High hydrogen yield and purity from palm empty fruit bunch and pine pyrolysis oils

Zin¹,

Lea‐Langton²,

Dupont³

et al. 2012

International Journal of Hydrogen Energy

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The benefits of CO 2 sorption enhanced steam reforming using calcined dolomite were demonstrated for the production of hydrogen from highly oxygenated pyrolysis oils of the agricultural waste palm empty fruit bunches (PEFB) and pine wood. At 1 atm in a down-flow packed bed reactor at 600 °C, the best molar steam to carbon ratios were between 2 and 3 using a Ni catalyst. After incorporating steam-activated calcined dolomite as the CO 2 sorbent in the reactor bed, the H 2 yield from the moisture free PEFB oil increased from 9.5 to 10.4 wt% while that of the pine oil increased from 9.9 to 13.9 wt%. The hydrogen purity also rose from 68 to 96% and from 54 to 87 % for the PEFB and pine oils respectively, demonstrating very substantial sorption enhancement effects.

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Section: Solids Characterisationmentioning

confidence: 99%

High hydrogen yield and purity from palm empty fruit bunch and pine pyrolysis oils

Zin¹,

Lea‐Langton²,

Dupont³

et al. 2012

International Journal of Hydrogen Energy

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“…Phase changes from CaO to CaCO 3 have also been identified by collecting dolomite aliquots at different times on stream during steam reforming coupled with in situ CO 2 capture. 36 When XRD is combined with Rietveld refinement it is possible to retrieve further information such as the magnitude of microstrain and crystallite size with crystallite being defined as a region with a continuous crystal lattice, and a particle as a collection of crystallites. Montez-Hernandez et al 37 carried out XRD on Ca(OH) 2 particles that had been carbonated at different pressures.…”

Section: Introductionmentioning

confidence: 99%

In situ X-ray diffraction of CaO based CO2 sorbents

Molinder

Comyn

Hondow

et al. 2012

Energy Environ. Sci.

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In situ X-ray diffraction coupled with Rietveld refinement has been used to study CO 2 capture by CaO, Ca(OH) 2 and partially hydrated CaO, as a function of temperature. Phase quantification by Rietveld refinement was performed to monitor the conversion to CaCO 3 and the results were compared to those derived using thermogravimetric analysis (TGA). It was found that Ca(OH) 2 converted directly to 100% CaCO 3 without the formation of a CaO intermediate, at ca. 600˚C. Both pure CaO and partially hydrated CaO (33.6 wt% Ca(OH) 2 ) reached the same capture capacity, containing approximately 65 wt% CaCO 3 at 800˚C. It was possible to provide direct evidence of the capture mechanism. The stresses in the Ca(OH) 2 phase of the partially hydrated CaO were found to be more than 20 times higher than its strength, leading to disintegration and the generation of nano-sized crystallites. The crystallite size determined using diffraction (75×16 nm) was in good agreement with the average crystallite size observed using TEM (of 83×16 nm). Electron diffraction images confirmed coexistence of CaO and Ca(OH) 2 . The analysis provides an explanation of the enhanced capture /disintegration observed in CaO in the presence of steam.Keywords: Rietveld analysis, in-situ X-ray diffraction, CaO, CO 2 capture, hydration, capture mechanism, attrition, regeneration, synchrotron. Graphical abstractIn situ XRD, in conjunction with phase quantification using Rietveld analysis, was used successfully to study CO 2 capture in CaO and Ca(OH) 2 as well as in partially hydrated CaO.The work shows how in situ XRD can be used as a supplemental technique to TGA, by which the mechanism of capture and hydration can be elucidated. IntroductionConcerns about global warming have prompted both national and international efforts to curb CO 2 emissions. CaO based materials are being considered as CO 2 sorbents for removal of CO 2 from flue gases at temperatures between 400˚C and 800˚C. Applications include pre-and post-combustion carbon capture technologies. [1][2][3][4][5][6][7][8][9][10] In addition, with the growing replacement of fossil fuels by biomass sources, and due to the high oxygen content of biomass, many of the processes of thermochemical fuel upgrading generate significant CO 2 at medium-high temperatures. [11][12] This provides the opportunity for in situ CO 2 capture in the 400-800˚C range and for improved heat transfer arising from the coupling of the endothermic gasification reactions with the exothermicity of the CO 2 chemisorption. This results in lower reaction temperatures and lower fuel consumption. [13][14] The advantages of CaO based materials as CO 2 sorbents for pre-and post-combustion CO 2 capture are their low cost, high abundance, large sorption capacity and fast reaction kinetics. 15-17 However, a major shortcoming of CaO based materials as CO 2 sorbents is the degradation in sorption capacity after multiple capture and regeneration cycles, due to loss of surface area through sintering. 18-21 For large scale CO 2 capture, th...

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“…Unstable adsorbents can lead to lower equilibrium hydrogen yields. 107 For fluidized bed operations, resistance to attrition 108 is an important parameter and largely governs the performance of the adsorbant and the process as a whole. The mode used for desorption and its assessment in terms of energy requirement and time of regeneration are also important to achieve better design and performance.…”

Section: Sorption Enhanced Steam Methane Reformingmentioning

confidence: 99%

Process intensification aspects for steam methane reforming: An overview

2009

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Steam methane reforming (SMR) is the most widely used process in industry for the production of hydrogen, which is considered as the future generation energy carrier. Having been perceived as an important source of H2, there are abundant incentives for design and development of SMR processes mainly through the consideration of process intensification and multiscale modeling; two areas which are considered as the main focus of the future generation chemical engineering to meet the global energy challenges. This article presents a comprehensive overview of the process integration aspects for SMR, especially the potential for multiscale modeling in this area. The intensification for SMR is achieved by coupling with adsorption and membrane separation technologies, etc., and using the concept of multifunctional reactors and catalysts to overcome the mass transfer, heat transfer, and thermodynamic limitations. In this article, the focus of existing and future research on these emerging areas has been drawn. © 2009 American Institute of Chemical Engineers AIChE J, 2009

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Sorbent enhanced steam reforming (SESR) of methane using dolomite as internal carbon dioxide absorbent: Limitations due to Ca(OH)2 formation

Cited by 69 publications

References 17 publications

High hydrogen yield and purity from palm empty fruit bunch and pine pyrolysis oils

High hydrogen yield and purity from palm empty fruit bunch and pine pyrolysis oils

In situ X-ray diffraction of CaO based CO2 sorbents

Process intensification aspects for steam methane reforming: An overview

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