Redox oxidative cracking of <i>n</i>-hexane with Fe-substituted barium hexaaluminates as redox catalysts

Tian, Xin; Dudek, Ryan B.; Gao, Yunfei; Zhao, Haibo; Li, Fanxing

doi:10.1039/c8cy02530d

Cited by 15 publications

(11 citation statements)

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“…During the past 30 years, the chemical looping strategy has witnessed a rapid development in not only combustion processes but also gasification, , reforming, − calcium looping, − hydrogen production, − air separation, − desulfurization, − dechlorination, − selective oxidation, − ammonia synthesis, − etc. As a result of the merits of in situ product separation and cascade energy utilization, chemical looping is anticipated to continually find its extensive applications in many other chemical engineering processes …”

Section: Introductionmentioning

confidence: 99%

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Zhao

Tian

et al. 2020

Energy Fuels

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Chemical looping combustion (CLC) has emerged as an efficient and promising combustion technique for fossil fuels during the past few decades. The main advantages of CLC lie in its inherent CO 2 sequestration and cascade energy utilization, being primarily benefited from the in situ reactive separation facilitated by the circulation of a solid intermediate. Up to date, the research on the CLC-related oxygen carrier, reactor, and system has made extensive and in-depth development worldwide. CLC units with thermal power ranging from the kW th to MW th scale were demonstrated with fuels of different types (gaseous, liquid, and solid fuels). Over the past 20 years, Chinese researchers have made significant progress in chemical looping technologies, extending from fundamental oxygen carrier studies to the implementation of pilot-scale CLC units. For the use of solid fuels, such as coal, in CLC, it is a rather challenging task but a lot of opportunities also remain. As a result of the particular "rich coal, meager oil, and deficient gas" energy reserve characteristics, China has become the main research battlefield on CLC of coal these years. In this paper, the main advances and research status on CLC of coal in China are reviewed and appraised. The contents in this paper cover most of, if not all, the research hotspots on CLC of coal, i.e., oxygen carrier screening, reactor design/construction/operation, pollutant emission, reaction kinetics, and numerical simulation. Chinese researchers have made substantial contributions to two bottleneck issues faced by the coal-derived CLC technique, i.e., developing and preparing a low-cost while well-performing oxygen carrier and promoting the slow char gasification process in the fuel reactor. In addition, remaining challenges that constrain the development of large-scale CLC units and indeed deserve in-depth investigation are analyzed. Particular attention is paid to the following three key challenges: severe mismatch of reaction rates in CLC of coal, difficulty in attaining a good balance between the oxygen carrier performance and cost, and challenge in controlling solid circulation to manage heat and mass transfer. Accordingly, potential opportunities for future research and scaling-up of the coal-derived CLC technique are discussed. The academic thoughts that are highlighted here include (1) achieving a good compromise between the oxygen carrier cost and performance through the rational design of a multifunctional and composite oxygen carrier and its scalable preparation using cheap raw materials, (2) coordination among reactor modeling− reactor design−reactor operation to attain effective management of heat and mass transfer in the CLC reactor, and (3) a complex while effective matching matrix among coal type, oxygen carrier particle, and reactor configuration to acquire the optimal performance of the whole CLC system. Overall, this review summarizes the contributions of Chinese scholars to CLC of coal and presents how these research achievements benefit the commercial-sca...

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Section: Introductionmentioning

confidence: 99%

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Zhao

Tian

et al. 2020

Energy Fuels

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“…As reported by Dudek et al and Tian et al, 23,24 ROC redox catalysts such as CaMnO 3 @Na 2 WO 4 exhibit olefin yields higher than n-hexane thermal cracking from 650 to 775 °C. For these redox catalysts, thermal cracking plays a critical role in nhexane conversion.…”

Section: ■ Results and Discussionmentioning

confidence: 56%

“…Na 2 WO 4 is essential for obtaining high olefin selectivities. 23,24 Hao et al further illustrated that Na 2 WO 4 -promoted CaMnO 3 has a core−shell structure, where a Na 2 WO 4 shell covers the bulk CaMnO 3 particle and undergoes dynamic phase transition during the ROC reaction cycles. 25 However, these reported redox catalysts still need operating temperatures higher than 700 °C in order to achieve satisfactory olefin yield.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Despite high naphtha conversions (>86%) under a typical operating temperature of 750 °C, high CO x yields (≥15%) were reported with light olefin yields limited to 44%. − Unlike conventional oxidative cracking, redox oxidative cracking (ROC) utilizes lattice oxygen from a metal oxide redox catalyst to facilitate naphtha conversion and hydrogen combustion in a so-called chemical looping approach. − Dudek et al and Tian et al reported Na 2 WO 4 -promoted CaMnO 3 , SrMnO 3 and BaFe x Al 12‑x O 19 and obtained up to 58% of olefin yield at 750 °C with CO x yield as low as 1.7%. Na 2 WO 4 is essential for obtaining high olefin selectivities. , Hao et al further illustrated that Na 2 WO 4 -promoted CaMnO 3 has a core–shell structure, where a Na 2 WO 4 shell covers the bulk CaMnO 3 particle and undergoes dynamic phase transition during the ROC reaction cycles . However, these reported redox catalysts still need operating temperatures higher than 700 °C in order to achieve satisfactory olefin yield.…”

Section: Introductionmentioning

confidence: 99%

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Zeolite–Perovskite Composites as Effective Redox Catalysts for Autothermal Cracking of n-Hexane

Gao

Wang

Hao

et al. 2020

ACS Sustainable Chem. Eng.

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“…The core of CL-ODH resides in the selection of a highly active as well as selective (to ethylene) redox catalyst. To date, various materials including perovskite-type oxides, − Mn-containing mixed oxides, ,− hexaaluminates, V-based oxides, Mo-based oxides, and Fe-based oxides have been tested as redox catalysts in CL-ODH of light alkanes. Generally, there are two different reaction routes proposed in the literature for CL-ODH of ethane (as shown in Figure ), depending on the redox catalysts used. , …”

Section: Introductionmentioning

confidence: 99%

Co and Mo Co-doped Fe₂O₃ for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation

Tian

Zheng

2021

ACS Sustainable Chem. Eng.

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In this study, we investigate Co and/or Mo doped Fe2O3 (Co x Mo1–x /Fe2O3, x = 0, 0.2, 0.3, 0.4, and 1) as redox catalysts for chemical looping oxidative dehydrogenation (CL-ODH) of ethane. Under the cyclic redox reaction mode, the five as-prepared samples behave differently toward ethane conversion. Among the five redox catalysts, CoFe2O4 (x = 1) is highly reactive and tends to overoxidize ethane into CO2, while Mo/Fe2O3 (x = 0) exhibits promising ethylene selectivity but inferior H2 removal capability. By tuning the molar ratio of Co/(Co + Mo), 87.4% ethylene selectivity at 56.2% ethane conversion can be achieved by the Co0.3Mo0.7/Fe2O3 (x = 0.3) redox catalyst at 825 °C and 6000 h–1. C2H6-TPR results show that the selectivity of Co0.3Mo0.7/Fe2O3 alters as the ODH reaction proceeds due to the dynamic change of surface properties of the redox catalyst in the reaction. XPS results indicate that a relatively low Fe content as well as a high Mo content at the near-surface of the redox catalyst is beneficial for its ethylene selectivity in CL-ODH of ethane. DFT calculations reveal that Co cations in the Co0.3Mo0.7/Fe2O3 structure are responsible for the activity and H2 combustion capability of the redox catalyst, while Mo plays a key role in tuning the ethylene selectivity.

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Redox oxidative cracking of n-hexane with Fe-substituted barium hexaaluminates as redox catalysts

Abstract: Promoted hexaaluminate redox catalysts achieved excellent olefin yield while allowing autothermal redox oxidative cracking of naphtha with low COx formation.

Cited by 15 publications

References 36 publications

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Zeolite–Perovskite Composites as Effective Redox Catalysts for Autothermal Cracking of n-Hexane

Co and Mo Co-doped Fe₂O₃ for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation

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Redox oxidative cracking of n-hexane with Fe-substituted barium hexaaluminates as redox catalysts

Abstract: Promoted hexaaluminate redox catalysts achieved excellent olefin yield while allowing autothermal redox oxidative cracking of naphtha with low COx formation.

Cited by 15 publications

References 36 publications

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Zeolite–Perovskite Composites as Effective Redox Catalysts for Autothermal Cracking of n-Hexane

Co and Mo Co-doped Fe2O3 for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation

Contact Info

Product

Resources

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Co and Mo Co-doped Fe₂O₃ for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation