Excellent promotion by lithium of a lanthanum–calcium oxide catalyst for oxidative dehydrogenation of ethane to ethane

Ji, Lang; Liu, Junsheng

doi:10.1039/cc9960001203

Cited by 20 publications

(5 citation statements)

References 6 publications

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“…Unlike the endothermic steam cracking reaction, the ODH reaction is exothermic, eliminating the need for external fuel combustion. A number of promising catalysts for ethane ODH have been studied, including various metal oxides (vanadium, , molybdenum, − nickel–niobium, , and lanthanum), platinum-group metals, − and supported alkali chlorides. , Despite extensive research and various potential advantages, the ethane ODH process has yet to be commercialized. One difficulty in commercial implementation is the tradeoff between ethane conversion and ethylene selectivity limiting per-pass yields.…”

Section: Introductionmentioning

confidence: 99%

Effect of Promoters on Manganese-Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme

2017

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Ethylene is an important building block in the chemical industry; state of the art ethylene production (steam cracking) has multiple drawbacks, including high energy consumption, coke formation, and significant CO 2 and NO x emissions. We propose a chemical looping oxidative dehydrogenation (CL-ODH) process to convert ethane into ethylene in a two-step, cyclic redox scheme. In this process, lattice oxygen in a metal oxide based redox catalyst is used to combust the hydrogen formed in ethane dehydrogenation, thereby enhancing ethylene formation while retarding coke formation. The oxygen-deprived redox catalyst is subsequently regenerated with air, releasing heat to balance the overall heat requirement. CL-ODH can realize a reduction of over 80% in primary energy consumption and pollutant emissions. The key to this process is an efficient redox catalyst with high selectivity and facile oxygen transport. Previously we determined that oxides with an Mg 6 MnO 8 structure allow high lattice oxygen mobility and satisfactory oxygen-carrying capacity for the proposed redox reactions. However, unpromoted Mg 6 MnO 8 exhibits poor ethylene selectivity, producing primarily CO 2 . In the current study, we examine the effects of various sodium-containing promoters on Mg 6 MnO 8 CL-ODH activity and mechanism. Sodium tungstate promoted Mg 6 MnO 8 was the most effective redox catalyst, showing an ethylene selectivity of 89.2% and yield of 68.2%, a significant improvement of thermal cracking (38.9% yield). Temperature-programmed reaction (TPR) experiments indicate that the reaction proceeds via gas-phase ethane thermal cracking in parallel with selective hydrogen combustion on the redox catalyst surface. XPS analysis indicates that the decreased ethane/ethylene oxidation activity on the sodium tungstate promoted redox catalysts results from the suppression of near-surface Mn 4+ . This is due to a combination of decreased surface manganese content and reduction in average Mn oxidation state. The suppression of Mn 4+ results in a decrease in electrophilic surface oxygen species, inhibition of ethylene combustion, and enhanced ethylene yield.

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Section: Introductionmentioning

confidence: 99%

Effect of Promoters on Manganese-Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme

2017

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“…Due to their unique strong basicity, 1 alkaline earth oxides can be used as adsorbent for acidic gas adsorption, [2][3][4][5][6][7][8][9] catalysts for biodiesel production via the transesterification of triglycerides with alcohol of low molecular weight, [10][11][12][13] and catalyst supports for the selective oxidation of light hydrocarbons. 14 Among the alkaline earth oxides, MgO and CaO have been investigated extensively. Calcium oxide is an exceptionally important material suitable for use as catalyst, toxic waste remediation agent, or an additive in refractory and paint.…”

Section: Introductionmentioning

confidence: 99%

“…Alkaline earth oxides have a wide range of applications in microelectronics, adsorption, and catalysis. Due to their unique strong basicity, alkaline earth oxides can be used as adsorbent for acidic gas adsorption, − catalysts for biodiesel production via the transesterification of triglycerides with alcohol of low molecular weight, − and catalyst supports for the selective oxidation of light hydrocarbons . Among the alkaline earth oxides, MgO and CaO have been investigated extensively.…”

Section: Introductionmentioning

confidence: 99%

Surfactant-Aided Hydrothermal Synthesis and Carbon Dioxide Adsorption Behavior of Three-Dimensionally Mesoporous Calcium Oxide Single-Crystallites with Tri-, Tetra-, and Hexagonal Morphologies

et al. 2008

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Three-dimensionally (3D) mesoporous single-crystalline CaO nano-and microparticles with tri-, tetra-, and hexagonal morphologies have been successfully fabricated using a surfactant (P123, CTAB, or PEG) assisted hydrothermal dissolution-recrystallization strategy with irregular nonporous CaO powders as the starting material. The as-synthesized calcium oxide samples are characterized by means of techniques such as X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy/selected area electron diffraction, Fourier-transfer infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry, and N 2 adsorption-desorption. It is shown that the introduction of a surfactant has an important effect on the morphology and pore structure of the synthesized CaO samples. With P123 or PEG as template, a higher hydrothermal temperature and longer hydrothermal time favor the generation of more regular morphological CaO entities with a higher surface area. Among the surfactants adopted in the present work, PEG is the most effective in the fabrication of high-surface-area 3D mesoporous CaO. Under the conditions of hydrothermal temperature of 240 °C and hydrothermal time of 72 h in the presence of PEG and after calcination at 600 °C for 3 h in an oxygen flow, one can obtain a single-crystalline 3D mesoporous CaO material with a surface area of 257 m 2 /g. The possible formation mechanism of single-crystalline 3D wormholelike mesoporous CaO is also discussed. These high-surface-area mesoporous CaO samples exhibit excellent CO 2 adsorption behavior. The highest amount of CO 2 desorbed from the CaO hydrothermally fabricated with PEG at 240 °C for 72 h and calcination at 600 °C for 3 h achieves 770 µmol CO 2 /g. It is suggested that the rise in surface area and the formation of 3D wormhole-like mesopores contribute to the enhanced CO 2 adsorption capacity of CaO.

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“…Furthermore, the ODH can be carried out at relatively low temperatures in the presence of properly selected catalysts. Until now, numerous catalysts were employed for the ODH of ethane, such as composite oxides between alkaline earths and rare earths [2][3][4], halogen (particularly F and Cl) and/or alkali ion-promoted oxides [5][6][7][8], as well as some transition metal (Mo, V, Bi, etc.) oxide-based catalysts [9,10].…”

Section: Introductionmentioning

confidence: 99%

Noncatalytic and catalytic conversion of ethane over VMg oxide catalysts prepared via solid reaction or mesoporous precursors

Chao

Ruckenstein

2004

Journal of Catalysis

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Excellent promotion by lithium of a lanthanum–calcium oxide catalyst for oxidative dehydrogenation of ethane to ethane

Abstract: New effective lanthanum-calcium oxides doped with alkali metals are highly selective for oxidative dehydrogenation of ethane to ethene; > 90% of ethene selectivity with > 40% ethene yield is attained over Li-doped La/CaO catalyst at 580-620 "C.

Cited by 20 publications

References 6 publications

Effect of Promoters on Manganese-Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme

Effect of Promoters on Manganese-Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme

Surfactant-Aided Hydrothermal Synthesis and Carbon Dioxide Adsorption Behavior of Three-Dimensionally Mesoporous Calcium Oxide Single-Crystallites with Tri-, Tetra-, and Hexagonal Morphologies

Noncatalytic and catalytic conversion of ethane over VMg oxide catalysts prepared via solid reaction or mesoporous precursors

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