Numerical Modeling of CO2 Splitting in High-Temperature Solar-Driven Oxygen Permeation Membrane Reactors

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Heng Pan ◽  
Youjun Lu ◽  
Liya Zhu
Keyword(s):  
Membrane Reactor ◽  
Continuous Production ◽  
Oxygen Permeation ◽  
Conversion Ratio ◽  
Inert Gas ◽  
Limiting Factors ◽  
Co2 Conversion ◽  
Permeable Membrane ◽  
Concentrated Solar Energy ◽  
Oxygen Permeation Membrane

Abstract H2/CO production via H2O/CO2 splitting powered by concentrated solar energy is a promising pathway for energy conversion/storage. Oxygen permeable membrane reactor serves as an alternative reactor concept for realizing this chemical path with the advantages of continuous production, easy integration, and high product selectivity. In this paper, a mathematical model of steady-state mass and heat transfer coupled with reaction kinetics in the oxygen permeation membrane reactor was established. CO2 splitting in the ceria membrane reactor was simulated and the effects of various factors, including inert/CO2 flow configurations, reaction conditions, and geometric parameters of the membrane, on the CO2 conversion process, were studied. The increase of operating temperature could effectively improve the CO2 conversion ratio, and the effect of decreasing the oxygen pressure of the inert gas is very limited. The oxygen accumulation in the inert gas could lead to considerably high inert demand. Furthermore, conversion-limiting factors were studied under different conditions and there are two critical rate constants of reactions signifying a transition from a chemical kinetics limited conversion to oxygen diffusion limited conversion. This work helps guide reactor design and operate toward achieving the maximum CO2 conversion ratio.

Catalytic Partial Oxidation of Coke Oven Gas to Syngas over Ni/SiO2 Catalyst Modified by Rare Earth Metal Oxide in a Membrane Reactor

2010 ◽  
Vol 156-157 ◽  
pp. 1024-1028
Author(s):  
Da Hai Hu ◽  
Xiong Gang Lu ◽  
Hong Wei Cheng ◽  
Wei Zhong Ding
Keyword(s):  
Rare Earth ◽  
Partial Oxidation ◽  
Membrane Reactor ◽  
Coke Oven ◽  
Oxygen Permeation ◽  
Catalytic Partial Oxidation ◽  
Permeation Flux ◽  
Coke Oven Gas ◽  
Permeable Membrane ◽  
Oxygen Permeation Flux

The performance of Ni/SiO2 Catalysts modified by La2O3, ZrO2 and CeO2 were tested in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor by catalytic partial oxidation of coke oven gas (COG) under atmospheric pressure. The results show that the oxygen permeation flux increased dramatically with Ni/RxOy/SiO2 (R = La, Zr or Ce) catalysts by adding the element of rare earth especially the La during the reforming reaction. At optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 16.4 ml/cm2•min and a CH4 conversion of 99.2% have been achieved at 900 oC.

Autothermal reforming of ethanol in dense oxygen permeation membrane reactor

2016 ◽  
Vol 264 ◽  
pp. 214-220 ◽  
Author(s):  
Yun Jin ◽  
Zebao Rui ◽  
Ye Tian ◽  
Y.S. Lin ◽  
Yongdan Li
Keyword(s):  
Membrane Reactor ◽  
Oxygen Permeation ◽  
Autothermal Reforming ◽  
Oxygen Permeation Membrane

scholarly journals Solid-State Redox Kinetics of CeO2 in Two-Step Solar CH4 Partial Oxidation and Thermochemical CO2 Conversion

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 723
Author(s):  
Mahesh Muraleedharan Nair ◽  
Stéphane Abanades
Keyword(s):  
Solid State ◽  
Solar Energy ◽  
Kinetic Models ◽  
Oxygen Carrier ◽  
Co2 Conversion ◽  
Oxidation Reactions ◽  
Redox Kinetics ◽  
Concentrated Solar Energy ◽  
Ceria Reduction ◽  
Kinetics Of

The CeO2/CeO2−δ redox system occupies a unique position as an oxygen carrier in chemical looping processes for producing solar fuels, using concentrated solar energy. The two-step thermochemical ceria-based cycle for the production of synthesis gas from methane and solar energy, followed by CO2 splitting, was considered in this work. This topic concerns one of the emerging and most promising processes for the recycling and valorization of anthropogenic greenhouse gas emissions. The development of redox-active catalysts with enhanced efficiency for solar thermochemical fuel production and CO2 conversion is a highly demanding and challenging topic. The determination of redox reaction kinetics is crucial for process design and optimization. In this study, the solid-state redox kinetics of CeO2 in the two-step process with CH4 as the reducing agent and CO2 as the oxidizing agent was investigated in an original prototype solar thermogravimetric reactor equipped with a parabolic dish solar concentrator. In particular, the ceria reduction and re-oxidation reactions were carried out under isothermal conditions. Several solid-state kinetic models based on reaction order, nucleation, shrinking core, and diffusion were utilized for deducing the reaction mechanisms. It was observed that both ceria reduction with CH4 and re-oxidation with CO2 were best represented by a 2D nucleation and nuclei growth model under the applied conditions. The kinetic models exhibiting the best agreement with the experimental reaction data were used to estimate the kinetic parameters. The values of apparent activation energies (~80 kJ·mol−1 for reduction and ~10 kJ·mol−1 for re-oxidation) and pre-exponential factors (~2–9 s−1 for reduction and ~123–253 s−1 for re-oxidation) were obtained from the Arrhenius plots.

scholarly journals Understanding the Impact of Hydrogen Activation by SrCe0.8Zr0.2O3−δ Perovskite Membrane Material on Direct Non-Oxidative Methane Conversion

2022 ◽  
Vol 9 ◽  
Author(s):  
Sichao Cheng ◽  
Su Cheun Oh ◽  
Mann Sakbodin ◽  
Limei Qiu ◽  
Yuxia Diao ◽  
...  
Keyword(s):  
Methane Conversion ◽  
Membrane Reactor ◽  
Membrane Reactors ◽  
Fixed Bed Reactor ◽  
Perovskite Oxide ◽  
Oxide Material ◽  
Hydrogen Activation ◽  
Permeable Membrane ◽  
The Impact

Direct non-oxidative methane conversion (DNMC) converts methane (CH4) in one step to olefin and aromatic hydrocarbons and hydrogen (H2) co-product. Membrane reactors comprising methane activation catalysts and H2-permeable membranes can enhance methane conversion by in situ H2 removal via Le Chatelier's principle. Rigorous description of H2 kinetic effects on both membrane and catalyst materials in the membrane reactor, however, has been rarely studied. In this work, we report the impact of hydrogen activation by hydrogen-permeable SrCe0.8Zr0.2O3−δ (SCZO) perovskite oxide material on DNMC over an iron/silica catalyst. The SCZO oxide has mixed ionic and electronic conductivity and is capable of H2 activation into protons and electrons for H2 permeation. In the fixed-bed reactor packed with a mixture of SCZO oxide and iron/silica catalyst, stable and high methane conversion and low coke selectivity in DNMC was achieved by co-feeding of H2 in methane stream. The characterizations show that SCZO activates H2 to favor “soft coke” formation on the catalyst. The SCZO could absorb H2in situ to lower its local concentration to mitigate the reverse reaction of DNMC in the tested conditions. The co-existence of H2 co-feed, SCZO oxide, and DNMC catalyst in the present study mimics the conditions of DNMC in the H2-permeable SCZO membrane reactor. The findings in this work offer the mechanistic understanding of and guidance for the design of H2-permeable membrane reactors for DNMC and other alkane dehydrogenation reactions.

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