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Catalyst-free ceramic-carbonate dual phase membrane reactor for the water gas Rxn CO2 separation.
The paper I will discuss in this post is this one: Catalyst-free ceramic-carbonate dual phase membrane reactor for hydrogen production from gasifier syngas (Xueliang Dong, Y.S. Lin, Journal of Membrane Science, Volume 520, 2016, Pages 907-913.)
I was motivated to call this paper up when reading another paper (by the same research group) offering some mathematical modeling of this very interesting device. That paper is this one, published a few weeks ago: Catalyst-Free Ceramic–Carbonate Dual-Phase Membrane Reactors for High-Temperature Water Gas Shift: A Simulation Study (Lie Meng, Oscar Ovalle-Encinia, and Jerry Y. S. Lin, Industrial & Engineering Chemistry Research 2021 60 (9), 3581-3588) This group is out of Arizona State University.
The importance of the water gas shift reaction - it is the source of most of the world's hydrogen, which is overwhelmingly produced by the reformation of dangerous natural gas - cannot be underestimated. Among other things, the world's food supply depends on this reaction, as it is widely used to make ammonia.
I oppose the use of all dangerous fossil fuels, and as such, I'm always imagining all kinds of Rube Goldberg heat networks to make carbon monoxide without the use of dangerous natural gas, and it occurs to me that this magnificent biphasic membrane is the sort of thing that could be plugged into such a scheme.
The second paper cited, the mathematical modeling paper gives a nice overview of the water gas shift reaction (WGS) so I'll excerpt that first, although it focuses on carbon capture and power generation, and not hydrogen for synthetic purposes:
Water gas shift (WGS) is an exothermic reaction (CO + H2O ? CO2 + H2, ?H = ?41 kJ mol–1) and is a critical step in the integrated gasification combined cycle process for electrical power generation with CO2 capture. WGS is traditionally performed in two adiabatic reactors arranged in series, a high-temperature WGS (300–450 °C) and a low-temperature WGS (200–250 °C), to maximize the CO conversion, followed by the separation of H2 and CO2 using energy-intensive processes such as solvent absorption or pressure swing absorption. Membrane reactor-based WGS has emerged as a high-efficiency alternative to the current industrial approaches in which hydrogen production is conducted in fixed-bed reactors.(1,2) Compared with conventional processing, membrane reactors allow H2 (kinetic diameter: 0.29 nm) and/or CO2 (kinetic diameter: 0.33 nm) to permeate through the membrane during the reaction. Thus, the conversion is increased beyond the equilibrium until the limitations imposed by reaction kinetics become dominant.
As demonstrated via experiments and simulations, palladium-based metal membrane reactors exhibit extremely high selectivity for hydrogen separation. Augustine et al.(3) developed a palladium membrane reactor for high-temperature WGS at a feed pressure up to 15 bar and achieved a maximum CO conversion of 98.2% with a H2 recovery of 81.2% at 450 °C. However, the palladium membrane suffers from several drawbacks that significantly limit its practicality: hydrogen embrittlement, surface poisoning, and high membrane cost.(4) Modified MFI-type zeolite membranes promise high-temperature-selective hydrogen separation due to good thermal and chemical stability and high hydrogen permeance. However, MFI-type zeolite membranes have relatively low H2 perm-selectivity, which should be improved for use in membrane reactors for WGS.
Many efforts have been devoted to improving the H2/CO2 selectivity of MFI zeolite membranes (pore diameter: 0.55 nm, Knudsen selectivity for H2/CO2: ?4.7), including narrowing the zeolitic pore by catalytic cracking deposition of monosilica.(5) For precise control of pore modification, Wang et al.(6) developed a porous ?-alumina-supported bilayer MFI zeolite membrane consisting of a ZSM-5 layer on a silicalite-1 layer to reduce the aluminum content in the zeolite top layer. At 500 °C, the modified MFI zeolite membrane exhibited a H2 permeance of ?1.2 × 10–7 mol m–2 s–1 Pa–1 and a H2/CO2 selectivity of ?23 in a 24 day long-term test. WGS conducted at temperatures lower than 500 °C is thermodynamically favored to a high CO conversion because of its exothermic nature, indicating, for high-temperature WGS, that the increase in reaction temperature has a negative effect on the equilibrium CO conversion. However, for these H2-selective membrane reactors, the H2 permeance through the membrane drops with decreasing temperature, resulting in a weak shift in WGS and a low H2 recovery rate. Moreover, most modified MFI-type zeolite membranes show a H2/CO2 selectivity below 30, suggesting that a low CO2 capture ratio could be expected.
Another strategy to enhance WGS in the membrane reactor is the use of CO2-permeable membranes. This will avoid or reduce a load of CO2 separation by amine absorption or adsorption process, reducing the costs for carbon capture in the IGCC process. Recently, we developed several high-performance ceramic–carbonate dual-phase (CCDP) membranes, which are high-temperature CO2 separation materials with remarkable CO2 permeance and theoretically infinite CO2 selectivity.
As demonstrated via experiments and simulations, palladium-based metal membrane reactors exhibit extremely high selectivity for hydrogen separation. Augustine et al.(3) developed a palladium membrane reactor for high-temperature WGS at a feed pressure up to 15 bar and achieved a maximum CO conversion of 98.2% with a H2 recovery of 81.2% at 450 °C. However, the palladium membrane suffers from several drawbacks that significantly limit its practicality: hydrogen embrittlement, surface poisoning, and high membrane cost.(4) Modified MFI-type zeolite membranes promise high-temperature-selective hydrogen separation due to good thermal and chemical stability and high hydrogen permeance. However, MFI-type zeolite membranes have relatively low H2 perm-selectivity, which should be improved for use in membrane reactors for WGS.
Many efforts have been devoted to improving the H2/CO2 selectivity of MFI zeolite membranes (pore diameter: 0.55 nm, Knudsen selectivity for H2/CO2: ?4.7), including narrowing the zeolitic pore by catalytic cracking deposition of monosilica.(5) For precise control of pore modification, Wang et al.(6) developed a porous ?-alumina-supported bilayer MFI zeolite membrane consisting of a ZSM-5 layer on a silicalite-1 layer to reduce the aluminum content in the zeolite top layer. At 500 °C, the modified MFI zeolite membrane exhibited a H2 permeance of ?1.2 × 10–7 mol m–2 s–1 Pa–1 and a H2/CO2 selectivity of ?23 in a 24 day long-term test. WGS conducted at temperatures lower than 500 °C is thermodynamically favored to a high CO conversion because of its exothermic nature, indicating, for high-temperature WGS, that the increase in reaction temperature has a negative effect on the equilibrium CO conversion. However, for these H2-selective membrane reactors, the H2 permeance through the membrane drops with decreasing temperature, resulting in a weak shift in WGS and a low H2 recovery rate. Moreover, most modified MFI-type zeolite membranes show a H2/CO2 selectivity below 30, suggesting that a low CO2 capture ratio could be expected.
Another strategy to enhance WGS in the membrane reactor is the use of CO2-permeable membranes. This will avoid or reduce a load of CO2 separation by amine absorption or adsorption process, reducing the costs for carbon capture in the IGCC process. Recently, we developed several high-performance ceramic–carbonate dual-phase (CCDP) membranes, which are high-temperature CO2 separation materials with remarkable CO2 permeance and theoretically infinite CO2 selectivity.
My whole adult life I've been thinking about this in terms of palladium membranes, and so I find this very cool.
The text of the first paper cited is similar to that excerpted above from the second:
Water gas shift (WGS) is an exothermic reaction (CO + H2O ? CO2 + H2, ?H = ?41 kJ mol–1) and is a critical step in the integrated gasification combined cycle process for electrical power generation with CO2 capture. WGS is traditionally performed in two adiabatic reactors arranged in series, a high-temperature WGS (300–450 °C) and a low-temperature WGS (200–250 °C), to maximize the CO conversion, followed by the separation of H2 and CO2 using energy-intensive processes such as solvent absorption or pressure swing absorption. Membrane reactor-based WGS has emerged as a high-efficiency alternative to the current industrial approaches in which hydrogen production is conducted in fixed-bed reactors.(1,2) Compared with conventional processing, membrane reactors allow H2 (kinetic diameter: 0.29 nm) and/or CO2 (kinetic diameter: 0.33 nm) to permeate through the membrane during the reaction. Thus, the conversion is increased beyond the equilibrium until the limitations imposed by reaction kinetics become dominant.
As demonstrated via experiments and simulations, palladium-based metal membrane reactors exhibit extremely high selectivity for hydrogen separation. Augustine et al.(3) developed a palladium membrane reactor for high-temperature WGS at a feed pressure up to 15 bar and achieved a maximum CO conversion of 98.2% with a H2 recovery of 81.2% at 450 °C. However, the palladium membrane suffers from several drawbacks that significantly limit its practicality: hydrogen embrittlement, surface poisoning, and high membrane cost.(4) Modified MFI-type zeolite membranes promise high-temperature-selective hydrogen separation due to good thermal and chemical stability and high hydrogen permeance. However, MFI-type zeolite membranes have relatively low H2 perm-selectivity, which should be improved for use in membrane reactors for WGS.
Many efforts have been devoted to improving the H2/CO2 selectivity of MFI zeolite membranes (pore diameter: 0.55 nm, Knudsen selectivity for H2/CO2: ?4.7), including narrowing the zeolitic pore by catalytic cracking deposition of monosilica.(5) For precise control of pore modification, Wang et al.(6) developed a porous ?-alumina-supported bilayer MFI zeolite membrane consisting of a ZSM-5 layer on a silicalite-1 layer to reduce the aluminum content in the zeolite top layer. At 500 °C, the modified MFI zeolite membrane exhibited a H2 permeance of ?1.2 × 10–7 mol m–2 s–1 Pa–1 and a H2/CO2 selectivity of ?23 in a 24 day long-term test. WGS conducted at temperatures lower than 500 °C is thermodynamically favored to a high CO conversion because of its exothermic nature, indicating, for high-temperature WGS, that the increase in reaction temperature has a negative effect on the equilibrium CO conversion. However, for these H2-selective membrane reactors, the H2 permeance through the membrane drops with decreasing temperature, resulting in a weak shift in WGS and a low H2 recovery rate. Moreover, most modified MFI-type zeolite membranes show a H2/CO2 selectivity below 30, suggesting that a low CO2 capture ratio could be expected.
Another strategy to enhance WGS in the membrane reactor is the use of CO2-permeable membranes. This will avoid or reduce a load of CO2 separation by amine absorption or adsorption process, reducing the costs for carbon capture in the IGCC process. Recently, we developed several high-performance ceramic–carbonate dual-phase (CCDP) membranes, which are high-temperature CO2 separation materials with remarkable CO2 permeance and theoretically infinite CO2 selectivity...
As demonstrated via experiments and simulations, palladium-based metal membrane reactors exhibit extremely high selectivity for hydrogen separation. Augustine et al.(3) developed a palladium membrane reactor for high-temperature WGS at a feed pressure up to 15 bar and achieved a maximum CO conversion of 98.2% with a H2 recovery of 81.2% at 450 °C. However, the palladium membrane suffers from several drawbacks that significantly limit its practicality: hydrogen embrittlement, surface poisoning, and high membrane cost.(4) Modified MFI-type zeolite membranes promise high-temperature-selective hydrogen separation due to good thermal and chemical stability and high hydrogen permeance. However, MFI-type zeolite membranes have relatively low H2 perm-selectivity, which should be improved for use in membrane reactors for WGS.
Many efforts have been devoted to improving the H2/CO2 selectivity of MFI zeolite membranes (pore diameter: 0.55 nm, Knudsen selectivity for H2/CO2: ?4.7), including narrowing the zeolitic pore by catalytic cracking deposition of monosilica.(5) For precise control of pore modification, Wang et al.(6) developed a porous ?-alumina-supported bilayer MFI zeolite membrane consisting of a ZSM-5 layer on a silicalite-1 layer to reduce the aluminum content in the zeolite top layer. At 500 °C, the modified MFI zeolite membrane exhibited a H2 permeance of ?1.2 × 10–7 mol m–2 s–1 Pa–1 and a H2/CO2 selectivity of ?23 in a 24 day long-term test. WGS conducted at temperatures lower than 500 °C is thermodynamically favored to a high CO conversion because of its exothermic nature, indicating, for high-temperature WGS, that the increase in reaction temperature has a negative effect on the equilibrium CO conversion. However, for these H2-selective membrane reactors, the H2 permeance through the membrane drops with decreasing temperature, resulting in a weak shift in WGS and a low H2 recovery rate. Moreover, most modified MFI-type zeolite membranes show a H2/CO2 selectivity below 30, suggesting that a low CO2 capture ratio could be expected.
Another strategy to enhance WGS in the membrane reactor is the use of CO2-permeable membranes. This will avoid or reduce a load of CO2 separation by amine absorption or adsorption process, reducing the costs for carbon capture in the IGCC process. Recently, we developed several high-performance ceramic–carbonate dual-phase (CCDP) membranes, which are high-temperature CO2 separation materials with remarkable CO2 permeance and theoretically infinite CO2 selectivity...
This groups molten carbonate membranes in many cases were supported on a type of zeolite known as "MFI zeolite," a type of porous silicate. Here in this paper, the support is a ceramic, "SDC," samarium doped ceria.
Some pictures from the text:
The caption:
Fig. 1. Schematic of catalyst-free ceramic-carbonate dual phase membrane reactor for syngas WGS reaction.
The caption:
Fig. 2. Schematic diagram of tubular SDC-carbonate dual phase membrane reactor for high temperature syngas WGS reaction.
The caption:
Fig. 3. (a) Photo of SDC substrates with different sizes; SEM images: (b) outer and (c) inner surfaces of SDC substrate sintered at 1420 °C for 12 h; (d) outer and (e) inner surfaces of SDC-carbonate membrane after infiltration; (f) cross section of SDC-carbonate membrane.
Both papers offer a considerable amount of more detail and analysis.
From the conclusion of the paper:
This work demonstrates a new process for hydrogen production from high temperature syngas WGS reaction in a SDC-carbonate dual phase membrane reactor with simultaneously CO2 removal. The membranes show good CO2 permeation flux and high thermal and chemical stability under syngas WGS reaction environment. The removal of CO2 by dual phase membrane from reaction process promotes the conversion of CO at high temperatures without a catalyst. Further improvement of CO2 separation performance in practical application is possible by increasing the feed pressure. This work also confirms the reliability of SDC-carbonate dual phase membranes for high temperature CO2 removal from industrial processes, such as IGCC.
To me, IGCC is an appalling idea, but the application of this technology may be very useful elsewhere. There is a heat engine cycle known as the "Allam Cycle" which with (unlike the cycles original conception) an external heat source, can be utilized to produce carbon monoxide from waste carbon materials, plastics, other garbage, biomass. (This is called "dry reforming.) Incorporating this very interesting technology suggests some very interesting possibilities.
I'm having a nice week, a molten carbonate kind of week: Electrolysis of Lithium-Free Molten Carbonates.
If you were to tell me that you found getting excited about molten carbonates is well, "a little off," well it's OK. To each his or her own.
Have a nice day tomorrow.
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