Efficient Ammonia Decomposition in a Catalytic Membrane Reactor To Enable Hydrogen Storage and Utilization

Zhang, Zhenyu; Liguori, Simona; Fuerst, Thomas F.; Way, J. Douglas; Wolden, Colin A.

doi:10.1021/acssuschemeng.8b06065

Cited by 93 publications

(75 citation statements)

References 66 publications

(120 reference statements)

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“…The mixture of 75% hydrogen and 25% nitrogen is characterized not only by increased heating value compared with neat ammonia (21.34 versus 18.6 MJ/kg), which is beneficial to the combustion process, but also by a relatively low Wobbe index compared with standard hydrocarbon fuels (about 10 versus 42-53 MJ/Nm 3 ), something that would negatively impact the fuel delivery system of the gas turbine and would require substantial changes. Irrespective of practical advantages and disadvantages of the resulting hydrogen/nitrogen mixture, a considerable amount of heat is required by the process of complete ammonia dissociation 51,52 or, alternatively, the oxidation of a nonnegligible fraction (∼7%) of the ammonia in the catalyst. 53 The required thermal energy can, in principle, be recovered from the gas turbine waste heat, but this withdraws it from the steam bottoming cycle (if present), lowering the overall efficiency of the power plant.…”

Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

et al. 2019

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Chemical-kinetic combustion mechanisms for hydrogen-oxygen-nitrogen systems, motivated originally by concerns about NO x emissions during hydrogen burning, have recently acquired renewed interest as a result of the possibility of employing ammonia-hydrogen mixtures in gas turbines and reciprocating engines as drop-in fuel to replace the use of natural gas. Specifically, this is of relevance to the implementation of engineering approaches for economical power generation with carbon sequestration or to large-scale energy-storage schemes, based on hydrogen or efficient hydrogen carriers such as ammonia. Because computational investigations are facilitated by short mechanisms (since the use of large mechanisms is often prohibitively expensive in reactive flow simulations), in response to the original concerns, a short nitrogen mechanism was developed in San Diego in the 1990s (not updated since 2004), without consideration of ammonia combustion. In view of the renewed interest in this topic, that mechanism has now been expanded to encompass 60 elementary steps among 19 reactive chemical species, including ammonia burning and NO x production, as reported herein, greatly improving predictions. With particular attention to high reactant temperatures and high-pressure conditions, relevant to industrial applications, it is shown that the present short mechanism retains satisfactory accuracy, exhibiting deviations that in most cases are within acceptable bounds (±20%). The revisions maintain the shortness of the original mechanism, adding only one more reactive species and six more elementary steps (while updating values of rate parameters of nine other steps, on the basis of newly available information). In addition, the short mechanism is applied herein to the analysis of fundamental combustion properties of ammonia/hydrogen/nitrogen-air laminar premixed flames, at unstrained and strained conditions, for comparison with methane-air flames as a reference gas-turbine fuel. It is found by comparing carbon-free and hydrocarbon laminar flames that these reactive mixtures, even if characterized by nearly identical adiabatic flame temperature and laminar flame speeds, nevertheless exhibit substantially different resistance to strain, with the ammonia/hydrogen flames exceeding the strain limit of methane flames by a factor of 5.

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Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

et al. 2019

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“…Previously, the benefits of CMRs have been demonstrated against PBRs mainly for dehydrogenation processes such as ammonia decomposition 21,32 and steam methane reforming 33 . These successful implementations rely heavily on well‐developed hydrogen‐permeable membranes based on Pd and Pd alloys 34 .…”

Section: Resultsmentioning

confidence: 99%

“…The permeation flux per volume, that is, the packing density of tubular membranes, inversely scales with the radius, at fixed ammonia permeance, and pressure driving force. Based on our previous work on with CMRs, 7,21 a typical L/r ratio is 40. Here, we assume L and r are 20 cm and 0.5 cm, respectively.…”

Section: Reactor Model Developmentmentioning

confidence: 99%

Design and operational considerations of catalytic membrane reactors for ammonia synthesis

2021

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Production of ammonia using hydrogen derived from renewable electricity instead of hydrocarbon reforming would dramatically reduce the carbon footprint of this commodity chemical. Novel technologies such as catalytic membrane reactors (CMRs) may potentially be more compatible with distributed ammonia production than the conventional Haber–Bosch process. A reactor model is developed based on integrating a standard industrial iron catalyst into a CMR equipped with an inorganic membrane that is selective to NH3 over N2/H2. CMR performance is studied as functions of wide ranges of membrane properties and operating conditions. Conversion and ammonia recovery are dictated principally by the ammonia permeance, and the benefits by using membranes become significant above 100 GPU = 3.4 × 10−8 mol m−2 s−1 Pa−1. To be effective, the CMR requires a minimum selectivity for ammonia of 10 over both nitrogen and hydrogen and purity scales with the effective selectivity. Increasing the pressure of operation significantly improves all metrics, and at P = 30 bar with a quality membrane, ammonia is almost completely recovered, enabling direct recycle of unreacted hydrogen and nitrogen without need for recompression. Temperature drives conversion and scales monotonically without thermodynamic limitations in a CMR. Alternatively, the temperature may be reduced as low as 300°C while achieving conversion levels surpassing equilibrium limits at T = 400°C in a conventional reactor.

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“…The membrane reactor for ammonia decomposition has been demonstrated at the lab scale, in which chemical reactions and the selective separation of a product co-occur. Thus, it may not need any downstream separation unit, which would help increase efficiencies at lower operating temperatures ( Zhang et al., 2019 ). However, using tantalum tubes as the membrane support, which exhibits selective hydrogen diffusion, would be prohibitively expensive for large-scale ammonia decomposition.…”

Section: Hydrogen Storage By Circular Hydrogen Carriersmentioning

confidence: 99%

Large-scale stationary hydrogen storage via liquid organic hydrogen carriers

et al. 2021

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Summary Large-scale stationary hydrogen storage is critical if hydrogen is to fulfill its promise as a global energy carrier. While densified storage via compressed gas and liquid hydrogen is currently the dominant approach, liquid organic molecules have emerged as a favorable storage medium because of their desirable properties, such as low cost and compatibility with existing fuel transport infrastructure. This perspective article analytically investigates hydrogenation systems' technical and economic prospects using liquid organic hydrogen carriers (LOHCs) to store hydrogen at a large scale compared to densified storage technologies and circular hydrogen carriers (mainly ammonia and methanol). Our analysis of major system components indicates that the capital cost for liquid hydrogen storage is more than two times that for the gaseous approach and four times that for the LOHC approach. Ammonia and methanol could be attractive options as hydrogen carriers at a large scale because of their compatibility with existing liquid fuel infrastructure. However, their synthesis and decomposition are energy and capital intensive compared to LOHCs. Together with other properties such as safety, these factors make LOHCs a possible option for large-scale stationary hydrogen storage. In addition, hydrogen transportation via various approaches is briefly discussed. We end our discussions by identifying important directions for future research on LOHCs.

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Efficient Ammonia Decomposition in a Catalytic Membrane Reactor To Enable Hydrogen Storage and Utilization

Cited by 93 publications

References 66 publications

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

Design and operational considerations of catalytic membrane reactors for ammonia synthesis

Large-scale stationary hydrogen storage via liquid organic hydrogen carriers

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