Household Aluminum Products as Insoluble Precursors for Directed

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Household Aluminum Products as Insoluble Precursors for Directed Growth of Metal-Organic Frameworks Jayraj Joshi, Colton Moran, Harold Feininger, James Dow, and Krista S. Walton Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.9b00452 • Publication Date (Web): 17 Jul 2019 Downloaded from pubs.acs.org on July 17, 2019

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Crystal Growth & Design

Household Aluminum Products as Insoluble Precursors for Directed Growth of Metal-Organic Frameworks Jayraj N. Joshi, Colton M. Moran, Harold P. Feininger, James M. Dow, Krista S. Walton* School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia, 30332, United States of America KEYWORDS: insoluble precursor, MIL-53, controlled growth, aluminum MOF

ABSTRACT. Converting unconventional precursors into advanced separation materials can reduce manufacturing complexity while affording economic and environmental benefits. Here we report the conversion of various aluminumcontaining commercial products, such as recycled beverage cans and aluminum foil, to both supported and non-supported metal-organic frameworks (MOFs). Supported MOF/aluminum composites grow from and on aluminum via hydrothermal treatment to create multiple supported MOF topologies. The same precursor is also employed to generate non-supported MOFs using HCl(aq) as an etching agent. High yields (~83%) of MIL-53(Al) are achieved using aluminum foil, with products possessing textural properties that are consistent with conventionally-synthesized materials. This study provides a synthesis methodology for enhancing the economic viability of next-generation separation materials.

Demonstrations of the landmark gas separation and catalysis potential of metal-organic frameworks (MOFs) have been pervasive in scientific literature for well over a decade (1-5). These materials show substantial promise towards addressing today’s greatest separation challenges (6) such as petrochemical upgrading/separation (7-8), uranium harvesting from seawater (9), and postcombustion and atmospheric CO2 capture (10-12). As a result, new technology companies have formed to produce MOFs for industrial applications (13,14). Petit recently reported a list of MOF-based companies, and highlighted the manufacture of both (i) supported and (ii) nonsupported MOF materials as marketable adsorption media (15). Porous nanomaterials supported on substrates such as monoliths, fibers, thin films, etc., accommodate end-use applications where structured adsorbent media are desirable (10,16). Alternatively, non-supported adsorbents are traditionally formed into pellets or granules for use in packed-bed separations (17). Supported and non-supported adsorbent production strategies are unique from one another. For instance, supported MOF synthesis reports entail multistep pathways, where the supporting substrate surfaces are often pre-treated through various cleaning, etching, and/or chemical functionalization steps. These preliminary steps facilitate subsequent metal precursor seeding or combinatorial MOF growth reactions involving the framework ligand and any other necessary reagents (1821). Non-supported MOFs are instead typically created through one-step solvothermal pathways. These synthesis

schemes commonly employ organic solvents, but solventfree or water-based approaches are more desirable for economical and environmentally-friendly large-scale MOF production (22). Traditional non-supported MOF syntheses also lack size and property control unless carefully tuned framework-specific syntheses are performed (23). Merging production methodologies for both supported and non-supported MOF growth can consequently simplify manufacturing strategies for both classifications of adsorbents. Zhan and Zeng thoroughly detailed how insoluble metal precursors can be advantageous for large-scale MOF production (24). Solid matters are readily accessible raw materials, typically inexpensive, and free of anion and hydrate impurities present with metal salts that are typically used to generate MOFs. Furthermore, solids can impart unique morphologies, particle sizes, architectures, and patterns for resulting hierarchical composite structures through controlled release of metal cations (24-27). The enhanced growth control and worldwide economic accessibility of insoluble metal precursors suggests these materials are ideal synthesis reagents. Present work demonstrates supported MOF production through various methods (2830). However, a flexible scheme of creating both supported and non-supported MOF products is not yet developed. Metallic aluminum (aluminum foil) was chosen in this work as a candidate solid precursor to allow convenient access to a variety of MOF topologies. Architectural replication of aluminum oxide substrates producing porous coordination polymers by Kitagawa and

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coworkers suggests aluminum MOF systems are amenable to insoluble growth strategies (26). From a practical standpoint, aluminum is the second most abundant metal in the earth’s crust and the cheapest metal worldwide, where everyday commercial goods such as aluminum foil and food and drink cans are frequently used (31). To take advantage of this availability, methods are developed here for converting commercially purchased aluminum foil and discarded aluminum cans into highly porous MOF materials. In lieu of using organic solvents typical in MOF syntheses, water is utilized to pursue cheaper, more environmentally friendly hydrothermal production. Commercially available aluminum-based products are shown here to act simultaneously as the support and metal precursor for localized supported MOF growth through a one-step process. Non-supported MOFs are also created through the same synthesis by adding dilute hydrochloric acid, which dissolves the aluminum to create nonsupported MOF products. The easily-tuned flexibility of this process to target supported or non-supported MOF fabrication shows how insoluble metals may play a critical role in formulating simple and economical MOF production strategies. Findings from this report are intended to facilitate future MOF manufacturing endeavors through the use of insoluble metal precursors, and to bridge disparate synthesis techniques employed for supported and non-supported material generation. Conversion of aluminum foil, tubing, and mesh to MIL-53. Reynolds Wrap® brand aluminum foil (Figure S1) purchased from a local grocery store was used as an unconventional metal precursor for one-step solvothermal MOF growth. Using terephthalic acid (BDC) as the organic linker, aluminum terephthalate MIL-53(Al) was generated on the surface of the foil. The cartoon in Figure 1a depicts the resulting composite. MIL-53(Al) growth results on the uppermost layer of aluminum. Metallic aluminum remains underneath as a supporting structure. The inherent white color of MIL-53(Al) coats the foil following reaction, as seen in Figure 1b. Framework formation was confirmed by ATR-FTIR and PXRD measurements, shown in Figures S2 and S3, respectively (32). The characteristic aluminum (1 1 1) reflection at 2θ = 38.47° in Figure S3 verifies the preservation of aluminum in the composite. Diffraction measurements in Figure S3 also confirm preferred crystal orientation through the atypically intense reflection at 2θ ≈ 10.4o in comparison to simulated data (33). Al 2p XPS spectra of the aluminum surface before and after reaction are shown in Figure S4. These data illustrate the chemical changes occurring in the passive aluminum oxide layer that is inherently present on aluminum surfaces. Evolution of MIL-53(Al) octahedra AlO4(OH)2 at 74.8eV (34) after the reaction is shown to dwarf the surface Al(s) and alumina spectral features, proving that MIL-53(Al) is the dominant surface species. EDS mapping of a partially exposed surface (Figure S5) provides further evidence of surface localization of MOF growth. TGA measurements (Figure

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Figure 1. One-step hydrothermal production of supported MIL-53(Al) on metallic aluminum foil: (a) Cartoon schematic of needle-like MIL-53(Al) growth on aluminum foil, denoting foil precursor thickness. (b) Image of post-reaction aluminum foil—white coating reflects surface MIL-53(Al) growth, while foil geometry and size is preserved. (c) SEM image of perpendicularly oriented MIL-53(Al) needles grown on post-reaction aluminum foil surface. MOF structures were physically removed from foil surface prior to imaging to provide visual perspective. (d) FIB-SEM cross-section of aluminum foil-MOF composite. Circled magnification depicts MOF-metal boundary. Cartoon on right-hand side illustrates components visualized in cross-section.

S6) show approximately 9wt% of the composite mass is MIL-53(Al). Needle-like nanocrystals emerge perpendicular to the foil surface and are clearly shown in the electron microscopy images in Figure 1c. This uniform, onedirectional morphology is unique from the typically heterogeneous and rectangular-shaped MIL-53(Al) aggregates obtained through conventional syntheses using soluble metal ions (35). Interestingly, the same needle-like morphology was observed by Moran et al. when producing MIL-53(Al) from insoluble aluminum carbide, suggesting the altered MOF growth mechanics fostered by insoluble metal precursors strongly impacts crystal morphology (36). Importantly, the insoluble metal reagent acts directly as both the metal source and support, which is fundamentally impossible for conventional, solubilized metal salts in a solvothermal reaction. Robatjazi et al. recently presented results corroborating surface MIL-53(Al) growth on aluminum particles in a similar system through a proposed

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Figure 2. Analysis of supported MOFs grown on and from aluminum-based mesh. (a) Crystal structure representations of MIL-53(Al) and MIL-96(Al) above simulated and experimental PXRD measurements of MIL53(red), MIL-96(blue), and bare aluminum mesh (black). Structures constructed using previously reported crystallographic data and VESTA visualization software (33,43,44). Graphics key: blue polyhedrals = metal clusters, red dot = oxygen, grey dot = carbon. SEM images of mesh (b) before reaction, (c) after MIL-53(Al) growth, and (d) after MIL-96(Al) growth shown on left. Arrows are intended to match diffraction data with corresponding product image.

“dissolution-and-growth” mechanism (37). Monolayer growth control conveniently results from the simple solvothermal scheme, whereas the more typical method for accomplishing this control requires use of a self assembled monolayer (SAM) organic precursor on the surface (38). Kang et al. observed monolayer termination while growing Ni2(L-asp)2(bipy) from a nickel net, similarly indicating the metal source becomes inaccessible for reaction (39). Focused ion beam (FIB) cross-sectional milling in Figure 1d clearly distinguishes crystal growth directly on the aluminum surface. Accompanying SEM and EDS data of the cross-sectioned sample in Figure S7-S9 elucidate framework and unreacted aluminum regions visualized in the Figure 1d cartoon.

Interfacial MOF growth through this method is insensitive to substrate geometry. To demonstrate this, standard ¼-inch aluminum tubing purchased from Grainger® was subjected to the same reaction. The general reaction methodology may be used to coat porous nanomaterials onto a variety of metal structures. Since aluminum is already fabricated into a myriad of structural materials, one can easily envision the one-step manufacture of metal substrates integrated with porous aluminum frameworks. This application-based manufacturing flexibility can result in MOF-coated substrates with large void volumes such as tubes (as in Figure S10), laminates, and monoliths. Such structures accommodate separation processes involving large gas flow rates and improve mass transfer for adsorptive



separations—desirable in direct-air capture and flue gas remediation operations (16). A 200 mesh (~74μm) aluminum filter in Figure 2 serves as a pertinent example of how filtration media is easily coated with MOFs. Extension of synthesis to other Al-MOFs and linker analogues. Supported MOFs have been produced from metals in prior work (40-42). However, the scheme presented here uniquely allows access to different aluminum-based MOF topologies via the same procedure. To establish the flexibility of MOF choice for this reaction methodology, trimesic acid (BTC) linkers were also used to produce supported porous aluminum trimesates. Diffraction measurements in Figure 2a confirm the growth of MIL-53(Al) and MIL-96(Al) after reaction with BDC and BTC linkers, respectively. Characteristic reflections for metallic aluminum at 2θ = 38.47° and 38.57° are still evident after MOF formation, evidencing the remaining aluminum backbone underneath newly-formed MOFs. SEM images of the composite formed with BDC in Figure 2c again reveal needle-shaped MIL-53(Al) crystals as was observed in the aluminum foil synthesis results in Figure 1c. Alternatively, 1-5µm dodecahedron MIL-96(Al) crystals densely coat the mesh when using BTC linkers (Figure 1d). Repeating the reaction a second time in the presence of an aluminum salt densifies MOF coverage. SEM images of secondary MIL53(Al) growth in Figure S11 show mesh gaps become completely infiltrated with MOF. Resulting MOF-mesh composites have potential use as adsorptive filters and hierarchical sieves. Such composites illustrate how novel porous nanomaterials can be integrated on easily accessible and industrially relevant support media, with additional potential for post-synthetic modification such as secondary growth treatments. Synthesis of non-supported MOFs. Aluminum foil also yields non-supported MOFs through slight alteration of the same reaction scheme. Investigations on supported MOF production showed surface aluminum becomes passivated from further conversion after established monolayer framework growth. Enhanced dissolution of aluminum would afford continuous MOF formation in the bulk solution until the metal reagent is exhausted. To this end, aqueous hydrochloric acid (HCl) was added to the synthesis mixture to facilitate metal cation release during reaction. Acid concentration directly dictates the relative yield of non-supported MOF. HCl(aq) concentrations were systematically varied from 0.01M to 1M HCl(aq) to optimize MIL-53(Al) yield. Photographs of the samples in Figure S12 show the foil precursor is less apparent in the post-synthesis precipitate as acid concentration is increased. No foil is visually observable in the 0.5M HCl(aq) product. Concentrations > 0.5M HCl(aq) failed to produce solid precipitates. Difficulty in linker deprotonation in such highly acidic conditions likely prevents metal-ligand coordination. This process was also unable to produce MOF when using DMF as a solvent, due to weak dissociation of HCl(aq) in DMF (45). Water is therefore crucial for non-supported MOF formation

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through this method. After conducting the reaction in absence of linker molecules, solution 27Al NMR (Figure S13) of the post-reaction supernatant confirmed the strong presence of Al3+ cations. This observation is in agreement with the initial mechanistic hypothesis for solubilizing metallic aluminum using an etching reagent like HCl(aq). A solid precipitate was also collected from the linkerabsent reaction and identified via PXRD measurements as crystalline boehmite [AlO(OH)] with amorphous alumina (Figure S14). This result suggests aluminum MOF formation is thermodynamically favored at tested conditions when coordinating framework ligands are present. Powder samples obtained from 0.05M, 0.1M, and 0.5M HCl(aq) syntheses with BDC all possess MIL-53(Al) topologies (Figure S15). However, variations in aluminum environments formed with different HCl(aq) concentrations were also evidenced through 27Al multiquantum magic angle spinning (MQMAS) solid-state NMR experiments. The corresponding MQMAS spectrum in Figure S16 for MIL-53(Al) produced using 0.1M HCl(aq) unambiguously reveals distinctive aluminum-based species unique from the 0.5M HCl(aq) product in Figure S17. The 1D spectra in Figure S16 shows a strong resonance at 5ppm in the 0.1M HCl(aq) spectrum, which is greatly diminished when 0.5M HCl(aq) is used. A similar feature has been previously ascribed to 6-coordinate alumina as a solid intermediate to MIL-53(Al) formation when using insoluble Al4C3 precursors, suggesting a similar alumina intermediate may exist for insoluble aluminum here (36). Diminishment of alumina at higher acid concentrations suggests greater conversion of this intermediate to MIL53(Al) when using 0.5M HCl(aq) across consistent (24h) reaction times. This species is surmised to be amorphous, since characteristic crystalline aluminum oxide reflections are absent from collected products (Figure S15). Other spectral features are consistent with previous reports on the various breathing modes of MIL-53(Al) (33,46). Mounfield and Walton (47) observed the same unique shoulder at -80ppm that is present in the 0.5M HCl(aq) MIL-53(Al) material here. This feature is attributed to np-MIL-53(Al) via PXRD measurements (Figure S18) and is present alongside the as-MIL-53(Al) reflections. These observations suggest multiple pore forms exist simultaneously in the material. Deviations from expected peak width and positions, signify lattice strain resulting from heterogeneous aluminum structural environments. Overall, the results show the importance of HCl(aq) concentration in determining both (1) if nonsupported MOF is precipitated and (2) framework properties. Non-supported MOF products described hereafter utilize the optimized 0.5M HCl(aq) reagent concentration. Different linker analogues of MIL-53(Al) can also be produced from the same reaction scheme. Precipitates of MIL-53-NH2(Al) were confirmed through PXRD measurements (Figure S20) when utilizing 2aminoterephthalic acid as the organic ligand (see SI for


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experimental details). Use of pre-functionalized framework ligands is a proven and simple MOF tuning strategy to enhance the selective adsorptive properties of parent frameworks (48-50). Optimized non-supported MOF formation is also applicable to non-terephthalate ligands. As with the supported MOF growth detailed earlier in this report, BTC linkers afforded the creation of nonsupported mesoporous MIL-96(Al), as confirmed by characteristic PXRD reflections (Figure S21) (43). Broad reflections at 2θ = 3.49° and 4.09° in the diffractogram additionally identify MIL-100(Al) crystalline phases (51). Previous work has commonly observed mixtures of MIL100(Al) and MIL-96(Al) because the structures possess isomeric building blocks (52,53). MIL-96(Al) produced from metallic aluminum notably displays a unique morphology from conventionally synthesized MIL-96(Al) in previous publications. SEM images in Figures 3a and b reveal a dodecahedron morphology, with crystallize sizes from 1-3μm. Liu and coworkers (54) previously reported the truncation of hexagonal spindle-shaped rod features on MIL-96(Al) crystallites, which correspond to the (1 0 0) plane, when crystal growth rates were decreased. Geometries observed at slow growth rates by Liu are consistent with crystal shapes imaged in this study. Subsequently, the resulting morphologies of MIL-96(Al) crystals strongly suggest a kinetic barrier to MOF growth exists when producing non-supported aluminum frameworks from the method proposed here. Controlled dissolution of metal cations restricts the growth of nonsupported MOFs by modulating metal concentration in the bulk solution, affecting framework nucleation and crystallization. Furthermore, HCl(aq) addition fosters a H+ concentration barrier partially hindering linker deprotonation. Importantly, this barrier does not prevent MOF formation at industrially relevant time scales; nonsupported MIL-53(Al) production was observed through the same method in as little as 2h, as shown in Figures 3c and d. See Supplementary Information for details on time trial studies. Characterization of non-supported aluminum-foil derived MIL-53. MIL-53(Al) production from aluminum foil was found to occur at reaction temperatures ≤ 220°C using 0.5M HCl. Pictured reaction precipitates in Figure S22 visually illustrate the onset of non-supported MOF recovery at 60°C. The Supplementary Information and Figure S23 provide more information on obtained reaction products at temperatures < 60oC. Figures 4a and S24 show that accessible BET surface areas plateau at approximately 1400 m2 g-1 (23% increase from 80°C) at reaction temperatures between 100°C-220°C. It was found HCl(aq) enhanced BET surface areas over 10% in comparison to traditionally synthesized MIL-53(Al) (Figure S25) (33,5557). Structural and morphological MIL-53(Al) features also evolve through increasing synthesis temperatures. Individual diffraction patterns for temperature trial reactions that successfully created non-supported MIL-

53(Al) are provided in Figure 4b. Diffraction peaks sharpen with increasing reaction temperature, partially reflective of lattice strain and poor crystallinity at low synthesis temperatures. Inspection of the 60°C sample pattern reveals residual Al(s) (2θ = 38°) and an unidentified aluminum derivative at 2θ = 16.2°, indicating the presence

Figure 3. Non-supported MOF production from aluminum foil. a and b) SEM images of MIL-96(Al) crystals, c) time trial samples for aluminum foil-derived MIL-53(Al) at 220°C, d) X-ray diffraction data of powders retrieved from 2h (blue) and 4h (red) experiments, with examples of corresponding MIL-53(Al) product appearance imaged on left-hand side.

of other side-products. These constituents supplement the comparatively low microporosity illustrated for the sample in Figure 4a. Interestingly, samples possess broad, low intensity reflections at 2θ ≈ 8.7° and 15.1° at low reaction temperatures which correspond to the lp-MIL-53(Al). This gradually disappears with increasing synthesis temperature. The formation of lp-MIL-53(Al) at lower reaction temperatures was also noticed by Mounfield and Walton, although observed phases in their previous report did not possess the simultaneous mixture of np- and lpforms seen here (47). The data suggest higher reaction temperatures encourage np-MIL-53(Al) phase homogeneity.



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Figure 4. Temperature trials for non-supported MIL-53(Al) production from aluminum foil: (a) BET surface areas for MIL53(Al) samples. (b) PXRD measurements of activated MIL-53(Al) produced using increasing temperatures (bottom to top). Patterns acquired immediately following desolvation. Expanded data range provided in Figure S27. Overlayed with crystallographic patterns for three characteristic MIL-53(Al) pore forms: as = as-synthesized, np = narrow pore/low temperature form, lp = large pore/high temperature form (30). (c) SEM photographs of MIL-53(Al) morphology aluminum at synthesis temperature of 80°C (left) and 220°C (right).

Crystal shape is significantly altered with reaction temperature as well. SEM micrographs in Figure 4c reveal agglomerated needle-like rod structures ~5µm in length, consistent with those observed for supported MIL-53(Al) growth discussed earlier in Figure 1c and d, at 80°C reaction temperatures. MIL-53(Al) obtained at 220°C contrastingly exhibits irregularly-sized rectangular geometries. Figure S26 illustrates the gradual evolution from rod to rectangular MIL-53(Al) structures with increasing reaction temperature. These morphological differences communicate important differences in non-supported MOF formation at different reaction temperatures. Because the Al(s) dissolution rate via HCl(aq) is decreased at lower temperatures, MOF nucleation occurs on the exposed surfaces of the solubilizing metal reagent. Consequently, resulting rod-like structures are fostered by initial surface-layer crystal growth along the planes of the insoluble precursor. Conversely, Al(s) dissolves rapidly with HCl(aq) at high reaction temperatures. Although

thermodynamically less favorable, crystal growth is subsequently forced in the bulk solution. This hypothesis is supported by the similarity of MIL-53(Al) morphologies obtained at high synthesis temperatures (180°C, 220°C) to previous visual observations of MIL-53(Al) made with ionic salts, where crystal growth also occurs in the bulk solution (35). As a process variable, temperature can be easily changed in most industrially-relevant operations. Consequently, the insoluble precursor scheme presented here affords a simple way to tune non-supported MIL53(Al) crystal size and morphology. Notably, this control is not provided directly by conventional solvothermal syntheses utilizing ionic salts—the dissolution behavior of insoluble aluminum here is critical for directing MOF growth at low synthesis temperatures, and allowing for bulk solution crystal formation at high reaction temperatures. Success with other aluminum precursors: alloys and soda cans. This methodology may be extended to a


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Crystal Growth & Design seemingly endless variety of potential aluminum metal precursors for MOF production. Figure 5a exemplifies this, where Coca-Cola cans retrieved from a nearby recycling bin were converted into MIL-53(Al) and MIL-96(Al) through the same non-supported MOF reaction scheme. N2 physisorption measurements of the materials in Figure 5b verify the creation of the highly microporous materials. The robust MOF synthesis pathway is clearly not hindered by the numerous impurities present in metal precursors such as recycled cans (e.g., epoxy coating, plastic labeling, etc.). Non-aluminum impurities predictably minimize the adsorption properties of resulting materials on a per-mass basis. For example, the BET surface area for MIL-53(Al) generated from Coca-Cola cans is only 800 m2 g-1—30% lower than the 1140 m2g-1 value reported by Loiseau et al. for conventionally-synthesized MIL-53(Al) (33). TGA measurements in Figure 5c illustrate resulting residual mass differences between MIL-53(Al) created from aluminum foil (relatively high metal purity) and recycled aluminum cans. Dry air was utilized as a carrier to create Al2O3 as the MOF combustion product at 1000°C. The theoretical building unit of MIL-53(Al) [Al(OH)(C6H4(COOH)2] is stoichiometrically normalized to 100wt% in Figure 5c after evacuation of solvent and entrapped linkers below 400°C. In this way, sample mass changes are compared to the theoretical mass loss of ~75.5wt%. The mass loss of aluminum foil-derived MIL-53(Al) adheres within 2wt% of calculated predictions for expected framework mass. In contrast, ~38wt% of the Coca-Cola can-derived MOF product is attributed to non-framework species, explaining its reduced nitrogen uptake in Figure 5b. Accordingly, cheap and readily accessible sources like aluminum foil present themselves as surprisingly usable precursors to obtain highly ordered and porous nanomaterials. An economic analysis is included in the Supporting Information.

Figure 5. Textural properties of MOFs created from unconventional metal precursors: (a) Images of collected aluminum can. Cans were halved and loaded into PTFE liner for batch reaction, due to size restrictions. (b) N2 uptake measurements at 77K for frameworks produced from a CocaCola can using BDC and BTC linkers. (c) TGA measurements for MIL-53(Al)-derived from a Coca-Cola can (red) and aluminum foil (blue) using air as a carrier. Building unit of MIL-53(Al) normalized as 100% with experimental data after desolvation and removal of entrapped linkers (≥ 400°C), along with stoichiometric combustion product Al2O3.

Aluminum-containing metal alloys 6061 and 2024 were also successfully converted to MIL-53(Al), and supplement these findings. PXRD patterns in Figure S28 from the two alloys and Coca-Cola can-derived product confirm the formation of MIL-53(Al). Fascinatingly, aluminum was selectively converted from the two alloys, demonstrating chemical specificity of the insoluble aluminum MOF reaction. Magnesium and silicon are the other major elements that compose Alloy 6061. Following MIL-53(Al) production and separation, an unreacted nonMOF solid was also recovered containing a pink surface region pictured in Figure S29a—reminiscent of magnesium silicate hydroxides, such as montmorillonite (58). Similarly, the post-reaction copper-rich Alloy 2024 by-product features a blue surface in Figure S29b, suggestive of cupric hydroxide formation after hydrothermal treatment. Overall, these results prove that metallic aluminum purity does not prevent aluminum framework formation, indicating a strong flexibility in material selection for Al-MOF production through this proposed insoluble aluminum method.



ASSOCIATED CONTENT Supporting Information Synthesis and characterization methods and cost analysis are including in the Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *K. S. Walton. Email: [email protected]

Notes

The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center, funded by U.S. Department of Energy (US DoE), Office of Science, Basic Energy Sciences (BES) under Award DE-SC0012577. Dr. Johannes Leisen and Dr. Leslie Gelbaum at the Georgia Institute of Technology are acknowledged for collecting 27Al NMR measurements. Finally, the authors would like to acknowledge Dr. Robert Marti and Dr. Sophia Hayes (Washington University, St. Louis, MO) for helpful discussions on characterization techniques for aluminum materials.

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Beverage cans and aluminum foil can produce both supported and nonsupported MOFs

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Household Aluminum Products as Insoluble Precursors for Directed

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