Solid-state synthesis of a MOF/polymer composite for hydrodeoxygenation of vanillin

A new solid-state method was used to introduce a furan-thiourea polymer into the pores of a MOF, Cr-BDC. Next, the activity of the new MOF-polymer composite containing Pd was assessed in the catalytic hydrodeoxygenation of vanillin, a biomass derived chemical

Densification and shaping of pure Cu-BTC powders using a solid-state chemical transformation

Abstract MOFs are a class of porous crystalline materials whose unique properties have led to applicability in several fields ranging from gas adsorption to drug delivery. Despite their high potential, MOFs are usually found as fine powders, a property that can limit their use in industrial applications. Here, a novel approach is proposed to form densified Cu-MOF (Cu-BTC) powders and monoliths using 1,2-ethanedisulfonic acid (EDSA) as a densification agent. A MOF/EDSA mixture was heated to ∼150 °C; the molten EDSA not only promotes the growth of larger MOF crystallites, but also stimulates condensation reactions between the carboxylate-based MOF ligands, further binding the particles together. When this reaction was done in a stainless-steel die under pressure MOF-based monoliths could also be formed. Notably, using this approach, the MOF had a higher density, significantly improving the volumetric CO2 adsorption capacity. We believe this contribution provides the basis for future work wherein the intrinsic MOF particle surfaces can be selectively engineered to improve their properties towards shaping for industrial applications.</jats:p

Efficient reductive amination of HMF with well dispersed Pd nanoparticles immobilized in a porous MOF/polymer composite

Aminated derivatives of 5-hydroxymethylfurfural (HMF) and furfural are critical intermediates for the pharmaceutical industry. The state-of-the-art catalysts currently used for these syntheses are mostly homogeneous in nature, motivating the design of recyclable, heterogeneous catalytic systems. As such, the present study illustrates a new method for the design of metal-organic framework (MOF)/polymer composites containing well-defined metal nanoparticles in a sustainable way. One such palladium functionalized MOF/polymer composite is then employed in the reductive amination of HMF under mild conditions. The catalyst shows excellent activity, including a high TON/TOF (h(-1)) of 604.8/302.4 and similar to 94% amine yield, which is maintained over a larger number of reaction cycles (up to 15) when compared to several state-of-the-art materials, such as a commercial Pd/C (3 cycles). It is thought that the origin of the improved catalyst recyclability is due to the added polymer, poly-para-phenylenediamine (PpPDA), which helps to prevent the aggregation and leaching of the palladium nanoparticles. The synthetic approach is further extended to design other potential catalysts with different metallic nanoparticles (NPs)

A post-synthetic modification strategy for enhancing Pt adsorption efficiency in MOF/polymer composites

A post-synthetic modification strategy was developed to graft metal chelating thiols to polydopamine inside Fe-BTC. X-ray absorption spectroscopy revealed interesting redox properties of the composite that help extract and reduce Pt(iv) from liquid.</jats:p

A post-synthetic modification strategy for enhancing Pt adsorption efficiency in MOF/polymer composites.

Growing polymers inside porous metal-organic frameworks (MOFs) can allow incoming guests to access the backbone of otherwise non-porous polymers, boosting the number and/or strength of available adsorption sites inside the porous support. In the present work, we have devised a novel post-synthetic modification (PSM) strategy that allows one to graft metal-chelating functionality onto a polymer backbone while inside MOF pores, enhancing the material's ability to recover Pt(iv) from complex liquids. For this, polydopamine (PDA) was first grown inside of a MOF, known as Fe-BTC (or MIL-100 Fe). Next, a small thiol-containing molecule, 2,3-dimercapto-1-propanol (DIP), was grafted to the PDA via a Michael addition. After the modification of the PDA, the Pt adsorption capacity and selectivity were greatly enhanced, particularly in the low concentration regime, due to the high affinity of the thiols towards Pt. Moreover, the modified composite was found to be highly selective for precious metals (Pt, Pd, and Au) over common base metals found in electronic waste (i.e., Pb, Cu, Ni, and Zn). X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption spectroscopy (XAS) provided insight into the Pt adsorption/reduction process. Last, the PSM was extended to various thiols to demonstrate the versatility of the chemistry. It is hoped that this work will open pathways for the future design of novel adsorbents that are fine-tuned for the rapid, selective retrieval of high-value and/or critical metals from complex liquids

Understanding Your Support System: The Design of a Stable Metal-Organic Framework/Polyazoamine Support for Biomass Conversion

Introducing oligomeric or polymeric units into metal- organic frameworks (MOFs) can result in composites that have significantly improved properties when compared with the individual MOF or polymer building blocks. With such synergy in mind, this work presents the design of a novel MOF/polyazoamine support that is used to stabilize Pd nanoparticles (NPs). The resulting composite catalyst, tested in the reductive amination of levulinic acid, is found to have a markedly improved lifetime when compared to just the MOF or polymer support containing Pd. It is demonstrated, for the first time, that the lifetime enhancement stems directly from the polymer, which plays a dual role: (i) the oligomer stabilizes the MOF support through the elimination of certain vibrational modes associated with the framework ligand and likely pore-filling effects in the largest MOF pore and (ii) the Lewis base functionality on the oligomer backbone binds to the surface of the Pd NPs, thus, increasing their activity and inhibiting their aggregation. Several complementary spectroscopic (IR, X-ray photoelectron spectroscopy, Raman spectroscopy) and computational tools (pore space and topology analysis, molecular mechanics, and density functional theory simulations) are used to describe the nature of the MOF-oligomer interaction and identify the most likely location of the polymer within the MOF pore

Understanding your support system: the design of a stable MOF/polyazoamine support for biomass conversion

Introducing oligomeric or polymeric units into metal-organic frameworks (MOFs) can result in composites that have significantly improved properties when compared to the individual MOF or polymer building blocks. With such synergy in mind, this work presents the design of a novel MOF/polyazoamine support that is used to stabilize Pd NPs. The resulting composite catalyst, tested in the reductive amination of levulinic acid, is found to have a markedly improved lifetime when compared to just the MOF or polymer support containing Pd. It is demonstrated, for the first time, that the lifetime enhancement stems directly from the polymer, which plays a dual role: i) the oligomer stabilizes the MOF support through the elimination of certain vibrational modes associated with the framework ligand and likely pore-filling effects in the largest MOF pore, and ii) the Lewis base functionality on the oligomer backbone binds to the surface of the Pd NPs, thus, increasing their activity and inhibiting their aggregation. Several complementary spectroscopic (IR, XPS, Raman spectroscopy) and computational tools (pore space and topology analysis, molecular mechanics, and density functional theory simulations) were used to describe the nature of the MOF-oligomer interaction and identify the most likely location of the polymer within the MOF pore