A Chromium Hydroxide/MIL‐101(Cr) MOF Composite Catalyst and Its Use for the Selective Isomerization of Glucose to Fructose

Homogeneous and Heterogeneous Catalysis of Glucose to Lactic Acid and Lactates: A Review

The current societal demand to replace polymers derived from petroleum with sustainable bioplastics such as polylactic acid (PLA) has motivated industry to commercialize ever-larger facilities for biobased monomers like lactic acid. Even though most of the lactic acid is produced by fermentation, long reaction times and high capital costs compromise the economics and thus limit the appeal of biotechnological processes. Catalytic conversion of hexose from biomass is a burgeoning alternative to fermentation. Here we identify catalysts to convert glucose to lactic acid, along with their proposed mechanisms. High Lewis acidity makes erbium salts among the most active homogeneous catalysts, while solvent coordination with the metal species polarize the substrate, increasing the catalytic activity. For heterogeneous catalysts, Sn-containing bimetallic systems combine the high Lewis acidity of Sn while moderating it with another metal, thus decreasing byproducts. Hierarchical bimetallic Sn-Beta zeolites combine a high number of open sites catalyzing glucose isomerization in the mesoporous regions and the confinement effect assisting fructose retro-aldol in microporous regions, yielding up to 67% lactic acid from glucose. Loss of activity is still an issue for heterogeneous catalysts, mostly due to solvent adsorption on the active sites, coke formation, and metal leaching, which impedes its large scale adoption.

Recent Advances in the Brønsted/Lewis Acid Catalyzed Conversion of Glucose to HMF and Lactic Acid: Pathways toward Bio-Based Plastics

One of the most trending topics in catalysis recently is the use of renewable sources and/or non-waste technologies to generate products with high added value. That is why, the present review resumes the advances in catalyst design for biomass chemical valorization. The variety of involved reactions and functionality of obtained molecules requires the use of multifunctional catalyst able to increase the efficiency and selectivity of the selected process. The use of glucose as platform molecule is proposed here and its use as starting point for biobased plastics production is revised with special attention paid to the proposed tandem Bronsted/Lewis acid catalysts.

Dual Naked-Eye and Optical Chemosensor for Morphine Detection in Biological Real Samples Based on Cr(III) Metal-Organic Framework Nanoparticles

The analytical detection and quantification of abuse drugs such as morphine (MOR) in biological samples are vital missions and remains to attract challenges for forensic toxicology, law enforcement, world antidoping organization, and social health fields. MOR, a benchmark analgesic drug known as "pain killer", is one of the powerful opioid medications for relieving pain, and overdose of MOR is toxic. In this article, novel promising chromium metal-organic framework nanoparticles [Cr(III)-MOF-NPs] were produced via facile synthesis and characterized using high-resolution transmission electron microscopy, field-emission scanning electron microscopy/energy-dispersive X-ray spectroscopy, mass spectrometry, X-ray photoelectron spectroscopy, elemental analysis, UV-vis, Fourier transform infrared, and thermogravimetry/differential scanning calorimetry, as well as photoluminescence (PL) investigation and magnetic properties. The PL study results revealed that the Cr(III)-MOF-NPs exhibited an emission band at 593 nm. The Cr(III)-MOF-NPs could be used in fast, selective, and sensitive MOR detection and quantification. Under the optimum experimental conditions, with the addition of MOR, a blueshift from 593 to 566 nm occurred with a remarkable PL intensity enhancement, and the color changed from brown to yellow (visually/naked-eye detection). The Cr(III)-MOF-NPs optical chemosensor exhibited a stable response for MOR in a concentration range between 0.1 and 350 nM. The detection and quantification limits were 0.167 and 0.443 nM, respectively, with a correlation coefficient (r 2) of 0.96. The developed PL chemosensor showed high selectivity for MOR over other competing interfering matrices. Moreover, the ultrasensitive chemosensor was extensively used for the determination of MOR spiked in different real samples (serum and urine samples) with acceptable recoveries and satisfactory results.

Three-Dimensional MOF-Assisted Self-Polarized Ferroelectret: An Effective Autopowered Remote Healthcare Monitoring Approach

In recent years, flexible and sensitive pressure sensors are of extensive interest in healthcare monitoring, artificial intelligence, and national security. In this context, we report the synthetic procedure of a three-dimensional (3D) metal-organic framework (MOF) comprising cadmium (Cd) metals as nodes and isoniazid (INH) moieties as organic linkers (CdI₂-INH═CMe₂) for designing self-polarized ferroelectret-based highly mechano-sensitive skin sensors. The as-synthesized MOF preferentially nucleates the stable piezoelectric β-phase in poly(vinylidene fluoride) (PVDF) and also gives rise to a porous ferroelectret composite film. Benefiting from the porous structure of 3D MOFs, composite ferroelectret film-based ultrasensitive pressure sensor (mechano-sensitivity of 8.52 V/kPa within 1 kPa pressure range) as well as high-throughput ( power density of 32 μW/cm²) mechanical energy harvester (MEH) has been designed. Simulation-based finite element method (FEM) analysis indicates that the geometrical stress confinement effect within the interpore region of the ferroelectret structure synergistically influences the mechano-electrical property of the MEH. In addition, 143 pC/N (∼4.5 times higher than commercial piezoelectric PVDF films) piezoelectric charge coefficient (d₃₃) magnitude and superior response time (t_r ∼ 8 ms) of this composite ferroelectret film enable the detection of different physiological signals such as coughing, pronunciation, and gulping behavior, making it a promising candidate for early intervention of healthcare, which may play a significant role in accurate alert of influenza and chronic obstructive pulmonary disease (COPD)-related symptoms. In addition, MEH enables the tracking of the subtle pressure change in the wrist pulse, indicating its usefulness in effective mechano-sensitivity. Since the cardiovascular signal is one of the vital parameters that can determine the on-going physiological conditions, the wireless transmission of the detected wrist pulse signal has been demonstrated. All of these features coupled with wireless data transmission indicate the promising application of MOF-assisted composite ferroelectret films in noninvasive real-time remote healthcare monitoring.

Modulation of Self-Separating Molecular Catalysts for Highly Efficient Biomass Transformations

The energetically viable fabrication of stable and highly efficient solid acid catalysts is one of the key steps in large-scale transformation processes of biomass resources. Herein, the covalent modification of the classical Dawson polyoxometalate (POMs) with sulfonic acids (-SO3 H) is reported by grafting sulfonic acid groups on the POM's surface followed by oxidation of (3-mercaptopropyl)trimethoxysilane. The acidity of TBA6 -P2 W17 -SO3 H (TBA=tetrabutyl ammonium) has been demonstrated by using 31 P NMR spectroscopy, clearly indicating the presence of strong Brønsted acid sites. The presence of TBA counterions renders the solid acid catalyst as a promising candidate for phase transfer catalytic processes. The TBA6 -P2 W17 -SO3 H shows remarkable activity and selectivity, excellent stability, and great substrate compatibility for the esterification of free fatty acids (FFA) with methanol and conversion into biodiesel at 70 °C with >98 % conversion of oleic acid in 20 min. The excellent catalytic performance can be attributed to the formation of a catalytically active emulsion, which results in a uniform catalytic behavior during the reaction, leading to efficient interaction between the substrate and the active sites of the catalyst. Most importantly, the catalyst can be easily recovered and reused without any loss of its catalytic activity owing to its excellent phase transfer properties. This work offers an efficient and cost-effective strategy for large-scale biomass conversion applications.

Tailoring acidity and porosity of alumina catalysts via transition metal doping for glucose conversion in biorefinery

Efficient conversion of food waste to value-added products necessitates the development of high-performance heterogeneous catalysts. This study evaluated the use of Al₂O₃ as a low-cost and abundant support material for fabricating Lewis acid catalysts, i.e., through the in-situ doping of Cu, Ni, Co, and Zr into Al₂O₃ followed by calcination. The characterisation results show that all catalysts were mainly amorphous. In particular, adding the transition metals to the Al₂O₃ matrix resulted in the increase of acidity and meso-/micro-pores. The catalysts were evaluated in the conversion of glucose, which can be easily derived from starch-rich food waste (e.g., bread waste) via hydrolysis, to fructose in biorefinery. The results indicate that the Ni-doped Al₂O₃ (Al-Ni-C) achieved the highest fructose yield (19 mol%) and selectivity (59 mol%) under heating at 170 °C for 20 min, of which the performance falls into the range reported in literature. In contrast, the Zr-doped Al₂O₃ (Al-Zr-C) presented the lowest fructose selectivity despite the highest glucose conversion, meaning that the catalyst was relatively active towards the side reactions of glucose and intermediates. The porosity and acidity, modified via metal impregnation, were deduced as the determinants of the catalytic performance. It is noteworthy that the importance of these parameters may vary in a relative sense and the limiting factor could shift from one parameter to another. Therefore, evaluating physicochemical properties as a whole, instead of the unilateral improvement of a single parameter, is encouraged to leverage each functionality for cost-effectiveness. This study provides insights into the structure-performance relationships to promote advance in catalyst design serving a sustainable food waste biorefinery.

Solvent-assisted ligand exchange (SALE) for the enhancement of epoxide ring-opening reaction catalysis based on three amide-functionalized metal-organic frameworks

In recent years, functionalized pillar ligands have gained significant interests due to their important role in MOF structure and performance. The synthesis of MOF compounds with a particular functionalized ligand is not always successful, and sometimes, synthesis cannot be achieved easily or directly, even by employing several methods. However, this limitation can be overcome by applying a post-synthesis step that swaps the functional groups without changing the backbone of the pillar ligand. Solvent-assisted ligand exchange (SALE) is a post-synthesis method that has been used for confronting this challenge by replacing a functional group with an alternative. Through this investigation, we tried to improve the properties of MOF compounds and increase their catalytic efficiency by importing new functional groups into their structures. The N1,N3-di (pyridine-4-yl) malonamide linker (S) is a pillar ligand, which does not easily enter into the structure during the synthesis of MOF compounds. Therefore, to solve this issue, amide-functionalized, benzene-core ligand derivatives were designed as linkers to manufacture the new 3D structures [Co(oba)(bpta)]·(DMF)₂ TMU-50 and [Co₂(oba)₂(bpfn)]·(DMF)_2.5 TMU-51 and the novel 2D structure [Co(oba)(bpfb)]·(DMF)₂ TMU-49. These structures were achieved by layering the compounds via hydrothermal reaction. Moreover, the ability of these structures to act as catalysts was evaluated using the methanolysis reaction of epoxides. To increase the MOF catalytic efficiency, we designed the N1,N3-di (pyridine-4-yl) malonamide linker (S) as a malonamide pillar ligand, which contains an acidic hydrogen that is suitable for catalyzing an epoxide ring-opening reaction and therefore enhancing the catalytic activity. As the synthesis of the MOF structure with this linker was not successful, we designed three new structures by incorporating different percentages of S linkers by exchanging the acylamide functional group with malonamide via the SALE pathway. The acylamide functional group was successfully replaced and produced daughter MOFs TMU-49S, TMU-50S and TMU-51S. PXRD and NMR spectroscopy confirmed that the S linker was incorporated into the acylamide-MOF structure. The obtained materials TMU-49S, TMU-50S and TMU-51S are isostructural with their parent frameworks. The S spacer significantly improved the catalytic properties of the MOF compounds in the ring-opening reaction of epoxides, with TMU-50S showing a 98% catalytic efficiency after incorporating the S linker. The catalysts could be recycled without any significant loss in the catalytic efficiency.