Nickel ferrite decorated noble metal containing nitrogen-doped carbon nanotubes as potential magnetic separable catalyst for dinitrotoluene hydrogenation.

The 2,4-toluenediamine (TDA) is one of the most important chemicals in the polyurethane industry, produced by the catalytic hydrogenation of 2,4-dinitrotoluene (DNT). The development of novel catalysts that can be easily recovered from the reaction mixture is of paramount importance. In our work, a NiFe2O4/N-BCNT supported magnetic catalyst was prepared by a modified coprecipitation method. The catalyst support alone also showed activity in the synthesis of TDA. Platinum nanoparticles were deposited on the catalyst support surface by a fast, relatively simple, and efficient sonochemical method, resulting in a readily applicable catalytically active system. The prepared catalyst exhibited high activity in hydrogenation tests, which was proved by the exceptionally high DNT conversion (100% for 120 min at 333 K) and TDA yield (99%). Furthermore, the magnetic catalyst can be easily recovered from the reaction medium by the action of an external magnetic field, which can greatly reduce catalyst loss during separation.

Bentonite as eco-friendly natural mineral support for Pd/CoFe2O4 catalyst applied in toluene diamine synthesis.

Toluene diamine (TDA) is a major raw material in the polyurethane industry and thus, its production is highly important. TDA is obtained through the catalytic hydrogenation of 2,4-dinitrotoluene (2,4-DNT). In this study a special hydrogenation catalyst has been developed by decomposition cobalt ferrite nanoparticles onto a natural clay-oxide nanocomposite (bentonite) surface using a microwave-assisted solvothermal method. The catalyst particles were examined by TEM and X-ray diffraction. The palladium immobilized on the bentonite crystal surface was identified using an XRD and HRTEM device. The obtained catalyst possesses the advantageous property of being easily separable due to its magnetizability on a natural mineral support largely available and obtained through low carbon- and energy footprint methods. The catalyst demonstrated outstanding performance with a 2,4-DNT conversion rate exceeding 99% along with high yields and selectivity towards 2,4-TDA and all of this achieved within a short reaction time. Furthermore, the developed catalyst exhibited excellent stability, attributed to the strong interaction between the catalytically active metal and its support. Even after four cycles of reuse, the catalytic activity remained unaffected and the Pd content of the catalyst did not change, which indicates that the palladium component remained firmly attached to the magnetic support's surface.

Simplified Synthesis of the Amine-Functionalized Magnesium Ferrite Magnetic Nanoparticles and Their Application in DNA Purification Method.

For pathogens identification, the PCR test is a widely used method, which requires the isolation of nucleic acids from different samples. This extraction can be based on the principle of magnetic separation. In our work, amine-functionalized magnesium ferrite nanoparticles were synthesized for this application by the coprecipitation of ethanolamine in ethylene glycol from Mg(II) and Fe(II) precursors. The conventional synthesis method involves a reaction time of 12 h (MgFe2O4-H&R MNP); however, in our modified method, the reaction time could be significantly reduced to only 4 min by microwave-assisted synthesis (MgFe2O4-MW MNP). A comparison was made between the amine-functionalized MgFe2O4 samples prepared by two methods in terms of the DNA-binding capacity. The experimental results showed that the two types of amine-functionalized magnesium ferrite magnetic nanoparticles (MNPs) were equally effective in terms of their DNA extraction yield. Moreover, by using a few minutes-long microwave synthesis, we obtained the same quality magnesium ferrite particles as those made through the long and energy-intensive 12-h production method. This advancement has the potential to improve and expedite pathogen identification processes, helping to better prevent the spread of epidemics.

Palladium Decorated, Amine Functionalized Ni-, Cd- and Co-Ferrite Nanospheres as Novel and Effective Catalysts for 2,4-Dinitrotoluene Hydrogenation.

2,4-diaminotoluene (TDA) is one of the most important polyurethane precursors produced in large quantities by the hydrogenation of 2,4-dinitrotoluene using catalysts. Any improvement during the catalysis reaction is therefore of significant importance. Separation of the catalysts by filtration is cumbersome and causes catalyst loss. To solve this problem, we have developed magnetizable, amine functionalized ferrite supported palladium catalysts. Cobalt ferrite (CoFe2O4-NH2), nickel ferrite (NiFe2O4-NH2), and cadmium ferrite (CdFe2O4-NH2) magnetic catalyst supports were produced by a simple coprecipitation/sonochemical method. The nanospheres formed contain only magnetic (spinel) phases and show catalytic activity even without noble metals (palladium, platinum, rhodium, etc.) during the hydrogenation of 2,4-dinitrotoluene, 63% (n/n) conversion is also possible. By decorating the supports with palladium, almost 100% TDA selectivity and yield were ensured by using Pd/CoFe2O4-NH2 and Pd/NiFe2O4-NH2 catalysts. These catalysts possess highly favorable properties for industrial applications, such as easy separation from the reaction medium without loss by means of a magnetic field, enhanced reusability, and good dispersibility in aqueous medium. Contrary to non-functionalized supports, no significant leaching of precious metals could be detected even after four cycles.

Development of Palladium and Platinum Decorated Granulated Carbon Nanocomposites for Catalytic Chlorate Elimination.

Granulated carbon nanotube-supported palladium and platinum-containing catalysts were developed. By using these, remarkable catalytic activity was achieved in chlorate ion hydrogenation. Nitrogen-doped bamboo-like carbon nanotubes (N-BCNTs) loaded gel beads were prepared by using Ca2+, Ni2+ or Fe3+ ions as precursors for cross-linking of sodium alginate. The gel beads were carbonized at 800 °C, and these granulated carbon nanocomposites (GCNC) were used as supports to prepare palladium and platinum-containing catalysts. All in all, three catalysts were developed and, in each case, >99 n/n% chlorate conversion was reached in the aqueous phase by using the Pd-Pt containing GCNCs, moreover, these systems retained their catalytic activity even after repeated use.

Development of Nickel- and Magnetite-Promoted Carbonized Cellulose Bead-Supported Bimetallic Pd-Pt Catalysts for Hydrogenation of Chlorate Ions in Aqueous Solution.

Cellulose grains were carbonized and applied as catalyst supports for nickel- and magnetite-promoted bimetallic palladium- and platinum-containing catalysts. The bimetallic spherical aggregates of Pd and Pt particles were created to enhance the synergistic effect among the precious metals during catalytic processes. As a first step, the cellulose bead-based supports were impregnated by nitrate salts of nickel and iron and carbonized at 973 K. After this step, the nickel was in an elemental state, while the iron was in a magnetite form in the corresponding supports. Then, Pd and Pt particles were deposited onto the supports and the catalyst surface; precious metal nanoparticles (10-20 nm) were clustered inside spherical aggregated particles 500-600 nm in size. The final bimetallic catalysts (i.e., Pd-Pt/CCB, Pd-Pt/Ni-CCB, and Pd-Pt/Fe3O4-CCB) were tested in hydrogenation of chlorate ions in the aqueous phase. For the nickel-promoted Pd-Pt catalyst, a >99% chlorate conversion was reached after 45 min at 80 °C. In contrast, the magnetite-promoted sample reached an 84.6% chlorate conversion after 3 h. Reuse tests were also carried out with the catalysts, and in the case of Pd-Pt/Ni-CCB after five cycles, the catalytic activity only decreased by ~7% which proves the stability of the system.

Purification of Fluorescently Derivatized N-Glycans by Magnetic Iron Nanoparticles.

A novel glycoanalytical approach was developed in this study for the purification of fluorescently derivatized N-glycans. Polyethylene glycol (PEG) modified iron-nanoparticles were synthetized by the combination of sonochemical treatment and combustion method. The prepared nanomaterials were applied for a systematic clean-up optimization to maximize purification efficiency of 2-AA labelled glycans. PEG 1000 modified iron-oxalate was found to be the most effective for the selective enrichment of serum N-glycans providing high reproducibility. Different acetonitrile percentages for binding and washing steps were also tested to ensure the same relative peak areas compared to the unpurified sample. The generated novel clean-up strategy provides a potential route to use in-house synthetized magnetic nanoparticles for glycan sample preparation.

Development and Application of Carbon-Layer-Stabilized, Nitrogen-Doped, Bamboo-Like Carbon Nanotube Catalysts in CO2 Hydrogenation.

Nitrogen-doped, bamboo-like carbon nanotubes (BCNTs) were synthesized from butylamine by catalytic chemical vapor deposition (CCVD method). The nanotubes were oxidized by H2SO4/HNO3 treatment and used to prepare calcium alginate gelled BCNT spheres. These beads were first carbonized and then Pd, Rh and Ni nanoparticles were anchored on the surface of the spheres. These systems were then applied as catalysts in CO2 hydrogenation. The BCNT support was examined by Raman spectroscopy, dynamic light scattering (DLS) and X-ray photoelectron spectroscopy (XPS). The prepared catalysts were characterized by HRTEM and SEM. The oxidation pretreatment of BCNTs was successful, with the electrokinetic potential of the water-based dispersion of BCNTs measuring -59.9 mV, meaning the nanotube dispersion is stable. Pyridinic and graphitic types of incorporated nitrogen centers were identified in the structure of the nanotubes, according to the XPS measurements. The Pd-containing BCNT sphere catalyst was the most efficient in the catalytic studies. The highest conversion was reached on the Pd catalyst at 723 K, as well as at 873 K. The difference in the formation rate of CO was much less at 873 K between the Pd and Rh compared to the 723 K values. Accordingly, the application of Pd-containing BCNT/carbon-supported catalyst favored the generation of CO. However, the Ni-BCNT/carbon catalyst leads to the formation of CH4 as the major product.