Palladium Nanocatalysts Research Articles

Recyclable palladium nanocatalyst for effective organic pollutants removal through reduction☆

Palladium is a metal catalyst with excellent performance, but its application is severely restricted due to low atomic utilization and weak recovery capacity. To address these issues, we prepared a palladium nanocatalyst through a universal nanocatalysts preparation strategy. It has a particle size of less than 100 nm, possesses good superparamagnetism, and its saturation strength is 71.48 emu/g. It demonstrates outstanding catalytic properties in the reduction and decolorization of organic fuels, and the achieving conversion rates are 92 %, 99 %, and 97 % for methylene blue, rhodamine B, and methyl orange, respectively. Additionally, it can catalyze the hydrogenation dehalogenation of p-chlorophenol, with a 100 % conversion rate and selectivity. The nanocatalyst shows outstanding recyclability in the test of recyclability. Therefore, our results show that the palladium nanocatalysts have attractive characteristics of simple preparation, excellent catalytic activity and reusability. This work lays the foundation for the preparation of palladium nanocatalysts and their potential applications in areas like environmental pollution treatment.

Synthesis and characterization of MgFe2O4@SiO2@CBCE-Pd as a novel, green organometallic catalyst, and study of its catalytic activity for C–C and C–O cross-coupling reactions

In this work, a new palladium nanocatalyst was supported on CBCE functionalized MNPs (MgFe2O4@SiO2@CBCE-Pd) and was characterized by EDS, FTIR, SEM, ICP, XRD, VSM, and TGA techniques. The performance of MgFe2O4@SiO2@CBCE-Pd was found to exhibit excellent catalytic activity for CO and C–C cross-coupling reactions. The nanocatalyst showed high activity and efficiency as evidenced by the excellent yields of products obtained from the C–O and CC coupling reaction. Additionally, the synthesized nanocatalyst can be retrieved using a magnet and employed for up to four cycles without diminishing its catalytic effectiveness.

Optimizing Cr(VI) reduction to Cr(III) using Pd-CNTs nanocatalyst: kinetic Monte Carlo simulation and experimental design insights

In this investigation, we explored the kinetics of Cr(VI) reduction to Cr(III) on carbon nanotube decorated with palladium (Pd-CNTs) nanocatalyst, using formic acid as the reducing agent. This study has been bone utilizing kinetic Monte Carlo simulation and experimental design methods. The mechanism and kinetic parameters of this reaction are provided. The effect various factors such as reaction time, pH level, dichromate (Cr2O72−) concentration, and formic acid concentration on Cr(VI) reduction was studied. Concentrations of HCOOH and Cr2O72− were identified as the crucial variables, while the HCOOH concentration has the most significant impact. Positive influences on Cr(VI) reduction were observed with increasing pH level and HCOOH concentration. Reaction time positively affects on Cr(VI) reduction efficiency. However, the concentration of Cr2O72− showed an increasing effect up to a threshold, negatively impacting the efficiency. The optimal conditions (Reaction time = 60 min, pH = 4.5, [Cr2O72−] = 5.05 × 10−3 M, and [HCOOH] = 0.95 M) for Cr(VI) reduction. At optimal conditions, the Cr(VI) reduction efficiency was obtained to be 100%.

Silica supported Schiff-based palladium nanocatalyst for n-alkylation at room temperature

This works documents a new silica gel-supported nanocatalyst (Si@NSBPdNPs 3) with low Pd loadings for n-alkylation reactions at room temperature. Post synthesis characterisation using SEM-EDX and ICP techniques provided a quantitative assessment of palladium species. Additionally, TEM analysis unveiled an average palladium nanoparticle size of 5.87 ± 0.2 nm. In-depth X-ray Photoelectron Spectroscopy (XPS) analysis revealed its predominant composition as Pd(0) complexed to a Schiff base ligand on low cost silica matrix. The nanocatalyst exhibited high efficacy in the catalysis of n-alkylation (Michael addition) reactions with various α,β-unsaturated Michael acceptors, yielding the corresponding n-alkyl products at room temperature with exceptional yields. Notably, the catalyst exhibited good stability and could be easily separated from the reaction mixture. Moreover, the catalyst displayed recyclability potential, maintaining its original catalytic efficacy for up to seven cycles without any discernible loss.

Environmentally-friendly fabrication of Pd nanocatalysts with efficient catalytic dehydrogenation of dodecahydro-N-ethylcarbazole

The environmentally-friendly preparation of high performance catalytic dodecahydro-N-ethylcarbazole (12H-NEC) dehydrogenation catalysts is consistent with green chemistry. Beta zeolite loaded ultrafine palladium nanocatalysts (Pd/Beta) were fabricated by ultrasound in-situ reduction (USR) in the absence of chemical reducing and stabilizing agents, and used to efficiently catalyze 12H-NEC dehydrogenation. The catalysts were characterized by XPS, XRD, TEM, SEM and FT-IR, which revealed that Pd nanoparticles (NPs) were highly dispersed on the surface of Beta zeolite with an average particle size of 1.84 nm. The USR method facilitated the metal-carrier interaction, which led to better catalytic activity and stability for dehydrogenation of 12H-NEC, the efficiency of dehydrogenation was 100 % at 6 h and the TOF achieved 70.44 min−1, when it still reached 94 % after 7 cycles.

Silica gel-supported Pd nanocatalyst: Efficient Mizoroki-Heck reactions and sustainable Ozagrel synthesis

We developed a cost-effective silica gel-supported palladium nanocatalyst in a three-step reactions process. Initially, silica gel (60–120 mesh) underwent amino group functionalization using 3-aminopropyltriethoxysilane, leading to the formation of a Schiff base through a reaction with the 1,10-phenanthroline-2,9-dicarboxaldehyde ligand. Subsequently, palladium nanocatalyst was introduced to the silica matrix ligand in the presence of palladium salt and hydrazine hydrate, resulting in the formation of the silica gel-supported Schiff-base palladium nanocatalyst (Si@SBPdNPs 3). Successful functionalization of the silica matrix was confirmed using various spectroscopic techniques. FT-IR spectra demonstrated the incorporation of organic moieties onto the silica surface, while SEM images revealed the modified spherical shape of the silica gel. TEM and XRD analyses confirmed the presence of palladium on the silica matrix. ICP and EDX measurements validated the anchoring of 0.55 mmol/g of palladium to the catalyst. Additionally, XPS analysis showed the complexation of Pd(0) with the organic ligand on the silica matrix, confirming the successful integration of palladium into the system. This nanocatalyst demonstrated outstanding performance in Mizoroki-Heck reactions, yielding high product outputs in the cross-coupling of various aryl halides and olefins under mild conditions. Additionally, the nanocatalyst was effectively utilized in synthesizing Ozagrel, a thromboxane A2 synthesis inhibitor used for treating noncardioembolic stroke patients. Remarkably, the catalyst demonstrated excellent reusability, maintaining high productivity across five consecutive cycles, underscoring its economic and sustainable potential for industrial applications.

Highly active palladium nanocatalyst for selective hydrogenation of 1,5-cyclooctadiene under atmospheric H2 pressure

An ionic liquid [CH3(OCH2CH2)22N+Et3][p-CH3C6H4SO3−] was synthesized and employed for stabilizing Pd nanocatalyst, which possesses the thermoregulated phase-separable property. The as-prepared Pd nanocatalyst was applied for the selective hydrogenation of 1,5-cyclooctadiene under atmospheric H2 pressure. The >99% conversion of 1,5-cyclooctadiene with 95% selectivity towards cyclooctene was achieved under the optimal reaction conditions. The Pd nanocatalyst could be reused for six cycles without evident loss in conversion and selectivity. The turnover frequency of 4232 h−1 is greater than those of previously reported Pd nanocatalyst under atmospheric H2 pressure.

Selective adsorption and removal of Congo red dye from waste water using catechol-stabilized reusable palladium nanoparticles

Several industries including textile, dye manufacturing industries, paper and pulp industries discharge colored wastewater. The majority of synthetic dyes is composed of toxic azo compounds. Eradication of toxic azo dyes, organic pollutants, radioactive materials from the global ecosystem has received remarkable attention due to their detrimental effects on human health and ecosystem. Nanotechnology-based applications on catalytic degradation of contaminants from aqueous ecosystem have evolved as a major topic of research in the scientific community, to develop a cost-effective and energy-effective strategy. In this context, nanomaterials have gained much attention because of its unique physico-chemical properties. Herein, catechol-generated palladium nanoparticles (PdNPs) have been utilized for the selective removal of congo red dye from wastewater. In this study, Palladium nanocatalyst (4 μg/ml) developed earlier by our group, was screened for degradation of dyes of different nature. The newly developed nanocatalyst was found to be effective against anionic dyes. Among the anaionic dyes, congo red was selected for degdradation study in detail. Complete degradation of congo red dye (CR) (150 μM) is found to happen within 10 min. Besides catalytic degradation, the efficiency of the recycled catalyst was evaluated, which exhibits 60 % efficiency even after the 3rd cycle. Gas chromatography-mass spectrometry (GC–MS) characterization of the degraded products reveals the formation of benzidine, indicating the reductive cleavage of azo linkage of the dye.In summary, the results highlight the potential development of a nanocatalyst for the selective and efficient removal of congo red, suggesting a simple,cost-effective, and reusable approach to prevent industrial pollutant in aqueous ecosystem.

Facile preparation and catalytic property of a sandwich composite membrane

Membrane as a support for metal nanocatalysts, can greatly enhance the catalytic activity of metal nanoparticles and promote the efficient production and separation of products. In this study, a novel sandwich-structured composite membrane was designed and facilely fabricated by using palladium nanocatalysts as the core catalytic layer and two different structured PVDF layers as the outer layers. The composite membrane was used as a reaction interface as well as a separation barrier between reactants and products, efficiently realizing the catalytic oxidation of benzyl alcohol and convenient separation of the product benzaldehyde. The membrane was characterized in detailed and the effects of the membrane structure and various reaction conditions on the catalytic oxidation were systematically investigated. The results indicated that the reaction could be conveniently carried out under very mild experimental conditions, obtaining the product benzaldehyde at as high selectivity as 93.17 %. The successful implementation of the sandwich membrane for the production of chlorine-free benzaldehyde provides a new method for the interface reaction.

Transfer hydrogenation of aldehydes and ketones with tetrahydroxydiboran in water by an amphiphilic resin-supported nano-palladium catalyst

Abstract We have developed a transfer hydrogenation of aldehydes and ketones with B2(OH)4 as a reductant and amphiphilic resin-dispersed palladium nanoparticles as a catalyst system in an aqueous medium, where water also serves as a hydrogen donor. A variety of aldehydes and ketones, including aliphatic carbonyl compounds, reacted to give the corresponding primary and secondary alcohols, respectively. The catalyst was recovered by filtration and reused 9 times without a significant loss of its catalytic activity.

Correction to: A way to prepare magnetically separable palladium nanocatalysts active in Heck reaction—SI‑RAFT/MADIX polymerization for modification of magnetic nanoparticles

Correction to: A way to prepare magnetically separable palladium nanocatalysts active in Heck reaction—SI‑RAFT/MADIX polymerization for modification of magnetic nanoparticles

3D-Continuous Nanoporous Covalent Framework Membrane Nanoreactors with Quantitatively Loaded Ultrafine Pd Nanocatalysts.

The confinement effect of catalytic nanoreactors containing metal catalysts within nanometer-sized volumes has attracted significant attention for their potential to enhance reaction rate and selectivity. Nevertheless, unregulated catalyst loading, aggregation, leaching, and limited reusability remain obstacles to achieving an efficient nanoreactor. A robust and durable catalytic membrane nanoreactor prepared by incorporating palladium nanocatalysts within a 3D-continuous nanoporous covalent framework membrane is presented. The reduction of palladium precursor occurs on the pore surface within 3D nanochannels, producing ultrafine palladium nanoparticles (Pd NPs) with their number density adjustable by varying metal precursor concentrations. The precise catalyst loading enables controlling the catalytic activity of the reactor while preventing excess metal usage. The facile preparation of Pd NP-loaded free-standing membrane materials allows hydrodechlorination in both batch and continuous flow modes. In batch mode, the catalytic activity is proportional to the loaded Pd amount and membrane area, while the membrane retains its activity upon repeated use. In continuous mode, the conversion remains above 95% for over 100h, with the reactant solution passing through a single 50µm-thick Pd-loaded membrane. The efficient nanoporous film-type catalytic nanoreactor may find applications in catalytic reactions for small chemical devices as well as in conventional chemistry and processes.

Excellent Pd-Loaded Magnetic Nanocatalyst on Multicarboxyl and Boronic Acid Biligands.

An effective palladium nanocatalyst (Fe3O4@SiO2-FPBA-DTPA-Pd) was proposed and prepared, which was immobilized on magnetic silica with ethylenediamine pentaacetic acid and formylphenylboronic acid as biligands. A series of characterizations showed that Fe3O4@SiO2-FPBA-DTPA-Pd was 5-15 nm and contained 1.44 mmol/g Pd2+/Pd0. It was stable below 232.7 °C, and its saturation magnetization value was 21.17 emu/g which was easily recycled by a magnet. Its catalytic ability was evaluated through 7 Suzuki reactions and 15 Heck reactions. Results showed that the yields of 14 reactions catalyzed by Fe3O4@SiO2-FPBA-DTPA-Pd were more than 90%, while were better than those of the other two immobilized Pd catalysts on a single diethyltriamine pentaacetic acid (DTPA) group or boronic acid group. Moreover, Fe3O4@SiO2-FPBA-DTPA-Pd showed good reusability in both Suzuki and Heck reactions. In two model Suzuki and Heck reactions, after seven cycles, its yields were still above 95% without significant loss, which exceeded those of many reported catalysts; therefore, it has great potential in future large-scale industrial production.

Pd nanocubes enclosed by {100} facets for activating electroless Cu deposition on liquid crystal polymer substrates with strong adhesion strength

In this study, we investigate the catalytic performance of palladium (Pd) nanocatalysts with different surface atomic structures for activating electroless copper (Cu) deposition on liquid crystal polymer (LCP) substrates. These nanocatalysts include Pd nanocubes featuring {100} facets of square atomic arrangement as their predominant surface structure and Pd spherical nanoparticles characterized by random atomic arrangements, synthesized using an aqueous method. Our electrochemical measurements reveal that the induction time for the growth of Cu films is significantly shorter when utilizing Pd nanocubes compared to Pd nanospheres. This shorter induction time signifies a quicker initiation of Cu growth, primarily due to the presence of Pd {100} facets. Furthermore, we also develop a surface modification approach involving a crosslinking reaction that utilizes the highly branched polyethylenimine and linear polyvinylpyrrolidone on the Pd nanocubes. This method not only facilitates the adsorption of Pd nanocubes onto the LCP substrates but also achieves a robust peel adhesion strength (630 gf/cm) of the resulting Cu films, exceeding the industrial adhesion goal of 500 gf/cm. Moreover, in-depth synchrotron X-ray photoelectron spectroscopy analysis provides valuable insights into the depth-dependent chemical changes within the Cu films and proves the removal of Cu oxides after the acid treatment.

Green synthesis of palladium nanoparticles mediated by Acer L. leaves as reducing agent, stabilizer, and carrier for Suzuki reaction

Plant fiber‐supported palladium nanocatalysts (Pdx/FAL) with high catalytic activity and good stability were synthesized by one‐pot method using Na2PdCl4 as palladium source, Acer L. leaves as reducing agent, stabilizer, and carrier without adding chemical reducing agents or stabilizers. The as‐prepared catalysts were characterized by XRD, FT‐IR, SEM, TEM, and so forth. During the preparation process, the extraction of organic matter from Acer L. leaves, the reduction and stabilization of Pd2+, and the loading of palladium nanoparticles (PdNPs) were carried out simultaneously, which greatly simplified the preparation steps and reduced the cost. Oxygen‐ and nitrogen‐containing groups in the Acer L. leaf extract preferentially formed complexes with Pd2+, and then, the polyphenols reduced Pd2+ to Pd0, which ensured that PdNPs with small particle sizes were formed and embedded in porous plant fibers (extraction residue of Acer L. leaves) with oxygen‐containing groups, thereby improving the catalytic activity and stability of the catalyst. The characterization results showed that the prepared PdNPs with a face‐centered cubic structure were uniformly distributed on the support, and the average particle size was 3.08 nm. The Suzuki coupling reaction of 4‐bromonitrobenzene and phenylboronic acid by the prepared catalysts at 40°C showed that the reaction yield could reach 97.72%, and the TOF could reach 3,240.6 h−1, exhibiting high catalytic performance. The reaction of 4‐bromotoluene with phenylboronic acid gave a yield of 98.58%, which remained above 90% after seven repetitions. This article provided a simple, high‐performance, and eco‐friendly synthesis idea for nanopalladium catalysts.

Preparation of recyclable magnetic palladium nanocatalysts by dispersion strategy based on sodium alginate for reduction of p-nitrophenol and Suzuki-Miyaura coupling

Palladium (Pd) has excellent catalytic performance, its application is seriously limited by low atomic utilization and weak recovery capacity. To solve these problems, we report a universal palladium nanocatalysts preparation strategy by taking advantage of the rich chemistry of sodium alginate (SA). SA units not only self-assemble into a cross-linked porous carboxyl and hydroxyl framework but also can coat different substrates. Benefiting from the distinguished chelation of SA, metallic nanocatalysts can be achieved. As a proof-of-concept demonstration, Pd loading on nano-Fe3O4 modified with SA and investigated their catalytic capabilities. The catalyst was Fe3O4 nanoparticles encapsulated by SA film loaded with 0.4 wt% of Pd. It has a particle size around 100 nm and has good superparamagnetism with a saturation strength of 76.26 emu/g. It exhibited good catalytic activity at TOF = 660 h−1 and TOF = 4311 h−1 in typical Suzuki-Miyaura coupling reaction and the reduction of p-nitrophenol, respectively, and showed appreciable recyclability in the test of recyclability. Thus, our findings demonstrate that recyclable magnetic palladium nanocatalysts have several attractive features, such as easy preparation, outstanding catalytic activity and reusability. This work lays the foundation for the preparation of palladium nanocatalysts and the potential application of SA in the field of catalysts.

Highly dispersed palladium nano-catalyst anchored on N-doped nanoporous carbon microspheres derived from chitosan for efficient and stable hydrogenation of quinoline

Under the background of green chemistry, the synthesis of N-heterocycles using efficient, stable and long-life catalysts has still faced great challenges. Herein, we used biomass resource chitosan to fabricate a nanoporous chitosan carbon microsphere (CCM), and successfully designed a stable and efficient Pd nano-catalyst (CCM/Pd). Various physicochemical characterizations provided convincible evidences that the palladium nanoparticles (NPs) were tightly and evenly dispersed on the CCM with a mean diameter of 2.28 nm based on the nanoporous structure and abundant functional N/O groups in CCM. Importantly, the graphitized constructure, the formed defects and larger surface area in CCM were able to promote the immobilization of Pd NPs and the electron transfer between Pd and CCM, thereby significantly improving the catalytic activity. The CCM/Pd catalyst was applied for hydrogenation of quinoline compounds, which showed excellent catalytic activity and durability, as well as good substrate applicability. The application of renewable biomass-based catalysts contributes to the progression of a green/sustainable society.

Anodic TiO2 nanotubes supported palladium catalysts for Heck coupling reactions: Excellent catalytic activity and reusability

A convenient method for preparing palladium nanocatalyst and its application in the Heck coupling reactions between various aryl halides and olefins are presented. Pd nanoparticles were photoreduced on anodic TiO2 nanotubes (ATNTs) to prepare the Pd@ATNTs catalyst by utilizing the large specific surface area of the ATNTs' hollow tubes. Pd nanoparticles were found to be highly dispersed on the walls of the nanotubes with an average particle size of 8.01 nm by characterization techniques. The heterogeneous Pd@ATNTs catalyst showed excellent catalytic efficiency (TOF up to 1010 h−1) due to the highly dispersed Pd within the ATNTs. Pd@ATNTs has remarkable properties of ease of separation and good reusability, allowing for at least 10 cycles of recovery and reuse without a significant decrease in catalytic activity.

Construction and application of MgAl LDH-Schiff base-supported palladium nanocatalyst for Heck reactions and reduction of organic pollutants

Construction and application of MgAl LDH-Schiff base-supported palladium nanocatalyst for Heck reactions and reduction of organic pollutants

Synthesis of palladium nanoparticles stabilized on Schiff base-modified ZnO particles as a nanoscale catalyst for the phosphine-free Heck coupling reaction and 4-nitrophenol reduction

Recently, the development of heterogeneous nanocatalytic systems using solid supports has been gaining importance due to some advantages such as easy handling, high thermal stability, high efficiency, reusability, and so on. Therefore, the design of catalyst supports for the preparation of stable heterogeneous catalytic systems is of great importance. In this work, Schiff base-modified ZnO particles have been developed (ZnO–Scb) as a novel support. A heterogeneous nanocatalyst system has then been prepared by immobilizing palladium nanoparticles (Pd NPs) on the ZnO-Scb surface as the support. The resulting palladium nanocatalyst (Pd–ZnO–Scb) structure has been characterized by different analytical techniques (FT-IR, XRD, TEM, FE-SEM, elemental mapping and EDS) and used to catalyze the Heck coupling reactions and 4-nitrophenol (4-NP) reduction. Test results revealed that Pd–ZnO–Scb could effectively couple various aryl halides with styrene in yields of up to 98% in short reaction times. Pd–ZnO–Scb was also efficiently used in the complete 4-NP reduction within 135 s at room temperature. Additionally, it was found that Pd–ZnO–Scb was more effective than other reported catalysts in the Heck coupling reaction. Moreover, the recycling tests indicated that Pd–ZnO–Scb could be easily isolated from the reaction medium and reused in seven consecutive catalytic runs while retaining its nanostructure.