Palladium nanoparticles immobilized on halloysite nanotubes covered by a multilayer network for catalytic applications

Tavakolian

2019

ChemistrySelect

Considering the high performance of ionic liquid decorated halloysite clay as a catalyst support, herein a halloysite ‐poly (ionic liquid) polymer composite is synthesized and characterized via BET, TGA, TEM, FTIR, XRD and ICP and then applied for the immobilization of Pd species to afford a catalyst for the hydrogenation of nitroarenes. To shed light to the effect of the content and nature of poly (ionic liquid) polymer on the catalytic activity, two control samples with different content and entity of poly (ionic liquid) polymer were synthesized and compared by FTIR, TGA and BET. The results confirmed that the content of poly (ionic liquid) polymer significantly affected the catalytic activity and the higher this value, the higher the Pd content and consequently the superior the catalytic activity would be. The study of the nature of poly (ionic liquid) polymer revealed that it did not dramatically influence the catalytic activity. However, the choice of the monomer affected the content of poly (ionic liquid) polymer formed on halloysite. Notably, the catalyst was highly selective toward reduction of nitro group and competing functionalities remained intact under the reaction condition. Moreover, the catalyst showed excellent recyclability with low Pd leaching.

Section: Resultscontrasting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Halloysite ‐ Poly (ionic liquid) Nanocomposite as an Efficient Catalyst Support: Study of the Effects of Ionic Liquid Nature and Content on the Catalytic Activity

Tavakolian

2019

ChemistrySelect

“…Considering the environmental and economic concerns, recently, use of natural and biocompatible materials that can meet the green chemistry criteria in research and industrial sectors have increased . In this context, utility of Hal that is a dioctahedral 1:1 layered aluminosilicate with tubular morphology and high mechanical and chemical stability for various fields of applications ranging from catalysis to cleaning and drug delivery has gained growing interest.…”

Section: Introductionmentioning

confidence: 99%

“…This naturally occurring clay with formula of (Al 2 Si 2 O 5 (OH) 4 .nH 2 O) has chemical and physical properties similar to kaolin. However, the unique features of Hal such as different electrical charges and chemical composition on the inner and outer surface and tune‐ability of its surface chemistry render this clay distinguished from classical ones . As mentioned, one of the most important features of Hal is the capability of modification of its surface via functionalization or hybridization with other materials.…”

Section: Introductionmentioning

confidence: 99%

Study of the effect of the ligand structure on the catalytic activity of Pd@ ligand decorated halloysite: Combination of experimental and computational studies

Dehghani

Bahri‐Laleh

et al. 2019

Applied Organom Chemis

Taking advantage of computational chemistry, the best diamine for the synthesis of a multi‐dentate ligand from the reaction with 3‐(trimethoxysilyl) propylisocyanate (TEPI) was selected. Actually, predictive Density Functional Theory (DFT) calculations provided the right diamino chain, i.e. ethylenediamine, capable to sequester a palladium atom, together with the relatively polar solvent toluene, and then undergo the experiments as a selective catalytic agent. The ligand was then prepared and applied for the decoration of the halloysite (Hal) outer surface to furnish an efficient support for the immobilization of Pd nanoparticles. The resulting catalyst exhibited high catalytic activity for hydrogenation of nitroarenes. Moreover, it showed high selectivity towards nitro functional group. The study of the catalyst recyclability confirmed that the catalyst could be recycled for several reaction runs with only slight loss of the catalytic activity and Pd leaching. Hot filtration test also proved the heterogeneous nature of the catalysis.

“…In recent years, the use of halloysite nanoclay (Hal) as a catalyst support has gained growing interest and numerous heterogeneous Hal‐based catalysts have been developed and successfully applied for promoting diverse organic transformations ranging from hydrogenation to coupling reactions . Moreover, Hal has been utilized for the preparation of novel photocatalysts .…”

Section: Introductionmentioning

confidence: 99%

Palladated cyclodextrin and halloysite containing polymer and its carbonized form as efficient hydrogenation catalysts

Koohestani

Léger

et al. 2019

Applied Organom Chemis

β-Cyclodextrin (β-CD) and glycidyl methacrylate monomer were polymerized in the presence of functionalized halloysite nanoclay (Hal) to afford a polymeric network (Hal-P-CD) containing Hal and CD. Hal-P-CD was then applied as a catalyst support for the immobilization of Pd nanoparticles. The resulting nanocomposite, Pd@Hal-P-CD, could serve as a catalyst for the hydrogenation of nitrobenzene. The precise study by the preparation of control samples confirmed the contribution of CD as both phase transfer and capping agent, P (polymer) and Hal to the catalysis. Moreover, the results confirmed the importance of CD: glycidyl methacrylate monomer ratio. Pd@Hal-P-CD was also carbonized to prepare Pd@Hal-C. Notably, the characterization of Pd@Hal-C showed that carbonization led to the growth of mean diameter of Pd nanoparticles, increase of Pd content and partial destruction of Hal. However, the catalytic activity of Pd@Hal-C was superior to Pd@Hal-P-CD. Pd@Hal-C was also highly recyclable and could be recovered and recycled for several reaction runs.The study of the carbonization temperature showed that this factor affected the nature of the resulting carbon and the catalyst prepared at elevated temperature showed higher catalytic activity.