Synthesis and support interaction effects on the palladium nanoparticle catalyst characteristics

Overcoming slow removal efficiency-induced highly toxic I-DBPs in water by oxygen vacancies enriched invasive plant biochar catalyst: Experimental and theoretical studies

Developing effective and safe catalysts operated in the in-depth removal of iodinated X-ray contrast media is important for overcoming slow removal efficiency-induced highly toxic iodine-replaced disinfection byproducts (I-DBPs). In this study, a novel oxygen vacancies enriched heterogeneous biochar catalyst (Mo-Co-ECM) from the invasive plant was synthesized by a facile one-step hydrothermal carbonization method and used for the in-depth removal of iohexol (IOH) by the activation of peroxymonosulfate (PMS). The results indicated that after adding PMS for 3 min, the removal efficiency of IOH in Mo-Co-ECM/PMS system reached 100% and exhibited a superior degradation efficiency compared to Co-ECM/PMS and ECM/PMS system. Only nine I-DBPs were found during the degradation, which were dominated by small molecules compounds (MW<400). The in-depth degradation suppresses the formation of the toxic intermediates. The density functional theory and electron spin resonance showed that due to the existence of Mo and oxygen vacancies, the electron transfer ability was improved, which accelerated the cycle of Co3+/Co2+, so as to enhance the catalytic activity of Mo-Co-ECM/PMS system. This study is expected to provide a general way for decreasing the production of toxic intermediates during the advanced oxidation of contaminants, meanwhile recovering resources.

Monometallic Cerium Layered Double Hydroxide Supported Pd-Ni Nanoparticles as High Performance Catalysts for Lignin Hydrogenolysis

Monometallic cerium layered double hydroxides (Ce-LDH) supports were successfully synthesized by a homogeneous alkalization route driven by hexamethylenetetramine (HMT). The formation of the Ce-LDH was confirmed and its structural and compositional properties studied by XRD, SEM, XPS, iodometric analyses and TGA. HT-XRD, N2-sorption and XRF analyses revealed that by increasing the calcination temperature from 200 to 800 °C, the Ce-LDH material transforms to ceria (CeO2) in four distinct phases, i.e., the loss of intramolecular water, dehydroxylation, removal of nitrate groups and removal of sulfate groups. When loaded with 2.5 wt% palladium (Pd) and 2.5 wt% nickel (Ni) and calcined at 500 °C, the PdNi-Ce-LDH-derived catalysts strongly outperform the PdNi-CeO2 benchmark catalyst in terms of conversion as well as selectivity for the hydrogenolysis of benzyl phenyl ether (BPE), a model compound for the α-O-4 ether linkage in lignin. The PdNi-Ce-LDH catalysts showed full selectivity towards phenol and toluene while the PdNi-CeO2 catalysts showed additional oxidation of toluene to benzoic acid. The highest BPE conversion was observed with the PdNi-Ce-LDH catalyst calcined at 600 °C, which could be related to an optimum in morphological and compositional characteristics of the support.

Gamma radiation-assisted in situ synthesis of palladium nanoparticles supported on ethylenediamine-functionalized polypropylene fabric as an efficient catalyst for reduction of 4-nitrophenol

Immobilization of Pd nanometals on a functionalized non-woven polypropylene fabric offers heterogenous catalytic activity in many chemical transformations and convenient separation from the reaction mixture.