Addition Of Pd Research Articles

Experimental investigation of natural polysaccharide-based mixed matrix membrane modified with graphene oxide and Pd-nanoparticles for enhanced gas separation performance

In this work, we proposed a mixed matrix membrane prepared by using a glycerol modified guar gum (GGP) polymer matrix incorporated with graphene oxide (GO). The influence of varying GO concentration on the gas separation performance was investigated and 2 wt% was found to be the optimum concentration for high performance. The 2 wt% GO mixed matrix membranes were further modified with Pd nanoparticles. When GO, and Pd nanoparticles were mixed, CO2 permeability increased by 49.94%, while the permeability of H2 gas molecules decreased by 98.11%, respectively, compared to the pristine GGP membrane. The selectivity of CO2/H2 was obtained as 18.27. The glass transition temperature of the membrane increased from 85 to 95.2 °C, tensile strength and elongation of the break were significantly improved by 29.09% and 84.37% through the addition of Pd and GO into the membrane. The scanning electron microscopy revealed a dense top surface after GO nanosheets incorporation. Further, the thermogravimetric analysis proposes that the modified membrane is thermally stable than GGP. Henceforth, the study suggests GO incorporation and Pd nanoparticles modification of guar gum membrane is a promising gas separation membrane with potentially high selectivity for CO2 gas.

Spectroscopic and microscopic studies of Co, Ce, and Pd containing gamma-alumina as catalysts for cyclohexene oxidation

The oxidation of cyclohexene belongs to the most important reactions in organic chemistry and leads to the production of the precursors for surfactants, polymers, agrochemicals, and drugs. So far, however, due to a complex reaction mechanism, it was hard to find the catalyst of satisfactory properties.Attractive catalysts in this reaction could be sonochemically prepared Co, Ce, and Pd containing γ-Al2O3, which is the object of the undertaken research. What is more, this combination of metals in the oxide system has not been studied. The analysis of catalytic performance indicated that all studied catalysts were active in the catalytic oxidation of cyclohexene. For metal-containing alumina (Me=Co, Ce, Pd), the conversion of cyclohexene was 61–84%. The best catalyst was Co5Ce5/γ-Al2O3s, prepared via the sonochemically-assisted procedure.It was also shown that the application of ultrasonic irradiation during the preparation of samples enhanced metal distribution over alumina support, resulted in smaller crystallites of prepared materials, and caused higher surface area with simultaneous smaller both pore size and pore volume in comparison with counterparts prepared via the standard procedure. XRD, Ra, and DR..-UV–vis spectroscopies indicated the coexistence of Co as Co3O4 and CoAl2O4 spinel, however, Ce was found in the form of CeO2. The addition of Pd to Co/γ-Al2O3 did not influence the status of cobalt.

First-principles study to explore the possibility of inducing martensitic transformation in ordered B2 TiRu phase by alloying with Pd

Density functional theory (DFT) based on the first-principles technique, CASTEP, was used to explore the possibility of inducing martensitic transformation (MT) in a stable B2 TiRu alloy by systematic introduction of palladium (Pd) on the ruthenium (Ru) site. The structural, mechanical and electronic properties of pure, as well as, Pd-doped TiRu were calculated. The elastic constants obtained show that the addition of Pd seems to induce MT in the ordered TiRu, as shown by mechanical instability (C΄= C11-C12 < 0) of the B2 phase against shear deformation at 0 K. This is an indication that B2 is likely to transform to low symmetry phases such as L10/B19/B19’. Moreover, the calculated total density of states (T-DOS) also indicated that the addition of Pd shifted the Fermi level (EF) from the centre of the pseudogap of the ordered pure TiRu towards the right (anti-bonding region), rendering the resulting B2 ternary phase unstable at certain Pd compositions higher than 10 atomic percent (at.%). The predicted induced martensitic transformation is one of the key characteristics of shape memory behaviour in B2 Ti-based alloys such as NiTi, TiPd and TiPt. Further work on the possible low temperature phases resulting from B2 Ti-Ru-Pd ternary alloys is underway.

The Efficiency of Pd Addition and Sr Substitution on La1−xSrxMnO3 to Remove Ventilation Air Methane in a Catalytic Flow Reversal Reactor

Ventilation air methane (VAM) is the main cause of greenhouse gas emissions in coal mining. Catalytic flow reverse reactor (CFRR) is widely used in VAM to mitigate methane emissions. In this study, palladium (Pd) and La1−xSrxMnO3 were used as catalysts in a CFRR. Different types of catalysts were prepared by loading La0.8Sr0.2MnO3, La0.9Sr0.1MnO3, and 0.1%Pd-La0.9Sr0.1MnO3 on a cordierite honeycomb reactor coated with γ-Al2O3 to compare their performances. In addition, this study compared the performance of the three catalysts in an 800 °C reactor based on different methane inlet concentrations, inlet speeds, and conversion times. The results showed: (1) 0.1% addition of Pd increased methane conversion. (2) La0.8Sr0.2MnO3 had higher efficiency at lower methane inlet concentrations, whereas La0.9Sr0.1MnO3 was more efficient at higher methane concentrations. This study demonstrates that a higher Sr loading is worth implementing only when the methane concentration of VAM is lower than 0.6%. (3) To achieve a higher methane conversion efficiency, the inlet velocity of methane should also be considered.

Rational design of low loading Pd-alloyed Ag nanocorals for high current density CO2-to-CO electroreduction at elevated pressure

Adjusting a bimetallic electrocatalyst's geometric and electronic structure to promote a certain reaction pathway and provide more active sites is a viable approach for improving the activity and selectivity of an electrocatalytic CO2 reduction process. Here, the authors, for the first-time design, self-supported 3D Ag–Pd nano-coral electrodes with a low loading Pd content through a simple and scalable approach using hydrogen bubble dynamic templates. At −0.6 V vs. Reversible hydrogen evaluation (RHE) CO2, the Ag96.1Pd3.9 bimetallic electrode converts CO2 to CO with a promoted faradic efficiency of 91.5% and partial current density (18.13 mA cm −2). This upgraded activity can be attributed to the aspects that the addition of Pd supports the vital intermediate generation with coral morphology, offers numerous active sites and rises CO2 concentration. In addition, because the catalyst is self-supported, there is no overpotential at the catalyst/support interface. Finally, CO achieved a partial current density of −318 mA cm−2 by rising CO2 pressure to as elevated as 9.5 bar to raise CO2 content. To the best of our knowledge, these findings establish a high record in neutral pH electrolytes for most Ag-based electrodes.

Postirradiation characterization of palladium as an additive for fuel cladding chemical interaction mitigation in metallic fuel

This work describes the microstructural and elemental characterization of irradiated metallic fuels containing palladium as an additive. The use of additives has been proposed to control Fuel-Cladding Chemical Interaction (FCCI) and thus to promote higher fuel utilization (i.e., higher burnup). In this work, Pd has been investigated as a potential additive to metallic fuel to bind lanthanides, impeding their migration and attack on the cladding. The influence of Pd on the microstructure, chemistry and performance of metallic fuel has been characterized via scanning electron microscopy for two metallic fuel designs—namely, annular and solid fuel. Pd was observed to play an important role in the chemistry of the fuel. Indeed, the addition of Pd leads to the formation of new phases. Pd was detected to combine not only with the lanthanides, as intended, but also with Zr, a main element of the fuel matrix. While Pd proved to be effective in preventing lanthanide migration and their attack on the cladding, the Pd-Zr compound may potentially lead to other unexpected fuel-performance issues, such as the formation of low-melting point phases and increased unalloyed U available for FCCI interaction with Fe in the cladding. Even the increase of Zr to 13wt%. did not completely mitigate this adverse phenomenon generated by the Pd-Zr interaction. Thus, the efficacy of using this additive needs further investigation.

Glycerol Hydrogenolysis to Produce 1,2-Propanediol in Absence of Molecular Hydrogen Using a Pd Promoted Cu/MgO/Al2O3 Catalyst

The catalytic process of glycerol hydrogenolysis to produce 1,2-propandiol (1,2-PD) in the absence of external hydrogen addition has been investigated. The methanol present in the crude glycerol from a biodiesel production process is used to provide in situ hydrogen produced via methanol steam reforming for the glycerol hydrogenolysis process. This process can reduce the additional cost for the transportation and storage of molecular hydrogen and also reduce the safety risks related to using high hydrogen pressure. It was found that the introduction of Pd onto a Cu/MgO/Al2O3 catalyst significantly improved the glycerol conversion and 1,2-PD selectivity. The pseudo-first-order kinetic results suggested that the promoting effect of Pd is primarily attributed to the enhanced activity for the hydrogenation of acetol, which is the intermediate formed via glycerol dehydration. A 27−3 fractional factorial design experiment was carried out to investigate the impacts of seven single factors and their binary effects on two responses, namely 1,2-PD selectivity and glycerol conversion. The results showed that the glycerol feed concentration has the most significant effect on the 1,2-PD selectivity, such that the 1,2-PD selectivity is lower if a more concentrated glycerol is used as the feedstock; stirring speed, inert gas pressure and water to methanol molar ratio have insignificant effects on the reaction system. The addition of Pd, higher temperature and higher catalyst loading are the essential factors in order to obtain a high selectivity of 1,2-PD and a high glycerol conversion.

Aptamer‐functionalized Ti3C2‐MXene Nanosheets with One‐step Potentiometric Detection of Programmed Death‐ligand 1

AbstractThis communication describes a simple sensitive one‐step potentiometric aptasensing method for quantitative detection of a referenced therapeutic biomarker (programmed death‐ligand 1, PD−L1). The aptasensor is constructed by modifying PD−L1‐specific aptamer on Ti3C2‐MXene nanosheets‐functionalized electrode. Introduction of PD−L1 induces the specific reaction between PD−L1 and aptamer, thereby resulting in the change of spatial structures. The surface electric potential of modified electrode is shifted upon addition of PD−L1 proteins before and after the reaction of aptamer with the analyte. Interestingly, potentiometric aptamer with Ti3C2‐MXene nanosheets can achieve a higher sensitivity and a lower detection limit toward target PD−L1 relative to aptamer‐modified electrode. Experimental results indicated that the linear range and detection limit of using Ti3C2‐MXene nanosheets were 0.01–100 ng mL−1 and 7.8 pg mL−1 PD−L1, respectively. Meanwhile, the specificity, reproducibility, storing stability and accuracy of potentiometric aptasensor are acceptable for the screening of PD−L1 in human serum samples.

Effects of alloying elements on the atomic structure, elastic and thermodynamic properties of L12-Co3(V, Ti) compound

In this work, first-principles calculations were used to study the effects of alloying elements on the atomic structure, elastic property and thermodynamic property of L12 ordered γ′-Co3(V, Ti) at finite temperature. Twenty transition metals (TM), including Sc, Cr, Mn, Fe, Ni, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir and Pt, have been considered as the alloying element at different crystallographic sites. The results show that Mn, Fe, Ru, Os, Rh, Ir, Ni, Pd, and Pt tend to occupy the Co site, while other elements prefer the Ti site of γ′-Co3(V, Ti). In the ground state, all TMs except Cr, Mn, Fe, Y, Tc and Ru could stabilize the γ′-Co3(V, Ti) compound, and the addition of Sc, Fe, Y, Rh, Pd, Ir and Pt can remain the compound a stable phase after involving its competitive phases. The mechanical property of TM-substituted γ'-Co3(V, Ti) was found to be linearly related to both the value of the electron density and the molar volume of compound. However, at finite temperature, only Sc, Y, and Os enhance the thermodynamic stability of the γ'-Co3(V, Ti) with the increasing temperature, which is different from the cases in the ground state.

Acetone Sensing and Catalytic Conversion by Pd-Loaded SnO2.

Noble metal additives are widely used to improve the performance of metal oxide gas sensors, most prominently with palladium on tin oxide. Here, we photodeposit different quantities of Pd (0–3 mol%) onto nanostructured SnO2 and determine their effect on sensing acetone, a critical tracer of lipolysis by breath analysis. We focus on understanding the effect of operating temperature on acetone sensing performance (sensitivity and response/recovery times) and its relationship to catalytic oxidation of acetone through a packed bed of such Pd-loaded SnO2. The addition of Pd can either boost or deteriorate the sensing performance, depending on its loading and operating temperature. The sensor performance is optimal at Pd loadings of less than 0.2 mol% and operating temperatures of 200–262.5 °C, where acetone conversion is around 50%.

Noble Metal-Added Titanate Nanosheets for PEFC Cathode

Improvement of the activity of the oxygen reduction reaction (ORR) at a polymer electrolyte fuel cell (PEFC) cathode is one of the serious problems to widespread PEFCs. We focused on Rh- or Pd-doped titanate nanosheets (TiNSs) to form the appropriate electron conduction path using tunneling effect of electrons and high quality active sites with Rh or Pd doping. To apply the tunneling effect of electrons to TiNSs, TiNSs were attempted to be supported on vapor growth carbon fiber (VGCF) with a large diameter. The surface of the VGCF was modified by poly (​diallyl dimethylammonium) chloride (PDDA) as polycation because the TiNSs were anionic. The electrostatic interaction improved slightly the contact between the PDDA modified VGCF and the TiNSs to increase the ORR activity of the TiNSs. Rh- or Pd-added TiNSs were successfully synthesized via the solid phase method and ionic exchange reaction processes.1 atomic % addition of Rh and Pd was found to be effective to enhance the ORR activity of the TiNSs.

Effect of addition of Pt, Pd and Ir to β-NiAl-bond coat on oxidation resistance and growth of interdiffusion zone

The addition of Pt to the β-NiAl bond coat enhances the service life of the turbine blade in jet engine application. However, it increases the growth of the unwanted precipitate containing an interdiffusion zone between the bond coat and superalloy. The role of Pd and Ir addition is examined in this study by comparing the growth of the interdiffusion zone without compromising the thermal cycle resistance of the oxide layer. The oxide layers on all the bond coats grow with duplex morphology. Ni and Ir-containing precipitates are found inside α-Al2O3 oxide layer on Ir-containing bond coats. The microstructural evolution of the interdiffusion zone is explained with the help of the diffusion path. The addition of Ir is found to decrease the growth of the interdiffusion zone significantly compared to the Pt containing bond coat without compromising the thermal cycle resistance of the oxide layer, which could be considered as an important addition in next-generation turbine blades.

Abstract MP29: A Cloned Anti-aminopeptidase N Scfv Antibody Blocks Enzymatic Activity And Rescues A Low Sodium Phenotype In Proximal Tubule Cells Isolated From Inverse Salt Sensitive Participants

Inverse Salt Sensitivity (ISS), defined as the paradoxical increase in blood pressure of individuals on a low sodium diet compared to a high sodium diet, may be associated with the increase in mortality and morbidity found in individuals on a low sodium diet. Our group has previously found that urine derived human renal proximal tubule cells (RPTC) isolated from ISS participants express higher Aminopeptidase N (APN) protein than cells isolated from salt resistant (SR) participants. An anti-Aminopeptidase N (APN) hybridoma was used construct a single chain variable fragment (scFv) into a bacterial expression system. The purified anti-APN scFv bound to live human renal proximal tubule cells, detected using an Alexa594 directly labelled anti-myc monoclonal antibody by immunofluorescent confocal microscopy. The anti-APN scFv was then tested to determine if it blocks APN enzymatic activity. We have previously shown that under low sodium conditions the amount of reduced-glutathione as determined by live cell fluorescence staining with the redox sensitive dye, monochlorobimane (mBCl), is decreased only in ISS cells under low sodium conditions at the two-hour time point. We hypothesized that the decreased mBCl signal may be due to the increased APN expression and activity altering the Ang II/Ang III ratio and reducing the Ang III activation of the AT 2 R. Low sodium reduced the mBCl signal in ISS (-29.2±4.3%, ISS vs SR, N=3 per group, p<0.05) and the addition of the anti-APN scFv at 1 ug/ml completely blocked the mBCl signal back to levels found in SR in normal salt conditions. In order to verify that the full rescue of this ISS specific response is due to enhanced Ang III – AT 2 R signaling, we next tried to block the effect of the anti-APN scFv by the addition of the AT 2 R antagonist, PD123319 (PD, 1 uM). Addition of PD alone to the ISS LS RPTCs did not significantly alter the mBCl signal, but when PD and anti-APN scFv are added to the LS treated ISS cells, there is complete reversal of the effect of anti-APN scFv alone (-38.1±3.9%, ISS anti-APN scFv + PD vs ISS anti-APN scFv, N=3 per group, p<0.05). The anti-APN scFv has potential therapeutic value by reducing APN enzymatic activity in ISS individuals and inducing the protective AT 2 R arm of the renin angiotensin system in low sodium conditions.

Localized Water‐In‐Salt Electrolyte for Aqueous Lithium‐Ion Batteries

AbstractWater‐in‐salt (WIS) electrolytes using super‐concentrated organic lithium (Li) salts are of interest for aqueous Li‐ion batteries. However, the high salt cost, high viscosity, poor wettability, and environmental hazards remain a great challenge. Herein, we present a localized water‐in‐salt (LWIS) electrolyte based on low‐cost lithium nitrate (LiNO3) salt and 1,5‐pentanediol (PD) as inert diluent. The addition of PD maintains the solvation structure of the WIS electrolyte, improves the electrolyte stability via hydrogen‐bonding interactions with water and NO3− molecules, and reduces the total salt concentration. By in situ gelling the LWIS electrolyte with tetraethylene glycol diacrylate (TEGDA) monomer, the electrolyte stability window can be further expanded to 3.0 V. The as‐developed Mo6S8|LWIS gel electrolyte|LiMn2O4 (LMO) batteries delivered outstanding cycling performance with an average Coulombic efficiency of 98.53 % after 250 cycles at 1 C.

Localized Water-In-Salt Electrolyte for Aqueous Lithium-Ion Batteries.

Water-in-salt (WIS) electrolytes using super-concentrated organic lithium (Li) salts are of interest for aqueous Li-ion batteries. However, the high salt cost, high viscosity, poor wettability, and environmental hazards remain a great challenge. Herein, we present a localized water-in-salt (LWIS) electrolyte based on low-cost lithium nitrate (LiNO3 ) salt and 1,5-pentanediol (PD) as inert diluent. The addition of PD maintains the solvation structure of the WIS electrolyte, improves the electrolyte stability via hydrogen-bonding interactions with water and NO3 - molecules, and reduces the total salt concentration. By in situ gelling the LWIS electrolyte with tetraethylene glycol diacrylate (TEGDA) monomer, the electrolyte stability window can be further expanded to 3.0 V. The as-developed Mo6 S8 |LWIS gel electrolyte|LiMn2 O4 (LMO) batteries delivered outstanding cycling performance with an average Coulombic efficiency of 98.53 % after 250 cycles at 1 C.

Enhanced catalytic reduction of p-nitrophenol by nano zerovalent iron - supported metal catalysts

Nano-sized zerovalent iron (NZVI) - supported metal catalysts were synthesized to characterize their reactivity for the reductive degradation of p-nitrophenol (PNP). Among the tested monometallic catalysts using metal promoters, Zn/NZVI showed the highest reactivity with complete reduction of PNP in 5 min (k = 0.0263 s−1). The addition of Pd accelerated the degradation kinetics of PNP with complete reduction in 1 min (k = 0.095 s−1) but promoter's presence on bimetallic catalyst surfaces simply decreased their reactivity. A proper Pd amount (1.5 wt% Pd/NZVI) showed the highest degradation rate (k = 0.248 s−1), while after its content increased to 10 wt% the rate was reduced by 5.8 times.

Zirconium-redox-shuttled cross-electrophile coupling of aromatic and heteroaromatic halides

Transition metal-catalyzed cross-electrophile coupling (XEC) is a powerful tool for forging C(sp2)-C(sp2) bonds in biaryl molecules from abundant aromatic halides. While syntheses of unsymmetrical biaryl compounds through multimetallic XEC is of high synthetic value, selective XEC of two heteroaromatic halides remains elusive and challenging. Herein we report a homogeneous XEC method which relies on a zirconaaziridine complex as a shuttle for dual palladium catalyzed processes. The zirconaaziridine-mediated palladium (ZAPd) catalyzed reaction shows excellent compatibility with various functional groups and diverse heteroaromatic scaffolds. In accord with density functional theory (DFT) calculations, a redox-transmetallation between the oxidative addition product and the zirconaaziridine is proposed as the crucial elementary step. Thus, cross-coupling selectivity using a single transition metal catalyst is controlled by the relative rate of oxidative addition of Pd(0) into the aromatic halide. Overall, the concept of a combined reducing and transmetallating agent offers opportunities for development of transition-metal reductive coupling catalysis.

Investigation of performances of commercial diesel oxidation catalysts for CO, C3H6, and NO oxidation.

Four commercial monolithic diesel oxidation catalysts (DOCs) with two different platinum group metal (PGM) loadings and Pt:Pd ratios of 1:0, 2:1, 3:1 (w/w) were investigated systematically for CO, C3H6, and NO oxidation, CO-C3H6 co-oxidation, and CO-C3H6-NO oxidation reactions via transient activity measurements in a simulated diesel engine exhaust environment. As PGM loading increased, light-off curves shifted to lower temperatures for individual and co-oxidation reactions of CO and C3H6. CO and C3H6 were observed to inhibit theoxidation of themselves and each other. Addition of Pd to Pt was found to enhance CO and C3H6 oxidation performance of the catalysts while the presence and amount of Pd was found to increase the extent of self-inhibition of NO oxidation. NO inhibited CO and C3H6 oxidation reactions while NO oxidation performance was enhanced in the presence of CO and C3H6 probably due to the occurrence of reduced Pt and Pd sites during CO and C3H6 oxidations. The optimum Pt:Pd ratio for individual and co-oxidations of CO, C3H6, and NO was found to be Pt:Pd = 3:1 (w/w) in the range of experimental conditions investigated in this study.

Modifications in the Composition of CuO/ZnO/Al2O3 Catalyst for the Synthesis of Methanol by CO2 Hydrogenation

Renewable methanol, obtained from CO2 and hydrogen provided from renewable energy, was proposed to close the CO2 loop. In industry, methanol synthesis using the catalyst CuO/ZnO/Al2O3 occurs at a high pressure. We intend to make certain modification on the traditional catalyst to work at lower pressure, maintaining high selectivity. Therefore, three heterogeneous catalysts were synthesized by coprecipitation to improve the activity and the selectivity to methanol under mild conditions of temperature and pressure. Certain modifications on the traditional catalyst Cu/Zn/Al2O3 were employed such as the modification of the synthesis time and the addition of Pd as a dopant agent. The most efficient catalyst among those tested was a palladium-doped catalyst, 5% Pd/Cu/Zn/Al2O3. This had a selectivity of 64% at 210 °C and 5 bar.

Evaluation of ((La0.60Sr0.40)0.95Co0.20Fe0.80O3-x)-Ag Composite Anode for Direct Ammonia Solid Oxide Fuel Cells and Effect of Pd Impregnation on the Electrochemical Performance

Ammonia produced using renewable hydrogen is being viewed as a promising media for the export of energy from locations rich in renewable energy sources. Solid oxide fuel cells (SOFCs) are efficient devices for converting such exported ammonia back into electricity at the point of use; however, investigations on materials and operating regimes for direct ammonia fuelled SOFCs are limited. In this work, we evaluated the direct ammonia SOFC performance with a Silver-Lanthanum Strontium Cobalt Ferrite (Ag-LSCF) composite anode and a novel Palladium (Pd) nanoparticle decorated Silver-Lanthanum Strontium Cobalt Ferrite (Pd-Ag-LSCF) composite anode in the temperature range of 500 °C to 800 °C. It is hypothesised that palladium nanoparticles in the anode provide hydrogen dissolution and shift the ammonia decomposition reaction towards the right. The cell performance was evaluated with both hydrogen and ammonia as fuels and a clear-cut improvement in the performance was observed with the addition of Pd for both the fuels. The results showed performance enhancements of 20% and 43% with hydrogen and ammonia fuels, respectively, from the addition of Pd to the Ag-LSCF anode. Open-circuit voltage (OCV) values of the cells with hydrogen and ammonia fuels recorded over the temperature range of 500 °C to 800 °C indicated the possibility of direct electro-oxidation of ammonia in SOFCs.