Influence Of Metal Oxides Research Articles

Influence of metal oxides on circumcorannulene for the design of new push-pull corannulene models: applications in nano-electronics, optoelectronics and non-linear optics

ABSTRACT The search for new high-performance push-pull materials for use in nonlinear optics (NLO) and optics is currently a popular area of research. In this study, the effects of metal oxides -(MO) n = 1,2 (monomer: MO=TiO2, CuO, Al2O3, and ZnO; and dimer: MO = Ti2O4, Cu2O2, Al4O6, and Zn2O2) on the electronic, absorption, optoelectronic and NLO characteristics of circumcorannulene (CO) in the gas phase and in acetonitrile have been investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) at the B3LYP and CAM-B3LYP/6-311+G(d,p)/LANL2DZ levels of theory. Research has shown that adding metal oxides to CO leads to the formation of new push-pull CO derivatives. These derivatives include T1, U1, A1, Z1, T2, U2, A2, and Z2 formed from TiO2, CuO, Al2O3, ZnO, Ti2O4, Cu2O2, Al4O6, and Zn2O2 metal oxides, respectively. They exhibit excellent stability, low |HOMO-LUMO| gap energy, high NLO, and photocurrent responses compared to CO in gaseous media and polar solvents. However, it is interesting to note that the use of the copper oxide monomer configuration on corannulene family compounds is effective in improving their NLO response, while increasing the alumina chain proves necessary to improve their photocurrent response in the visible region.

Ni and Ce Grafted Ordered Mesoporous Silica KIT-6 for CO2 Adsorption

In this study, the Ni/KIT-6 and Ce/KIT-6 materials were prepared through the impregnation method and then amino-functionalized materials were obtained by the grafting of an amino-silane coupling agent 3-aminopropyl triethoxysilane (APTES). The samples were characterized by thermogravimetric analysis (TGA-DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, scanning electron microscopy (SEM) and nitrogen adsorption at 77 K. The study of CO2 adsorption–desorption on prepared materials was investigated using thermogravimetric analysis (TGA-DTA) coupled with mass spectrometry (MS). The influence of metal oxides on the performance of CO2 adsorption on functionalized mesoporous silica was presented. The results showed that doping the molecular sieve with cerium oxide can significantly increase the adsorption capacity of the amino-functionalized KIT-6. As the CO2 adsorbents were prepared by functionalization through grafting with APTES, the amount of amine loading is one of the important factors which improves CO2 adsorption capacity. Additionally, CO2 adsorption performance depends on the textural properties and the temperature used for the adsorption process. The maximum adsorption capacity of Ce/KIT-6 Sil is 3.66 mmol/g, which is 2.4 times higher than Ni/KIT-6 Sil. After the nine cycles of cyclic CO2 adsorption/desorption, the Ce/KIT-6 Sil still had higher adsorption capacities, indicating their good cyclical stability.

PAN-based activated carbon nanofiber/metal oxide composites for CO2 and CH4 adsorption: influence of metal oxide.

In the present study, we successfully prepared two different electrospun polyacrylonitrile (PAN) based-activated carbon nanofiber (ACNF) composites by incorporation of well-distributed Fe2O3 and Co3O4 nanoparticles (NPs). The influence of metal oxide on the structural, morphological, and textural properties of final composites was thoroughly investigated. The results showed that the morphological and textural properties could be easily tuned by changing the metal oxide NPs. Even though, the ACNF composites were not chemically activated by any activation agent, they presented relatively high surface areas (SBET) calculated by Brunauer–Emmett–Teller (BET) equation as 212.21 and 185.12 m2/g for ACNF/Fe2O3 and ACNF/Co3O4 composites, respectively. Furthermore, the ACNF composites were utilized as candidate adsorbents for CO2 and CH4 adsorption. The ACNF/Fe2O3 and ACNF/Co3O4 composites resulted the highest CO2 adsorption capacities of 1.502 and 2.166 mmol/g at 0 °C, respectively, whereas the highest CH4 adsorption capacities were obtained to be 0.516 and 0.661 mmol/g at 0 °C by ACNF/Fe2O3 and ACNF/Co3O4 composites, respectively. The isosteric heats calculated lower than 80 kJ/mol showed that the adsorption processes of CO2 and CH4 were mainly dominated by physical adsorption for both ACNF composites. Our findings indicated that ACNF-metal oxide composites are useful materials for designing of CO2 and CH4 adsorption systems.

Influence of Metal Oxides and Their Precursors on the Composition of Final Products of Aquathermolysis of Raw Ashalchin Oil

Experiments were conducted simulating hydrothermal conversion of heavy oil in the presence of carbonate, kaolin, Al2O3, Ni2+ and Cu2+, NiO mixed with poly-α-olefins, C6H8O7, C2H4O2 at 290–375 °C and 10–135 bar. Al2O3, carbonate at 375 °C and 135 bar, accelerated the resin degradation. Experiments with carbonate at 350 °C and 10 bar showed no significant composition changes. NiSO4, CuSO4, kaolin mineral, at 350 °C and 78 bar, accelerated decomposition of resins (from 35.6% to 32.5%). Al2O3 and carbonate at 290 °C and 14 bar led to the destruction of asphaltenes (from 6.5% to 4.7% by weight), which were adsorbed on the surface of carbonate. Al2O3, NiO, poly-α-olefins at 350 °C and 78 bar accelerated C–C bond cracking of high-boiling asphaltenes. C6H8O7, rock-forming carbonate, at 360 °C and 14 bar, contributed to the polymerization and polycondensation of hydrocarbons with the formation of additional resins. C2H4O2 and kaolin at 360 °C and 12 bar affected the reduction in the resin content from 35.6% to 31.9% wt. C2H4O2 interacted with the active metals with the formation of acetate salts exhibiting catalytic activity.

Influence of metal oxide and heteropoly tungstate location in mesoporous silica towards catalytic transfer hydrogenation of furfural to γ-valerolactone

One pot conversion of furfural to γ-valerolactone by transfer hydrogenation has been achieved over bifunctional mesoporous silica catalysts containing Zr and tungstophosphoric acid (TPA).

Influence of metal oxides and their precursors on the composition of final products of aquathermolysis crude oil

Experiments were conducted simulating the hydrothermal effect on heavy oil in the presence of carbonate, kaolin, Al2O3, Ni+2 and Cu+2, NiO mixed with poly-α-olefins, C6H8O7, C2H4O2 at temperatures of 290-375°C and pressures from 1,0 to 13.5 MPa. As a result of the research, a decrease in the viscosity of the organic end products of hydrothermal exposure due to the redistribution of n-alkanes in the direction of the formation of low-molecular homologs was established. This led to an increase in the content of saturated hydrocarbons and light fractions in the final products of the conducted studies. Under hydrothermal conditions of heavy oil conversion, products of the reactions of destruction of the results of the research can be applied in the development of new innovative technologies for the development of unconventional hydrocarbon resources.

Influence of metal oxide (V2O5) in recycled waste materials for advanced durable construction technology

For replacement of Portland cement as well as advancement of concrete technology, the low calcium based fly ash with alkali activators plays a significant role as cementitious material in current scenario. As efficacy of fly ash requires very high temperature (≥1400 °C) activation, alternative approach of fly-ash with addition of 5% vanadium pentoxide (V2O5) has been established for mullitization process at lower temperature (≤1000 °C) in this present exertion. The sintered fly ash has been used along with alkali activator for developing the construction composite at ambient temperature. Strength measurement, Ultrasonic pulse velocity, Chloride ion permeability, water absorption and sulphate resistant tests reveal that the V2O5 assimilated fly-ash based geopolymer structures possess higher mechanical strengths and durability. The microstructural studies (FESEM, EDS, XRD, FTIR) of the samples confirm the needle shaped nano sized mullite formation at 1000 °C temperature in its matrices. Thermal behaviour of the V2O5 based fly-ash depicted the synthesized nanoparticle was exothermic in reaction. The investigation demonstrates the formation of needle shaped mullite helps to enhance durability with higher bond strength of the composite structure and a new approach to utilize/recycle the vast resources of fly-ash with lower temperature requirement as an effective cementitious-based engineering materials.

The influence of metal oxides on the separation properties of hybrid alginate membranes

ABSTRACTAlginate membranes filled with different metal oxide particles were prepared and the influence of the presence of different amounts of Fe3O4, ZnO, and Ag2O particles on ethanol and water permeation was discussed. Ethanol and water vapour permeation rates were determined using the measuring cell method, and the mass transport coefficients were evaluated. It was found that the highest transport parameters were obtained for membranes with the highest metal oxide content. Furthermore, the highest flux, equal 8.49 kg·m−2·h−1, was obtained for the alginate membrane filled with 15 wt% of silver oxide particles, while the greatest selectivity coefficients were noted for membranes containing magnetite. In this case, for the alginate membrane with 15 wt% of magnetite content, the selectivity coefficient reached the best value of 108.15.

Transition Metal Oxides as Catalysts for Hydrogen Production from Supercritical Water Gasification of Glucose

In the present study, 12 kinds of metal oxides (V2O5, Cr2O3, MnO2, Fe2O3, Co2O3, CuO, ZnO, ZrO2, MoO3, SnO2, WO3 and CeO2) were tested in supercritical water gasification of glucose at 600 °C. Quartz capillary reactor was used to eliminate the potential catalytic effect of the reactor wall. The influence of metal oxides on the gasification efficiency, gas composition and yield was studied. Most metal oxides improved the gasification efficiency, and Cr2O3, CuO, WO3 and V2O5 were the most effective ones. Most oxides had little influence on H2 fraction but showed significant influence on CO fraction. The lowest CO fraction was achieved with MnO2 and CuO. The catalytic activity of the metal oxides was summarized and compared based on their impacts on the gas composition and yield. Through the visualization of the reactor, CuO was found to be reduced into Cu metal during gasification. Both the presence of Cu metal and released oxygen were supposed to enhance the gasification. Further study on the valence state of metal oxides after gasification may help to reveal the catalytic mechanism of the metal oxides.

Evidence of a strong effect of defect-free metal oxide supports on Pt nanoparticles.

Influence of metal oxide (MO) supports on nanoparticle (NP) catalysts is still under investigation. Theoretical studies demonstrate that active defect sites on the surface of a MO support can affect the structure and activity of metal clusters. In the present work, we show that even defect-free surfaces of MOs can cause considerable restructuring and accumulation of interfacial charges on Pt NPs of size 1 nm (Pt55). Independent of the type of MO support, we find that supported Pt55 behaves like a conductor since the binding energy of a test adsorbate on top of it is similar to that on an intact Pt55. However, adsorption energy at binding sites close to the perimeter of the nanoparticle/support interface can vary by 1.8 eV depending on the distance between the adsorbate and surface cations (possibility of forming ionic bonds) as well as the amount and sign of charges (ionization energy) of interfacial Pt atoms.

In situ UV–VIS spectrophotometry within the second time scale as a research tool for solid-state catalyst and liquid-phase reactions at high temperatures: Its application to the formation of HMF from glucose and cellulose

We successfully developed an in situ UV–VIS absorption spectroscopic flow reactor system for investigation of solid-liquid two-phase reactions within the second time scale at high temperatures (solid-state-catalyst-mediated hydrothermal flow reactor system, SSCM-HF). The SSCM-HF consisted of a water reservoir, high-pressure pump, sample injector, high-temperature reactor involving solid-state catalysts, a cooling bath, a pressure regulator, and a temperature controller. The high-temperature reactor contains a reactor column having micrometer sized solid particles, and is connected to an optical window using transparent fused-silica capillary tubing. Liquid samples are exposed for the second time scale, which can be adjusted by changing the flow rate. In situ monitoring of reactions using SSCM-HF was performed at 200–1114nm within 7.36–117.79s at temperatures up to 300°C and pressures up to 30MPa. We demonstrated the usefulness of SSCM-HF by inspecting 5′-hydroxymethylfurfural (HMF) formation from glucose and cellulose. The influence of metal oxides, such as WO3 and Nb2O5, was investigated using both a conventional batch reactor and the SSCM-HF. The simple metal oxides showed catalytic activities for the dehydration of glucose to HMF. The SSCM-HF demonstrated in situ detection of a small amount of HMF in the presence of WO3 deposited solid particles within 29.4s at 200°C. This study demonstrates the application of the SSCM-HF as a new research tool for screening and investigating solid-state catalysts in detail in liquid-phase reactions at high temperatures.

Influence of metal oxides on the performance of Pd/Al2O3 catalysts for methane combustion under lean-fuel conditions

Pd/Al2O3 catalysts modified by different metal oxides (Mn, Fe, La, Mg and Ni oxides) were prepared and tested for fuel-lean methane/air catalytic combustion. It was found that the support material influenced the combustion performance significantly. The addition of NiO or MgO effectively improved the activity and hydrothermal stability of catalysts. X-ray diffraction (XRD) results showed the presence of spinel phase in the Pd/Al2O3–NiO and Pd/Al2O3–MgO catalysts. Temperature-programmed desorption of ammonia (NH3-TPD) measurements indicated that the supports became weakly acidic because of the formation of NiAl2O4 or MgAl2O4 spinel. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed the well dispersion of Pd particles on the Al2O3–NiO and Al2O3–MgO supports. It was concluded that the formation of the NiAl2O4 or MgAl2O4 spinel phase during preparation would be beneficial for the methane catalytic performance of Pd catalysts.

Influence of metal oxide on LiBH4/2LiNH2/MgH2 system for hydrogen storage properties

In this study, various nanoscale metal oxide catalysts, such as CeO2, TiO2, Fe2O3, Co3O4, and SiO2, were added to the LiBH4/2LiNH2/MgH2 system by using high-energy ball milling. Temperature programmed desorption and MS results showed that the Li–Mg–B–N–H/oxide mixtures were able to dehydrogenate at much lower temperatures. The order of the catalytic effect of the studied oxides was Fe2O3>Co3O4>CeO2>TiO2>SiO2. The onset dehydrogenation temperature was below 70°C for the samples doped with Fe2O3 and Co3O4 with 10wt.%. More than 5.4wt.% hydrogen was released at 140°C. X-ray diffraction indicated that the addition of metal oxides inhibited the formation of Mg(NH2)2 during ball milling processes. It is thought that the changing of the ball milling products results from the interaction of oxide ions in metal oxide catalysts with hydrogen atoms in MgH2. The catalytic effect depends on the activation capability of oxygen species in metal oxides on hydrogen atoms in hydrides.

Influences of metal oxides on carbon corrosion under imposed electrochemical potential conditions

Graphite electrodes, whose surface is partially covered with metal oxides, are prepared by the electrochemical deposition of MoO x , WO x , and SnO 2 particles, and their corrosion behaviors under the imposed electrochemical potential conditions are investigated. Scanning electron microscopy observation shows that highly oriented pyrolytic graphites (HOPGs) modified with MoO x and WO x particles (MoO x |HOPG and WO x |HOPG) suffer from carbon corrosion and show pits formation on the surface of HOPG after an electrochemical potential cycling in a range of 0.8–1.0 V. In contrast, SnO 2-modified HOPG (SnO 2|HOPG) exhibits superior tolerance to electrochemical oxidation. Cyclic voltammograms show that the SnO 2 modification prevents an increase in the redox currents for quinone/hydroquinone reactions and the electrochemical double layer capacitances on the HOPG electrode. These results indicate that the influence of metal oxides on carbon corrosion varies depending on the kind of metal oxides, and that SnO 2 is a proper choice to protect the surface of HOPG from carbon corrosion, under electrochemical potentials.

Influence of Metal Oxide on the Fixation of Chlorine in Thermal Decomposition of Poly (vinylidene chloride co vinyl chloride)

Influence of Metal Oxide on the Fixation of Chlorine in Thermal Decomposition of Poly (vinylidene chloride co vinyl chloride)

Studies on the influence of metal oxides on the galvanic characteristics of hot-dip zinc coating

In the present work, hot dip zinc coating incorporated with various composite was developed. The effect of ZnO and V 2O 5 in the galvanizing characteristics of zinc coating was studied with a view to apply the coating for functional application. The pretreatment conditions and bath compositions were fixed based on the available literatures and on the preliminary test results. Different electrochemical techniques were followed to study the corrosion tolerance of the coating. The presence of ZnO had a beneficial influence on the protection span of the coating compared to that of V 2O 5. The presence of composite reinforced inner layer influenced the alloying reaction between Fe and Zn. The surface topography of the coating was also improved due to the metal oxide incorporation.

Influence of metal oxides in the colorimetric determination of acid volatile sulfide in sediments

AbstractThe sediment of Lagoa dos Patos‐MS, Brazil, was investigated to verify the influence of metal sulfides and oxyhydroxides of Mn and Fe on the heavy metal availability. The spectrophotometric method of methylene blue was used, with 8 interlinked tubes containing the samples with SnCl2, where N2 was introduced to release the H2S extracted with 6.0 mol L–1 HCl, and trapped in 0.05 M NaOH solution. The influence of SO42–, Mn(IV) and Fe(III) oxyhydroxides was investigated with samples constituted by a mixture of MnO2; Na2SO4; FeCl3, and sediments. The presence of SnCl2 was very important to avoid the interferences of iron and manganese oxyhydroxides. The method of standard addition was applied and the efficiency was (100.8 ± 9.4)%. The ratio among the quantities of metals potentially available and the acid volatile sulfide (AVS) indicate that the system presents small metals availability to the benthic community, by the existence of sulfide capable to immobilize the metal as insoluble sulfide.

Influence of metal oxides on the catalytic behavior of Au/Al 2O 3 for the selective reduction of NO x by hydrocarbons

The reduction of NO by propene in the presence of excess oxygen over mechanical mixtures of Au/Al 2O 3 with a bulk oxide has been investigated. The oxides studied were: Co 3O 4, Mn 2O 3, Cr 2O 3, CuO, Fe 2O 3, NiO, CeO 2, SnO 2, ZnO and V 2O 5. Under lean C 3H 6-SCR conditions, these oxides (with the exception of SnO 2) convert selectively NO to NO 2. When mechanically mixed with Au/Al 2O 3, the Mn 2O 3 and Co 3O 4 oxides and, to a much greater extent, CeO 2 act synergistically with this catalyst greatly enhancing its SCR performance. It was found that their synergistic action is not straightforwardly related to their activity for NO oxidation to NO 2. The exhibited catalytic synergy may be due to the operation of either remote control or a bifunctional mechanism. In the later case, the key intermediate must be a short-lived compound and not the NO 2 molecule in gas-phase.

Influence of metal oxides on PCDD/Fs formation from pentachlorophenol

Chlorophenols (ClPhs) are considered as important precursors for PCDD/Fs formation. The influences of series of metal oxides including MgO, Al 2O 3, CaO, BaO, TiO 2, V 2O 5, MnO 2, Fe 2O 3, Co 3O 4, CuO, Ag 2O, ZnO, HgO, SnO, PbO, La 2O 3, CeO 2, and Eu 2O 3 on PCDD/Fs formation from pentachlorophenol (PCP) were investigated in a laboratory-scale reactor. The results indicated that most of the above metal oxides have obvious suppressing effects on the total amount of PCDD/Fs formation from precursor PCP except for CuO, ZnO, MnO 2, TiO 2 and Co 3O 4 with promotion effects at 280 °C for 2 h. Although MgO, Al 2O 3, Fe 2O 3, PbO, La 2O 3 and Eu 2O 3 could reduce the amount of octachlorinated dibenzo- p-dioxin (OCDD), they promote the formation of more toxic 1,2,3,4,6,7,8-HpCDD at the same time. The total suppressing efficiencies of several metal oxides including CaO, BaO, PbO, Ag 2O, HgO and SnO which have lower Z/ r (charge to radius ratio) <2 are all over 90%. The theories of generalized acid–base and atomic parameter ( Z/ r) were used to speculate the effecting mechanisms. The factors including time and temperature on suppressing efficiencies of CaO, BaO and PbO have also been studied in the present paper. The results showed that the total suppressing efficiencies of CaO, BaO and PbO increase with the increase of heated time and temperature.

Influence of metal oxides on the catalytic activity of nickel

Nickel catalysts supported on BeO, MgO, ZnO, Al 2O 3, Cr 2O 3, SiO 2, TiO 2, ZrO 2, ThO 2, and UO 2, with different metal loading, have been prepared by coprecipitation or by impregnation of the basic nickel carbonate with a water solution of nitrate of the support. Metal surface areas were measured by hydrogen chemisorption. The activity of the catalysts have been determined under flow conditions, at atmospheric pressure, for the deuterium exchange reaction between ammonia and hydrogen. The reaction rates normalised to metal surface area are strongly affected by the nature of the support. Generally, the presence of the support enhances the intrinsic activity of catalyst compared to that of the nickel black; the highest increase is shown by TiO 2 (ca. 800-fold). The results emphasize the importance of the support in the enhancement of the catalytic activity for the deuterium exchange reaction between hydrogen and ammonia. It is assumed that the role of the support is to create new active sites at the interface between the metal and the support, either through a direct or an indirect involvement of the support in activation of the ammonia molecule.