Effect of nickel loadings

Figure 8. Effect of nickel loading on adsorption of methyl iodide and TOF reaction conditions, 250°C,10 atm, PQQ=4atm, P V Qi=0.6atm adsorption, at 250 C.

Figure 1 Effect of nickel loading on stability of catalysts for C02 reforming CtyCH4= 4.

Figure 6. Reflectance spectra of NiHYi5 zeolites in their hydrated state Effect of nickel loading.

The nickel dispersion of the catalyst on alumina support was less than that on silica support. This may be due to the strong interaction between nickel and alumina and undeveloped support pore structure than that of silica support. However, high catalytic activity and resistance to carbon deposition were obtained on the nickel catalyst supported on alumina. This indicated that metal dispersion was not the decisive factor that influenced the catalyst performance. Actually, the catalytic performance of the catalysts were integrative effect of nickel loading, metal dispersion, support, promoter, preparation and activation. 

Figure 4.2 Effect of nickel loading and electrostatic field of the zeolite on the catalytic capacity (same operative conditions as Table 4.3) (Kim et al., 1994).

Li, Z., Hu, X., Zhang, L., Liu, S., Lu, G. (2012). Steam reforming of acetic acid over NiyZt02 catalysts effects of nickel loading and particle size on product distribution and coke formation. Applied Catalysis A General, 4I7-4I8, 281—289. 

Chen S, Chen X, Jiang Q, Yuan J, Lin C, Shangguan W (2014) Promotion effect of nickel loaded on CdS for photocatalytic H-2 production in lactic acid solution. Appl Surf Sci 316 590-594... 

The catalysts were reduced with 100% H2 at 371 °C and an inlet space velocity of 1000/hr. Because of the carbon-forming potential of a dry gas recycle composition and the cost of reheating the recycle if the water produced by the methanation reaction is removed, a wet gas recycle composition was used. The catalyst loading, gas composition, and test conditions for these tests are listed in Table II, and the effects of nickel content are compared in Table III. 

The present work reports on results of the liquid-phase catalytic hydrogenation of butynediol on supported nickel catalysts specifically tailored for these processes. In this respect, we have studied support effects, the influence of nickel loading as well as the influence of Cu as a second metal. 

Some practical cases are determination of residual stress in steel springs, the effect of mechanical loading on stress relaxation of machined and shot-peened nickel-base alloys,65 determination of residual stress level in turbine engine disks as they accumulate engine cycles,65 66 effect of manufacturing processes on residual stress, measurement of stress gradients in mechanical, electronic and structural components, effect of heat treatment on residual stress in steel coil springs, effect of variable heat treatment temperature on residual stress in iron alloys, measurement of stress in multiphase materials and composites and stress measurements at locations of stress concentrations. 

Fig. 5 shows the effect of various supports of nickel-loaded catalysts and reaction temperature on the methane conversion, in the partial oxidation of methane. At methane to oxygen ratio of 5 1, the maximum conversion of methane is 40 %, when reaction (5) proceeded, and 10% when complete oxidation proceeded. Only the oxidized diamond-supported Ni catalyst exceeded 10% conversion above 550 C, indicating that the synthesis gas formation proceeded. Ni-loaded LazOz catalyst afforded considerable methane conversion above 450 °C, but the product is mainly COz. Other supports to nickel showed no or only slight catalytic activity in the partial oxidation of methane. These results clearly show that oxidized diamond has excellent properties in the partial oxidation of methane at a low temperature, giving synthesis gas. Fig. 6 shows the effect of temperature on the product distribution, in the partial oxidation of methane. Above 550 °C, Hz and CO were produced, and below 500 °C, only complete oxidation occurred. The Hz to CO ratio should be 2 according to the stoichiometry. However, 3.2 and 2.8 were obtained at 550 and 600 °C, respectively. 

The increase in magnetic properties of vulcanized NR clearly shows that the ferromagnetic characteristics of nickel particles are retained in the composites. The elastic modulus of the samples shows improvement as the nickel content in the composites increases. The increase in the strains modulus as the amount of nickel increases reflects the reinforcing effect of nickel nanoparticles in NR matrix. However, there is a monotonous decrease in elongation at break with the increase in filler loading. This may be due the formation of agglomerates of filler particles in the NR matrix. 

Figure 51.36 Vartavented nickel-cadmium battery type F20/40HI (24 V, 40Ah) effect of initial load on battery voltage at -12.2°C (Courtesy of Varta)...

The composition of the codeposition bath is defined not only by the concentration and type of electrolyte used for depositing the matrix metal, but also by the particle loading in suspension, the pH, the temperature, and the additives used. A variety of electrolytes have been used for the electrocodeposition process including simple metal sulfate or acidic metal sulfate baths to form a metal matrix of copper, iron, nickel, cobalt, or chromium, or their alloys. Deposition of a nickel matrix has also been conducted using a Watts bath which consists of nickel sulfate, nickel chloride and boric acid, and electrolyte baths based on nickel fluoborate or nickel sulfamate. Although many of the bath chemistries used provide high current efficiency, the effect of hydrogen evolution on electrocodeposition is not discussed in the literature. 

Fig. 7.5 The effect of temperature on the loading and separation of cobalt and nickel. Solvent 15vol% DEHPA 5vol% TBP 80vol% kerosene.

On non-zeolitic particles in the absence of a vanadium passivator, vanadium (when present at the 0.4 wt% level) makes a greater contribution to contaminant coke and hydrogen yields than nickel at constant surface area and metals loading. Incorporation of a vanadium passivator into the catalyst matrix can greatly alter the selectivity effects of vanadium, and can essentially negate its effect on non-zeolitic particles as in the case of magnesium. 

Ermakova and co-workers manipulated the Ni particle size to achieve large CF yields from methane decomposition. The Ni-based catalysts employed for the process were synthesized by impregnation of nickel oxide with a solution of the precursor of a textural promoter (silica, alumina, titanium dioxide, zirconium oxide and magnesia). The optimum particle size (10 0 nm) was obtained by varying the calcination temperature of NiO. The 90% Ni-10% silica catalyst was found to be the most effective catalyst with a total CF yield of 375 gcp/gcat- XRD studies by the same group on high loaded Ni-silica... 

The explanation is that Cu (or Pt, or Pd) produces spillover hydrogen which considerably accelerates the nucleation of nickel metal in the reduction conditions. At low loading, the high dispersion of NiO makes that nucleation is rate-limiting if NiO is pure copper permits nucleation and, consequently, reduction. The effect is proportionally smaller for high NiO loading, because the NiO crystallites are larger and can nucleate more easily (see Sections 2.2.2.0.B.a and 2.2.2.1, and Ref. 3). 

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