SYNTHESIS AND CHARACTERIZATION OF MORPHOLOGY-DEPENDENT NICKEL OXIDE CATALYST TO AID HYDRODEOXYGENATION OF PHENOL TO BIOFUEL. A project thesis submitted to the Chemical Engineering program Universiti Teknologi PETRONAS as partial fulfillment of the requirement for
BACKGROUND OF STUDY
9 In this research paper we focus on the hydrodeoxygenation of phenols in the formation of biofuels. In general, bio-oils are continuously produced by fast pyrolysis of a large amount of biomass and have played a role as a feedstock for the renewable production of biofuels. To produce the biofuels, we use the method of hydrodexygenation of the phenols.
It is important for biofuels, which are derived from oxygen-rich precursors such as sugars.” Bio-oil produced from fast pyrolysis of lignocellulosic biomass is a promising alternative fuel to replace fossil fuels. By bypassing hydrogenation and cracking reactions, hydrogen can be used efficiently due to the high oxygen content of the bio-oils and the desire for fully renewable fuels.
Bio-oil has environmental advantages compared to fossil fuels because when burned, bio-oil produces less pollution than fossil fuels, specifically half the NOx, negligible amounts of SOx emissions, and it is considered CO2 neutral. Bio-oil chemical properties vary with materials used for its production or the conditions under which it is produced.
PROBLEM STATEMENT
OBJECTIVE AND SCOPE OF STUDY
Nickel and nickel oxide
In addition, some experimentalists found that nickel became a recovered catalyst for processes when used in a high pH atmosphere. The figure above shows the influence of temperature and water concentration on the physical characterizations of nickel oxide nanoparticles, from 623 to 923K for almost three hours were performed by XRD with changed amounts of water. It shows a common face-centered cubic (FCC) arrangement of nickel with three distinct peaks, labeled as replications from and {220} flat surfaces.
15 Accordingly, the formation of Ni and NiO nanoparticles and their structural features were strongly dependent on the calcination temperature. With increasing calcination temperature, the intensities of the diffraction peaks of NiO increased and the degree of crystallinity would be improved. To investigate the effects of H2O on the synthesis, 10, 20 and 40 mass% H2O were applied in the systems and nanoparticles of Ni and NiO were again obtained.
Considering the effects of H2O concentration on the formation of NiO nanoparticles, the metallic Ni nanoparticles are presented with few amounts of NiO at 623K (Fig. While the H2O concentration was increased at this calcination temperature (623 K), the diffraction peaks of NiO became more obviously, as shown in fig.
Hydrodeoxygenation
18 The diagram below shows the schematic diagram of a traditional hydrodeoxygenation pathway in a more detailed visual explanation. The rates of the four successive reactions of phenol hydrodeoxygenation were compared over two Ni catalysts. In three hydrogenation reactions of phenol, cyclohexanone and cyclohexene, Ni/Al2O3-HZSM-5 was more active than Ni/HZSM-5 due to the higher Ni dispersion on Ni/Al2O3-HZSM-5.
The cyclohexanol dehydration reaction rate on Ni/HZSM-5 was slightly higher due to higher BAS concentration, and such dehydration was strongly enhanced by close proximity of acidic sites and metal sites where cyclohexene is irreversibly hydrogenated[2].
Materials and Equipment
Procedures
The table 1 below shows the pH value obtained for each bases before the preparation of the nickel oxide catalyst. It has been found that the lower the pH value of a base, the better it is, but this does not apply to some of the bases. The bases with one of the lowest pH values are for example the 2M NaF and this base did not show any effects on the nickel oxide catalyst, as it was even difficult to dissolve it in the distilled water and also deionized water.
The best base to use is the 0.125M NaOH followed by 2M KOH, 2M NaOH, 4M NaOH, 2M Na₂CO₃, 5M NaOH and 2M NH₃. It is chosen based on few reasons just like the structure of the nickel oxide catalyst, the Raman results, the surface area of the catalyst, XRD result and also the EELS result. As you can see from the images in Figure 5 and 6, the base reactivity does affect the structure of the nickel oxide catalyst. The lower the pH values of the base, the better the structure of the nickel oxide catalyst.
The EELS of Figure 14 (a) which is nickel oxide with NaOH bases shows a better graph compared to the other one. The graph below shows the graph of the degree of reactivity against the pH values of the bases. This proves that pH values have an effect on the degree of reactivity as stated at the beginning of the research paper.
The of a “sawtooth” pattern. This is chosen based on some reasons such as the structure of the nickel oxide catalyst, the Raman results, the surface area of the catalyst, the XRD result and also the EELS result.
The rate of reaction of nickel nitrate is affected by the pH value of the bases used. The rate of reaction of nickel nitrate is affected by the pH value of the bases used and also their concentration. Finally, my recommendation is to provide more different nickel oxide catalyst structures with higher surface area and also to research a different method of nickel catalyst production other than the hydrothermal process.
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31 Moreover, as you can imagine in Figure 4, the bases are arranged in a descending order from the best base to be used to the lowest base to be used. 39 Figure 13 (b) and (d) shows the detailed and focused of 2M NaOH and also 4M NaOH using TEM „Transmission Electron Microscopy‟. EELS also known as "electron energy loss spectroscopy" is an equipment used for a contracted range of kinetic energies also known to be visible to a beam of electrons.
From the comparison, we can conclude that 0.125 M NaOH has the best result followed by 2 M KOH, then 2 M NaOH and finally 4 M NaOH. As you can see in the graph, as the pH increases, the rate of reactivity decreases. The examination from the pattern shows that it is a classic alpha-type nickel oxide in their powder form.
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