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Acids and Bases
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
This question is nonsense! Both are important. In the reaction of hydroxide with HCl (an acid–base reaction), the products are water and the chloride ion. One can also view chloride as a base, and water as an acid. Only understanding that HCl is a stronger acid than water and that hydroxide is a stronger base than the chloride ion allows for a full understanding of the reaction. As will be seen, the acid strength of the acid and conjugate acid, as well as the base strength of the base and the conjugate base must be examined in every acid–base reaction to really understand acidity and basicity. Is an acid–base reaction reversible?
Surface Acidity and Catalytic Activity
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
Accordingly, the strength or proton-donating power of an acid is directly related to its pKa value; the smaller the numerical value, the stronger the acid strength of the medium in which the acid is dissolved. Similarly, the strength of a base is given by its pKb value, although it is conventionally expressed in terms of the pKa of the corresponding conjugate acid, according to Equation 2.8: () −pKb=pKa=pH+log[BH+][B]
Characterization of a Set of Improved, CMPO-Based, Extraction Chromatographic Resins: Applications to the Separation of Elements Important for Geochemical and Environmental Studies
Published in Solvent Extraction and Ion Exchange, 2023
Another salient feature is the differential behavior of the light and heavy lanthanides as a function of increasing nitric acid strength. Specifically, the uptake of the lightest lanthanides decreases at high acid concentration (in >2 M and >3 M HNO3 for P-2 and P-3, respectively), while, in contrast, the heavy lanthanides display an enhanced extraction (Figure 7). This increase of Dw’s has a marked atomic number dependence, thereby causing a large drop of the mutual fractionation of the heavy lanthanides as the nitric acid concentration increases: for both resins, DGd/DLu decreases from ~17 in 0.5 M HNO3 to 2.4 in 5 M HNO3, or even 1.4 in 7 M HNO3 for P-3. These changes result in an anticlockwise rotation of Dw’s profiles, around an axis located close to Eu when the nitric acid molarity increases. Eventually, almost flat patterns from Sm to Lu are achieved in 7 M HNO3, in marked contrast with the steeply inclined profiles typically obtained in less concentrated acids (Figure 8).
The effect of copper loading method on the performance of Cu/HZSM-5 nanocatalysts in methanol to gasoline conversion
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Saeed Soltanali, Rouein Halladj, Alimorad Rashidi, Zeinab Hajjar, Amin Shafeghat
Product distribution is a function of pore size and acidic sites. It is also very much dependent on zeolite structure, spatial imitations of the atom, and secondary processes such as the transfer of active hydrogen and coke. In the case of nanocatalyst S2, increase in the production of heavier hydrocarbons in the liquid product can be attributed to the catalyst acidic strength. Although the number of acid sites decreases during ion exchange, the acid strength considerably increases and this causes the production of heavier hydrocarbons. However, when S4 is used, the great amount of Cu impregnation on the surface leads to consecutive penetrations and thus increased reactions. Therefore, S4 catalyst results in the formation of more hydrocarbons in the gasoline boiling point range compared with S3.
Effect of Ni loading and impregnation method on the hydrodenitrogenation of coal tar over Ni-Mo/γ-Al2O3
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zegang Qiu, Qiao Li, Lei Shi, Zhiqin Li, Liang Ding, Liangfu Zhao
Ni loadings intensively changed the physical and chemical properties of Ni-Mo/γ-Al2O3 catalysts. Suitable Ni loading could make the active group disperse evenly. The best dispersion of MoO3 and NiO was attained on Ni-Mo/γ-Al2O3 with a Ni loading of 6.25%. Ni loading could change the acid content and acid strength of the catalysts. With the increase of Ni loading, the total amount of acid first increased and then decreased, and the maximum value appeared on Ni-Mo/γ-Al2O3 with a Ni loading of 2.34%. Disparate hydrodenitrification (HDN) performances were observed on Ni-Mo/γ-Al2O3 with diffrent Ni loadings. The highest denitrogenation rate for coal tar was attained on catalyst NiMo-5 with a Ni loading of 6.25%, which had the higher total acid amount and the better dispersion of active components.