The effect of the nanosize on surface properties of NiO nanoparticles for the adsorption of Quinolin-65

Abstract

Using Quinolin-65 (Q-65) as a model-adsorbing compound for polar heavy hydrocarbons, the nanosize effect of NiO nanoparticles on the adsorption of Q-65 was investigated. Different-sized NiO nanoparticles with sizes between 5 and 80 nm were prepared by the controlled thermal dehydroxylation of Ni(OH)2. The properties of the nanoparticles were characterized using XRD, BET, FTIR, HRTEM and TGA. The effects of the nanosize on the textural properties, the shape and the morphology were studied. The adsorption of Q-65 molecules onto different-sized nanoparticles was tested in toluene-based solutions. On a normalized surface area basis, the number of Q-65 molecules adsorbed per nm(2) of the NiO surface was the highest for NiO nanoparticles of size 80 nm, while that for 5 nm sized NiO nanoparticles was the lowest. Excitingly, the adsorption capacity of other NiO sizes varied from loading suggesting different adsorption behavior, which exhibits the significance of textural properties during the adsorption of Q-65. Computational modeling of the interaction between the Q-65 molecule and the NiO nanoparticle surface was carried out to get more understanding of its adsorption behavior. A number of factors contributing to the enhanced adsorption capacity of nanoscale NiO were determined. These include surface reactivity, topology, morphology and textural properties.

Nanosize effects of NiO nanosorbcats on adsorption and catalytic thermo‐oxidative decomposition of vacuum residue asphaltenes

“…Thus, the bigger the particle size of NiO, the better relaxation of asphaltene molecules or aggregates on the surface, taking into consideration its shape and morphology, resulting in higher uptake (Figure ). Indeed, these results line up with the case of a Q‐65 model molecule selected to mimic asphaltenes to address the adsorption behaviour of asphaltenes onto the same prepared different‐sized NiO nanosorbcats, not only experimentally but also computationally . Both studies emphasize the effect of the nanosorbcats surface textural properties on its adsorption of heavy hydrocarbon molecules .…”

“…Indeed, these results line up with the case of a Q‐65 model molecule selected to mimic asphaltenes to address the adsorption behaviour of asphaltenes onto the same prepared different‐sized NiO nanosorbcats, not only experimentally but also computationally . Both studies emphasize the effect of the nanosorbcats surface textural properties on its adsorption of heavy hydrocarbon molecules . Thus, different degree of adsorption behaviours of those NiO nanosorbcats towards Q‐65 and VR n‐C 5 asphaltenes must then be expected.…”

“…Despite the fact that adsorption is expressed by a normalized surface area basis, the largest particle size (80 nm) showed a higher adsorption capacity in comparison to the smaller different‐sized NiO nanosorbcats as indicated by the position of plateau in Figure and the values in Table . This indicates that the adsorption behaviour of VR n‐C 5 asphaltenes over different‐sized NiO nanosorbcats goes beyond the increase or decrease in the surface areas and involves other factors, such as dispersion ability, intrinsic reactivity, asphaltenes self‐association, and subsequent aggregation, and the nanoparticle surface topology and morphology . However, one could argue that this is not the case for the samples in photograph shown in the inset in Figure .…”

“…NiO nanosorbcats with nominal sizes of 5, 10, 20, 40, and 80 nm were prepared by the controlled thermal dehydroxylation of Ni(OH) 2 , as described in our previous study . The major steps for the preparation method as well as the used characterization techniques are shown in Scheme .…”

“…In our previous work, Quinolin‐65 (Q‐65) was used as an asphaltene model compound, which showed that the NiO nanosized particles play a significant role on their adsorption and catalytic behaviours . This was attributed to the substantial changes in surface properties, topology, morphology, and textural properties of NiO nanoparticles upon undergoing down in the nanoscale.…”