Interplay Between Ni and Brønsted and Lewis Acid Sites in the Hydrodesulfurization of Dibenzothiophene.

Ni-MoS2/γ-Al2O3 catalysts are commonly used in hydrotreating to enhance fossil fuel quality. The extensive research on these catalysts reveals a gap in understanding the role of Ni, often underestimated as an inactive sulfide phase or just a MoS2 promoter. In this work, we focused on analyzing whether well-dispersed supported nickel nanoparticles can be active in the hydrodesulfurization of dibenzothiophene. We dispersed Ni by Strong Electrostatic Adsorption (SEA) method across four supports with different types of acidity: silica (~ neutral acidity), γ-Al2O3 (Lewis acidity), H+-Y zeolite, and microporous-mesoporous H+-Y zeolite (both with Brønsted-Lewis acidity). Our findings reveal that Ni is indeed active in dibenzothiophene hydrodesulfurization, even with alumina and silica as supports, although their catalytic activity declines abruptly in the first hours. Contrastingly, the acid nature of zeolites imparts sustained stability and performance, attributed to robust metal-support interactions. The efficacy of the SEA method and the added mesoporosity in zeolites further amplify catalytic efficiency. Overall, we demonstrate that Ni nanoparticles may perform as a hydrogenating metal in the same manner as noble metals such as Pt and Pd perform in hydrodesulfurization. We discuss some of the probable reasons for such performance and remark on the role of Ni in hydrotreatment.

Influence of reaction variables on the surface chemistry of cellulose nanofibers derived from palm oil empty fruit bunches.

Nanocellulose, a versatile nanomaterial with a wide range of applications, is gaining significant attention for its sustainable and eco-friendly properties. In this study, we investigate the influence of reaction variables on the surface chemistry of TEMPO-oxidized cellulose nanofibers (TOCN) from palm oil empty fruit bunch (EFB) fibers, a high cellulose content biomass. Reaction time, primary oxidizing agent, and a pretreatment process affect, to various extents, the surface chemistry of EFB-TOCN. Conductometric titrations (CT), X-ray photoelectron spectroscopy (XPS), and statistical analysis indicate a positive and significant influence of reaction time and primary oxidizing agent on EBF-TOCN degree of oxidation and surface charge density. Partial EFB delignification increased EFB-TOCN oxidation and reaction yield compared to EFB without pretreatment. Interestingly, only reaction time has a significant effect on the EFB-TOCN hydrodynamic radii, with a reaction time of over 120 minutes required to obtain nanocellulose less than 100 nm in size. Utilizing palm oil residual biomass for nanocellulose extraction not only valorizes agricultural waste but also enhances the palm oil industry's economic prospects by reducing waste disposal costs and improving material circularity. This research contributes to the growing body of knowledge on nanocellulose production from renewable sources and highlights the potential of palm oil EFB fibers as a valuable raw material for sustainable nanomaterial development.