We synthesized Ag, Pd, Pt, and Ru nanoparticles by employing antioxidants in the natural reductants, i.e., green tea leaf, coffee, peppermint leaf, and grape seeds. The results from the characterization with transmission electron microscopy (TEM) show metal nanoparticles with different shapes. The catalytic testing in the hydrogenation of α-methylstyrene (AMS) shows very high activity of the produced Pt nanodendrites. This excellent activity is due to the anisotropic structure of Pt nanodendrites which provides many defects, kinks, steps, and edges, thus providing a high number of active sites. In a challenging reaction such as the hydrogenation of levulinic acid, which is normally carried out at high temperature (100−240 °C) and high pressure (50−100 bar), the produced Pt nanodendrites are already active at much lower reaction conditions (1.3 bar and 70 °C), with an overall performance of about 100% of γ-valerolactone (GVL) selectivity and 94% conversion in 5 h.
Utilization of spent catalysts serves to meet the needs of vanadium and to overcome the environmental problem since vanadium is categorized as a hazardous, toxic material. Vanadium from the spent catalysts can be recovered in the form of V2O5 or NH4VO3. However, vanadate compounds (NH4VO3) are considered to be more valuable due to their higher price and easier production process, compared with V2O5. This study aims to find adequate operating conditions to obtain high yields and high purity of NH4VO3 crystals. The results showed that the presence of iron compounds in the extract made the crystals contaminated by brownish colour, so it decreased its purity. Therefore, iron compounds need to be separated first with precipitation. Crystals of NH4VO3 with yield of 60% on spent catalysts and purity of 75% were obtained by extraction using solvent Na2CO3 1.887 M for 60 minutes at room temperature with weight ratio of V2O5 in spent catalyst toward solvent volume (Rvp), 0.006 gram V2O5/mL Na2CO3. It was then continued by precipitation of iron compounds at pH of 12 for 2 hours and crystallization of NH4VO3 using NH4Cl 11.215 M for 4 - 5 hours at 60oC.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.