Uncovering the changes on Raney Ni properties under Biomass upgrading reactions
To better understand a catalyst largely used in industrial processes, here employed in new and renewable applications. Detailed structural and surface analyses of Raney Ni used in the wood catalytic upstream and dehydrogenation of limonene process was performed. Several techniques as (1) X-ray diffraction (XRD), (2) X-ray photoelectron spectroscopy (XPS), (3) transmission electronic microscopy (TEM), (4) energy-dispersive X-ray spectroscopy (EDX), and (5) superconducting quantum interference device (SQUID) were used in order to gain in-depth insight into the remarkable material properties which confer Raney Ni exceptional durability in the processes. The bulk properties of Raney Ni, were more affected by the dehydrogenation process, presenting significant changes, such as fragmentation of the particles, leaching, and loss of the magnetic properties. The catalyst surface was highly affected by both processes, leading to a decrease in the surface area, the formation of a thin film of organic material on the catalyst surface, and the modification of the chemical composition. Notably, Raney Ni could be regenerated by a simple reactivation treatment (i.e., cooking the catalyst in 2-propanol at 180-200°C) or the stability was improved by the mixing of the solvents. The chemical and physical changes of the surface show distinguishing features that are associated with the changes in selectivity observed in the processes. More recently storage studies of this catalyst in a different solvent have shown the effects of time and different solvents functional groups on the Raney Ni proprieties.