Palladium Supported on Fluorinated Magnesium Hydroxide: An Efficient Catalyst for Hydrogenation under Ambient Conditions

Abstract

In this study palladium supported on fluorinated magnesium hydroxide (Pd‐MgF2‐x(OH)x) was synthesized by fluorination of magnesium hydroxide using aqueous HF as fluorinating agent. The Mg(OH)2 dissolves in HF and precipitates as magnesium hydroxide fluoride. The Pd precursor was added in the same pot during precipitation of MgF2‐x(OH)x. The final catalyst after drying at 250 °C has shown very high efficiency for hydrogenation of styrene and range of nitro aromatics at room temperature and atmospheric pressure. Hydrogenation of styrene has led to 37% conversion with 100% selectivity for hydrogenation of double bond after 3 h. The catalyst was successfully recycled for styrene hydrogenation without appreciable loss in the activity. Further hydrogenation of nitro‐aromatics was achieved with 99% conversion and 100% aniline selectivity at room temperature and atmospheric pressure. The turnover number of ∼21774 was obtained for nitrobenzene hydrogenation. The catalyst has shown mesoporous nature (pore volume 0.25 cc/g, pore diameter 4.8 nm) with very high surface area of 106 m2/g. The palladium particle size was found to be in the range of 10–11 nm. Acidity measurements by FTIR of adsorbed pyridine revealed presence of Lewis acidic sites with moderate acidity. Mechanistic studies using in‐situ FTIR analysis for nitrobenzene hydrogenation revealed activation of nitrobenzene on the Lewis acid sites of the support whereas activation of hydrogen by heterolytic cleavage on Pd center.

Mg–O–F Nanocomposite Catalysts Defend against Global Warming via the Efficient, Dynamic, and Rapid Capture of CO2 at Different Temperatures under Ambient Pressure

“…These diffraction peaks were sharp and predominant in the case of Mg­(OH) 2 -20% F, then their intensity decreased gradually with increasing ( x ) % F added to Mg­(OH) 2 , see Figure a. On the other hand, a group of diffraction peaks associated with the formation of tetragonal MgF 2 (ICCD file: 6-0290) in these mixtures ,− was recorded along with the crystallographic planes (110), (101), (111), (201), (211), and (220), which correspond to the Bragg reflections at 2θ values of 27.265, 35.174, 40.405, 43.613, 53.468, and 56.149°, respectively. The sharpness and intensity of these diffractions increased steadily from Mg­(OH) 2 -20% F up to Mg­(OH) 2 -50% F due to the formation of further MgF 2 in these nanocomposite mixed samples.…”

“…This may be attributable to the increased amounts of the liberated HF that participate in reactions and in these mixtures. Furthermore, melting NH 4 F·HF as a fluorinating agent in these mixtures facilitates the formation of both MgF 2 and magnesium fluoride hydroxide Mg­(OH)F at a low-temperature range in all prepared samples. , It is a benefit of this method that MgF 2 can be prepared more easily. This phenomenon has a negative impact on these samples’ surface area, as will be discussed later.…”

Bicomponent CuO/NiCo2O4 nanocomposites for the dehydrogenation of ammonia borane and the tandem hydrogenation of halogenated nitroaromatics

“…7 The NO bond is further activated at the LAS of the catalyst, which leads to susceptible hydrogenation by activated H atoms on the catalyst surface. 54 Consequently, the NO 2 group is selectively reduced to the NH 2 group, accompanied by completely inhibited dehalogenation.…”

Poly(amic acid) salt‐mediated palladium and platinum nanoparticles as highly active and recyclable catalysts for hydrogenation of nitroarenes in water under ambient conditions

“…In this respect, Pd and Pt nanoparticles (NPs)‐based catalysts have distinct advantages because of their high affinity to hydrogen . Recently, Pd NPs were supported on carbon materials, oxides, micelles, and other novel materials, and showed excellent catalytic activity for the hydrogenation of nitroarenes at ambient conditions . However, it is still difficult to achieve satisfactory chemoselectivity at full conversion when other reducible groups are present in the reactant, unless some sophisticated poisoning or blocking strategies are used .…”