Hierarchical nanocrystalline NiO with coral-like structure derived from nickel galactarate dihydrate: An active mesoporous catalyst for methyl ethyl ketone production

Nanocrystalline NiO with a coral-like structure (38 nm) has been prepared via thermal decomposition of a new precursor, nickel galactarate (NiC6H8O8·2H2O), at 500 °C for 3 h in air. Thermal decomposition of that precursor was studied by TG and DSC techniques. The resultant NiO was physicochemically characterized by XRD, FTIR, SEM, surface area, porosity and CO2-TPD. NiO was found to exhibit a remarkable activity towards the synthesis of MEK from 2-butanol between 200 and 325 °C. In addition, it has shown a great tendency to ease regeneration of the used catalyst after 192 h in stream by simple refreshing method. Keywords: 2-Butanol, Characterizations, Catalysis, Nickel galactarate, Nanocrystalline, Methyl ethyl keton

Mg–O–F nanocomposite catalysts defend against global warming via the efficient, dynamic, and rapid capture of CO2 at different temperatures under ambient pressure

[Image: see text] The utilization of Mg–O–F prepared from Mg(OH)(2) mixed with different wt % of F in the form of (NH(4)F·HF), calcined at 400 and 500 °C, for efficient capture of CO(2) is studied herein in a dynamic mode. Two different temperatures were applied using a slow rate of 20 mL·min(–1) (100%) of CO(2) passing through each sample for only 1 h. Using the thermogravimetry (TG)-temperature-programed desorption (TPD) technique, the captured amounts of CO(2) at 5 °C were determined to be in the range of (39.6–103.9) and (28.9–82.1) mg(CO(2))·g(–1) for samples of Mg(OH)(2) mixed with 20–50% F and calcined at 400 and 500 °C, respectively, whereas, at 30 °C, the capacity of CO(2) captured is slightly decreased to be in the range of (32.2–89.4) and (20.9–55.5) mg(CO(2))·g(–1), respectively. The thermal decomposition of all prepared mixtures herein was examined by TG analysis. The obtained samples calcined at 400 and 500 °C were characterized by X-ray diffraction and surface area and porosity measurements. The total number of surface basic sites and their distribution over all samples was demonstrated using TG- and differential scanning calorimetry-TPD techniques using pyrrole as a probe molecule. Values of (ΔH) enthalpy changes corresponding to the desorption steps of CO(2) were calculated for the most active adsorbent in this study, that is, Mg(OH)(2) + 20% F, at 400 and 500 °C. This study’s findings will inspire the simple preparation and economical design of nanocomposite CO(2) sorbents for climate change mitigation under ambient conditions

Synthesis of highly basic, low-cost iron oxides from tin can waste as valorization of municipal solid waste and study of their catalytic efficiency as potent catalysts for MEK production

In the present study, low-cost iron oxide catalysts have been prepared by a simple precipitation method using tin food can waste as a source of iron and sodium hydroxide or ammonium hydroxide solution as a precipitating agent. The prepared catalysts were characterized by thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), FT-IR spectra, scanning electron microscopy (SEM), EDAX quantitative elemental analysis, and BET surface area measurements. Surface basicity of iron oxide catalysts was measured by adsorption of carbon dioxide as an acidic probe molecule, followed by desorption measurements using the TGA technique. The prepared iron oxide catalysts were tested by dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) at a temperature range of 275–375 °C. Commercial iron oxide was tested under identical reaction conditions for comparison with the prepared catalysts. The results indicated the superiority of the prepared catalysts over the commercial one and the superiority of the catalyst prepared using NaOH over that prepared using NH4OH as precipitating agents. The use of different precipitating agents affects the surface morphology and, consequently, the catalytic activity of the produced iron oxide catalysts

Assessment of Lewis-Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

Measuring the Lewis‐acidic surface sites in catalysis is problematic when the material‘s surface area is very low (S(BET) ≤1 m(2) ⋅ g(−1)). For the first time, a quantitative assessment of total acidic surface sites of very small surface area catalysts (MoO(3) as pure and mixed with 5–30 % CdO (wt/wt), as well as CdO for comparison) was performed using a smart new probe molecule, tetrahydrofuran (THF). The results were nearly identical compared to using another commonly used probe molecule, pyridine. This audition is based on the limited values of the surface area of these samples that likely require a relatively moderate basic molecule as THF with pK (b)=16.08, rather than strong basic molecules such as NH(3) (pK (b)=4.75) or pyridine (pK (b)=8.77). We propose mechanisms for the interaction of vapour phase molecules of THF with the Lewis‐cationic Mo and Cd atoms of these catalysts. Besides, dehydration of isopropyl alcohol was used as a probe reaction to investigate the catalytic activity of these catalysts to further support our findings in the case of THF in a temperature range of 175–300 °C. A good agreement between the obtained data of sample MoO(3)‐10 % CdO, which is characterised by the highest surface area value, the population of Lewis‐acidic sites and % selectivity of propylene at all the applied reaction temperatures was found