Fe-MOF Materials as Precursors for the Catalytic Dehydrogenation of Isobutane

Abstract

We investigate the use of a series of iron-based metal−organic frameworks as precursors for the manufacturing of isobutane dehydrogenation catalysts. Both the as-prepared and spent catalysts were characterized by PXRD, XPS, PDF, ICP-OES, and CHNS+O to determine the physicochemical properties of the materials and the active phases responsible for the catalytic activity. In contrast to the previous literature, our results indicate that (i) the formation of metallic Fe under reaction conditions results in secondary cracking and coke formation; (ii) the formation of iron carbide only contributes to coke formation; and (iii) the stabilization of the Fe 2+ species is paramount to achieve stable and selective catalysts. In this sense, promotion with potassium and incorporation of titanium improve the catalytic performance. While potassium is well known to improve the selectivity in iron-catalyzed dehydrogenation reactions, the unprecedented effect of titanium in the stabilization of a nanometric titanomaghemite phase, even under reductive reaction conditions, results in a moderately active and highly selective catalyst for several hours on stream with a remarkable resistance to coke formation.

Self-adaptive Metal–Organic Framework Assembles Di-iron Active Sites to Mimic Monooxygenases

“…Building on these successes, recent efforts have been extended to designing MOF-based artificial enzymes for CO 2 reduction, monooxygenation with O 2 , and other important reactions. − In particular, a dicopper system has been built on the SBUs of a Ti-MOF to mimic the structures and functions of monooxygenases (Figure ). However, these SBU-based monooxygenase mimics do not allow the incorporation of nitrogen-based ligands which play crucial roles in natural enzymes.…”

Facile Preparation of Interlocked Fe2O3/MOF Composite for Boosted Rate and Cycle Performance of Lithium-Ion Batteries

“…The C 1s spectrum can be deconvoluted into four peaks at 284.8, 285.9, 289.0, and 290.6 eV, corresponding to C–C/CC, C–O, CO, and OC–O, respectively (Figure b). , Among these component peaks, the C–C/CC occupies a considerable proportion, indicating the existence of huge graphitic carbons in Fe 2 O 3 @HA-Fe-BPDC. In the high-resolution O 1s spectrum (Figure c), the four fitted peaks are located at 530.9, 531.9, 533.2, and 533.9 eV, which can be assigned to Fe–O, Fe–OH, C–O, and CO, respectively. , The high relative intensities of Fe–O and Fe–OH components suggest the formation of Fe 2 O 3 as well as the coordination between oxygen-containing functional groups and iron ions. In terms of the Fe 2p spectrum shown in Figure d, two peaks are observed at 712.0 and 725.7 eV, corresponding to Fe 2p 3/2 and Fe 2p 1/2 , respectively .…”

Controlled Manufacture of Heterogeneous Catalysts for the Hydrogenation of CO2 via Steam Pyrolysis of Different Metal–Organic Frameworks

“…H 2 -TPR profiles of the materials showed a similar behavior, a first hydrogen consumption peak from ∼300 to 500 °C corresponding to the reduction of Fe 3 O 4 to FeO and the one at ∼600 °C associated with the reduction of FeO to Fe(0) and the decomposition of the carbon matrix (Figure S38). 27 Based on these results, Fe@C600 and Fe@C600-25 were pretreated at 350 °C under a hydrogen atmosphere for 4 h before the catalytic studies. The iron catalysts were tested in the CO 2 hydrogenation reaction at 350 °C, 50 bar, H 2 /CO 2 = 3, and two different gas hourly space velocities (GHSVs), 7500 and 15,000 mL g −1 h −1 .…”