8031-35-4Relevant articles and documents
Mechanisms of Methylenecyclobutane Hydrogenation over Supported Metal Catalysts Studied by Parahydrogen-Induced Polarization Technique
Salnikov, Oleg G.,Burueva, Dudari B.,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Kovtunov, Kirill V.,Koptyug, Igor V.
, (2022/03/15)
In this work the mechanism of methylenecyclobutane hydrogenation over titania-supported Rh, Pt and Pd catalysts was investigated using parahydrogen-induced polarization (PHIP) technique. It was found that methylenecyclobutane hydrogenation leads to formation of a mixture of reaction products including cyclic (1-methylcyclobutene, methylcyclobutane), linear (1-pentene, cis-2-pentene, trans-2-pentene, pentane) and branched (isoprene, 2-methyl-1-butene, 2-methyl-2-butene, isopentane) compounds. Generally, at lower temperatures (150–350 °C) the major reaction product was methylcyclobutane while higher temperature of 450 °C favors the formation of branched products isoprene, 2-methyl-1-butene and 2-methyl-2-butene. PHIP effects were detected for all reaction products except methylenecyclobutane isomers 1-methylcyclobutene and isoprene implying that the corresponding compounds can incorporate two atoms from the same parahydrogen molecule in a pairwise manner in the course of the reaction in particular positions. The mechanisms were proposed for the formation of these products based on PHIP results.
Preparation of the Ru/HZSM-5 catalyst and its catalytic performance for the 2-pentanone hydrodeoxygenation reaction
An, Hualiang,Wang, Yanji,Xi, Xi,Yang, Ye,Zhao, Xinqiang
, p. 17692 - 17698 (2021/10/04)
Levulinic acid is an ideal model compound for complex oxygenated components in bio-oil. To assist the understanding of its hydrodeoxygenation (HDO) performance, it is necessary to investigate separately the HDO property of the ketonic carbonyl group and carboxyl group. Herein, 2-pentanone was selected as a model to study the HDO property of the ketonic carbonyl group. The Ru/HZSM-5 catalyst was prepared by an excessive impregnation method and its structure and acidity were characterized by H2-TPR, NH3-TPD, HRTEM, SEAD, Py-IR, TG-DSC, and ICP analyses. The effect of preparation conditions on the catalytic performance of Ru/HZSM-5 was studied; the suitable preparation conditions were determined as follows: a calcination temperature of 450 °C, a calcination time of 3 h, a reduction temperature of 350 °C, and a reduction time of 4 h. The catalytic performance of Ru/HZSM-5 for the 2-pentanone HDO reaction was evaluated; pentane selectivity of 77.7% at a 2-pentanone conversion of 91.8% was achieved under the conditions of a reaction pressure of 5 MPa, a reaction temperature of 190 °C, a catalyst amount of 6 wt% and a reaction time of 6 h. 2-Pentanone HDO follows the reaction path of 2-pentanone hydrogenation to 2-pentanol and then 2-pentanol dehydration and hydrogenation to the target product pentane. The acidity of the catalyst plays a certain role in influencing its catalytic performance: Lewis acid sites show high activity for activating C-O bonds and Br?nsted acid sites are the key to accelerate the further dehydration of 2-pentanol and hydrogenation to alkanes.
Tungsten Catalyst Incorporating a Well-Defined Tetracoordinated Aluminum Surface Ligand for Selective Metathesis of Propane, [(≡Si?O?Si≡)(≡Si?O?)2Al?O?W(≡CtBu) (H)2]
Werghi, Baraa,Bendjeriou-Sedjerari, Anissa,Jedidi, Abdesslem,Morlanes, Natalia,Abou-Hamad, Edy,Bhatte, Kushal,Guan, Erjia,Ma, Tao,Aguilar-Tapia, Antonio,Ould-Chikh, Samy,Cavallo, Luigi,Gates, Bruce C.,Basset, Jean-Marie
, p. 614 - 620 (2019/01/04)
A well-defined aluminium-bound hydroxyl group on the surface of mesoporous SBA-15, [(≡Si?O?Si≡) (≡Si?O)2 Al?OH], 3 was obtained by reacting di-isopropyl aluminium hydride with SBA-15 treated at 700 °C. The resulting surface [(≡Si?O?Si≡) (≡Si?O) 2 Al (isobutyl) fragment undergoes β-H elimination at 400 °C leading to [(≡Si?O?Si≡)(≡Si?O?)2Al?O) Al?H]. Further oxidation of this Al-hydride with N2O leads to 3. This acidic support was used to create a well-defined surface organo-tungsten fragment [(≡Si?O?Si≡)(≡Si?O?)2Al?O?W(≡CtBu)(CH2tBu)2] by reacting 3 with W(≡C-tBu)(CH2-tBu)3. A further reaction with hydrogen under mild conditions afforded the tungsten carbyne bis-hydride [(≡Si?O?Si≡)(≡Si?O?)2Al?O?W(H)2(≡C-tBu)]. The performance of each of the W-supported catalysts was assessed for propane metathesis in a flow reactor at 150 °C. [(≡Si?O?Si≡)(≡Si?O?)2 Al?O?W(≡CtBu)(H)2] was found to be a single-site catalyst, giving the highest turnover number (TON=800) and the highest reported selectivity for butane (45 %) vs. ethane (32 %) known for oxide-supported tungsten complex catalysts (with the supports being silica, silica-alumina, and alumina). The results demonstrate that modification of the oxide ligands on silica via the creation of Al Lewis acid center as an anchoring site for organometallic complexes opens up new catalytic properties, markedly enhancing the catalytic performance of supported organo-tungsten species.
