96-37-7Relevant articles and documents
Niobium-containing lindqvist isopolyanions [NbxW6-xO19](2+x)- used as precursors for hydrodesulfurization catalysts with isomerization properties
Bouadjadja-Rohan, Karolina,Lancelot, Christine,Fournier, Michel,Bonduelle-Skrzypczak, Audrey,Hugon, Antoine,Mentré, Olivier,Lamonier, Carole
, p. 2067 - 2075 (2015)
Lindqvist isopolyanions [NbxW6-xO19](2+x)- (x = 0-4 and 6) were prepared and their spectroscopic and thermal properties were determined by Raman and IR spectroscopy as well as TGA/DSC. The structure of the [NbW5O19]3- anion obtained as single crystal was determined. Ni-promoted alumina-supported hydrodesulfurization (HDS) catalysts were prepared from the best soluble NbW polyoxometalates. In the calcined catalysts, better dispersion of the metallic species is observed when using NbW isopolyanions instead of the conventional ammonium metatungstate. The presence of niobium was expected to introduce acidity leading to isomerization property in classical NiW HDS catalysts. In HDS reaction conditions (under hydrogen pressure and sulfided environment) the cyclohexane isomerization into methylcyclopentane activity of niobium-based catalysts was found up to 5 times superior to that of conventional NiW catalyst, showing the beneficial effect of niobium for this reaction. [NbxW6-xO19](2+x)- Lindqvist type isopolyanions were synthesized and characterized to prepared NbWNi-based alumina-supported hydrodesulfurization catalysts. Nb-containing catalysts showed improved CC6 isomerization properties under HDS conditions (H2 pressure and H2S presence) compared to those of a reference NiW catalyst related to the acid properties induced by niobium.
Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
supporting information, p. 846 - 857 (2022/02/09)
The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
Improved Hydrodeoxygenation of Phenol to Cyclohexane on NiFe Alloy Catalysts Derived from Phyllosilicates
Han, Qiao,Wang, Hui,Rehman, Mooeez Ur,Shang, Xin,Chen, Haijun,Ji, Na,Tong, Xinli,Shi, Hui,Zhao, Yujun
supporting information, p. 5069 - 5076 (2021/12/14)
A phyllosilicate-derived NiFe/SiO2 catalyst (NiFe/SiO2?AE) was successfully prepared by the ammonia evaporation method and applied in the hydrodeoxygenation of phenol to cyclohexane. Another two catalysts were also prepared for a comparison by impregnation (NiFe/SiO2?IM) and deposition-precipitation (NiFe/SiO2?DP) methods, respectively. It was found that Ni?Fe alloy, the active sites for the hydrogenolysis of C?O bond, can be obtained by the reduction of NiFe2O4 (IM) or phyllosilicate (DP and AE) by H2. The AE strategy can generate more phyllosilicate structure, which improves the dispersion of both Ni?Fe alloy and metallic Ni sites and allows the formation of more interface between these two kinds of sites as well. Therefore, the NiFe/SiO2?AE exhibits a significantly high catalytic performance in the HDO of phenol to cyclohexane. Moreover, the turnover frequency of Ni?Fe alloy sites over NiFe/SiO2?AE catalysts is much higher than those of other two catalysts. It is suggested that the enhanced synergy between the two kinds of active sites in the adsorption of C?O groups and hydrogen molecules ensures the superior intrinsic activity in HDO process.
Phospholane-Based Ligands for Chromium-Catalyzed Ethylene Tri- And Tetramerization
Boelter, Scott D.,Davies, Dan R.,Klosin, Jerzy,Margl, Peter,Milbrandt, Kara A.,Mort, Darrek,Rosen, Mari S.,Vanchura, Britt A.,Wilson, David R.,Wiltzius, Molly
supporting information, (2020/02/27)
Chromium complexes with bis(phospholane) ligands were synthesized and evaluated for ethylene tetramerization in a high-throughput reactor. Three ligand parameters - the phospholane substituent, the ligand backbone, and the type of phosphine (cyclic vs acyclic) - were investigated. The size of the phospholane substituent was found to impact the selectivity of the resulting catalysts, with smaller substituents leading to the production of larger proportions of 1-octene. Changing the ligand backbone from 1,2-phenylene to ethylene did not impact catalysis, but the use of acyclic phosphines in place of the cyclic phospholanes had a detrimental effect on catalytic activity. Selected phospholane-chromium complexes were evaluated in a 300 mL Parr reactor at 70 °C and 700 psi of ethylene pressure, and the ethylene oligomerization performance was consistent with that observed in the smaller, high-throughput reactor. MeDuPhos-CrCl3(THF) (MeDuPhos = 1,2-bis(2,5-dimethylphospholano)benzene; THF = tetrahydrofuran) gave activity and selectivity for 1-octene (54.8 wt %) similar to the state-of-the-art i-PrPNP-CrCl3(THF) (64.0 wt %) (PNP = bis(diphenylphosphino)amine), while EtDuPhos-CrCl3(THF) (EtDuPhos = 1,2-bis(2,5-diethylphospholano)benzene) exhibited even higher activity, with catalyst selectivity shifted toward 1-hexene production (90 wt %). These results are surprising, given the prevalence of the aryl phosphine motif in ligands used in ethylene oligomerization catalysts and the inferior performance of previously reported catalysts with alkyl phosphine-containing ligands.
