F+:Highly flammable;75-56-9Relevant articles and documents
Epoxidation of propane with oxygen and/or nitrous oxide over silica-supported vanadium oxide
Held, A.,Janiszewska, E.,Jankowska, A.,Kowalska-Ku?, J.,Nowińska, K.
, p. 231 - 243 (2021/10/21)
Propane to propene oxide (PO) oxidation over V-containing mesoporous silica of SBA-3 structure has been studied using different oxidants (nitrous oxide, oxygen, and their mixture) in the temperature range 673–773 K. Electron spin resonance spectroscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS), as well as X-ray diffraction, temperature-programmed reduction with hydrogen (H2 TPR), and low-temperature N2 adsorption/desorption, were applied for characterization of fresh and spent catalysts. XPS spectra and H2 TPR profiles revealed a significant reduction of V-species as a result of propane oxidation with N2O alone, which leads to a decrease in both propane conversion and the space–time yield (STY) of PO. The use of an N2O–oxygen mixture as an oxidant of propane allows the vanadium valence to be stabilized at a level similar to the initial sample, which results in stable activity with time on stream. Propane conversion of 40%, propylene selectivity of 45%, and propylene oxide selectivity of 11%, corresponding to a STY of propylene oxide of about 15 g kgcat-1h?1, have been obtained, which makes these results very promising compared with the data reported in the literature. Vanadium catalyst used with only oxygen results in stable propane conversion with high total oxidation and stable propene selectivity, although the STY of PO is 10 times lower. N2O applied as the only oxidant results in rapid catalyst deactivation, and after 2 h on stream, STY of PO is only 2.5 g kgcat-1h?1.
The design, synthesis and catalytic performance of vanadium-incorporated mesoporous silica with 3D mesoporous structure for propene epoxidation
Czerepińska, Justyna,Held, Agnieszka,Janiszewska, Ewa,Kowalska-Ku?, Jolanta
, p. 10144 - 10154 (2020/03/26)
V-containing mesoporous silica with 3D structure was prepared by a hydrothermal procedure using NH4VO3 as the vanadium precursor and with varied reaction mixture pH values (pH = 3 and pH = 5). The combined use of DR UV-vis and H2-TPR techniques confirmed the successful incorporation of vanadium into the structure of the mesoporous silica material. The number of acid sites, evidenced by ammonia TPD, strongly correlates with the vanadium content. Propene oxidation with N2O revealed the noticeable activity of the synthesised vanadium-containing mesoporous materials in epoxidation reactions. The activity of the synthesized vanadosilicates is compared with the performance of vanadium-supported catalysts (on mesoporous silica of 3D structures) prepared by wet-impregnation method. On the basis of TOF analysis indicating the activity of particular vanadium ions, it was evidenced that although the presence of isolated V species is crucial in propene epoxidation, the availability of the active species is of paramount importance for proper vanadium utilization.
Critical Roles of Doping Cl on Cu2O Nanocrystals for Direct Epoxidation of Propylene by Molecular Oxygen
Chen, Jiayu,Fu, Gang,Han, Xiao,Tian, Zhongqun,Wang, Qiuxiang,Wang, Ye,Wanyan, Yongyin,Xie, Zhaoxiong,Zhan, Chao,Zheng, Yanping,Zhou, Lingyun
supporting information, p. 14134 - 14141 (2020/09/16)
Direct epoxidation of propylene by molecular oxygen alone is one of the dream reactions in heterogeneous catalysis. Despite much effort, the yield of propylene epoxide is still too low to be commercially attractive due to the trade-off between conversion and selectivity. Here, we demonstrate that doping Cl into the lattice of Cu2O nanocrystals by the intergrowth method not only can enhance the catalytic selectivity and conversion of direct propylene epoxidation but also can solve the long-existing Cl loss problem. In particular, Cl-doped rhombic dodecahedral Cu2O with (110) exposing facets exhibited 63% PO selectivity with a 12.0 h-1 turnover frequency at 200 °C, outperforming any other coinage metal-based catalysts under mild conditions. Comprehensive characterization and theoretical calculations revealed that the Cl-decorated Cu(I) facilitated formation of electrophilic oxygen species, thus boosting the production of propylene oxide. This work provides a general strategy to develop catalysts and explore the promoter effect by creating uniform isolated anion doping to activate a nearby metal center by virtue of well-defined nanocrystals.
Catalytic epoxidation of propylene over a Schiff-base molybdenum complex supported on a silanized mesostructured cellular foam
Chen, Dawei,Jiang, Haoran,Yuan, Xia,Zhang, Xiaoyu
, (2020/08/19)
A Schiff-base molybdenum complex (MoO2–salen) supported on mesostructured cellular foam (MCF) was initially prepared by an in situ synthesis method under acidic conditions. Following silanization modification, a MoO2–salen?MCF-S sample with improved surface hydrophobicity was obtained. The ligand environment of molybdenum within the samples has been analyzed by Fourier-transform infrared spectroscopy, ultraviolet/visible spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the textural and structural properties of the corresponding materials have been characterized by nitrogen adsorption–desorption isotherms and transmission electron microscopy. Despite of the presence of fewer MoO2 species, the results showed that MoO2–salen?MCF-S has more active Mo centers than MoO2–salen and MoO2–salen?MCF on the basis of maintaining the mesoporous structure. The catalytic performances of the synthesized samples were assessed in the epoxidation of propylene with tert-butyl hydroperoxide (TBHP) as an oxidant, and the mechanism of propylene epoxidation under MoO2–salen?MCF was given. The prepared MoO2–salen?MCF-S material showed the best epoxidation performance with 1,2-dichloroethane as a solvent and a molar ratio of propylene to TBHP of 10:1 at 120 °C, giving a TBHP conversion of up to 100% after 1 h, with selectivities for propylene oxide and tert-butyl alcohol reaching 94.7% and 84.6%, respectively.
GAS-PHASE HOMOGENEOUS OXIDATIVE DEHYDROGENATION AND COUPLING OF ORGANIC MOLECULES
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Paragraph 0200, (2020/05/28)
Disclosed are gas-phase ODH and OCP processes for converting alkanes (e.g., C2H6 and C3H8) to alkenes (e.g., C2H4 and C3H6) or oxygenates (e.g., methanol, ethanol, isopropanol, or propylene oxide) or converting alkenes (e.g., ethylene and propene) and oxygenates (e.g., methanol, ethanol, isopropanol or propylene oxide) to longer carbon-chain alkenes or longer carbon-chain alkanes with or without solid catalysts.
METHOD FOR PRODUCING PROPYLENE OXIDE
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Paragraph 0092-0102, (2020/05/29)
A method for producing propylene oxide involves an oxidation step, a distillation step, an epoxidation step, and a separation step. The distillation step involves distilling the reaction mixture containing cumene hydroperoxide to separate it into a concentrate containing cumene hydroperoxide and a distillate. The reaction mixture is continuously distilled so that the ratio of the flow rate of the distillate to the flow rate of the reaction mixture to be distilled is 0.037 to 0.13. The epoxidation step involves obtaining a reaction mixture containing propylene oxide and cumyl alcohol by contacting the concentrate with propylene in the presence of a catalyst in one or more reactors to cause a reaction between propylene and cumene hydroperoxide in the concentrate, in which the outlet temperature of the final reactor is adjusted to 115° C. or more and less than 140° C.
The Construction of Au–Fe–TS-1 Interface Coupling Structure for Improving Catalytic Performance of Propylene Epoxidation with H2 and O2
Li, Xiaohan,Gao, Along,Wan, Zhehong,Huang, Qingming,Chen, Xiaohui
, p. 3149 - 3158 (2020/05/25)
Abstract: The gas-phase propylene epoxidation for noble metal system as a green process has confronted a great challenging task in metal utilization and stability. In this work, we realize the enhancement of Au capture efficiency and high-dispersed Au nanoparticles by supports modification and interfacial regulation to construct Au–Fe–TS-1 interface coupling structure. The Au capture efficiency of the optimum catalyst arrived at 69percent and it displayed a 7.3percent C3H6 conversion with a PO selectivity of 89.9percent, giving a H2 efficiency of about 25.7percent. Then some typical characterizations systematically elucidate that Fe is not only incorporated into TS-1 framework and captures Au species with high dispersion and stability, but also inhibits the losing of Ti species. Furthermore, Fe-modified catalysts change the property of Au active site and maintain lower apparent activation energy. This report may provide a new strategy to design advanced catalysts for enhancing metal utilization efficiency by the construction of interface coupling structure. Graphic Abstract: [Figure not available: see fulltext.].
One-pot synthesis of vanadium-containing silica SBA-3 materials and their catalytic activity for propene oxidation
Janiszewska, Ewa,Held, Agnieszka,Nowińska, Krystyna,Kowalak, Stanis?aw
, p. 4671 - 4681 (2019/02/27)
V-containing silica SBA-3 mesoporous catalysts were prepared by means of one-pot hydrothermal procedure with NH4VO3 or VOSO4 as vanadium precursors under various acidic medium of the reaction mixture (pH 2-TPR allowed to determine the nature of vanadium species in the studied samples. A successful incorporation of vanadium into the structure of silica SBA-3 was attained for the samples with low V content (5 wt%) exhibited the presence of isolated vanadium and also of polynuclear surface species. The resulting V-bearing samples contain the Br?nsted and Lewis acidic centres evidenced by FTIR spectra of adsorbed pyridine and by catalytic activity for 2-propanol decomposition and cumene cracking. Ammonia TPD allowed to estimate the number and strength of acid sites in regards to the vanadium content. Propene oxidation with N2O revealed noticeable activity of the synthesised V-SBA-3 samples in epoxidation reaction. On the basis of TOF analysis indicating the activity of particular vanadium ions it seems that not all of the introduced V atoms take part in the formation of mild electrophilic oxygen species responsible for propene oxide formation.
Method for improving activity of propylene epoxide catalyst and co-producing ketal (acetal)
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Paragraph 0019-0032; 0041-0045, (2019/01/17)
The invention provides a method for synthesizing propylene epoxide and co-producing ketal (acetal) by taking a by-product PG as a raw material in propylene epoxidation in the presence of heteropoly acid as a catalyst. Negative effects of alcohol substances to the activity of the catalyst in epoxidation reaction are eliminated, the activity of the catalyst is improved, the catalyst is used stably,meanwhile, downstream application of the by-product PG is expanded, and a preparation method for ketal (acetal) is provided. The method has the advantages of gentle reaction conditions, good catalyzing stability, good catalyst using effect, and resource utilization of the by-product.
Synergistic Enhancement over Au-Pd/TS-1 Bimetallic Catalysts for Propylene Epoxidation with H2 and O2
Li, Zhishan,Gao, Lin,Zhu, Xiangshuai,Ma, Weihua,Feng, Xiang,Zhong, Qin
, p. 5116 - 5123 (2019/10/28)
Au?Pd bimetallic catalyst has attracted significant research interests due to its fascinating properties. Herein, Au?Pd nanoparticles (NPs) supported on titanium silicalite-1 (denoted as Au?Pd/TS-1) were prepared by the alcohol reduction method. The Au?Pd alloy structure was proven via multiple characterization. This Au?Pd/TS-1 bimetallic catalyst showed improved activity compared with monometallic catalyst for propylene epoxidation with H2 and O2. The synergistic enhancement over Au?Pd/TS-1 could be elaborated by H-spillover process, which reduced the apparent activation energy significantly. The insights in this work are of referential importance to understanding the effect of interaction between bimetallic components on reaction system.
