12163-69-8Relevant articles and documents
Utilizing hydrogen underpotential deposition in CO reduction for highly selective formaldehyde production under ambient conditions
Bentalib, Abdulaziz,Pan, Yanbo,Peng, Zhenmeng,Shen, Xiaochen,Wu, Dezhen,Yao, Libo
, p. 5639 - 5647 (2020)
Formaldehyde is an essential building block for hundreds of chemicals and a promising liquid organic hydrogen carrier (LOHC), yet its indirect energy-intensive synthesis process prohibits it from playing a more significant role. Here we report a direct CO reduction to formaldehyde (CORTF) process that utilizes hydrogen underpotential deposition to overcome the thermodynamic barrier and the scaling relationship restriction. This is the first time that this reaction has been realized under ambient conditions. Using molybdenum phosphide as a catalyst, formaldehyde was produced with nearly a 100% faradaic efficiency in aqueous KOH solution, with its formation rate being one order of magnitude higher compared with the state-of-the-art thermal catalysis approach. Simultaneous tuning of the current density and reaction temperature led to a more selective and productive formaldehyde synthesis, indicating the electrochemical and thermal duality of this reaction. DFT calculations revealed that the desorption of the ?H2CO intermediate likely served as the rate-limiting step, and the participation of H2O made the reaction thermodynamically favorable. Furthermore, a full-cell reaction set-up was demonstrated with CO hydrogenation to HCHO achieved without any energy input, which fully realized the spontaneous potential of the reaction. Our study shows the feasibility of combining thermal and electrochemical approaches for realizing the thermodynamics and for scaling relationship-confined reactions, which could serve as a new strategy in future reaction design.
A new approach to the synthesis of molybdenum phosphide via internal oxidation and reduction route
Yao,Wang, Li,Dong, Haitao
, p. L10-L12 (2009)
A new method for the preparation of molybdenum phosphide was reported. Dispersed MoP with lamellar morphology was obtained from the decomposition of a mixed-salt precursor containing (NH4)4Mo7O24·2H2O
Binary and ternary transition-metal phosphides as HDN catalysts
Stinner,Prins,Weber, Thomas
, p. 187 - 194 (2001)
Transition-metal phosphides (Co2P, Ni2P, MoP, WP, CoMoP, NiMoP) were prepared by reducing metal oxide/phosphate precursors in a flow of H2. The solids obtained were tested in the hydrodenitrogenation of o-propylaniline at 643 K and 3 MPa. All the catalysts were active, with product selectivities resembling those of sulfidic catalysts. The influence of H2S on the activity and selectivities was tested and is discussed with regard to a possible surface modification. Based on the surface area of each catalyst, we estimated the relative intrinsic activities of the different phosphides. According to this estimation, MoP was intrinsically the most active catalyst.
Reduction of sodium cyclotriphosphate by metallic molybdenum
Aueshov,Levchenko,Eskibaeva,Shustikova,Sinyaev
, p. 935 - 937 (2000)
The products of the reaction between sodium cyclotriphosphate and powder Mo in vacuum at temperatures up to 1000°C were characterized by x-ray diffraction and 31P nuclear magnetic resonance. Above 650-700°C, the reaction yields MoP and amorphous sodium phosphates (orthophosphate, pyrophosphate, and cyclotetraphosphate) containing Mo in the oxidation state 5+. At the Mo content ensuring the largest percentage of sodium cyclotetraphosphate in the reaction products, these also contain a small amount of elemental phosphorus.
A novel and facile synthetic route to MMo (M = Ni or Co) bimetallic phosphides
Yao, Zhiwei,Dong, Meijun,Shi, Yan,Sun, Yue,Liu, Qingyou
, p. 165 - 172 (2020)
A novel and facile route to bimetallic molybdenum phosphides was described. Both NiMoP and CoMoP phosphides were successfully prepared by a hexamethylenetetramine (HMT) route. Mixed-salt precursors containing HMT, M-HMT (M = Ni, Co or Mo) complexes, MMo-HMT (M = Ni or Co) complexes and P-containing species can be directly converted to bimetallic molybdenum phosphides under a flow of Ar at 800 °C. It was proposed that the bimetallic phosphides were formed via two possible reaction pathways: (i) MMo-HMT complexes/P→MMoP (M = Ni or Co) and (ii) M-HMT (M = Ni, Co or Mo) complexes/P→M2P/MoP→MMoP (M = Ni or Co). Additionally, it was found that the dispersions and surface areas of NiMoP and CoMoP prepared by HMT route were higher than those of corresponding bimetallic phosphides prepared by traditional H2 reduction method.
Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides
Guo, Lijuan,Zhao, Yu,Yao, Zhiwei
, p. 1225 - 1232 (2016)
This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.
On the surface sites of MoP/SiO2 catalyst under sulfiding conditions: IR spectroscopy and catalytic reactivity studies
Wu, Zili,Sun, Fuxia,Wu, Weicheng,Feng, Zhaochi,Liang, Changhai,Wei, Zhaobin,Li, Can
, p. 41 - 52 (2004)
In recent decades, there has been worldwide interest in the development of new technologies for the production of clean fuels because of the more stringent environmental legislation and the increase of low-quality stocks. The surface sites of MoP/SiO2 catalysts and their evolution under sulfiding conditions were characterized by IR spectroscopy using CO as probe molecule. The HDS activities of thiophene were measured on the MoP/SiO2 catalyst that was subjected to different sulfidation and reactivation pretreatments. The surface of MoP/SiO2 was gradually sulfided in HDS reactions. Although the surface of a MoP/SiO2 catalyst became partially sulfided, the HDS activity tests show that MoP/SiO2 was fairly stable in the initial stage of the HDS reaction, providing further proof that molybdenum phosphide is a promising catalytic material for industrial HDS reactions. Two kinds of surface sulfur species were formed on the sulfided catalyst, i.e., reversibly and irreversibly bonded S species. The MoP/SiO2 catalyst remained stable in the HDS of thiophene because most sulfur species formed under HDS conditions were reversibly bonded on the catalyst surface. A detrimental effect of presulfidation on the HDS activity was observed for the MoP/SiO2 catalyst treated by H2S/H2 at > 623 K. The irreversibly sulfided catalyst could be completely regenerated by an oxidation and a subsequent reduction under mild conditions.
MoP Nanoparticles Supported on Indium-Doped Porous Carbon: Outstanding Catalysts for Highly Efficient CO2 Electroreduction
Sun, Xiaofu,Lu, Lu,Zhu, Qinggong,Wu, Congyi,Yang, Dexin,Chen, Chunjun,Han, Buxing
, p. 2427 - 2431 (2018)
Electrochemical reduction of CO2 into value-added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal–organic frameworks as the carbon precursor, and initial work on CO2 electroreduction using the MoP-based catalyst were carried out. It was discovered that MoP nanoparticles supported on In-doped porous carbon had outstanding performance for CO2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm?2, respectively, when using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In2O3 cooperated very well in catalyzing the CO2 electroreduction.
Hydrodesulfurization of dibenzothiophene and its hydrogenated intermediates over bulk MoP
Bai, Jin,Li, Xiang,Wang, Anjie,Prins, Roel,Wang, Yao
, p. 161 - 169 (2012)
The hydrodesulfurization (HDS) of dibenzothiophene (DBT) and its hydrogenated intermediates 1,2,3,4-tetrahydro-dibenzothiophene (TH-DBT) and 1,2,3,4,4a,9b-hexahydro-dibenzothiophene (HH-DBT) over a bulk MoP catalyst was studied at 340 °C and 4 MPa both in the presence and absence of piperidine. The results indicated that sulfur was incorporated on the surface of MoP during HDS reactions, probably leading to the formation of new active sites, which possessed higher direct desulfurization (DDS) activity than the fresh MoP. The hydrogenation pathway and DDS pathway played an equally important role in the HDS of DBT. The desulfurization of TH-DBT was much faster than that of DBT, whereas HH-DBT mainly desulfurized by dehydrogenation to TH-DBT and subsequent desulfurization of TH-DBT. Piperidine decreased the rates of all reactions, but that of hydrogenation more than of desulfurization. It not only competed with the sulfur-containing molecules for adsorption on the active sites but also slowed down the sulfidation of MoP surface.
Characterization of silica-supported molybdenum and tungsten phosphide hydroprocessing catalysts by 31P nuclear magnetic resonance spectroscopy
Clark,Wang,Oyama
, p. 256 - 265 (2002)
Silica-supported molybdenum phosphide, MoP/SiO2, and tungsten phosphide, WP/SiO2, were prepared and characterized for their catalytic activity in hydrodenitrogenation (HDN) and hydrodesulfurization (HDS). The silica-supported phosphides were tested in the simultaneous hydroprocessing of quinoline and dibenzothiophene at 3.1 MPa and 643 K and were compared to a MoS2/SiO2 sample. The supported phosphides had superior HDN and lower HDS activity compared to the sulfide under these conditions. The conversion levels of MoP/SiO2 were similar to those of bulk MoP, while the WP/SiO2 was somewhat less active than its bulk WP counterpart. However, when compared on a CO uptake basis, the bulk materials had a clear performance advantage. Solid state nuclear magnetic resonance measurements indicated 31P shifts from 85% H3PO4 of 255 ppm for WP and 214 ppm for MoP. Comparison of freshly prepared and passivated samples indicated that the supported phosphides were susceptible to surface oxidation on exposure to the atmosphere as a result of their small particle size.
A novel synthetic approach to synthesizing bulk and supported metal phosphides
Guan, Qingxin,Li, Wei
, p. 413 - 415 (2010)
This paper presents a novel synthetic approach to synthesizing metal phosphides. Both bulk and supported Ni2P, Cu3P, MoP, and InP were synthesized by thermal decomposition of their metal oxide and hypophosphite precursors. Mechanistic studies of Ni2P were carried out using a separated-bed tube reactor, and the result indicates that NiO is reduced by PH3 (produced from decomposition of NaH2PO2) at 300 °C. Ni2P hollow spheres were successfully synthesized by this method, which indicates that it is possible to synthesize metal phosphides with special morphology by using metal oxides with special morphology as precursors.
Formation, structure, and HDN activity of unsupported molybdenum phosphide
Stinner,Prins,Weber, Th.
, p. 438 - 444 (2000)
Transition metal sulfides are used as catalysts in HDS and HDN. The removal of nitrogen- and sulfur-containing compounds from fuels is essential for NOx and SO2 abatement. To test the idea that phosphate may react with Ni-MoS2 to form a catalyst with (partly) phosphide-like character, a pure MoP was prepared from an aqueous solution of (NH4)6Mo7O24 · 4H2O and (NH4)2HPO4 by precipitation, calcination, and subsequent reduction in H2 at 923 K. The aqueous solutions contained MoO42-, HPO42-, and P2Mo5O236- anions. Pure MoP formed after precipitation and reduction with H2. MoP crystallized in the tungsten carbide structure in which each Mo atom is trigonal-prismatically coordinated by six P atoms. The intrinsic HDN activity of the surface Mo atoms of MoP was nearly six times higher than that of Mo edge atoms in γ-Al2O3-supported MoS2. Their selectivity was comparable to that of an Ni-promoted MoS2 catalyst.
Structural stability and mutual transformations of molybdenum carbide, nitride and phosphide
Yao, Zhiwei,Lai, Zhuangchai,Zhang, Xiaohong,Peng, Feng,Yu, Hao,Wang, Hongjuan
, p. 1938 - 1941 (2011)
The structural stability and transformations of Mo carbide, nitride and phosphide were investigated under various atmosphere conditions by X-ray diffraction (XRD). The results indicated that the order of structural stability of these Mo-based compounds was as follows: Mo2N 2C 2C and Mo2N can be transformed to MoP, whereas the reverse transformations did not occur. Noticeably, compared with those Mo sources containing oxygen, the use of Mo2C/Mo2N as Mo-source can produce finely dispersed MoP nanoparticles by the temperature-programmed reaction (TPR) method. The result was probably due to the fact that lower-levels H2O generated during synthesis process can avoid strong hydrothermal sintering. The influence of formation energy had been considered and was found to relate to the structural stability and transformations of these Mo-based compounds.
