Synergistic interaction of anions and cations in preparation of VPO catalysts promoted by polyoxometalate-ionic liquids

Phosphorus-Based Ionic Liquid as Dual Function Promoter Oriented Synthesis of Efficient VPO Catalyst for Selective Oxidation of n-butane

“…5). This finding is greatly significant because the phosphorus surface enrichment in VPO is generally believed to be responsible for stabilizing the V 4+ and isolating the active phase [25,32]. However, excessive surface phosphorus also could lead to the overoxidation to CO x [51].…”

“…Extensive researches indicated that addition of metal dopants [7,[11][12][13][14][15][16][17][18][19], organic structural directing agent [20][21][22][23] and surfactant [24] during the preparation of VPO were usually employed as effective strategies to enhance its catalytic performance by modulating the crystal structure, morphology as well as chemical properties of the surface (such as P/V ratio, valence state of V, amounts of lattice oxygen, etc.). Recently, metal-based ionic liquids (ILs) acting as additives and promoters were firstly proposed and applied in the synthesis of VPO catalyst for selective conversion of n-butane in our previous work [25,26], the ILs including iron metal was observed to have largely increased the proportion of active phase (VO) 2 P 2 O 7 and induced a great change in structure morphology of VPO owing to their synergistic action between the metal anions and structureguided cations in ILs, the obtained VPO catalyst exhibited excellent performance with high conversion of n-butane and selectivity of MA. In the light of the enlightenment from ILs, the efforts were further made to employ deep eutectic ILs as structural modifier and crystal induced agent to assist the preparation of VPO and obtained a good catalytic behavior [27].…”

“…In addition, a significant number of literatures and patents revealed that the phosphorus as body element in VPO is dominant contributor affecting the catalytic activities of n-butane oxidation [28][29][30][31][32][33]. On the one hand, the phosphorus is usually deemed to have the capability to regulate the proportion of V 4+ /V 5+ crystal phase in VPO and to stabilize V 4+ specie by means of preventing the overoxidation of V 4+ species to V 5+ [25,26]. Generally, the valence state of V plays a vital role in the improvement of VPO catalyst performance.…”

Phosphoric Acid: A Key Role in Control of Structure and Properties of Vanadium Phosphorus Oxide Catalysts During Synthesis

“…In addition, organic promoters such as polyethylene glycol (PEG), [5b,c] poly(acrylic acid‐co‐maleic acid) (PAAMA), [5d] and poly(styrene‐alt‐maleic acid) (PSMA) [5e] were used as structure‐directing agents to enhance the crystallinity of VPO. Recently, our group found ionic liquid [4h,6] and deep eutectic solvents (DES) [7] could not only influence the surface chemical state and redox characteristic of catalyst but also benefit for forming single‐crystal structure on precursor surface. Both metal and organic promoters cannot influence the phase composition and structure of the catalyst significantly, key point still exist in the preparation of VPO precursor which determined the form of the active phase (amorphous versus crystallized) and the nature of the active components [8] .…”

Mesoporous Ni–Cu/WOx/ZrO2 Catalyst with Highly Dispersed WOx Clusters: Efficient Catalysts for Selective Hydroisomerization of Isobutane to n-Butane

“…Usually, n -butane and isobutane were separated from the C 4 . n -Butane was used as raw materials for the synthesis of maleic anhydride, light olefins, and aromatics. − With the increasing demand for the above industrial products, the demand for n -butane gradually increases. However, isobutane was dehydrogenated to isobutene, which was converted to MTBE (methyl tert -butyl ether) to improve the octane number of gasoline .…”