Performance In Partial Oxidation Research Articles

Increased hydroxyl concentration by tungsten oxide modified h-BN promoted catalytic performance in partial oxidation of methane

Hexagonal boron nitride (h-BN) as a layered inorganic nonmetallic material has been widely used. Hydrogen peroxide (H2O2) modification can trigger exfoliation and afford abundant B–OH active sites at edge of h-BN, which can enhance methane activation ability. Introducing tungsten oxide (WO3) to h-BN produces a similar effect, because doping WO3 into h-BN resulted in electron transfer to N, inducing fracture of B–N bond, resulting in N vacancy (triboron center), exposing more B sites and promoting the generation of B–OH. Significantly, the introduction of WO3 on the modified h-BN dramatically increased the concentration of B–OH compared with the unmodified h-BN, because H2O2 modification weakened B–N bond. By means of XRD, TEM, XPS,EPR, FT-IR, it is proved that the high concentration of B–OH active sites contributed to activating C–H bond, thus methane conversion and CO and H2 selectivity were significantly improved.

Upgrading of Heavy Oil with Chemical Looping Partial Oxidation over M2+ Doped Fe2O3

Producing light fuels from heavy oil by means of partial oxidation (POX) is a potential method. Chemical looping POX (CLPOX) process using active oxygen species from metal oxides can avoid the direct contact between hydrocarbon molecules and air. The key of CLPOX is the selection of oxygen carrier. In this study, bivalence metal oxides M2+ including Cu, Ni, Zn, Mg and Ca doped Fe2O3 were prepared, and their POX performances were evaluated at 550 °C for 1 h under atmospheric pressure by using vacuum residue as heavy oil to screen the oxygen carrier for CLPOX. The results showed that Ca doped Fe2O3 (denoted as Fe–Ca) exhibits the best POX performance with respect to the highest diesel oil yield being 39.2 wt %, and the gasoline and VGO yields are 8.5 and 27.4 wt %, separately. The characterization of the oxygen carrier revealed that the improvement of POX performance is mainly associated with the largest specific surface area and high concentration of O–. The utilization of Fe–Ca as oxygen carrier showed go...

Upgrading of vacuum residue with chemical looping partial oxidation over Fe-Mn mixed metal oxides

Heavy oil upgrading to produce light fuels is an important strategy to solve the depletion of light crude oil. Partial oxidation using transition metal oxides as oxygen carrier is a potential method for heavy oil upgrading. A series of Fe-Mn mixed metal oxides were synthesized and used for partial oxidation of vacuum residue (VR) in this study. As a result, the gasoline and diesel oil yields increase on Fe-Mn mixed metal oxides. The carbonaceous residue yield decreases with the increasing Mn content. A variety of characterizations were carried out to reveal the correlation between the physicochemical properties of the mixed metal oxides and partial oxidation performance. To achieve oxygen regeneration and stable production of light fuels, a chemical looping partial oxidation process using Fe1Mn3 as carrier of oxygen was proposed. The Fe1Mn3 shows potential application in VR upgrading with partial oxidation.

Partial oxidation of n-butane over ceria-promoted nickel/calcium hydroxyapatite

LPG has good infrastructure and is anticipated to be used for production of hydrogen, and n-butane which constitutes a main component of LPG for vehicles. Partial oxidation (POX) of n-butane is investigated in this research by employing ceria-promoted Ni/calcium hydroxyapatite catalysts (Ce x Ni2.5/Ca10(OH)2(PO4)6 x=0.1–0.3) which have recently been reported to exhibit good catalytic performance in POX of methane and propane. The experiments were carried out with changing ceria content, O2/n-C4H10 ratio and reaction temperature. As the O2/n-C4H10 ratio increased up to 2.75, the n-C4H10 conversion and H2 yield increased and the selectivity of methane and other hydrocarbons decreased. But with O2/n-C4H10=3.0, the n-C4H10 conversion and H2 yield decreased. Ce0.1Ni2.5/Ca10(OH)2(PO4)6 showed the highest n-C4H10 conversion and H2 yield on the whole. In durability tests, higher hydrogen yield and better catalyst stability were obtained with the O2/n-C4H10 ratio of 2.75 than with the ratio of 2.5.

Synthesis of β-MoO3 through evaporation of HNO3-added molybdic acid solution and its catalytic performance in partial oxidation of methanol

Abstract Two types of molybdenum trioxide were synthesized by evaporating the molybdic acid solution prepared via cation-exchange of an aqueous solution of Na2MoO4·2H2O. When the molybdic acid solution was evaporated to dryness at 323 K under reduced pressure and then calcined at 573 K in a stream of oxygen, α-MoO3 was exclusively produced. However, addition of HNO3 to the solution before the evaporation resulted in formation of a bright yellow powder which was identified as β-MoO3. The phase ratio of β/α was dependent on the quantity of HNO3; pure β-MoO3 was successfully synthesized when the molar ratio of HNO3/Mo in the solution was in the range of 1–2. It was also found that the HNO3 addition made no structural change of the isopolymolybdates in the solution and the dried precursor, but did affect the dehydration of the dried precursor to induce the crystallization of the β-phase. In partial oxidation of methanol, β-MoO3 exhibited much higher methanol conversion than the α-form. IR spectra of chemisorbed pyridine elucidated that the higher catalytic activity was caused by the relatively large number and high acidity of Lewis acid sites on the surface of β-MoO3.