Co-Mo Oxide Research Articles

CATALYTIC PRODUCTION OF ELEMENTAL SULFUR FROM THE THERMAL DECOMPOSITION OF H2S IN THE PRESENCE OF CO2

Abstract The feasibility of using a cobalt-molybdenum (Co-Mo) sulfide catalyst that was prepared from a commercial Co-Mo oxide catalyst for the production of elemental sulfur from hydrogen sulfide (H2S) and carbon dioxide (CO2) in a packed bed catalytic reactor was studied. It was demonstrated that the desired sulfide catalyst could be prepared by first reducing, then sulphiding the corresponding oxide. The results showed that the prepared catalyst was capable of producing elemental sulfur from the thermal decomposition of H2S in the presence of CO2 over a temperature range of 465–700°C and at atmospheric pressure. A specific rate coefficient was calculated as well as the Arrhenius parameters for the non-equilibrated reaction. The H2S decomposition reaction was found to be a second order reaction and have an activation energy of 114.4kJ/mol(27.3kcal/mol).

Water-gas shift reaction on a cobalt-molybdenum oxide catalyst

The activity of a commercial Co-Mo oxide catalyst in the water-gas shift reaction was studied with transient response experiments in a gradientless spinning basket reactor operating at 350-400 °C and at atmospheric pressure. The Co-Mo oxide catalyzed the shift reaction at temperatures above 350°C, whereas the activity was low at 350 ° C. The transient response experiments showed that hydrogen was always formed faster from the surface than carbon dioxide. This principal effect was observed in transients obtained after different catalyst pretreatments with N 2 , with N 2 and H 2 O as well as with N 2 , H 2 O and H 2 . Pretreatment with H 2 O enhanced the transient responses of both H 2 and CO 2 . Separate chemisorption studies of H 2 , CO, and CO 2 indicated that CO 2 is a more abundant surface species than CO and H 2 . Based on the transient response experiments and the chemisorption studies a reaction mechanism was proposed, which involves water adsorption and decomposition steps, a reaction step between CO and surface hydroxyls giving H 2 and adsorbed CO 2 , and finally, a CO 2 desorption step. The surface reaction and CO 2 desorption steps were assumed to be rate determining. The stationary kinetics were described with a rate equation based on the rate determining steps, and the behaviour of the transient responses was explained with the proposed surface reaction mechanism.

HYDRODESULFURIZATION OF QAIYARAH 80-205°C NAPHTHA FRACTION OF ALUMINA SUPPORTED Co-Mo-OXIDES ( PART 2) USING STOPPED FLOW GAS CHROMATOGRAPHY

The authors report the effective desulfurization of Qaiyarah 80-205{sup 0}C, naphtha fraction on alumina supported Co-Mo oxides, assembled in a GC column using H{sub 2} as a carrier gas and the stopped-flow technique. Over 90% of sulfur was removed from this partially cracked naphtha and a similar result (Ca 90%) was obtained when hydrodesulfurizing an acid-base treated naphtha. /sup 1/H nmr studies on the chromatographically separated hydrodesulfurized fractions revealed interesting structural parameters which leads to suggestions related to the occurrence of a reforming reaction and the liberation of fresh H{sub 2} gases which further promotes hydrodesulfurization.

Characterization of Mixed Cobalt‐Molybdenum Oxides Prepared by Evaporative Decomposition of Solutions

The synthesis of Co‐Mo oxides by the evaporative decomposition of solutions method has been investigated. The oxides were prepared from atomized metal salt solution precursors decomposed in less than 3 s in air at 700°C. The materials obtained were primarily hollow spheres (1 to 6 μm) composed of fine (100 to 500 Å (10 to 50 nm)) crystallites. CoO, Co2Mo3O8, and CoMoO4 were the major crystalline phases identified. The Co‐Mo oxides were depleted in Mo relative to the precursor solutions and could not be prepared with Co/Mo atom ratios less than unity. A schematic Co‐Mo‐O isothermal section was constructed to explain the compositions, morphologies, and phase distributions observed for materials having different Co/Mo ratios. The loss in Mo was explained by the high vapor pressure of MoO3.

An infrared-spectroscopic study of the structure of Co-Mo oxide catalysts

An infrared-spectroscopic study of the structure of Co-Mo oxide catalysts