The deactivation of Au/CeO2 catalysts during low-temperature water–gas shift reaction and the underlying physical origin were investigated, comparing the deactivation in different reaction atmospheres and subsequent regeneration of the catalysts by reactive treatment in O2/N2 or H2O/N2 gas mixtures. Based on TEM and XRD measurements, Au and ceria particle sintering (irreversible deactivation) c...

Catalyst deactivation is usually indispensable, although the rate at which it occurs varies greatly. At first, this article discusses the causes of deactivation in a commercial hydrocracking unit called Isomax. Then, a 5-lump kinetic model including catalyst decay function for hydrocracking of vacuum gas oil in a commercial plant is proposed. The model considers vacuum gas oil (VGO) having boil...

in a novel dual bed reactor fischer-tropsch synthesis was studied by using two diffrent cobalt catalysts. an alkali-promoted cobalt catalyst was used in the first bed of a fixed-bed reactor followed by a rutenuim promoted cobalt catalyst in the second bed. the activity, product selectivity and accelerated deactivation of the system were assessed and compared with a conventional single bed react...

The present XANES study aims at elucidating the roles of carbon deposits and metal sulfides in the catalyst deactivation in steam reforming reactions with the presence of sulfur. CeO(2)-Al(2)O(3)-supported Ni and Rh-based catalysts were tested in steam reforming of liquid hydrocarbon fuel containing 350 ppm sulfur for H(2) production at 800 degrees C. The Rh catalyst demonstrated much better su...

Various distillates are treated with hydrogen gas during hydrotreatment in the presence of catalyst in order to reduce the sulfur and aromatic content of the product. Optimal hydrotreater performance is essential for producing Nynas specialty oils, in order to fulfill the planned production volume and to meet the product specification. Loss of catalyst activity is inevitable during the producti...

The deactivation pattern of a “model” Ni/MgO catalyst in the pre-reforming of n-hexane with steam (T, 450 °C; P, 5–15 bar) is reviewed. The influence of the steam-to-carbon ratio (S/C, 1.5–3.5) on the rate of catalyst fouling by coking is ascertained. Catalyst fouling leads to an exponential decay in activity, denoting 1-order dependence of the coking process on active sites availability. Hydro...

The paper relates to a catalyst, comprising copperchromium spinel, coated on carrier γ-Al2O3. The effect of preparation conditions on the active component composition and activity behavior of the catalysts is discussed. It was found that the activity of carbon monoxide, DME, formaldehyde and methanol oxidation reaches a maximum at an active component content of 20 – 30 wt. %. Temperature calcin...

Frequently the activity of fresh catalyst changes with time in use. The decrease or increases of the catalyst activity with time during the course of reaction forces the system to an unsteady state operation ([1], [2], [3], [4] and [5]). One of these catalysts is the copper/zinc oxide catalyst, which is industrially used for methanol production. The activity of copper/zinc oxide catalyst declin...

Highly active, supported Au−Pd catalysts have been tested for catalyzing benzyl alcohol oxidation in a siliconglass micropacked bed reactor. The effects of Au−Pd composition and anion content during catalyst preparation on catalyst deactivation were studied, and a relationship between the deactivation rate and the amount of Cl− and Au used in the catalyst formulation was found. While Au aids in...