Hydrogen production through steam reforming of ethanol was investigated with conventional supported nickel catalysts and a Ni-containing smectite-derived catalyst. The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition. Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these...

The aim of this work was to study the possible deactivation effects of biogas trace ammonia concentrations on methanation catalysts. It was found that small amounts of ammonia led to a slight decrease in the catalyst activity. A decrease in the catalyst deactivation by carbon formation was also observed, with ammonia absorbed on the active catalyst sites. This was via a suppression of the carbo...

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...

Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation JAVIER BARRIENTOS Akademisk avhandling som med tillstånd av KTH i Stockholm framlägges till offentlig granskning för avläggande av teknologie doktorsexamen fredagen den 23 september kl. " True wisdom comes to each of us when we realize how little we understand about life, ourselves, and the world around us....

Dehydration of methanol to produce dimethyl ether (DME) was studied at relatively high temperatures (400–600 °C) on biomass-derived phosphorus-containing carbon impregnated with a zirconium salt. Highly thermally stable phosphate surface groups could be obtained the final catalyst, which were responsible for stability and selectivity DME catalyst lower than 400 °C. However, harder operation con...

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 purpose of this study is to identify the deactivation mechanism(s) that occurs during aromatization dilute ethylene at 500 °C on Zn/H-MFI catalyst. More than 15 catalysts, with a Zn/H+ molar ratio ranging from 0 (H-ZSM5) 1.8 (Zn/H-ZSM5), were prepared by wet impregnation. Deactivation does not result Zn sublimation, but coking. function and coke deposition can be modelled simple exponential...

The commercial application of cobalt-based Fischer-Tropsch synthesis (FTS) suffers from catalyst deactivation. One the main deactivation mechanisms under industrial conditions is sintering. In this work, we explored role manganese oxide as a structural promoter against sintering in carbon nanofiber supported cobalt model catalyst. We employed situ Mössbauer emission spectroscopy to study gas fu...

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...