Catalyst sintering in fixed‐bed reactors: Deactivation rate and thermal history

Abstract

An experimental study has been carried out of the in situ thermal degradation of a commercial dehydrogenation catalyst in a fixed-bed reactor. The activity of catalyst particles sampled at different reactor positions after several reaction-regeneration cycles has been related to their time-temperature history, according to the following kinetics:-da,/dt=O.147 exp(-73,600/RT)d2The above equation represents the loss of activity under coke-free conditions, that is, activity loss due to sintering. The results of the study show that important differences in catalytic activity can be obtained for different positions of a fixedbed catalytic reactor after several operation-regeneration cycles.

Selective methanation of carbon monoxide over Ru-based catalysts in H2-rich gases

“…At the same time, the catalyst washing with diluted ammonia strongly decreases the chlorine content. These results agree with those of other studies previously reported in the literature [60][61][62].…”

Deactivation Studies of the CrOx/Al2O3 Dehydrogenation Catalysts under Cyclic Redox Conditions

“…The CrOx/Al 2 O 3 catalyst has been the subject of research and development in the field of paraffin dehydrogenation for over 100 years. Previous studies have reported that the potential mechanisms for the deactivation of the CrOx/Al 2 O 3 catalyst include the coke formation; − the irreversible poisoning of the catalyst; the chemical and structural changes of the catalyst, such as CrOx agglomeration; the nature, phase, and structure changes of active sites; and the degradation of the support; etc. − , The deactivation of the CrOx/Al 2 O 3 catalyst within one dehydrogenation cycle has been mainly attributed to the blockage of active sites by carbonaceous species deposited on the catalyst surface. ,, Weckhuysen et al gained insight on the formation and burning of coke deposits on an industrial CrOx/Al 2 O 3 catalyst under reaction conditions using operando ultraviolet–visible (UV–vis) spectroscopy. It was found that the formation of coke during the dehydrogenation step is faster at the top of the reactor as compared to the bottom where coke deposition is a gradual process .…”

Modeling of oxidative dehydrogenation of ethane to ethylene on a MoVTeNbO/TiO2 catalyst in an industrial-scale packed bed catalytic reactor

“…The wall-cooled catalytic reactor with low tube-to-particle diameter ratio (d t /d p < 5) seems a suitable option to commercially achieve the ODH-Et over the MoVTeNbO formulation [24,25], since this configuration and catalyst design promote the fast removal of the heat generated, maximize the desirable product yield, and avoids strong catalyst deactivation by a sintering process [26][27][28][29][30][31][32][33][34], as observed for other well-known studied exothermic partial oxidation reactions. In fact, several researches [35][36][37][38][39][40][41] have considered the wall-cooled packed bed catalytic reactor for simulating the possible performance of the ODH-Et over catalytic systems different to the MoVTeNbO formulation.…”