Advances in Catalyst Deactivation and Regeneration

Abstract

Catalyst deactivation, the loss over time of catalytic activity and/or selectivity, is a problem of great and continuing concern in the practice of industrial catalytic processes. Costs to industry for catalyst replacement and process shutdown total tens of billions of dollars per year. While catalyst deactivation is inevitable for most processes, some of its immediate, drastic consequences may be avoided, postponed, or even reversed through regeneration.Accordingly, there is considerable motivation to better understand catalyst decay and regeneration. Indeed, the science and technology of catalyst deactivation and regeneration have been developing rapidly as evidenced by the considerable literature addressing these topics, including about 24,000 journal articles, presentations, reports, reviews, and books; and more than 33,500 patents for the period of 1980 to 2015. About 15% of this literature appeared in the last three years, a rate of growth double that of the past 35 years. New insights into the science of catalyst deactivation and regeneration are laying the foundation for new developments in the technology, e.g., for substantial improvements in catalyst stability and catalyst deactivation models leading to better process economics, and more effective regeneration processes.Research and development activities in catalyst deactivation and regeneration range over a broad spectrum, which includes (1) fundamental and applied studies of deactivation and regeneration at the nano, micro, and reactor scales to understand mechanistic, process, and catalyst chemistries; (2) laboratory reactor studies of deactivation and regeneration rates to develop reaction kinetics and process variable-rate relationships important in scale-up; and (3) development of models of deactivation and regeneration processes at the catalyst surface, pellet, reactor, and process scales for controlling, optimizing, and scaling-up these processes. OPEN ACCESS

Catalytic Conversion of Furan to Hydrocarbons using HZSM‐5: Coking Behavior and Kinetic Modeling including Coke Deposition

“…Selectivity changes of hydrocarbons with coke content are shownF igure 4a tt he pyrolysis temperature of 600 8C, WHSVof1 1.2 h À1 ;a nd partial pressureo f1 2.31 Torr (1 Torr % 133 Pa).F igure 4s hows the selectivity variation compared with the initial value.T he results showedc learly that selectivities to propylene and C4 + C5 increased with coke content initially,i ndicating that moderate coke accumulation will promote the catalyst and shape the selectivities.T he initial coke deposition would decoratet he catalyst pores and changet he catalyst shape selectivity.I ti sa cceptable that changes in the product selectivity caused by coke deposition on the zeolite may be attributed to changes in the intrinsic reaction,c atalyst acidity, and shape selectivity. [27,28] Thed ata above present constant selectivitiest oh ydrocarbons at different conversions for the fresh catalyst, which is apparent from the almostl inear OPE curves.T his means that the conversion itself will not change the product selectivity and the influence of conversion can be neglected. Ac age is regarded as am icroreactor, and the coke formationl ed to ad ecrease in the number of microreactors.T he number of active sites per reactor was 0.8 as predicted.…”

“…The initial coke deposition would decorate the catalyst pores and change the catalyst shape selectivity. It is acceptable that changes in the product selectivity caused by coke deposition on the zeolite may be attributed to changes in the intrinsic reaction, catalyst acidity, and shape selectivity . The data above present constant selectivities to hydrocarbons at different conversions for the fresh catalyst, which is apparent from the almost linear OPE curves.…”

New trends in improving gasoline quality and octane through naphtha isomerization: a short review

“…Table 4 shows the maximum tolerable limit of various contaminants in the feedstock stream. The zeolite-based catalysts have maximum tolerance for the impurities, and chlorinated alumina has the minimum tolerance for the impurities [24]. Whereas mixed metal oxide catalysts lie in between both of them and have intermediate characteristics of both the zeolite and chlorinated alumina catalyst.…”

Regeneration/Optimization of Activated Carbon Monolith in Simultaneous SO2/NOx Removal from Flue Gas

“…Regeneration of the spent catalyst is highly important in terms of the economic feasibility of the adsorption process, since the adsorption capacity of the spent adsorbent can be restored through the regeneration process. Regeneration processes can clean large volumes of flue gases at a competitive cost without substantial loss of adsorption capacity [6]. Thermal regeneration is one of the most common regeneration methods and can be done in various atmospheres, such as steam, carbon dioxide, or inert gas [7].…”