Catalyst Cycle Life

Commercially available processes for resid HCK deal with catalyst life cycle issues by the use of different catalyst/reactor/configuration arrangements. In Ref. [142], Morel et al. discuss the performance and features of these arrangements. A summary of conditions for each reaction system is collected in Table 11. 

Economics The EBOne process features consistently high product yields over the entire catalyst life cycle, high-product purity, low-energy consumption, low investment cost, and simple, reliable operation. 

In any commercial application, the process economy depends mainly on catalyst life cycle which in turn is a function of catalyst metal retention capacity. The experimental tests have shown that INT-RI catalyst is able to accept a metal content equivalent to 100% without losing significant catalytic activity. Nevertheless, these results guarantee a stable operation with... 

This reaction constitutes a compromise between reactant conversion, product selectivity and catalyst life (cycle length). It is therefore important to fine tune the reaction parameters in order to realize maximum gain from the reaction. Hence an experimental study constituting collection of conversion and yield data as a function of reaction parameters was undertaken with the objective of developing an empirical model and optimizing the reaction parameters. 

Determine gas composition over the catalyst life cycle and compare the purity requirements needed for the shift reactors and pressure swing adsorption unit. 

Complete detailed analysis of the product over the catalyst life cycle. 

At one point in time, however, a catalyst change is required, thus marking the end of a catalyst life cycle. Catalyst (Rh and hgand) should be... 

The surface cleaning consists in removing water vapour or other pollutants adsorbed on the catalyst. This step should be chosen according to the catalyst nature and catalyst life cycle. For instance, the cleaning conditions should be determined in function of the treatments performed on the catalyst. In case of a new catalyst the promoters of metal deposition should be removed to avoid any... 

The dehydrogenation of 2-butanol is conducted in a multitube vapor-phase reactor over a zinc oxide (20—23), copper (24—27), or brass (28) catalyst, at temperatures of 250—400°C, and pressures slightly above atmospheric. The reaction is endothermic and heat is suppHed from a heat-transfer fluid on the shell side of the reactor. A typical process flow sheet is shown in Figure 1 (29). Catalyst life is three to five years operating in three to six month cycles between oxidative reactivations (30). Catalyst life is impaired by exposure to water, butene oligomers, and di-j -butyl ether (27). 

Regenerahility often is also a requirement. In the life cycle of a catalyst the most severe conditions are not always the reaction conditions regeneration conditions may well be more severe that the regular reaction conditions. Examples are hydrogenation catalysts that are regenerated by oxidative treatment in diluted oxygen. These catalysts must be resistant to oxidative treatment at high temperatures. This makes alumina a suitable carrier for these processes. 

One of the main concerns for resid HDT catalysts is the life cycle, since it is shorten by the deactivating reactions (formation of ammonia, from HDN coke from poor hydrogenation, and metals accumulation from demetallization, etc.) and the complexity of the... 

Eijsbouts, S., Life Cycle of Hydroprocessing Catalysts and Total Catalyst Management, In Hydrotreatment and Hydrocracking of Oil Fractions. 1999, Elsevier Science B. V New York, NY. pp. 21-36. 

In the lubricant sector, oleochemically-based fatty acid esters have proved to be powerful alternatives to conventional mineral oil products. For home and personal care applications a wide range of products, such as surfactants, emulsifiers, emollients and waxes, based on vegetable oil derivatives have proved to provide extraordinary performance benefits to the end-customer. Selected products, such as the anionic surfactant fatty alcohol sulfate, have been investigated thoroughly with regard to their environmental impact compared with petrochemical based products by life-cycle-analysis. Other product examples include carbohydrate-based surfactants as well as oleochemical based emulsifiers, waxes and emollients. The catalysts used in the synthesis of these molecules need further development. 

The reaction can be controlled in an aqueous medium via pH and the use of a catalyst [91]. While the material hydrogen capacity can be high and the hydrogen release kinetics fast, the borohydride regeneration reaction must take place off-board. Regeneration energy requirements, cost and life-cycle impacts are key issues... 

Handbook of Green Chemistry and Technology, J. H. Clark and D. J. Macquarrie, Eds., Blackwell Publishing 2002, 540 pp., ISBN 0-632-05715-7. This collection of 22 review essays covers all the important areas of green chemistry, including environmental impact and life-cycle analysis, waste minimization, catalysts and their industrial applications, new synthesis methods, dean energy, and novel solvent systems. The chapters are well referenced and contain pertinent examples and case studies. 

Figure 3.59 Life cycles of catalysts for olefin coordination polymerisation (a) early-generation Ziegler-Natta catalysts for ethylene and propylene polymerisation (b) Phillips catalysts for ethylene polymerisation (c) fourth-generation Ziegler-Natta catalysts for ethylene polymerisation (d) fourth-generation Ziegler-Natta catalysts for propylene polymerisation (e) metallocene-based catalysts for olefin polymerisation leading to polymers of various stereoregularity...

During a cell s normal life cycle under aerobic conditions, some of the consumed oxygen is reduced to highly reactive molecules called reactive oxygen species (ROS). Transition metal ions such as iron, with their frequently unpaired electrons, act as excellent catalysts for the creation of ROS. The body s inability to modulate free iron availability creates an environment prone to the formation of ROS and free-radical induced cellular damage in the event of iron overload. The classical reaction between Fe3+ and superoxide (02 ) is known as the Haber-Weiss reaction ... 

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