Results continuous catalyst regeneration

None of the above properties and characteristics act independently. When one among them is changed with a view to improvement, the others are also modified and not necessarily in the direction of an overall improvement. As a result, industrial catalysts are never ideal. Fortunately, however, the ideal is not altogether indispensable. Certain properties, such as activity and reproducibility, are always necessary, but selectivity, for example, has hardly any meaning in reactions such as ammonia synthesis, and the same holds true for thermal conductivity in an isothermal reaction. Stability is always of interest but becomes less important in processes that include continuous catalyst regeneration. Regenerability must be optimized in this case. 

Exceptional results were obtained in a test on naphtha reformer catalyst which utilized a continuous catalyst regeneration section. In this type of service, it is possible for a graphitic carbon deposit to build up over a period of time. This form of carbon does not regenerate easily. When is does burn, the localized high temperatures generated can collapse the catalyst structure resulting in a low surface area inactive pellet. 

Until recently only a few papers were available on moving beds in cross flow [11-18]. This type of reactor is sometimes a favorable process solution for a selective catalytic process with a moderate catalyst rcsidence time and with a short gas residence time, especially when the process is accompanied by a continuous catalyst regeneration. The use of conventional short-contact-time reactors like fluidized-bed reactors, risers, and fixed-bed reactors does not always yield satisfactory results. This may be explained by problems connected with gas back-mixing, channeling of gas, low catalyst holdup, attrition of the solid catalyst, or difficulties in temperature control. 

Since the first catalytic reformers were used in the 1950s the hydrogen/ hy-drocaibon mole ratio and the reformer operating pressure have both been gradually decreased. These developments resulted from improvements in the alumina support, the use of bimetallic catalysts, and finally the introduction of the low-pressure, continuous catalyst regeneration processes. The trends in operation are shown in Table 6.18. 

I. G. Farben also produced butene by butane dehydrogenation. A moving catalyst bed system was used in a tubular reactor. The total catalyst charge was 1.5 tonnes with a residence time of 4 h in the tubes. Yields of 85% at 20-25% conversion were obtained at a liquid space velocity of 2 h and 620°-650°C operating temperature. This was an impressive result for a new reactor design that has now been developed as the continuous catalyst regeneration process and is widely used in refineries. 

A good example of the ruggedness of the beta zeolite catalyst can be found in the case of JLM s Blue Island (Illinois) Q-Max operation. The operation started in August 1996 as the first Q-Max process operation with UQP beta zeolite catalyst. Initial operating results were reported in 1997. The unit has continued to operate with stable performance for more than 7 yr without catalyst regeneration in spite of the presence of significant levels of feed contaminants. 

Mol sieves are routinely used for drying a number of reaction feeds to very low water levels. This is particularly important where expensive catalysts are susceptible to wet feed. Pervaporation has the advantage of continuous, steady operation, minimizing operational upsets, which can result from sieve regeneration. Simpler systems are especially attractive where toxic materials are involved. 

The term "catalyst" was first introduced in 1836 by Berzelius and was defined in 1894 by Otswald. Otswald stated that a catalyst is a substance that increases the rate of a chemical reaction without itself being consumed. This basic definition continues to be commonly used. During a catalytic reaction, the catalyst undergoes a series of transformations to generate product, and this series of reactions must regenerate the starting catalyst. As a result, the catalyst can be used in substoichiometric amounts relative to the reagents. 

In the pilot-scale experiments, the continuous reaction-regeneration is also investigated. The details of the results will not be discussed here. However, we wiU focus on the influence of the average residence time and catalyst to methanol on the MTO reaction in pilot-scale fluidized bed reactor. 

Cu(l)X is needed for activation, these methods utilize chemical additives [101] or electrochemical equipment (i.e., electrodes) [102] to recycle generated CullllX back to Cu(l) X. One example for a novel method is initiators for continuous activator regeneration (ICAR) which uses a radical sources [e.g., azobisisobutyronitrile (AIBN)] to convert the in situ formed Cu(ll)X2 back to Cu(l)X [101]. As a result, ICAR ATRP only requires 10-50ppm catalyst. 

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