Zeolites cracking catalysts

Zeolite Y, 2 345t, 5 238-239, 11 678, 679 coke formation on, 5 270 for liquid separation adsorption, 1 674 manufacture, 2 359 structure, 1 675 Zeolite ZSM-5, 11 678 Zeolitic cracking catalysts, 16 835 Zeolitic deposits, 16 813 Zeonex, 10 180 Zeotypes... 

Table 2. Microactivity test results for several pillared clay catalysts after calcination in air at 400 C for lOh. The zeolitic cracking catalyst has been aoed for 5 hours at 760 C with 100% steam at 1 atm. ...

The Use of Rare Earth Elements in Zeolite Cracking Catalysts... 

Following their introduction to the refining industry in 1962, zeolite cracking catalysts, have virtually replaced the amorphous silica alumina cracking catalysts that had previously dominated the marketplace. To the rare earth industry the development of zeolite catalysts represented a new end use without precedent. Nearly all zeolite cracking... 

Since 1962 rare earths have been used to stabilize zeolite cracking catalysts for the petroleum industry (1, 2. Until recently this application to catalysis has been the only commercially significant one. Currently, however, a number of new applications of potential commercial significance are appearing. One of the most important of these is the use of cerium in catalysts for automobile exhaust emission control. We will emphasize this application in our review without neglecting other applications. 

The revolutionary zeolite cracking catalyst (synthetic Linde X and Y) was introduced commercially over 28 years ago, but considerable effort is still being expended on the improvement of its stability and catalytic properties. Decreasing the aluminum content of the zeolite framework and the replacing the rare-earth with the hydrogen form have greatly increased activity at the expense of stability. The thermal stability of the faujasites is fairly well understood, while the reasons for the increased catalytic activitity are still not fully known. 

In zeolites, cracking catalysts and in activated carbons we deal in many cases with a combination of microporosity, mesoporosity and macroporosity. Here the isotherms are type I + type IV. Strictly speaking, BET analysis is not allowed here nevertheless it is frequently applied. 

A more recent development in fixed bed residue processing is the use of zeolitic cracking catalysts. These have been developed primarily in Japan, and are quite stable according to the literature (64). 

More specifically, over microporous catalysts such as zeolites, cracking catalysts and clays, the lower the catalyst acidity ... 

One of the simplest ways of extending this single-pore model is to assume that variations in the size of pore spaces can be represented by a variable-diameter assembly of such pores, referred to as a parallel bundle of pores. An example is shown in Fig. 3, for a variation of the model applied to a supported zeolite cracking catalyst. In this example [10] the zeolite pores are simply configured along the pore walls, so that the parallel bundle represents the Si/Alumina-support pore spaces. 

In many cases the temperature of desorption of the ammonia can be correlated to the acid strength (intensive factor) of the sites. Corma and coworkers correlated the information given by ammonia TPD with the acidity for various zeolite cracking catalysts. Similarly, Figure 3 shows a relationship obtained in the author s laboratory... 

Plank, C.J. The invention of zeolite cracking catalysts. Chem. Tech. 1984, April, 243. 

We launched an Intensive effort to develop these highly ordered crystalline zeolites for commercial use, and by the early 1960s we commercialized the first synthetic zeolite cracking catalyst (Refs. 2,3). This catalyst was derived from a synthetic faujasite, first made by Union Carbide. Converting the faujasite into a useful cracking catalyst was a rather involved procedure, incluoing the removal of sodium, the introduction of rare earth, and severe steam treatment. 

We introduced the first zeolite cracking catalyst at one of our refineries in 1962 (Ref. 4). It was like a shot heard around the world. Figure 1 shows why. 

Over the years, the savings in petroleum resources have been enormous. In the U.S. alone, the zeolite cracking catalyst has saved the U.S. petroleum industry the equivalent of some 3.5 billion barrels (500 million tonnes) of crude oil since 1962. It lowered crude imports even more and enabled industry to produce higher gasoline volumes without additional investments in refinery expansion. 

The success of the zeolite cracking catalyst led to a more intense catalyst research effort in Mobil — and to more milestones. At first our choice of zeolites was very limited. Most zeolites were naturally occurring, and those that were synthetic, like faujasite, tended to replicate natural materials. 

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