Catalyst crush strength

Sphere> pellet > trilobe > hollow extrudate > wagon wheel/ minilith The definitive catalyst size selection will be a compromise between high reaction rate (small partiele, exotic shape), low pressure drop (large particle, exotic shape), large crushing strength... 

For regeneration to be technically viable, it must be able to remove deposited vanadium and nickel quantitatively as well as the carbonaceous coke which was co-deposited. The catalyti-cally active metals should remain unaffected in amount, chemistry, and state of dispersion. The alumina support should remain intact, with the surface area, pore-size distribution and crush strength after treatment comparable to that of the original. To be economically viable, the process should be accomplished in a minimum of steps at nearly ambient temperatures and preferably in aqueous solution. The ultimate proof of any such scheme is for the catalytic activity of the regenerated catalyst to be equal to that of a fresh one. 

Nickel and Other Base Metal Catalysts. Supported Ni is widely utilized as a catalyst for the industrial SR of hydrocarbons. The type of feedstocks and reaction conditions used for SR determine the choice of support, promoter, and loading of Ni. Typically, 15-25% nickel oxide loading is used in commercial SR catalysts. These supports must have high crush strength and stability so they can sustain severe reaction conditions. 

A with macropore diameters of 1000 to 5000 A. The pore volume and the pore size distribution within a porous support determine its surface area. The surface area of supports can range from 0.06 m2/mL (18,300 ftVft3) to 600 m2/mL (1.83 x 108 ffVft3) and above. Higher pore volume catalysts have higher diffusion rate at the expense of reduced crush strength and increased particle attrition. 

Characterization, as it applies to catalyst science, is usually used to describe both the performance characteristics (evaluation) and the physical attributes (analyses) of the materials under investigation. Personnel involved in catalyst evaluation utilize custom designed equipment to determine the performance of a catalyst in a particular process. The design of the equipment typically follows that of the process, but on a much smaller laboratory scale. These simulations attempt to "mimic" the process, or parts of the process, and as such the data generated are relative not only to the process but to the test equipment and conditions (see Dartzenburg). Conversion, activity, stability, abrasion resistance, crush strength, etc. are terms often encountered in evaluation. Analysis, on the other hand, describes or measures the physical quantities of size or mat-... 

Neal (14), and Bertolacini (15). Similar standardization groups have since been formed in Japan, United Kingdom, Europe, and the Soviet Union. Twenty-five standards have been developed by the American Society for Testing Materials Committee D-32--Catalysts including tests for attrition, crush strength, particle size distribution, and vibrated apparent packing density (16). 

Single-Pellet Crush Strength Testing of Catalysts... 

With the development of catalytic processes such as reforming, hydrocracking and hydrotreating, which utilize formed particles, single pellet crush strength tests were devised by the manufacturers and users of such catalysts. These tests were developed in order to determine the ability of the catalyst particles to maintain integrity during use in catalytic reactors. (2)... 

Results of the second round robin testing of spheres and tablets are shown in Tables I and II. These data are included in ASTM Research Report Number 1004 for Standard Test Method D-4179 for Single Pellet Crush Strength of Formed Catalyst Shapes. 

Figure 1. Method of test for radial crush strength of extruded catalyst shapes.

A test method for single pellet crush testing of catalytic spheres and tablets was developed by ASTM Committee D-32 on Catalysts. A procedure for the single pellet crush strength of extrudates that gives satisfactory interlaboratory variation is yet to be attained. An alternate method will test the assumption that the inter laboratory variations, seen in all round robins, were caused by moisture absorption during testing and the use of a specialized anvil in the test instrument. 

Through a series of round robin tests conducted by participating laboratories, ASTM Committee D-32 on Catalysts has characterized a variety of catalyst materials using standard test methods. Materials include fluid cracking catalysts, zeolites, silicas, aluminas, supported metals, and a gas oil feedstock. Properties characterized include surface area, crush strength, catalytic microactivity, particle size, unit cell dimensions and metal content. These materials are available from the National Institute of Standards and Technology as reference materials. 

Although several standard test methods have been developed for the chemical analysis of catalysts only small samples of supported platinum and palladium reference materials are available. Zeolites have been characterized for zeolite area, unit cell dimensions, and relative x-ray diffraction intensity. The crush strength of alumina pellets has also been determined. As the needs of catalyst users and producers change so will the materials characterized. To the extent that adequate amounts of material can be donated, standard test methods developed, and round robin tests performed Committee D-32 on catalysts will continue to make them available through NIST as reference materials. 

Performance depends abov all on the in which the catalyst is employed, and this takes place in two dififerent ways, isothermal and adiabatic Hence the same catalyst formula offers greater abrasion resistance and crushing strength characterized by a lower water to ethylbenzene w dght ratio at the reactor inlet and longer life if operation is isothermal The steam ratio is usually 110 1,2 in this case as compared with 1.6 to 2.5 in adiabatic conditions, and the corresponding lives are 5 to 6 years, against 18 months to 2 years. The essential reason for these differences is the lower feed preheat temperature... 

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