Catalyst life testing units

Fig.2. HBr conversion during catalyst life testing in single full-scale reactor tube showing high conversion throughout the test. The brief time at lower conversion was due to a unit upset.

The findings from two long term test runs in the SASOL plant relevant to catalyst life under design conditions in a commercial methane synthesis plant have already been published (3). This paper reports further test results from both demonstration units concerning the effect of certain reaction parameters which are the basis for flexibility and operability of the Lurgi methanation scheme. 

Fig. 1. Schematic of the pilot unit used for catalyst life and heat management testing.

Relationship between Liquid Mass Velocity and Catalyst Life. The laboratory test units were operated with a catalyst system composed of demetallization and... 

Having defined process conditions to obtain satisfactory gasoline yield, acceptable product quality, and adequate catalyst life in bench-scale tests, fixed-bed MTG development would normally be considered complete, and the process ready for commercialization. However, to obtain large quantities of gasoline for testing and to confirm scale-up, a demonstration unit with a capacity of 4 B/D of methaijol was built and operated. 

It is necessary to determine rj(e) under reaction conditions, and a life test should be included in any catalyst development effort. The data from this test will allow r] to be fitted as a function of time on stream, 6. Equations 10.35 and 10.36 can obviously be used to model deactivation processes other than site sintering, and ko can be regarded as an empirical constant with units of reciprocal time. 

The Amoco Oil Company developed an ITSL process very similar to HRFs CTSL process. The main differences were the use of a higher-temperature, smaller-volume, thermal first-stage TLU and a lower temperature in the catalytic hydrotreater. This process was tested on HRFs bench-scale unit. The higher temperature in the TLU (820-850°F, 438-455°C) resulted in a 30 percent higher gas yield than HRFs CTSL process, whereas the lower temperature in the HTR (ca. 700°F, 370°C) contributed to longer catalyst life. However, the distillate yield for the Amoco process was considerably lower than that of HRFs CTSL process. 

Stability tests of catalyst. All catalysts deactivate during their life by various causes (see Chapter 3). The aim of stability tests is to examine the cause and rate of deactivation. These experiments are usually performed at conditions similar to those planned for the commercial unit. In some cases, accelerated tests are carried out using a feedstock with an elevated level of impurities or at a temperature significantly higher than that anticipated for the full-scale reactor. A laboratory reactor used for such tests is usually a down-scaled reactor or a part of the full-scale-reactor. Standard analytical equipment is used. 

Three reviews have been made (22,25,26) the latest (26) summarized Bureau of Mines tests of nitrided iron in fluid-bed, slurry, and oil circulation reactors of small pilot-plant size. In these units the nitrides operated nicely, having the longest life of any catalyst used in these reactors. The yields of C and Cp hydrocarbons and oxygenates are often larger than some would like. 

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