3 replies to this topic

[polipo]

Dear all,

Now I'd like to test the catalyst (Pd/Al2O3) performance of C4-hydrogenation reactor (Packed bed reactor/totally liquid phase). I want to know that apart from conversion, which other possible variables and methods I can check. Selectivity is not important because all the products totally are single-bonded. The purposes of the test are to inspect the catalyst's performance and predict its remaining lifetime. Hot spot in reactor and channelling are the malfunctions in the reactor. Actually, the simply basic target and approach is to compare with the design of the catalyst which is 100% conversion. Anyway, I need other way to test it so that it can support the result. If the result is not total conversion, other result could assure that it results from the deactivation of the catalyst which may be aging or poisoning, not from channelling or too-short residence time. I have only 3 weeks left to check it. Please help me, just simple way is fine.

Thank you for you assistance.

[kkala]

Now I'd like to test the catalyst (Pd/Al2O3) performance of C4-hydrogenation reactor (Packed bed reactor/totally liquid phase). I want to know that apart from conversion, which other possible variables and methods I can check. Selectivity is not important because all the products totally are single-bonded. The purposes of the test are to inspect the catalyst's performance and predict its remaining lifetime. Hot spot in reactor and channeling are the malfunctions in the reactor. Actually, the simply basic target and approach is to compare with the design of the catalyst which is 100% conversion. Anyway, I need other way to test it so that it can support the result. If the result is not total conversion, other result could assure that it results from the deactivation of the catalyst which may be aging or poisoning, not from channelling or too-short residence time.

Probably you have to contact catalyst supplier for this issue. Following may be trivial (or barely applicable), for I do not have practical knowledge on the matter (more data would have probably helped).
Principal question is apparently "how to distinguish between catalyst deactivation and channeling, in case of low conversion".
1. In order to verify channeling, check whether ΔP is high enough through each catalyst bed by direct measurement during reactor operation. Small ΔP indicates channeling. Same for liquid temperatures before and after each catalyst bed, small Δt indicates channeling (pressures may give more precise results).
2. Visually inspection of the catalyst beds can spot channeling. Channeling is usually auto-developped, so big cracks can be observed on the bed. Solid catalyst masses due to sintering, if spotted, also cause channeling.
3. Visually check liquid distributor system into reactor, any plug or damage can cause channeling.
4. Probably a residence time distribution (RTD) measurement by injecting an inert tracer during reactor operation can "diagnose" channeling. See Perry, "Residence time distribution and reactor efficiency" (p. 23-15 to 23-23 in 7th edition). Besides books on reaction engineering (e.g. "Chem Engineering kinetics" by Smith, Levenspiel, etc) report catalyst deactivation, channeling, etc, probably with some ways to cure.
Above had better be done before the test, to "cure" channeling before it. If there is enough certainty of no channeling, catalyst deactivation has be assumed. Status of catalyst can be grossly assessed in advance by sending it to special institutions for measurements (active centers, poisons, etc).

[Zauberberg]

I don't know if this is applicable for your case, but normally what we used to do in Refinery was to send a sample of the catalyst to the vendor for detailed analysis. They are the most qualified to address of questions of interest related to the catalyst performance.

[kkala]

I don't know if this is applicable for your case, but normally what we used to do in Refinery was to send a sample of the catalyst to the vendor for detailed analysis. They are the most qualified to address of questions of interest related to the catalyst performance.

Provision for catalyst sampling is usually realized (according to my information) through catalyst "baskets" embedded in the catalyst bed. Every "busket" (containing the catalyst) is a sieve with a solid handle, so that the whole can be grabbed and taken away by hand. This catalyst sample is brought to special institutions (or to catalyst supplier) for assessment.