EFFECT OF POROSITY OF CARBOGENIC MOLECULAR-SIEVE CATALYSTS ON ETHYLBENZENE OXIDATIVE DEHYDROGENATION

Citation
Ms. Kane et al., EFFECT OF POROSITY OF CARBOGENIC MOLECULAR-SIEVE CATALYSTS ON ETHYLBENZENE OXIDATIVE DEHYDROGENATION, Industrial & engineering chemistry research, 35(10), 1996, pp. 3319-3331
Citations number
39
Categorie Soggetti
Engineering, Chemical
ISSN journal
08885885
Volume
35
Issue
10
Year of publication
1996
Pages
3319 - 3331
Database
ISI
SICI code
0888-5885(1996)35:10<3319:EOPOCM>2.0.ZU;2-7
Abstract
The conversion of ethylbenzene to styrene by oxidative dehydrogenation is compared over several carbogenic molecular sieves. At 300 degrees C, Carbosieve G deactivated rapidly due to its nanoporous structure. D uring deactivation, the apparent activation energy dropped nearly a fa ctor of 2 with a corresponding pore volume decrease from 87 to 15 mg/g . The carbogenic Ambersorb adsorbents have meso- and macroporosity in addition to nanoporosity. With 1% oxygen in the feed and at 400 degree s C, the rates of coke deposition on Ambersorb 563 were below measurab le levels. The initial yield of styrene was over 70% and slowly fell t o 55% with time on stream. For Carbosieve G under the same conditions, the initial yield rose rapidly to 70% but then fell to approximately 10%. The differences in these materials can be attributed to the effec ts of differences in pore structure and their influence on the coupled reaction and diffusion phenomena. These results indicate that carboge nic catalysts can produce commercially relevant levels of styrene with minor deactivation, providing the pore structure includes substantial amounts of transport porosity and the oxidizing potential of the gas phase is mediated properly.