Hydrogen recycling process

T. Tanabe, Reconsideration of Hydrogen Recycling Process at the First Wall, Proc. The 4" Int. WS on Tritium Effects in Plasma Facing Components, Santa Fe, New Mexico, 47-49 (1998). 

The catalyst is then transferred back to the first process reactor and is reheated to the reforming process temperature at the reactor inlet using a flow of hydrogen-rich process recycle gas, thereby achieving reduction of the platinum to a catalyticaUy active state. 

Finally, these aqueous suspensions of rhodium(O) and iridium(O) are the most efficient systems for the hydrogenation of a large variety of mono-, di-substituted and/or functionalized arene derivatives. Moreover, in our approach, the reaction mixture forms a typical two-phase system with an aqueous phase containing the nanoparticle catalyst able to be easily reused in a recycling process. 

HARP [Hybrid argon recovery process] A process for extracting argon from the hydrogen recycle stream in ammonia synthesis. Both PSA and a cryogenic process are used. Krishnamurthy, R., Lemer, S. L., and MacLean, D. M., Gas Sep. Purif, 1987,1, 16. 

Recently, Dupont and coworkers described the use of room-temperature imi-dazolium ionic liquids for the formation and stabilization of transition-metal nanoparticles. The potential interest in the use of ionic liquids is to promote a bi-phasic organic-organic catalytic system for a recycling process. The mixture forms a two-phase system consisting of a lower phase which contains the nanocatalyst in the ionic liquid, and an upper phase which contains the organic products. Rhodium and iridium [105], platinum [73] or ruthenium [74] nanoparticles were prepared from various salts or organometallic precursors in dry 1-bu-tyl-3-methylimidazolium hexafluorophosphate (BMI PF6) ionic liquid under hydrogen pressure (4 bar) at 75 °C. Nanoparticles with a mean diameter of 2-3 nm... 

The effects of added C02 on mass transfer properties and solubility were assessed in some detail for the catalytic asymmetric hydrogenation of 2-(6 -meth-oxy-2 -naphthyl) acrylic acid to (Sj-naproxen using Ru-(S)-BINAP-type catalysts in methanolic solution. The catalytic studies showed that a higher reaction rate was observed under a total C02/H2 pressure of ca. 100 bar (pH2 = 50bar) than under a pressure of 50 bar H2 alone. Upon further increase of the C02 pressure, the catalyst could be precipitated and solvent and product were removed, at least partly by supercritical extraction. Unfortunately, attempts to re-use the catalyst were hampered by its deactivation during the recycling process [11]. 

Bascones, E., Imperial, J., Ruiz-Argueso, T. and Palacios, J. M. (2000) Generation of new hydrogen-recycling rhizobiaceae strains by introduction of a novel hup minitransposon [In Process Citation]. Appl. Environ. Microbiol., 66, 4292-9. 

Recycling of algal cells after hydrogen evolution process. 

Figure 15. Applications map for hydrogen recovery process A, ammonia purge gas B, refinery stream C, coal conversion recycle gas D, ethylene plant cracked gas E, FCC minus gas...

Scheme 3.2 shows recently established industrial processes for PO production. The cumene recycling process uses an organic hydroperoxide process combined with hydrogenation of cumyl alcohol to cumene. This process consumes only hydrogen... 

The major process variables are (1) reactor temperature (2) hydrogen pressure (3) liquid hourly space velocity and (4) hydrogen recycle rate. Other variables such as reactor type and catalyst type have been discussed in an earlier part of this chapter, while the influence of the feedstock type will be discussed in a later chapter (Chapter 6). 

Scheme 3.6 Reaction, separation, and recycling processes in hydrogenation of a, / -unsaturated aldehydes with Ru complex catalyst under gas (H2, C02)-liquid (PEG) biphasic conditions (Reproduced from Ref. [39] with permission from The Royal Society of Chemistry)...

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