Gas separation: processes – Solid sorption – Including reduction of pressure
Patent
1998-01-21
1999-06-15
Spitzer, Robert
Gas separation: processes
Solid sorption
Including reduction of pressure
95130, 95139, 95140, 95143, B01D 5347
Patent
active
059124229
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for the purification of hydrogen-based gas mixtures contaminated by various impurities, including carbon monoxide and at least one other impurity chosen from carbon dioxide and saturated or unsaturated, linear, branched or cyclic C.sub.1 -C.sub.8 hydrocarbons.
The process of the invention makes it possible in particular to improve the conventional processes for the separation of hydrogen of PSA type, or pressure-swing adsorption processes, using zeolites as adsorbent.
BACKGROUND OF THE INVENTION
The production of high-purity hydrogen is of great interest industrially, the latter being widely used in many synthetic processes, such as hydrocracking, the production of methanol, the production of oxoalcohols and isomerization processes.
In the prior art, PSA processes have proved to be very efficient in the separation of gas mixtures and in particular in the production of pure hydrogen or oxygen from gas mixtures contaminated by various impurities. PSA processes take advantage of the adsorption selectivity of a given adsorbent for one or a number of the contaminating substances of the gas mixture to be purified.
The choice of the adsorbent is problematic: it depends, on the one hand, on the nature of the mixture to be treated. As a general rule, the adsorbents are selected according to their ability to adsorb and to desorb a specific compound. In fact, PSA processes involve the operation of pressure cycles. In a first phase, the adsorbent bed separates at least one constituent of the mixture by adsorption of this constituent on the adsorbent bed. In a second phase, the adsorbent is regenerated by lowering the pressure. At each new cycle, it is therefore essential for the desorption to be efficient and complete, so that there is an identical regenerated state at each new cycle. However, it is clear that this ability to adsorb and then desorb a specific constituent of a gas mixture is a function of the specific operating conditions of the PSA process envisaged and in particular of the temperature and pressure conditions.
A distinction must therefore be made between PSA processes intended for the production of oxygen, which generally operate at adsorption pressures of less than 5.times.10.sup.5 Pa, and PSA processes intended for the production of hydrogen, which can involve adsorption pressures of between 5.times.10.sup.5 and 70.times.10.sup.5 Pa.
However, insofar as the mixture to be purified generally comprises more than one impurity, it is desirable for the adsorbent to be able to adsorb and then desorb not one alone but a number of these impurities.
In point of fact, the adsorption profile and selectivity for a given constituent are often influenced by the presence, in the gas mixture, of other impurities, this being due, for example, to possible competition or to poisoning of the adsorbent.
These various considerations account for the complexity of the problem of the optimization of PSA processes by improvement of the adsorbent.
Recent studies have shown that, in the case of mixtures containing nitrogen, oxygen, hydrogen, methane and argon or helium, lithium-exchanged zeolites make possible a marked improvement in the performance characteristics. The result in particular of the various research studies carried out is that the selection criteria to be taken into account in choosing the adsorbent are its nitrogen adsorption capacity, its nitrogen/oxygen selectivity, its mechanical strength (the packing of the adsorbent having to be possible over a certain height, without crushing) and the pressure drop occasioned, this naturally being the situation in the case of gas mixtures comprising both nitrogen and oxygen for the purpose of purification of the oxygen.
Reference will be made, for example, to documents U.S. Pat. No. 5,152,813 and U.S. Pat. No. 5,258,058 and to Patent Application EP-A-0,297,542, which describe the use of lithium-exchanged zeolites of type X in PSA processes intended for the production of oxygen.
The teaching of these documents, h
REFERENCES:
patent: 2882244 (1959-04-01), Milton
patent: 3140933 (1964-07-01), McKee
patent: 3150942 (1964-09-01), Vasan
patent: 3430418 (1969-03-01), Wagner
patent: 3702525 (1972-11-01), Simonet et al.
patent: 3986849 (1976-10-01), Fuderer et al.
patent: 4077779 (1978-03-01), Sircar et al.
patent: 4153428 (1979-05-01), Saunders et al.
patent: 4322394 (1982-03-01), Mezey et al.
patent: 4381189 (1983-04-01), Fuderer
patent: 4477267 (1984-10-01), Reiss
patent: 4696680 (1987-09-01), Ghate et al.
patent: 4813980 (1989-03-01), Sircar
patent: 4859217 (1989-08-01), Chao
patent: 4957514 (1990-09-01), Golden et al.
patent: 4963339 (1990-10-01), Krishnamurthy et al.
patent: 4964888 (1990-10-01), Miller
patent: 5013334 (1991-05-01), Maurer
patent: 5096470 (1992-03-01), Krishnamurthy
patent: 5133785 (1992-07-01), Kumar et al.
patent: 5152813 (1992-10-01), Coe et al.
patent: 5203887 (1993-04-01), Toussaint
patent: 5203888 (1993-04-01), Maurer
patent: 5234472 (1993-08-01), Krishnamurthy et al.
patent: 5258058 (1993-11-01), Coe et al.
patent: 5258060 (1993-11-01), Gaffney et al.
patent: 5268023 (1993-12-01), Kirner
patent: 5294247 (1994-03-01), Scharpf et al.
patent: 5354346 (1994-10-01), Kumar
patent: 5464467 (1995-11-01), Fitch et al.
patent: 5489327 (1996-02-01), Otsuka et al.
patent: 5505764 (1996-04-01), Fuentes
patent: 5529610 (1996-06-01), Watson et al.
patent: 5531808 (1996-07-01), Ojo et al.
patent: 5658370 (1997-08-01), Vigor et al.
patent: 5672195 (1997-09-01), Moreau et al.
patent: 5674311 (1997-10-01), Notaro et al.
Bomard Olivier
Jutard Jerome
Moreau Serge
Vigor Xavier
L'Air Liquide, Societe Anonyme Pour L'Etude et L'Exploitation de
Spitzer Robert
LandOfFree
Method for purifying hydrogen based gas mixture using a lithium- does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for purifying hydrogen based gas mixture using a lithium-, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for purifying hydrogen based gas mixture using a lithium- will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-403845