Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Nitrogen or nitrogenous component
Patent
1995-03-24
1996-12-24
Bos, Steven
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Nitrogen or nitrogenous component
B01J 800
Patent
active
055871356
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the catalytic decomposition of dinitrogen monoxide which is pure or present in gas mixtures using a catalyst prepared by combining R-Al.sub.2 O.sub.4 where R is an element of group Ib, VIIb or VIII of the Periodic Table of the Elements, with tin, lead, an element of group IIa or IIb of the Periodic Table of the Elements as an oxide or salt or in elemental form, and calcining at 300.degree.-1300.degree. C. under 0.1-200 bar.
A review of the energies of activation for the catalytic decomposition of dinitrogen monoxide (laughing gas) on oxide catalysts, especially on mixed oxides, is given in Catalysis Today 4 (1989) 235-251.
The catalysts described therein are unsatisfactory in terms of activity, or useful life, contain costly elements such as noble metals.
It is an object of the present invention to remedy the abovementioned disadvantages.
We have found that this object is achieved by a novel and improved process for the catalytic decomposition of dinitrogen monoxide which is pure or present in gas mixtures at 200-900.degree. C., which comprises employing a catalyst prepared by combining CuAl.sub.2 O.sub.4 with tin, lead, an element of group IIa or IIb of the Periodic Table of the Elements as an oxide or salt or in elemental form, and calcining at 300.degree.-1300.degree. C. under 0.1-200 bar.
The process according to the invention can be carried out by preheating pure dinitrogen monoxide or gas mixtures containing it or off-gas containing it in a furnace or heat exchanger to the required reactor temperature of, as a rule, 200.degree.-900.degree. C., preferably 250.degree.-800.degree. C., particularly preferably 350.degree.-700.degree. C., and then passing it through a reaction tube packed with the catalyst described. The preheating of the reaction gas can also take place directly in the reaction tube in a preceding layer of inert material which is at the reaction temperature. The catalyst and/or inert material can be heated by using an external source of heat and/or the heat liberated in the decomposition of the dinitrogen monoxide.
It is possible to employ dinitrogen monoxide in extra pure form, or mixed with oxygen or air, or mixed with air containing large amounts of water and/or large amounts of other nitrogen oxides such as nitrogen monoxide and nitrogen dioxide or high concentrations of nitrogen oxides and other gases such as NO.sub.x, N.sub.2, O.sub.2, CO, CO.sub.2, H.sub.2 O and inert gases, especially off-gases from adipic acid plants, and it can be selectively decomposed to the elements nitrogen and oxygen with negligible decomposition of other nitrogen oxides to the elements. The content of nitrogen oxides NO.sub.x can, as a rule, be 0-50%, preferably 1-40%, particularly preferably 10-30%, by volume and the N.sub.2 O content can, as a rule, be 0.01-65%, preferably 1-55%, particularly preferably 5-45%, by volume. It is possible, for example, to decompose dinitrogen monoxide mixed with, for example, 20% water and 65% nitrogen dioxide (NO.sub.2) selectively into the elements.
Suitable catalysts are those which can be prepared by combining CuAl.sub.2 O.sub.4 with the element as such or oxides or salts of tin, lead, an element of group IIa or IIb of the Periodic Table of the Elements, and, calcining at 300.degree.-1300.degree. C. under 0.1-200 bar. These catalysts contain no noble metals (Ag, Au, Pd, Pt) and have a BET surface area of 1-350 m.sup.2 /g.
The starting material may be a solid oxide which is wholly or partly, ie. 1-100%, preferably 10-90%, particularly preferably 20-70%, by weight, a spinel of the composition CuAl.sub.2 O.sub.4 in an Al .sub.2 O.sub.3 matrix, and this can be mixed with the same or higher concentration of tin, lead, an element of group IIa or IIb of the Periodic Table of the Elements, as oxide or salt or in elemental form, and calcined at 300.degree.-1300.degree. C., preferably 500.degree.-1200.degree. C., particularly preferably 600.degree.-1100.degree. C., under 0.1-200 bar, preferably 0.5-10 bar, particularly preferably und
REFERENCES:
Angeletti et al. "Structure and Catalytic Activity of Co.sub. 1-xA1.sub.2 O.sub.4 Spinal Solid Solutions", 1977 (no month) pp. 1595-1603.
Buechele Wolfgang
Buerger Gert
Fetzer Thomas
Otto Bernhard
Pijl Paul
BASF - Aktiengesellschaft
Bos Steven
Dunn Jr. Thomas G.
Shurtleff John H.
LandOfFree
Process for the catalytic decomposition of dinitrogen monoxide i does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the catalytic decomposition of dinitrogen monoxide i, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the catalytic decomposition of dinitrogen monoxide i will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1176970