Selective adsorption of mercury from gas streams

• US 4,101,631 A
• Filed: 11/03/1976
• Issued: 07/18/1978
• Est. Priority Date: 11/03/1976
• Status: Expired due to Term

• Current Assignee: UOP Des Plaines IL A NY General Partnership
• Original Assignee: Union Carbide Corporation (Dow, Inc.)
• Inventors: Anderson, Richard Alan, Ambrosini, Ronald Frank, Manchanda, Krishan Dayal, Fornoff, Louis Leonard
• Primary Examiner(s): Thomas, Earl C.
• Application Number:
  US05/738,529
• Time in Patent Office: 622 Days
• Field of Search: 423/210, 55/72, 55/75
• US Class Current: 423/210
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury

Abstract

Mercury vapor is selectively chemisorbed from gas streams by contact with zeolitic molecular sieves containing elemental sulfur. The selectivity and capacity of the zeolite adsorbent in the process is not affected adversely by the presence of adsorbed water vapor or water vapor in the gas stream being treated.

Claims

1. Process for removing mercury vapor from gas streams which comprises providing a gas stream containing water vapor and at least 0.02 micrograms of mercury vapor per normal cubic meter, passing said gas stream at a temperature of from -40°

to 100°

C. through a sorption zone containing a crystalline zeolitic molecular sieve having a SiO₂ /Al₂ O₃ molar ratio of from 2 to 20, and having elemental sulfur loaded thereon in an amount of at least 0.5 weight percent, based on the anhydrous weight of the molecular sieve, whereby mercury is adsorbed from said gas stream, and recovering the mercury-depleted effluent gas stream from said sorption zone.

2. Process according to claim 1 wherein the gas stream is natural gas.

3. Process according to claim 1 wherein the gas stream contains at least 2 micrograms of mercury vapor per normal cubic meter.

4. Process according to claim 3 wherein the crystalline zeolite contains in addition to the sulfur loading at least 2 weight percent adsorbed water.

5. Process according to claim 3 wherein the crytalline zeolitic molecular sieve has a faujasite type crystal structure.

6. Process according to claim 5 wherein the molecular sieve is zeolite X.

7. Process according to claim 5 wherein the molecular sieve is zeolite Y.

8. Process according to claim 5 wherein the cations electrovalently balancing the net negative charge on the AlO₄ -tetrahedra of the zeolite structure consist essentially of one or a mixture of at least two of cations selected from the group consisting of Na⁺, K⁺, Li⁺, Ca⁺⁺, Ba⁺⁺, Mg⁺⁺ and Sr⁺⁺.