Systems Utilizing Non-Zeolitic Metal-Containing Molecular Sieves Having The CHA Crystal Structure
First Claim
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1. An emission treatment system for treatment of an exhaust gas stream comprising NOx and particulate matter, the emission treatment system comprising:
- a SCR catalyst substrate containing a catalyst comprising a Cu-loaded non-zeolitic molecular sieve having a CHA crystal structure and a Cu loading so that the catalyst is effective to selectively reduce nitrogen oxides with ammonia in the presence of oxygen and ammonia in an exhaust gas stream at 200°
C. when the catalyst has been deposited on a honeycomb substrate having a cell density of 400 cpsi at target a loading between about 2 and 2.5 g/in3 and tested at a space velocity of 80,000 hr−
1 where the feed stream is a mixture of 10% O2, 5% H2O, 500 ppm NO, and 500 ppm NH3 to provide at least about 70% NOx conversion; and
an ammonia injector or an ammonia-precursor injector positioned upstream of the SCR catalyst substrate for injecting ammonia or an ammonia-precursor.
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Abstract
Systems for treating exhaust gas incorporating catalysts comprising metal-loaded non-zeolitic molecular sieves having the CHA crystal structure, including Cu-SAPO-34, and methods for preparing such catalysts are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stability at high reaction temperatures.
9 Citations
26 Claims
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1. An emission treatment system for treatment of an exhaust gas stream comprising NOx and particulate matter, the emission treatment system comprising:
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a SCR catalyst substrate containing a catalyst comprising a Cu-loaded non-zeolitic molecular sieve having a CHA crystal structure and a Cu loading so that the catalyst is effective to selectively reduce nitrogen oxides with ammonia in the presence of oxygen and ammonia in an exhaust gas stream at 200°
C. when the catalyst has been deposited on a honeycomb substrate having a cell density of 400 cpsi at target a loading between about 2 and 2.5 g/in3 and tested at a space velocity of 80,000 hr−
1 where the feed stream is a mixture of 10% O2, 5% H2O, 500 ppm NO, and 500 ppm NH3 to provide at least about 70% NOx conversion; andan ammonia injector or an ammonia-precursor injector positioned upstream of the SCR catalyst substrate for injecting ammonia or an ammonia-precursor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An emission treatment system for treatment of an exhaust gas stream comprising NOx and particulate matter, the emission treatment system comprising:
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a SCR catalyst substrate containing a catalyst comprising a Cu-loaded non-zeolitic molecular sieve having a CHA crystal structure and a Cu loading so that the catalyst is effective to selectively reduce nitrogen oxides with ammonia in the presence of oxygen in an exhaust gas stream at low temperature to provide at least about 70% NOx conversion upon hydrothermal aging; and an ammonia injector or an ammonia-precursor injector positioned upstream of the SCR catalyst substrate for injecting ammonia or an ammonia-precursor.
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26. A method of manufacturing Cu-SAPO-34 comprising:
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mixing a neutral, nitrogen-containing organic template, an alumina source, a silica source and a phosphorous source in a gel mixture; heating the gel to less than about 200°
C. for at least 12 hours to form crystalline SAPO-34;filtering and washing the crystalline SAPO-34; calcining the crystalline SAPO-34; and ion exchanging the crystalline SAPO-34 with a copper salt to provide Cu-SAPO-34.
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Specification