摘要 |
The present invention relates to a process for reducing cold start emissions in an exhaust gas stream (such as from an internal combustion engine) by contacting the exhaust stream with a combination of molecular sieves (1) a small pore crystalline molecular sieve or mixture of molecular sieves having pores no larger than 8 membered rings selected from the group consisting of SSZ-13, SSZ-16, SSZ-36, SSZ-39, SSZ-50, SSZ-52 and SSZ-73 molecular sieve and having a mole ratio of at least 10 of (a) an oxide of a first tetravalent element to (b) an oxide of a trivalent element, pentavalent element, second tetravalent element which is different from said first tetravalent element or mixture thereof and (2) a medium-large pore crystalline molecular sieve having pores at least as large as 10 membered rings selected from the group consisting of SSZ-26, SSZ-33, SSZ-64, zeolite Beta, CIT-1, CIT-6 and ITQ-4 and having a mole ratio of at least 10 of (a) an oxide of a first tetravalent element to (b) an oxide of a trivalent element, pentavalent element, second tetravalent element which is different from said first tetravalent element or mixture thereof. |
申请人 |
CHEVRON U.S.A. INC.;ZONES, STACEY, I.;WILLIAMS, CABRAL, M.;RUFAEL, TECLE, S.;BURTON, ALLEN, W. |
发明人 |
ZONES, STACEY, I.;WILLIAMS, CABRAL, M.;RUFAEL, TECLE, S.;BURTON, ALLEN, W. |