\nHai-Ying Chen<\/strong>
\nEmis\u00adsion Con\u00adtrol Tech\u00adnolo\u00adgies
\nJohn\u00adson Matthey Inc.
\nWayne, PA <\/em>
\nchenh@\u200bjmusa.\u200bcom<\/a>
\n
\nAbstract<\/strong> \u2014 Reduc\u00adtion of NOx emis\u00adsions from lean-burn engine exhaust has been a main top\u00adic of envi\u00adron\u00admen\u00adtal catal\u00ady\u00adsis in the past 20 years. The chal\u00adlenge is the selec\u00adtive con\u00adver\u00adsion of a low con\u00adcen\u00adtra\u00adtion of NOx (~100 ppm) in the pres\u00adence of large excess of O2 (~10%). Although zeo\u00adlite sup\u00adport\u00aded tran\u00adsi\u00adtion met\u00adal cat\u00ada\u00adlysts were iden\u00adti\u00adfied in ear\u00adly 1990s as promis\u00ading cat\u00ada\u00adlysts, such a tech\u00adnol\u00ado\u00adgy was not imple\u00adment\u00aded till recent\u00adly. <\/p>\n
Ear\u00adly stud\u00adies main\u00adly focused on the devel\u00adop\u00adment of zeo\u00adlite sup\u00adport\u00aded tran\u00adsi\u00adtion met\u00adal, pri\u00admar\u00adi\u00adly Cu and Fe, cat\u00ada\u00adlysts for the selec\u00adtive cat\u00adalyt\u00adic reduc\u00adtion of NOx with hydro\u00adcar\u00adbons (HC-SCR). Even though the HC-SCR tech\u00adnol\u00ado\u00adgy has been con\u00adsid\u00adered as the \u201choly grail\u201d of auto\u00admo\u00adtive catal\u00ady\u00adsis, tech\u00adni\u00adcal chal\u00adlenges on the activ\u00adi\u00adty, selec\u00adtive and dura\u00adbil\u00adi\u00adty of the cat\u00ada\u00adlysts were rec\u00adog\u00adnized to be dif\u00adfi\u00adcult to over\u00adcome for the tech\u00adnol\u00ado\u00adgy to be imple\u00adment\u00aded into real world appli\u00adca\u00adtions. How\u00adev\u00ader, the vast amount of research work, espe\u00adcial\u00adly the fun\u00adda\u00admen\u00adtal stud\u00adies on the reac\u00adtion and the cat\u00ada\u00adlyst deac\u00adti\u00adva\u00adtion mech\u00ada\u00adnisms, demon\u00adstrat\u00aded that the activ\u00adi\u00adty and selec\u00adtiv\u00adi\u00adty of this type of cat\u00ada\u00adlysts can be dras\u00adti\u00adcal\u00adly improved if an alter\u00adna\u00adtive reduc\u00adtant, NH3, is avail\u00adable in the feed. <\/p>\n
Exten\u00adsive inves\u00adti\u00adga\u00adtions on the selec\u00adtive cat\u00adalyt\u00adic reduc\u00adtion of NOx with NH3 (NH3-SCR) began in the mid\u00addle 2000s aimed to enable diesel pow\u00adered vehi\u00adcles to meet the US EPA 2007\/2010 emis\u00adsion reg\u00adu\u00adla\u00adtions. Both Cu and Fe cat\u00ada\u00adlysts were con\u00adsid\u00adered. Zeo\u00adlite sup\u00adport\u00aded Cu SCR cat\u00ada\u00adlysts are more active at low tem\u00adper\u00ada\u00adture, thus more attrac\u00adtive for appli\u00adca\u00adtions with low exhaust tem\u00adper\u00ada\u00adture. The con\u00adven\u00adtion\u00adal medi\u00adum-pore zeo\u00adlite (10-ring, such as ZSM-5) or large-pore zeo\u00adlite (12-ring, such as beta) sup\u00adport\u00aded Cu cat\u00ada\u00adlysts, how\u00adev\u00ader, can\u00adnot meet the long-term dura\u00adbil\u00adi\u00adty require\u00adments. To over\u00adcome this major tech\u00adni\u00adcal hur\u00addle, small-pore zeo\u00adlite (8-ring) sup\u00adport\u00aded Cu cat\u00ada\u00adlysts were invent\u00aded. On the oth\u00ader hand, zeo\u00adlite sup\u00adport\u00aded Fe SCR cat\u00ada\u00adlysts are more selec\u00adtive in uti\u00adliz\u00ading NH3 for NOx reduc\u00adtion at high tem\u00adper\u00ada\u00adtures but show a strong depen\u00addence on the NO to NO2 ratio in the feed gas at low tem\u00adper\u00ada\u00adtures. Sys\u00adtem approach\u00ades were devel\u00adoped to enhance the low tem\u00adper\u00ada\u00adture SCR activ\u00adi\u00adty of the Fe SCR cat\u00ada\u00adlysts. As such, both Cu and Fe SCR cat\u00ada\u00adlysts were suc\u00adcess\u00adful\u00adly com\u00admer\u00adcial\u00adized and applied on lean-burn diesel vehi\u00adcles meet\u00ading the strin\u00adgent US EPA 2010 emis\u00adsion stan\u00addards. <\/p>\n
![\"Hai-Ying](\"http:\/\/catalysisclubphilly.org\/awe9a91v\/uploads\/2014\/04\/Haiying_Chen.jpg\")
<\/a>Biog\u00adra\u00adphy<\/strong> \u2014 Dr. Hai-Ying Chen is a Sci\u00aden\u00adtif\u00adic and Prod\u00aduct Devel\u00adop\u00adment Man\u00adag\u00ader at John\u00adson Matthey, where he leads a team of sci\u00aden\u00adtists to devel\u00adop advanced emis\u00adsion con\u00adtrol cat\u00ada\u00adlysts and tech\u00adnolo\u00adgies for both gaso\u00adline engine and diesel engine pow\u00adered vehi\u00adcles to meet the gov\u00adern\u00adment emis\u00adsion reg\u00adu\u00adla\u00adtions. <\/p>\n