Catalytic Performance Of SSZ-13 Supported Metal Catalyst For NOx Removal Through CO-SCR

Air pollution,especially NOx,becomes a real challenge nowadays.Many scientists have developed and tried to reduce NOx concentration,and ammonia SCR is the best applied-methods for today.Many industries have been using vanadium-based catalysts due to the most well-developed catalyst but toxic to the environment.Meanwhile,carbon monoxide(CO)alternatively used and developed to overcome ammonia-SCR issues.CO-SCR provides more eco-friendly methods than others,but it still does not have a suitable catalyst that performs at low temperatures.Transition metals,such as copper,ceria,and manganese,become a prominent catalyst because of low price,low toxic pollution,high expected efficiency,medium cost,and applicable.Although its low-temperature activity and stability,it needs further improvements.Zeolite,especially SSZ-13,attracts many researchers as the support of the catalyst due to adsorption capacity and stability enhancement.The cage-type of SSZ-13 would increase the NOx conversion and have better N2 selectivity compared to other zeolites by decreasing the possibility of by-product generation.Thus,by combining the catalytic activity of metal oxides and SSZ-13 was expected to give promising results.This research elaborated on the preparation method of M-SSZ-13(M=Cu,Ce,Mn)and MM'-SSZ-13(M=Cu,Ce,Mn;M'=Cu,Ce,Mn)and CeMnCu-SSZ-13 using impregnation method.XRD and H2-TPR characterized the catalyst structure and properties.Its catalytic activity of NO conversion was measured by the CO-SCR method,including its conversion in various parameters.The order of single metal loaded catalyst to show the NO conversion as follow:Cu-SSZ-13>Ce-SSZ-13>Mn-SSZ-13.Besides,the order of combined metal is as follow:CeMn-SSZ-13>MnCu-SSZ-13>CeCu-SSZ-13>CeMnCu-SSZ-13.Thus,Cu-SSZ-13 and CeMn-SSZ-13 were used for further tests.Space velocity of 24000 ml.h-1.g-1 as the best condition compared to 48000 and 96000 ml.h-1.g-1 for Cu-SSZ-13 and CeMn-SSZ-13.In terms of CO/NO ratio,they exhibited the highest catalytic performance for CO/NO ratio 3:1;however,CO/NO ratio also showed just a slight difference,which makes CO/NO ratio 2:1 more promising and economics.Cu-SSZ-13 and CeMn-SSZ-13 catalysts could keep high performance in 100-300 ppm of NO in the inlet while showing a significant decrease for 2500 ppmThe catalysts showed a promising result on hydrothermal conditions,650? for 12 h.Cu-SSZ-13 only showed a 2%decrease while CeMn-SSZ-13 had 6%.Other tests also displayed that they have stability in 100 ppm of NO at 200? for 24 h.All the tests showed catalytic NO conversion above 85%.This stability could be the best sign for a good activity for low-temperature performanceIt proposed that Cu-SSZ-13 uses the L-H reaction mechanism,while CeMn-SSZ-13 uses the E-R reaction mechanism in CO-SCR.