Diesel Oxidation Catalyst Converter(DOC) Monolithic Catalyst Preparation And Performance Study

Diesel oxidation catalyst converter(DOC)can greatly remove the gas pollutions,such as carbon monoxide(CO),SOF and hydrocarbon,and also has an effect on nitric oxide convert.Compared with the tail gas from petrol,the diesel exhaust has property with lower temperature and higher sulfur.These hard conditions require that the catalyst for DOC should have excellent catalytic combustion performance at low temperature(about 100 to 300 centigrades),superior anti-sulfer property,high flux and low pressure drop.First.We study the coating preparation technology of monolithic catalyst in the DOC and effection of caking agent,solid contents,proportion and so on,using cordierite as a carrier.The best coating can be obtained by using 8.33%glycol,16.67%citric acid and 42.50%solid contents.And the same time,the proportion of Ce0.8Zr0.2O2 and AlOOH is 10:1.The coating is firmly integrated on the carrier.Second.We found catalyst prepared by serosity depositing is more effective than impregnation and absorption method.The former has active constituent with homogeneous distribution.Catalyst prepared by the latter has low load ratios and inferior catalytic activity.The function of platinum and molybdenum are also invested in the catalytic combustion performance and anti-sulfer property.The conclusion can be listed as follows:First,Inversion curve of carbon monoxide and propene gradually moved to low temperature areas with increasing the platinum loading.Simultaneously,conversion of nitric oxide also improved.Second,Catalyst with 1%molybdenum additive has the most catalytic activity when the platinum additive is controlled by 2%.Whereas,catalyst with 3%and 5%molybdenum additive has better sulfur resistance ability.Because of the desorption of S02 on the catalyst surface,catalytic activity are increased with temperature raising and can be maintained for a long time in the sulfureous atmosphere.