利用Ir-ZSM5分子筛催化剂控制稀燃汽油机NO_x排放的试验研究

Experimental Study on NO_x Emission Control of Lean Burn Gasoline Engine Using Ir-ZSM5 Zeolite Catalyst

为控制汽油机稀燃NOx排放,对Ir-ZSM5分子筛催化剂在实际稀燃排气条件下进行了试验研究.试验结果表明,应用IrZSM5催化剂,可以实现CO对稀燃NOx的选择催化还原反应.在空燃比为15～20时,空速为30000/h时,NOx最高转化效率可达50%～80%,并且具有较宽的高活性温度窗口.随着空燃比的增加,NOx转化效率减小.Ir-ZSM5催化剂对HC、CO也可以实现较高的转化率,有望应用于当量空燃比条件,从而降低空燃比控制精度.该催化剂尤其适合稀燃汽油机的需要.

Ir-ZSM5 zeolite catalyst is investigated experimentally under practical exhaust conditions of lean burn gasoline engine in order to control NOx emission. The results show that SCR(selective catalytic reduction) reaction between CO and NOx can be realized using Ir-ZSM5 catalyst. The maximal conversion efficiency reaches 50% to 80% when the air fuel ratio is 15-20 and space velocity ratio is 30000/h. In addition, there is a wide temperature range of high conversion efficiency. The NOx conversion efficiency reduces as the air fuel ratio increases. A high conversion efficiency of HC and CO can be realized by using Ir-ZSM5 catalyst. It has the potential application in the stoichiometry condition, so that the control precision of air fuel ratio can be reduced. The catalyst is especially applicable to lean burn gasoline engine.