关键词: 柴油车尾气, 选择性催化还原, 整体式催化剂活性评价装置, V₂O₅-TiO₂整体式催化剂

Abstract:

Selective Catalytic Reduction (SCR）is the key technology for diesel effluent to meet today’s emission standards. The De NO_x efficiency is directly determined by the activities of the catalyst. In purpose of precisely and efficiently evaluating the activities of the catalysts, a device that is intelligently controlled by robots for evaluations of the activities of SCR catalytic ensembles is presented in this research. The device is using circulated hot air heating to maintain the temperature of the catalyst sample. By separating the reaction channels from the heating air, NO and Ammonia mixture is flowing through a small portion of the heated catalyst substrate while the NO concentration is monitored continuously. In this way, NO conversion rate and temperature curve is measured. Under the conditions of space speed 40 000 h^-1, NO initial concentration of 1.2 ‰, in the temperature range of 150 ℃ to 250 ℃, the conversation rates of a V₂O₅/WO₃/TiO₂ SCR catalytic ensemble sample are from 18% to 88%. The stability and intelligent level of the device are also tested by evaluating the SCR catalytic ensemble samples. The same sample is tested twice and the conversion curves are overlapped. For comparisons, the samples are also tested in a micro reactor and a diesel engine bench. Results attained in all these test fixtures are comparable. In addition, the cost of testing a sample on the device is only 1% of that when tested on a diesel engine bench. The intelligent device described in this research is a well-designed non-destructive test fixture. It is non-destructive, similar to a diesel engine bench, and is also very economical and easy to operate, similar to a micro reactor. The device can be used for daily operation of scale up experiments, as well as for products inspections.

Key words: Diesel exhaust, selective catalytic reduction, intelligent controlled device, V₂O₅-TiO₂ monolithic catalyst