Low-temperature diesel exhaust reducing agent and preparation method thereof

Abstract

The invention discloses a low-temperature diesel exhaust reducing agent and a preparation method thereof. The reducing agent is composed of a component A, a component B, a component C and a component D and is characterized in that the components A, B, C and D are dissolved and mixed in a certain ratio. The component A is high-purity water with mass fraction of 40 to 70%; the component B is urea with mass fraction of 20 to 35%; the component C is micromolecular liquid amide with mass fraction of 5 to 20%; and the component D is micromolecular alcohol with mass fraction of 2 to 35%. Compared with a traditional urea reducing agent, the low-temperature diesel exhaust reducing agent can be used at low and ultralow temperature. The freezing point of the prepared reducing agent is lower than -15 to -35 DEG C, has surface tension obviously smaller than common urea reducing agents and is applicable in four seasons in the south China and in spring, summer, autumn, early winter and cold seasons in north China.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a new type of low-temperature diesel exhaust catalytic reducer and its composition. Background technique [0002] On May 15, 2014, the State Council issued the "2014-2015 Action Plan for Energy Conservation, Emission Reduction and Low-Carbon Development", pointing out that before the end of 2014, the national IV standard vehicle diesel will be supplied nationwide. During the "October" period of 2014, many provinces, including Jiangsu, Fujian, and Sichuan, issued their own national four oil promotion policies. The Ministry of Industry and Information Technology announced that starting from January 1, 2015, diesel vehicles nationwide will enforce the National IV emission standards. With the promotion and implementation of the National IV emission standard for vehicle diesel, the domestic vehicle urea market has ushered in a new opportunity. Although this market has just...

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Problems solved by technology

The urea solution with this concentration has the lowest crystallization point, and it will crystallize when it is lower than -11°C. In actual use, it will be completely frozen at -20°C, which restricts its use in cold winter weather in the north, especially in the northeast.

[0005] Adding a modifier to reduce the freezing point of the urea solution for vehicles is the most convenient and low-cost method, but due to the high requirements of the SCR catalyst on the purity and cleanliness of the urea solution for vehicles, metal salts that can significantly reduce the freezing point of the aqueous solution cannot be used, making the modification The choice of sex agents is very limited

There are many existing patents that use urea as the ammonia source and add modifiers to improve the freezing point, but most of them contain crystalline or powdered ammonium substances, such as ammonium formate, ammonium carbonate, ammonium bicarbonate, etc., which easily lead to uneven dissolution and affect Overall stability of the solution and increased process cost

When the content of ammonium carbonate and ammonium bicarbonate is high, CO 2 The detected amount is easy to exceed the standard, and the stability is poor, and it is easy to decompose

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