Diesel vehicle urea solution with low-temperature properties and preparation method thereof

Abstract

The invention provides a diesel vehicle urea solution with low-temperature properties and a preparation method thereof. The diesel vehicle urea solution with the low-temperature properties is composed of components of A, B, C and D, wherein the component A is high-purity water, the component B is urea, the component C is micromolecular liquid hydramines and the component D is micromolecular liquid alcohols. By weight part, the diesel vehicle urea solution with the low-temperature properties is composed of 40-70 parts of the component A, 20-25 parts of the component B, 5-25 parts of the component C and 5-40 parts of the component D. The diesel vehicle urea solution with the low-temperature properties obtains a freezing point lower than -18 DEG C--35 DEG C and a surface tension level lower than that of ordinary vehicle urea, thereby being applicable to all seasons in southern and northern regions, particularly to cold seasons in Northeast China.

Description

technical field [0001] The invention belongs to the field of diesel engine tail gas treatment, and in particular relates to a urea solution for diesel vehicles with low-temperature performance and a preparation method thereof. Background technique [0002] In recent years, every winter, smog occurs frequently in most parts of the central and eastern regions, and the number of smog days generally exceeds 5 days, and the national smog days generally show an increasing trend. Especially in the past two years, the smoggy weather has lasted longer. For example, in 2015, Beijing had only 186 days when the air reached the standard. In 2016, less than 50% of the days in Beijing met the air standard in November. Haze is a general expression of the excessive content of hundreds of suspended particulate matter in the atmosphere, especially PM2.5 (particulate matter with an aerodynamic equivalent diameter less than or equal to 2.5 microns) is considered to be the "culprit" of haze weath...

AI Technical Summary

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.

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 selection range of the neutralizer is very limited, the inorganic salt can only choose ammonium substances, and most of the organic modifiers choose amines or amides

[0006] The search found that there are many existing patents that use urea as the ammonia source and add modifiers to improve the freezing point, but most of them are ammonium substances, such as ammonium formate, ammonium carbonate, ammonium bicarbonate, etc. When the content is high, CO 2 The detected amount is easy to exceed the standard, and the stability is poor, and it is easy to decompose

Triethanolamine is used in China's published patent 201410193227 "Automobile Exhaust Emission Purification Treatment Liquid", but the composition of the treatment liquid is very complicated, which greatly increases the cost and difficulty of the process, and according to the general standard of urea for vehicles, the detection amount of phosphate (≦0.5 ) also exceeds the standard

Complex components are likely to easily poison sensitive catalysts and affect their reactivity

[0007] Many patents such as Chinese patents CN201110134706.3 "A Urea Solution Composition for Low-Temperature Vehicles", CN201110134698.2 "A Urea Solution Composition for Ultra-low Temperature Vehicles", CN201510015958 "A Low Freezing Point Nitrogen Oxide Reductant and Its Preparation Method " and CN 201510017530 "An Ultra-low Freezing Point Nitrogen Oxide Reductant and Its Preparation Method" both use small molecule liquid alcohols as composite additives, but the composition is more complicated than this patent, which increases the difficulty of the process

In addition, all of them contain formamide, which is flammable. In the presence of a catalyst, heated to below 35°C, it can decompose highly toxic hydrogen cyanide, and can strongly corrode copper, brass, lead, and rubber, which is inconvenient. storage and transportation