Preparation method of low formaldehyde urea solution used for urea

Abstract

The invention discloses a preparation method of a low formaldehyde urea solution used for urea, which belongs to the technical field of chemical technology, and especially relates to a preparation method of a low formaldehyde urea solution used for urea. The preparation method comprises the following steps: 1)dissolving industrial grade urea in deionized water to obtain an urea solution A; 2)employing a filtration system 1, filtering an insoluble substance in the urea solution A to obtain an urea solution B; 3)removing aldehyde on the urea solution B through a photocatalysis system to obtain an urea solution C; 4)decolouring the urea solution C through active carbon to obtain an urea solution D; and 5)passing through the urea solution D through a two-grade filtration system 2, and purifying to obtain the low formaldehyde urea solution used for vehicle. The low formaldehyde urea solution has the advantages of low cost and simple technology, formaldehyde content in the urea solution is reduced, and formaldehyde content can reach a GB2951-2013 requirement.

Description

technical field [0001] The invention discloses a preparation method of a low-formaldehyde vehicle-use urea solution, belongs to the technical field of chemical technology, and particularly relates to a preparation method of a low-formaldehyde vehicle-use urea solution. Background technique [0002] In December 2010, the Ministry of Environmental Protection of the People's Republic of China required that the heavy-duty diesel vehicles sold by my country's automobile factories since January 1, 2012 should meet the National IV emission standards, and the SCR (Selective Catalytic Reduction, Selective Catalytic Reduction, which uses urea as the reducing agent) Reduction) system, which uses the urea solution for vehicles to react with the nitrogen oxides in the exhaust of diesel vehicles such as heavy trucks and buses to generate N 2 and H 2 O to purify the exhaust gas, so that the discharged nitrogen oxides can meet the national IV emission standards or even higher emission stand...

AI Technical Summary

Problems solved by technology

The liquid vehicle urea currently on the market is generally prepared by dissolving solid high-purity vehicle urea in pure water. However, due to the high price of high-purity solid vehicle urea, the price of liquid vehicle urea on the market also remains high.

In addition, due to the high formaldehyde content of industrial grade urea, it cannot be directly dissolved in industrial urea to prepare vehicle urea