One-step method used for synthesis of iron-based molecular sieve catalyst, and applications thereof

Abstract

The invention provides a one-step method used for synthesis of an iron-based molecular sieve catalyst. The one-step method comprises following steps: a Fe-complex solution and an aluminosilicate molecular sieve gel system are prepared respectively; the Fe-complex solution is added into the aluminosilicate molecular sieve gel system slowly, full stirring is carried out, an obtained mixture is allowed to stand for aging, is introduced into a reaction kettle for crystallization, is washed with deionized water, and is subjected to pumping filtration, drying, and roasting so as to obtain a solid iron-based molecular sieve; and then ammonium exchange is carried out so as to obtain the iron-based molecular sieve catalyst. The technology of the one-step method is simple; adoption of a plurality oftimes of ammonium nitrate and iron salt solution ion exchange and calcining is avoided, a defect in the prior art that later stage ion exchange technology is needed for loading of the active component is avoided, the synthesized iron-based molecular sieve catalyst is better in catalytic activity, Fe distribution is more uniform, excellent NH3-SCR catalytic activity is maintained in a wider temperature window, and at the same time, excellent high temperature activity and N2 selectivity are achieved.

Description

technical field [0001] The invention belongs to the field of chemistry, and relates to a preparation method of an iron-based molecular sieve catalyst (Fe-zeolite), and the catalyst prepared by the method is used for the selective catalytic reduction of nitrogen oxides (NH 3 -SCR) process. Background technique [0002] Environmental issues have become a hot issue in the current society, and the harm caused by nitrogen oxides to the environment is becoming more and more significant. As a major air pollutant, nitrogen oxides mainly come from factory exhaust and motor vehicle exhaust. Among them, diesel vehicle exhaust nitrogen oxides (NO x ) pollution has become one of the most prominent problems in my country's air pollution. In mobile source denitrification, selective catalytic reduction of ammonia (NH 3 -SCR) to eliminate nitrogen oxides (NO x ) has become the most potential and widely used denitrification technology due to its advantages of high efficiency and low cost...

AI Technical Summary

Problems solved by technology

However, there are a series of problems in the preparation of Fe-zeolite molecular sieve catalysts by the traditional ion exchange method: due to the hydration of Fe 3+ The ionic radius is much larger than the pore diameter of molecular sieves (Appl.Catal.B:Environ.180(2016)775–787)

However, there is another problem in the one-pot synthesis of Fe-based aluminosilicate molecular sieves: the synthetic aluminosilicate molecular sieve gel system is generally in an alkaline environment. If Fe salt is directly added to the gel, it will cause Fe salt to form a precipitate. During the ion exchange process in the later stage of molecular sieve, it is difficult to form Fe 3+ Entering the molecular sieve exchange site, most of Fe exists in the form of oxides, which is not conducive to NH 3 -SCR response

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