Ruthenium-based ammonia synthetic catalyst and preparation thereof

Abstract

The invention provides a Ru-based ammonia synthesis catalyst and a preparation method thereof. The catalyst takes magnesium oxide as a carrier, metal ruthenium as an active constituent and at least one of alkali metal, alkaline earth metal or rare earth metal as an assistant; the composition is Ru-M1 / MgO, Ru-M2 / MgO, Ru-M1-M2 / MgO or Ru-(M1+M2) / MgO and the preparation method is as follows: the precursor, Ru-magnesium hydroxide catalyst, is prepared by a coprecipitation and dipping method: magnesium nitrate and ruthenium chloride are dissolved in water; the mixed solution is added into an alkaline solution to generate a precipitation; the precipitation is centrifugally washed, dried, sintered by reduction or soaked by equivoluminal soaking auxiliary after sintering, thus obtaining the catalyst that is required. The catalyst prepared by the synthesis method of the invention has good performance, relatively cheap raw material that is required, low energy consumption as well as simple devices and flow; besides, the catalyst is beneficial to reducing the cost and realizing mass production.

Description

technical field The invention belongs to the technical field of ammonia synthesis catalyst preparation, and more specifically relates to a ruthenium-based ammonia synthesis catalyst and a preparation method thereof. Background technique Ammonia synthesis catalyst is the most important catalyst in ammonia synthesis industry. In the 1980s and 1990s, people have studied the application of various oxides in ruthenium-based ammonia synthesis catalysts. Some early literatures introduced the research results of this part: that is, the ammonia synthesis activity of ruthenium catalysts is generally comparable to that of carrier oxides. The basicity (electronegativity) of the carrier is related, the higher the basicity of the carrier (the smaller the electronegativity), the better the activity of the catalyst, such as 673K, 80kPa, with Ru 3 (CO) 12 The ammonia synthesis activity order of the ruthenium catalyst prepared for the precursor is as follows: Ru / MgO>Ru / CaO>Ru / Al 2 o ...

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Problems solved by technology

The method uses Mg(OEt) 2 Prepare magnesium gel with ammonia water, and then use the impregnation method to load ruthenium carbonyl on the gel to prepare a catalyst with a high specific surface, with a specific surface as high as 290-359m 2 / g, which is 4 to 7 times that of commercial magnesium oxide, but due to Mg(OEt) 2 and Ru 3 (CO) 12 Precursors are relatively expensive precursors, which is not conducive to the use and promotion of catalysts

Directly prepare the method of ruthenium / magnesium oxide catalyst by co-precipitation of ruthenium chloride and magnesium nitrate has not been reported

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