Patent PL-189581-B1 (PL)
Title: Method of obtaining an impregnative catalyst for simultaneous reduction of nitrogen oxides and oxidation of sulphur dioxide to sulphur trioxide in flue gas and equipment system therefor
Inventor: GRZEGORCZYK WIESLAW
IPC: B01J37/02
Filed: 1998-02-23
Abstract: 1. The method of obtaining an impregnating catalyst for a simultaneous reduction of nitrogen oxides and oxidation of sulphur dioxide in waste gases consists in a wet activation of the components, followed by mixing and homogenisation of liquid components, filtering and separation of liquid fractions from solid components, followed by drying the solid substrates, grinding them and calcination. It is characterised in that 590 to 610 parts by mass, preferably 600 parts by mass, of pulverised magnesium oxide MgO is introduced into the reactor. The geometrical surface of the pulverised material is between 11m2>/g and 25m2>/g, while the apparent bulk density is between 0.2 g/cm3> and 0.5 g/cm3>. The proportioned material is constantly stirred to mix it with 14800 to 15800 parts by mass, but preferably 15000 parts by mass of 1 mole solution of sodium salt of ethylenediaminetetraacetic acid (EDTA). The mixed components are contacted with each other by constant stirring for the period of at least 30 minutes, while the mixture temperature is maintained at the level of about 50 degrees Celsius. The resultant dense liquid mixture, containing a suspension of solid particles, is directed to be separated in a nutsche filter or a centrifugal separator, to obtain a post-impregnation filtrate with the pH between 8.5 and 9. The filtrate is returned into the process after restoring the EDTA concentration. The separated precipitate of the magnesium oxide MgO activated in this manner, which forms the Mg-EDTA complex, is dried at the temperature which does not exceed 115 degrees Celsius at the end, until the humidity level does not exceed 8 percent. It is ground in a ball or impact grinder, while simultaneously adding 28 to 32 parts by mass, but preferably 30 parts by mass, of pulverised graphite. The resultant complex is introduced into the reactor, filled with 6000 to 6500 parts by mass, but preferably 6300 parts by mass, of 1 mole solution of soluble magnesium salt (II), preferably magnesium nitrate Mg(NO3)2, 2400 to 2600 parts by mass, but preferably 2500 parts by mass of 1 mole aqueous solution of soluble zinc salt (II), preferably zinc nitrate Zn(NO3)2, and 3700 to 3800 parts by mass, but preferably 3750 parts by mass of technological demineralised water, preferably distilled water. Once the substrates reach the temperature of at least 50 degrees Celsius, while intensely stirred, the following are introduced into the reactor: 24000 to 26000 parts by mass, but preferably 25000 parts by mass of aqueous solution of sodium vanadium at the concentration of 0.66 percent by mass in terms of V2O5. The mixture is intensely stirred for the period of at least 15 minutes. After the period, 4900 to 5100 parts by mass, but preferably 5000 parts by mass of 1-mole aqueous solution of sodium carbonate Na2CO3 are added to the homogenised mixture in a continuous process which lasts between 5 and 7 minutes. The sodium carbonate temperature at the moment of proportioning is maintained between 40 degrees Celsius and 50 degrees Celsius. The mixture is intensely stirred again for the period of at least 10 minutes. Immediately after this time, the obtained suspension of solid particles in the liquid is directed - while the stirring process is continued in the reactor - to be separated in a separating device, especially a nutsche filter or a centrifugal separator. The obtained post-filtration filtrate, characterised by pH between 9.0 and 9.5, is, preferably, returned into the process, to be used again for obtaining next portions of vanadium. The precipitate obtained in the filtrating device is dried at the temperature of up to 150 degrees Celsius, until the humidity of up to 8 percent is reached. Then, it is ground in a ball or impact grinder, until the biggest particle size does not exceed 0.5 mm. Then...