DK146678B - PROCEDURE FOR PREPARING A USER CATALYST AND USING THEREOF - Google Patents

Description

λ 146678 ο

The present invention relates to a process for preparing a carrier catalyst and its use.

In recent years, efforts have been made to reduce or eliminate lead emissions in exhaust fumes from cars. Pore using unleaded gasoline to achieve the same efficiency of the engine and the required octane strength, it is necessary to add the fuel to methanol. In addition, in recent times, for other future transportable energy carriers, engines have been built which can be operated with high percent methanol or alternatively with gasoline or gasoline-methanol mixtures or methanol.

However, combustion engines powered by methanol or gasoline-methanol mixtures emit, especially in the cold phase, formaldehyde with the exhaust gas. However, formaldehyde concentrations greater than 2-3 ppm in the inhalation air cause irritation to the nose, throat and eyes (see INDUSTRIAL HYGIENE AND TOXICOLOGY, Volume II, Interscience Publishers,

New York, 1963, page 1972).

20 From East German Patent No. 110,916 there is known a method for oxidizing carbon monoxide and hydrocarbons from exhaust gases from internal combustion engines in the presence of a support catalyst. This support catalyst is prepared by compressing pure alumina, obtained by hydrolysis of aluminum chloride into a hydrogen-oxygen flame, after addition of graphite to mold bodies. The moldings are annealed at 1000 to 1200 ° C after firing. of the graphite. The moldings, which serve as carriers, are first soaked with an aqueous solution of the nitrates of copper, manganese and nickel. After the nitrates decompose at 300 to 600 ° C, the metal oxide-containing moldings are annealed at 800 ° C to 1200 ° C, after which the oxides of copper, nickel and manganese are present as aluminates. Optionally, the alumina carrier and the copper, manganese and nickel aluminates 35 as active constituents comprising catalyst may be soaked with an aqueous cerium nitrate solution, after drying of the applied cerium nitrate and after its decomposition is finally annealed at temperatures of 700 to 900 ° C by incremental heating.

The present invention has for its object to provide a process for preparing such a carrier catalyst from pure alumina as a carrier which, in addition to carbon monoxide, also satisfactorily oxidizes formaldehyde and, in addition, exhibits a high compressive strength. This object is achieved according to the invention in that the pure aluminum oxide is recovered by hydrolysis of aluminum alkyl compounds in the liquid phase.

Thus, the present invention relates to a process for preparing a support catalyst in which pure alumina is compressed during the addition of graphite to mold bodies, and after burning the graphite at 600 to 700 ° C the mold bodies are annealed at 1000 to 1200 ° C. and by soaking the annealed mold bodies with copper and / or manganese nitrates and / or nickel and / or cerium nitrates and decomposing the metal nitrates deposited on the mold bodies 20 at temperatures of 350 to 500 ° C For example, the metal oxide-containing mold bodies emit at temperatures of 800 to 1100 ° C, the process of which is the extraction of pure alumina by hydrolysis of aluminum alkyl compounds in the liquid phase.

The present invention also relates to the use of the carrier catalyst as claimed in claim 1 or claim 2.

The process of the invention may also be carried out by hydrolyzing aluminum trialkyls, preferably aluminum triethyl.

When using the carrier catalyst prepared by the process according to the process, oxidized constituents such as carbon dioxide and water already present in exhaust gas from combustion engines do not interfere.

35 The use of excess oxygen in the reaction of the exhaust gases also ensures a far-reaching formaldehyde decomposition. In addition, the use of excess oxygen does not reduce the catalytic activity of the carrier catalyst prepared by the process of the present invention.

In the following examples, the determination of the oxidation activity against carbon monoxide and formaldehyde is carried out at all times with 50 ml of carrier catalyst contained in a special steel tube with 24 mm LW, thereby passing a defined preheated gas stream of 850 Nl / h.

The test gas used here contains 2% by volume CO, 3% by volume O2, 400 ppm formaldehyde, 10% by volume water vapor and N2 for the remainder. In the unreacted gas, the residual content of CO and formaldehyde is determined analytically and from this the percentage conversion of these two components is obtained. As a measure of the oxidation activity, the temperature at which 50% or 90% CO and formaldehyde are converted to C 2 and H2 O (U50 co, U90 co, U 50 form ^ U 9Q form) is highlighted.

An alumina prepared by gas phase hydrolysis is stirred in water and the obtained porridge is dried in a heat cabinet at 100 ° C. The dried mass is ground and compressed after the addition of 5% graphite to cylindrical bodies having a length 20 of 2.4 mm and a diameter of 2.4 mm. After burning the graphite added as a pressing aid at 650 ° C, the press bodies are annealed for 20 hours at 1100 ° C. The molds thus produced exhibit a specific surface (measured by BRUNAUER, EMMET und TELLER, J. Am. Chem. Soc. 60 (1938) p. 309) of 5.6 m / g as well as a pore volume of 0.30 ml / ml. g. To the molds, upon soaking with an aqueous metal salt solution, 5.1% Cu, 2.94% Mn and 1.57% Ni are applied in the form of their nitrates.

The soaked metal nitrates are converted by heating to 400-450 ° C to the corresponding metal oxides. The catalyst is then annealed for 20 hours at 1000 ° C. Then its compressive strength (measured by pressing on the casing line of the cylinder bodies between plane parallel plates) is 4.15 kg / mm. The activity determination of the catalyst gives:

35 U5Q co: 160 ° C U50 240 ° C

U90 CO: 190 ° C U90 Form5 350 ° C · 4 146678 o

Example 2 On cylindrical moldings made according to Example 1, by soaking with aqueous metal salt solution, 6.0% Cu and 1.7% Mn are applied in the form of their nitrates. Upon heating to 450 ° C, the soaked metal nitrates are converted to the corresponding metal oxides. After a 20 hour annealing of the catalyst at 1050 ° C, its compressive strength as measured in Example 1 is 2 kg / mm. The activity determination of the catalyst gives: 10

D50 CO! 170 ° C U50 Form = 255 ° C

° 90 CO = 205 ° C ° 90 Shape! Example 3 On the catalyst prepared according to Example 1, by soaking with aqueous cerium salt solution, 3.0% Ce is applied in the form of its nitrate. After drying and decomposing the cerium nitrate at 500 ° C, the catalyst is annealed for 10 hours at 800 ° C. Then its compressive strength measured as in Example 1 is 5.42 kg / mm. The activity determination of the catalyst is:

% 0 CO! 145 ° c ° 50 Form = 230 ° C

D90 c0 = 180 ° C U90 Form = 350 ° C.

Example 4

An alkali-free alumina obtained by hydrolysis of aluminum triethyl in aqueous phase is pressed after the addition of 7.5% graphite in cylindrical bodies having a length of 2.4 mm and a diameter of 2.4 mm. After burning the graphite added as a pressing aid at 700 ° C, the press bodies are annealed for 20 hours at 1150 ° C. The thus formed mold bodies exhibit a BET surface of 5 m / g and a pore volume of 0.32 ml / g. To the molding bodies are placed | 5.1% Cu, 2.94% Mn and 1.57% in the form of their nitrates. The further treatment is carried out as described in Example 1. The catalyst has a compressive strength of 4.0 kg / mm as measured in Example 1 and exhibits the following activities:

5 ϋ50 CO; 165 ° C U50 Form: 245 ° C

u90 co: 190 ° C U90 Form: 345 ° C.

Example 5 Cylindrical moldings are prepared as indicated in Example 1. On these moldings, by soaking with an aqueous copper salt solution, 6.0% Cu is applied as nitrate.

The soaked copper nitrate is heated to 450 ° C by heating it to its oxide and then annealed for 20 hours at 1000 ° C.

The catalyst is post-coated by soaking in aqueous cerium nitrate solution with 6.0% Ce. The soaked cerium nitrate is decomposed by heating to 500 ° C and the catalyst is then annealed for 10 hours at 800 ° C. Thereafter, its compressive strength (as measured in Example 1) is 4.6 kg / mm.

20 The activity provision provides:

U50 co: 190 ° C U50 Form: 395 ° C

U90 CO 5 240 ° C U90 Form: 600 ° C ·