Pressed parts based on pyrogenically produced silicon dioxide, method of their production and their use

• US 5,086,031 A
• Filed: 04/10/1990
• Issued: 02/04/1992
• Est. Priority Date: 04/17/1989
• Status: Expired due to Fees

• Current Assignee: Degussa AG (Rag-Stiftung)
• Original Assignee: Degussa AG (Rag-Stiftung)
• Inventors: Forster, Martin, Deller, Klaus, Krause, Helmfried
• Primary Examiner(s): DEES, CARL
• Application Number:
  US07/507,040
• Time in Patent Office: 665 Days
• Field of Search: 502/232, 502/251, 502/263, 502/413, 502/240, 502/8, 423/335
• US Class Current: 502/251
• CPC Class Codes: B01J 21/08 Silica
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77
• CPC Class Codes: B01J 35/613 10-100 m2/g
• CPC Class Codes: B01J 35/615 100-500 m2/g
• CPC Class Codes: B01J 35/635 0.5-1.0 ml/g
• CPC Class Codes: B01J 35/638 more than 1.0 ml/g
• CPC Class Codes: B01J 35/66 Pore distribution
• CPC Class Codes: B01J 37/0018 Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 35/14 based on silica
• CPC Class Codes: C04B 35/632 Organic additives
• CPC Class Codes: C04B 35/6325 based on organo-metallic compounds
• CPC Class Codes: C04B 35/634 Polymers C04B35/636 takes precedence
• CPC Class Codes: C04B 35/6365 Cellulose or derivatives thereof
• CPC Class Codes: C04B 38/00 Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof treating slag with gases or gas generating material C04B5/06 ; expanded graphite C04B35/536

Abstract

Pressed parts based on pyrogenically produced silicon dioxide with the following physicochemical characteristic data:

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Outer diameter 2 to 15 mm BET surface 50 to 400 m² /g Pore volume 0.6 to 1.3 ml/g Breaking strength 50-150 N Pore distribution no pores <5 mn diameter only meso and macropores Composition >99% by weight SiO₂ Abrasion <1.0% Bulk weight: 400-500 g/l ______________________________________

are produced by homogenizing pyrogenically produced silicon dioxide with urea, methyl cellulose and/or magnesium stearate, graphite and aluminum stearate with the addition of water, dried at a temperature of 80° to 120° C., comminuted to a powder, pressing the powder to pressed parts and tempering the pressed parts for a period of 0.5 to 8 hours at a temperature of 400° to 1200° C.

Claims

1. Shaped articles comprising phyrogenically produced silicon dioxide, said shaped articles having the following physicochemical characteristic data:

space="preserve" listing-type="tabular">______________________________________ Outer diameter 2 to 15 mm BET surface 50 to 400 m.sup.2 /g Pore volume 0.6 to 1.3 ml/g Breaking 50-150 N strength Pore distribution no pores <

5 [nm] diameter, only meso and macropores Composition >

99% by weight SiO.sub.2 Abrasion <

1.0% Bulk weight 400-500 g/l ______________________________________

2. A catalyst comprising the shaped articles of claim 1 as a carrier and a catalytically active substance thereon.

3. A method for producing pressed parts based on pyrogenically produced silicon dioxide said pressed parts having the following physico-chemical characteristics:

space="preserve" listing-type="tabular">______________________________________ Outer diameter 2 to 15 mm BET surface 50 to 400 m.sup.2 /g Pore volume 0.6 to 1.3 ml/g Breaking strength 50-150 N Pore distribution no pores <

5 nm diameter only meso and macropores Composition >

99% by weight SiO.sub.2 Abrasion <

1.0% Bulk weight;

400-500 g/l ______________________________________

said method comprising homogenizing pyrogenically produced silicon dioxide with (1) at least one member of the group consisting of urea, methyl cellulose and magnesium stearate, (2) graphite and (3) aluminum stearate with the addition of water, drying the homogenizate at a temperature of 80°

to 120°

C, comminuting the dried homogenizate to a powder, pressing the powder to pressed parts and tempering the pressed parts for a period of 0.5 to 8 hours at a temperature of 400°

to 1200°

C.