Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
440 words
A process for the manufacture of olefin polymers by polymerization of C 2-8 α-monoolefins at temperatures of from 60° to 160° C and olefin pressures of from 0.5 to 40 bars by means of a silicic xerogel/chromium trioxide catalyst obtained by (1) synthesizing a particulate silicic xerogel having a particle diameter of from 10 to 2000 μm, (2) doping said xerogel with from 0.1 to 10 percent by weight (based on the xerogel and calculated as chromium) of chromium trioxide or a chromium compound capable of conversion to chromium trioxide under the conditions of stage (3) and (3) finally maintaining the resulting product at a temperature of from 400° to 1100° C for 10 to 1000 minutes in a water-free stream of gas containing oxygen in a concentration of more than 10% v/v, wherein the silicic xerogel/chromium trioxide catalyst used is one which has been obtained by 1. synthesizing the silicic xerogel in the first stage by 1.1. taking an aqueous solution of a sodium silicate (water glass) which contains from 0.1 to 20% by weight of solids (calculated as silicon dioxide, SiO 2 ), 1.2. exchanging the sodium ions contained in said solution for hydrogen ions by means of an ion exchanger so that the sodium content (calculated as sodium oxide, Na 2 O) in the silicic xerogel is not more than 0.2%, 1.3. introducing a water-soluble aluminum salt and, if necessary, water into the resulting aqueous silicic acid solution such that the ratio of water to silicic acid (calculated as silicon dioxide, SiO 2 ), by weight, is from 100:0.05 to 100:24 and the ratio of silicic acid (calculated as silicon dioxide) to aluminum salt (calculated as aluminum oxide, Al 2 O 3 ), by weight, is from 100:100 to 100:2, 1.4. adjusting, if necessary, the pH of the solution obtained in stage (1.3) to from 0.1 to 3.5 by means of a water-soluble inorganic acid such that the ratios of water to silicic acid and silicic acid to aluminum salt, by weight, remain in the ranges given under (1.3), 1.5. adjusting the pH of the solution obtained in (1.3) or (1.4) to from 4 to 12 by means of a water-soluble nitrogen-base compound having a neutralizing action, 1.6. extracting the resulting product in the solid phase obtained under (1.5) (silicic hydrogel) by means of an organic liquid selected from the series of C 1-4 alkanols and/or C 3-5 alkanones until the organic liquid absorbs no more water, and, finally, 1.7. drying the dehydrated gel obtained in (1.6) and saturated with organic liquid for a period until no further loss of weight occurs at 120° C (xerogel formation).
Claim 2
Dependent Claim
440 words
A process for the manufacture of olefin polymers by polymerization of C 2-8 α-monoolefins at temperatures of from 60° to 160° C and olefin pressures of from 0.5 to 40 bars by means of a silicic xerogel/chromium trioxide catalyst obtained by (1) synthesizing a particulate silicic xerogel having a particle diameter of from 10 to 2000 μm, (2) doping said xerogel with from 0.1 to 10 percent by weight (based on the xerogel and calculated as chromium) of chromium trioxide or a chromium compound capable of conversion to chromium trioxide under the conditions of stage (3) and (3) finally maintaining the resulting product at a temperature of from 400° to 1100° C for 10 to 1000 minutes in a water-free stream of gas containing oxygen in a concentration of more than 10% v/v, wherein the silicic xerogel/chromium trioxide catalyst used is one which has been obtained by 1. synthesizing the silicic xerogel in the first stage by 1.1. taking an aqueous solution of a sodium silicate (water glass) which contains from 0.1 to 20% by weight of solids (calculated as silicon dioxide, SiO 2 ), 1.2. exchanging the sodium ions contained in said solution for hydrogen ions by means of an ion exchanger so that the sodium content (calculated as sodium oxide, Na 2 O) in the silicic xerogel is not more than 0.2%, 1.3. introducing a water-soluble aluminum salt and, if necessary, water into the resulting aqueous silicic acid solution such that the ratio of water to silicic acid (calculated as silicon dioxide, SiO 2 ), by weight, is from 100:0.05 to 100:24 and the ratio of silicic acid (calculated as silicon dioxide) to aluminum salt (calculated as aluminum oxide, Al 2 O 3 ), by weight, is from 100:100 to 100:2, 1.4. adjusting, if necessary, the pH of the solution obtained in stage (1.3) to from 0.1 to 3.5 by means of a water-soluble inorganic acid such that the ratios of water to silicic acid and silicic acid to aluminum salt, by weight, remain in the ranges given under (1.3), 1.5. adjusting the pH of the solution obtained in (1.3) or (1.4) to from 4 to 12 by means of a water-soluble nitrogen-base compound having a neutralizing action, 1.6. extracting the resulting product in the solid phase obtained under (1.5) (silicic hydrogel) by means of an organic liquid selected from the series of C 1-4 alkanols and/or C 3-5 alkanones until the organic liquid absorbs no more water, and, finally, 1.7. drying the dehydrated gel obtained in (1.6) and saturated with organic liquid for a period until no further loss of weight occurs at 120° C (xerogel formation).