| 摘要 |
Catalysts for the polymerization of alkenes are prepared by impregnating kieselguhr in the form of porous pieces with phosphoric acid and dehydrating the pieces without substantially changing the particulate character of the kieselguhr; the porosity of the kieselguhr is such that pieces which will pass a screen of 15mm. mesh, but will be retained on a screen of 2 mm. mesh, can absorb, per 100 gms., at least about 150 gms. of P2O5 in the form of pyrophosphoric acid at about 100 DEG -200 DEG C. Kieselguhr products known as Sterchamol and Mollerstein may be used, or a kieselguhr paste containing a boric acid or soda ash may be extruded or pressed, and the pieces hardened; higher porosity may be obtained by adding sawdust which is subsequently burned out. Preferably the kieselguhr pieces have a strength such that a spherical piece of 7 mm. diameter is able to withstand a pressure of at least 0.5 kg. Impregnation is carried out at 100 DEG -200 DEG C (preferably 150 DEG -180 DEG C) and dehydration at 200 DEG -900C (preferably 300 DEG -400 DEG C). The final catalyst has a preferred phosphoric acid content, calculated as P2O5 of 60-80 per cent by weight, and a preferred free or water-extractable acid content of 10-20 per cent. The catalysts may be used for the polymerization of propene to form motor fuels or propene tetramer, pentamer, or hexamer. |
