Solid phosphoric acid with controlled porosity

1. A solid phosphoric acid catalyst comprising silicon orthophosphate and, optionally, silicon pyrophosphate, having a total pore volume of at least about 0.17 cm 3 per gram, of which at least about 0.15 cm 3 per gram is due to pores with diameter of at least about 10,000 Å, and having an integrated XRD reflectance intensity ratio of silicon orthophosphate to silicon pyrophosphate which is at least about 5:1.

2. The solid phosphoric acid catalyst of claim 1 wherein said integrated XRD reflectance intensity ratio is at least about 8:1.

3. The solid phosphoric acid catalyst of claim 1 wherein at least 0.20 cm 3 per gram of pore volume is due to pores with a diameter of at least about 10,000 Å.

4. The solid phosphoric acid catalyst of claim 1 wherein at least 0.15cm 3 per gram of pore volume is due to pores with a diameter of at least about 20,000 Å.

5. The solid phosphoric acid catalyst of claim 1 wherein at least 0.12 cm 3 per gram of pore volume is due to pores with a diameter of at least about 50,000 Å.

6. The solid phosphoric acid catalyst of claim 5 wherein said integrated XRD reflectance intensity ratio is at least about 8:1.

7. The solid phosphoric acid catalyst of claim 1 having a total pore volume of at least about 0.22 cm 3 per gram of catalyst.

8. A solid phosphoric acid catalyst, prepared from a siliceous material and one or more oxides or oxyacids of pentavalent phosphorus, having a total pore volume of at least about 0.17 cm 3 per gram, of which at least about 0.15 cm 3 per gram is due to pores with diameter of at least about 10,000 Å, and having an integrated XRD reflectance intensity ratio of silicon orthophosphate to silicon pyrophosphate which is at least about 5:1.

9. The catalyst of claim 8 wherein the siliceous material is chosen from the group consisting of kieselguhr, diatomaceous earth, infusorial earth, and porous silica, and mixtures thereof.

10. The catalyst of claim 9 in the form of a calcined extrudate.

11. The solid phosphoric acid catalyst of claim 9 wherein said integrated XRD reflectance intensity ratio is at least about 8:1.

12. The catalyst of claim 9 wherein at least 0.12 cm 3 per gram of pore volume is due to pores with a diameter of at least about 50,000 Å.

13. A process for the conversion of hydrocarbons in the presence of a solid phosphoric acid catalyst by contacting a hydrocarbon feedstock with a solid phosphoric acid catalyst comprising silicon orthophosphate and, optionally, silicon pyrophosphate, having a total pore volume of at least about 0.17 cm 3 per gram, of which at least about 0.15 cm 3 per gram is due to pores with diameter of at least about 10,000 Å, and having an integrated XRD reflectance intensity ratio of silicon orthophosphate to silicon pyrophosphate which is at least about 5:1, and wherein the conversion of hydrocarbons is an alkylation process or a catalytic condensation process.

14. The process of claim 13 wherein the solid phosphoric acid catalyst has a total pore volume of at least 0.22 cm 3 per gram.

15. The process of claim 13 wherein the solid phosphoric acid catalyst has a total pore volume of at least about 0.17 cm 3 per gram, of which at least 0.12 cm 3 per gram is due to pores with diameter of at least 50,000 Å.

16. The process of claim 13 wherein the catalytic condensation process occurs under hydrocarbon conversion conditions including a temperature between about 140° C. and about 290° C. and a pressure between about 6 atmospheres and 102 atmospheres.

17. The catalyst of claim 8 wherein the total pore volume is at least 0.30 cm 3 per gram, wherein at least about 0.10 cm 3 per gram is due to pores with diameter of at least about 20,000 Å.

18. The catalyst of claim 8 wherein at least about 0.10 cm 3 per gram is due to pores with diameter of at least about 50,000 Å.