Promoted solid phosphoric acid catalysts and methods of use
View Patent ↗The present invention relates to solid phosphoric acid (SPA) catalysts, processes for making the catalysts, and processes for conversion of hydrocarbons using the catalysts, such as oligomerization of propylene. In an exemplary embodiment, the catalyst comprises a calcined extrudate of phosphoric acid, diatomaceous earth, and niobic acid. Methods for converting hydrocarbons to olefins comprise contacting a hydrocarbon feedstock with the catalyst at hydrocarbon conversion conditions.
1. A solid phosphoric acid catalyst, comprising:
an amount of silicon orthophosphate and, optionally, an amount of silicon pyrophosphate, having an integrated XRD reflectance intensity ratio of silicon orthophosphate to silicon pyrophosphate of at least about 5:1, and
a promoter comprising niobium, titanium, zirconium, tungsten, vanadium, chromium, molybdenum, aluminum, boron, or any mixture thereof.
2. The catalyst of claim 1 , wherein the promoter comprises niobic acid.
3. The solid phosphoric acid catalyst of claim 1 , in the form of a calcined extrudate.
4. A process of preparing the solid phosphoric acid catalyst of claim 1 , comprising the steps of: mixing a phosphorus source, a silicon source, and a promoter; forming the mixture into a shape; and calcining the formed shape.
5. The process of claim 4 , wherein the phosphorus source, the silicon source, and the promoter are mixed at a temperature of about 10° C. to about 250° C.
6. The process of claim 4 , wherein the phosphorus source and the silicon source are present in the mixture in a ratio of about 2:1 to about 4:1.
7. The process of claim 4 , wherein the promoter is present in the mixture at a concentration of about 5% to about 10% w/w of the silicon source.
8. The process of claim 4 , wherein the formed shape is calcined at a temperature of about 200° C. to about 500° C.
9. The process of claim 4 , wherein the phosphorus source comprises phosphoric acid, a compound that forms phosphoric acid by hydrolysis, or any mixture thereof, the silicon source comprises a natural or artificial porous siliceous material, and the promoter comprises niobium, titanium, zirconium, tungsten, vanadium, chromium, molybdenum, aluminum, boron, or any mixture thereof.
10. The process of claim 9 , wherein the phosphorus source comprises orthophosphoric acid, pyrophosphoric acid, or any mixture thereof, the silicon source comprises diatomaceous earth, infusorial earth, ciliate earth, kieselguhr, kaolin, fuller's earth, artificial porous silica, or any mixture thereof, and the promoter comprises niobic acid.
11. A process of converting hydrocarbons catalyzed by the solid phosphoric acid catalyst of claim 1 , comprising providing a hydrocarbon feedstock at hydrocarbon conversion conditions and contacting the feedstock with said solid phosphoric acid catalyst.
12. The process of claim 11 , comprising alkylating an aromatic hydrocarbon or oligomerizing an olefin.
13. The process of claim 12 , wherein the olefin comprises propylene or butylene.