Processes for stabilizing antimony catalysts
The present disclosure relates to a process for stabilizing an antimony ammoxidation catalyst in an ammoxidation process. The process may comprise providing an antimony ammoxidation catalyst to a reactor; reacting propylene with ammonia and oxygen in the fluidized bed reactor in the presence of the antimony ammoxidation catalyst to form a crude acrylonitrile product; and adding an effective amount of an antimony-containing compound to the antimony ammoxidation catalyst to maintain catalyst conversion and selectivity; wherein the antimony-containing compound has a melting point less than 375° C. The present disclosure also relates to catalyst compositions and additional processes using the antimony ammoxidation catalyst stabilized by an antimony-containing compound.
1. A process for stabilizing an antimony ammoxidation catalyst in an ammoxidation process, the process comprising:
providing an antimony ammoxidation catalyst to a fluidized bed reactor;
reacting propylene with ammonia and oxygen in the fluidized bed reactor in the presence of the antimony ammoxidation catalyst to form a crude acrylonitrile product; and
adding an effective amount of an antimony-containing compound to the antimony ammoxidation catalyst to maintain catalyst conversion and selectivity;
wherein the antimony-containing compound has a melting point less than 375° C.
2. The process of claim 1 , wherein the catalyst conversion is maintained within 10% of a target conversion over a period of at least 1 year.
3. The process of claim 1 , wherein the catalyst selectivity to acrylonitrile is maintained within 10% of a target selectivity over a period of at least 1 year.
4. The process of claim 1 , wherein the catalyst conversion is at least 45% over a period of at least 1 year.
5. The process of claim 1 , wherein the catalyst selectivity to acrylonitrile is at least 50% over a period of at least 1 year.
6. The process of claim 1 , wherein the antimony-containing compound is a solid.
7. The process of claim 1 , wherein the adding is conducted at a temperature of less than 300° C.
8. The process of claim 1 , wherein the antimony-containing compound comprises an antimony acetate.
9. The process of claim 1 , further comprising the step of releasing antimony ammoxidation catalyst vapors from the antimony ammoxidation catalyst in the reactor.
10. The process of claim 9 , further comprising the step of vaporizing the antimony-containing compound to suppress the release of the antimony ammoxidation catalyst vapors.
11. The process of claim 1 , wherein the adding comprises:
adding the antimony-containing compound directly into a catalyst hopper comprising replenishing the antimony ammoxidation catalyst and then feeding the resultant replenished antimony catalyst composition to the reactor;
mixing the antimony-containing compound with the antimony ammoxidation catalyst and then feeding the resultant replenished antimony catalyst composition directly to the reactor;
dissolving antimony-containing compound in water to form an aqueous solution and then adding the aqueous solution to the reactor; or
combinations thereof.
12. The process of claim 1 , wherein the antimony-containing compound and the antimony ammoxidation catalyst comprises less than 1 wt % potassium, lithium, sodium, cesium, indium, rubidium, samarium, calcium, strontium, barium or tellurium.
13. The process of claim 1 , wherein the antimony ammoxidation catalyst further comprises molybdenum and/or a molybdenum oxide.
14. The process of claim 1 , wherein the adding step further comprises adding an effective amount of a molybdenum-containing compound to the antimony ammoxidation catalyst.
15. The process of claim 1 , wherein the antimony-containing compound comprises antimony triacetate, antimony oxides, or organoantimony compounds, or combinations thereof.
16. The process of claim 1 , wherein the adding further comprises adding at least one additive to the fluidized bed reactor.