Dehydration of alcohols on crystalline silicates
The present invention relates to a process for the dehydration of at least an alcohol to make at least an olefin, comprising: introducing in a reactor a stream (A) comprising at least an alcohol, optionally water, optionally an inert component, contacting said stream with a catalyst in said reactor at conditions effective to dehydrate at least a portion of the alcohol to make an olefin, recovering from said reactor an olefin containing stream (B), Wherein the catalyst is: a crystalline silicate having a ratio Si/Al of at least about 100, or a dealuminated crystalline silicate, or a phosphorus modified zeolite, the WHSV of the alcohols is at least 2 h −1 , the temperature ranges from 280° C. to 500° C. It relates also to the same process as above but wherein the catalyst is a phosphorus modified zeolite and at any WHSV. The partial pressure of the alcohol in the dehydration reactor advantageously ranges from 1.2 to 4 bars absolute (0.12 MPa to 0.4 MPa), the temperature of the dehydration reactor ranges advantageously from 300° C. to 400° C. and the alcohol is selected among ethanol, propanol, butanol and phenylethanol.
1. A process for the dehydration of an alcohol having at least 2 carbon atoms to produce a corresponding olefin comprising:
forming a catalyst comprising a phosphorous modified zeolite by:
selecting a zeolite with an Si/Al ratio between 4 and 30 from an H + or NH 4 + form of MFI, MEL, FER, MOR, or clinoptilolite;
steaming the zeolite at a temperature ranging from 400 to 870° C. for 0.01 to 200 hours;
leaching the zeolite at conditions effective to remove at least 10% of Al from the zeolite;
introducing P at conditions effective to introduce at least 0.05 wt % of P;
separating solids from liquids; and
calcining;
introducing a first stream into a reactor, wherein the first stream comprises an alcohol;
contacting the first stream with the catalyst in the reactor at conditions effective to dehydrate at least a portion of the alcohol to produce an olefin; and
recovering from the reactor a second stream comprising an olefin;
wherein the reactor is operated under conditions comprising an alcohol WHSV of at least 2 h −1 and temperatures ranging from 280 to 500° C.
2. The process of claim 1 , wherein the first stream comprises water.
3. The process of claim 1 , wherein the first stream comprises an inert component.
4. The process of claim 1 , wherein the alcohol WHSV ranges from 2 to 20 h −1 .
5. The process of claim 1 , wherein the alcohol WHSV ranges from 4 to 20 h −1 .
6. The process of claim 1 , wherein the reactor is operated under pressures ranging from 0.05 to 3 MPa.
7. The process of claim 1 , wherein the alcohol in the reactor has a partial pressure ranging from 0.12 to 0.4 MPa.
8. The process of claim 1 , wherein the alcohol in the reactor has a partial pressure ranging from 0.12 to 0.2 MPa.
9. The process of claim 1 , wherein the temperature of the reactor ranges from 300 to 400° C.
10. The process of claim 1 , wherein the alcohol is selected from the group consisting of ethanol, propanol, butanol, phenylethanol, and combinations thereof.
11. The process of claim 1 , further comprising, prior to introducing P, steaming the zeolite followed by leaching the zeolite with an aqueous acid solution.
12. The process of claim 1 , wherein the zeolite is steamed at a temperature ranging from 480 to 760° C. for 0.01 to 200 hours.