Method for forming light olefins from methanol
AssigneeKing Fahd University of Petroleum and Minerals
InventorsMohammad Ashraf ALI, Shakeel AHMED
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Abstract
A catalyst system and a process for methanol to light olefin conversion with enhanced selectivity towards propylene. The catalyst system comprises a honeycomb monolith catalyst support coated with aluminosilicate nanozeolite catalysts on the edges and inside the channels of the support structure. The aluminosilicate nanozeolite catalysts have not been pre-modified with a promoter metal. The catalyst system gives higher hydrothermal stability to the catalyst compared to randomly packed pellet catalysts and allows methanol to be converted to predominantly propylene at a low temperature, with decreased selectivity towards C2, higher olefins and paraffinic hydrocarbons.
Claims9
1:
- A method for forming light olefins from methanol, comprising:
- contacting gaseous methanol with a catalyst system for a time and at a temperature effective for converting the methanol to propylene and for forming a light olefin mixture,
- wherein the contacting is carried out with a selectivity towards converting methanol to propylene of at least 40% relative to a total mass of the light olefin mixture and a selectivity towards forming propylene is greater than a selectivity towards forming ethylene relative to a total mass of the light olefin mixture and that is greater than a selectivity towards forming butylene relative to a total mass of the light olefin mixture,
- wherein the catalyst system comprises:
- 7-12 wt % of the zeolite nanoparticles relative to the total weight of the catalyst system of zeolite nanoparticles having a silica to alumina molar ratio of 260-5000 in the form of crystals having an average particle diameter of 10-50 nm;
- and
- a honeycomb monolith support with 500-1200 cells per square inch coated with the zeolite nanoparticles on the edges and inside the channels of the honeycomb monolith support;
- wherein the zeolite nanoparticles are not modified with a promoter metal.
2:
- The method of claim 1, wherein the zeolite nanoparticles are microporous molecular sieves having an MFI framework type, which have a BET surface area of 100-1000 m2g−1 and which have a pore size distribution of 0.6-1.0 nm.
3:
- The method of claim 1, wherein the zeolite nanoparticles have a silica to alumina molar ratio in the range of 280-2000.
4:
- The method of claim 1, wherein the honeycomb monolith support is coated with
- a first layer of zeolite nanoparticles having a silica to alumina molar ratio of 260-5000 in the form of crystals having an average particle diameter of 10-50 nm on the edges and inside the channels of the honeycomb monolith;
- and
- a second layer of zeolite nanoparticles in the form of crystals having an average particle diameter of 10-50 nm and having a silica to alumina molar ratio of greater than the first layer of zeolite nanoparticles on the edges and inside the channels of the honeycomb monolith.
5:
- The method of claim 1, wherein the honeycomb monolith support comprises 700-1000 cells per square inch.
6:
- The method of claim 1, wherein the honeycomb monolith support has an average cross-sectional dimension of 0.5-2.0 inches by 0.5-2.0 inches.
7:
- The method of claim 1, wherein the catalyst system further comprising a binder.
8:
- The method of claim 1, wherein the selectivity of the conversion of methanol towards propylene is 40-80% of the total mass of the light olefin mixture.
9-20. (canceled)