LOW PRESSURE DIMETHYL ETHER SYNTHESIS CATALYST
A catalyst and process for synthesis of dimethyl ether from synthesis gas are disclosed. The catalyst and process allow dimethyl ether synthesis at low pressures (below 20 bars) at a conversion rate close to the expected equilibrium rate. The catalyst is a combination of a methanol synthesis catalyst and a methanol dehydration catalyst, wherein the dehydration catalyst is a mixture of dehydration agents which allow optimum production of dimethyl ether.
1 . A catalyst composition for the synthesis of dimethyl ether from synthesis gas, comprising:
a methanol synthesis component comprising co-precipitated metal components containing Cu, Zn and Al, wherein an atomic ratio of Al to Cu is 0.05 to 2 and an atomic ratio of Al to Zn is 0.1 to 1; and
a dehydration component comprising a mixture of dehydrating agents selected from at least two of the group consisting of: silica alumina, kaolin, gamma alumina, aluminum silicate, montmorillonite, mullite, mesostructured aluminosilicate, and zeolites;
wherein the dehydration component is separately calcined from the methanol synthesis component and the dehydrating agents are selected to yield a CO conversion rate to dimethyl ether exceeding 60% at reaction pressures below 20 bar at temperatures above 220° C. and below 300° C.
2 . The catalyst composition according to claim 1 , wherein in which a weight ratio of methanol synthesis component to dehydration component varies from 5:1 to 1:5.
3 . The catalyst composition according to claim 1 , wherein the dehydrating component is calcined at temperatures exceeding 500° C.
4 . The catalyst composition according to claim 1 , wherein the methanol synthesis component is calcined at temperatures below 400° C.
5 . The catalyst composition according to claim 1 , wherein a silica alumina concentration varies from 10% to 60% and a kaolin concentration varies from 10% to 50%.
6 . The catalyst composition according to claim 1 , wherein a silica alumina concentration varies from 10% to 60%, a kaolin concentration varies from 10% to 40%, and a gamma alumina concentration varies from 10% to 50%.
7 . The catalyst composition according to claim 1 , wherein a silica alumina concentration varies from 10% to 60% and a gamma alumina concentration varies from 10 to 50%.
8 . The catalyst composition according to claim 1 , wherein a zeolite concentration varies from 25% to 75%, a kaolin concentration varies from 10% to 50% and a gamma alumina concentration varies from 10% to 50%.
9 . The catalyst composition according to claim 1 , wherein the dehydration component is produced using pore former materials selected from the group consisting of: microcrystalline cellulose, starch, lignocellulosic compounds, acrylates, carboxylases, and sulfonates.
10 . The catalyst composition according to claim 1 , wherein the dehydration agents cause a temperature rise between 0.8° C. and 1.6° C. when 2.000 g of the agents is calorimetrically titrated against a 20% buty amine/hexane solution.
11 . A method of producing dimethyl ether from synthesis gas comprising hydrogen and carbon monoxide, the method comprising:
contacting the synthesis gas with a catalyst;
wherein the catalyst comprises:
a methanol synthesis component comprising co-precipitated metal components containing Cu, Zn and Al, wherein an atomic ratio of Al to Cu is 0.05 to 2 and an atomic ratio of Al to Zn is 0.1 to 1; and
a dehydration component comprising a mixture of dehydrating agents selected from at least two of the group consisting of silica alumina, kaolin, gamma alumina, aluminum silicate, montmorillonite, mullite, mesostructured aluminosilicate, and zeolites;
wherein the dehydration component is separately calcined from the methanol synthesis component and the dehydrating agents are selected to yield a CO conversion rate to dimethyl ether exceeding 60% at reaction pressures below 20 bar at temperatures above 220° C. and below 300° C.
12 . The method according claim 11 , wherein a weight ratio of methanol synthesis component to dehydration component varies from 5:1 to 1:5.
13 . The method according to claim 11 , wherein the dehydrating component is calcined at temperatures exceeding 500° C.
14 . The method according to claim 11 , wherein the methanol synthesis component is calcined at temperatures below 400° C.
15 . The method according to claim 11 , wherein a silica alumina concentration varies from 10% to 60% and a kaolin concentration varies from 10% to 50%.
16 . The method according to claim 11 , wherein a silica alumina concentration varies from 10% to 60%, a kaolin concentration varies from 10 to 40%, and a gamma alumina concentration varies from 10 to 50%.
17 . The method according to claim 11 , wherein a silica alumina concentration varies from 10% to 60% and a gamma alumina concentration varies from 10 to 50%.
18 . The method according to claim 11 , wherein a zeolite concentration varies from 25% to 75%, a kaolin concentration varies from 10% to 50% and a gamma alumina concentration varies from 10% to 50%.
19 . The method according to claim 11 , wherein the dehydration component component is produced using pore former materials selected from the group consisting of: microcrystalline cellulose, starch, lignocellulosic compounds, acrylates, carboxylates, sulfonates.
20 . The method according to claim 11 , wherein the dehydration agents cause a temperature rise between 0.8° C. and 1.6° C. when 2.000 g of the agents is calorimetrically titrated against a 20% butylamine/hexane solution.