Catalyst-loaded coal compositions, methods of making and use
The present invention relates to catalyst-loaded coal compositions having a moisture content of less than about 6 wt %, a process for the preparation of catalyst-loaded coal compositions, and an integrated process for the gasification of the catalyst-loaded coal compositions. The catalyst-loaded coal compositions can be prepared by a diffusive catalyst loading process that provides for a highly dispersed catalyst that is predominantly associated with the coal matrix, such as by ion-exchange.
1. An integrated process for the steady-state gasification of an optimized reactor feed catalyst-loaded coal composition, comprising the steps of:
(a) providing a ground raw coal solid stream into a diffuse catalyst loading contactor, wherein the coal comprises a matrix containing ion exchange sites comprising acidic functional groups;
(b) introducing an influent stream comprising a salt of a Group I alkali metal catalyst into the diffuse catalyst loading contactor to create a slurry, wherein the influent stream is comprised of a raffinate stream, a recycle stream and a makeup stream;
(c) controlling the amount of catalyst in the influent stream such that the amount of Group I alkali metal catalyst in the influent stream is equal to or greater than the amount to achieve saturation ion-exchange loading of the coal;
(d) holding the slurry at a contact temperature and for a contact time so as to provide ample opportunity to achieve substantial and uniform catalyst loading such that the Group I alkali metal catalyst is highly dispersed throughout the coal matrix;
(e) dewatering the slurry by filtration to form a catalyst-loaded wet coal cake and the raffinate solution;
(f) recycling the raffinate solution into the influent stream;
(g) thermally-treating the catalyst-loaded wet coal cake under a flow of inert dry gas to reduce the moisture content to less than about 6 wt %, such that greater than about 50% of the total amount of the catalyst loaded is Group I alkali metal catalyst associated with the coal matrix;
(h) gasifying the catalyst-loaded thermally-treated coal composition in a fluidized bed reactor in the presence of steam, CO and H 2 at a temperature ranging from about 450° C. to about 750° C. and a pressure ranging from about 50 psig and about 1000 psig, to produce a char and a raw gas stream comprising methane;
(i) withdrawing the raw gas stream from the fluidized bed reactor;
(j) withdrawing the char from the fluidized bed reactor;
(k) extracting catalyst from the char; and
(l) recycling extracted catalyst into the influent stream as the recycle stream.
2. The integrated process according to claim 1 , wherein the amount of Group I alkali metal catalyst in the influent stream is controlled by a method comprising the steps of:
(a) monitoring the amount of Group I alkali metal catalyst in the raffinate stream;
(b) monitoring the amount of Group I alkali metal catalyst in the recycle stream; and
(c) adjusting the amount of Group I alkali metal catalyst in the makeup stream.
3. The integrated process according to claim 1 , wherein the concentration of Group I alkali metal catalyst in the influent stream is sufficient to provide the catalyst-loaded coal composition having a ratio of Group I alkali metal catalyst atoms to carbon atoms in the range of about 0.01 to about 0.1.
4. The integrated process according to claim 1 , wherein the amount of Group I alkali metal catalyst in the influent stream ranges from about 0.3 mol/kg to about 3.0 mol/kg.
5. The integrated process according to claim 1 , wherein the coal is sub-bituminous, bituminous, lignite, anthracite or mixtures thereof.
6. The integrated process according to claim 1 , wherein the ground raw coal is sub-bituminous, the catalyst is potassium cation, the salt of said catalyst is potassium carbonate, and the influent solution comprises a concentration of the catalyst salt sufficient to provide the catalyst-loaded coal composition having a ratio of catalyst atoms to carbon atoms in the range of about 0.03 to about 0.05.
7. The integrated process according to claim 1 , wherein greater than about 70% of the total amount of catalyst loaded is Group I alkali metal catalyst associated with the coal matrix.
8. The integrated process according to claim 1 , wherein greater than about 50% of the total amount of the catalyst loaded is Group I alkali metal catalyst associated with the coal matrix by ion exchange on the acidic functional groups of the coal.
9. The integrated process according to claim 1 , wherein greater than about 70% of the total amount of the catalyst loaded is Group I alkali metal catalyst associated with the coal matrix by ion exchange on the acidic functional groups of the coal.
10. The integrated process according to claim 1 , wherein the slurry is held at a contact temperature ranging from about 20° C. to about 95° C. for a contact time ranging from about 1 hours to about 48 hours.
11. The integrated process according to claim 1 , wherein the thermally-treating step is performed at a temperature ranging from about 90° C. to about 250° C.
12. The integrated process of claim 1 , wherein the Group I alkali metal is potassium.
13. The integrated process of claim 2 , wherein the Group I alkali metal is potassium.
14. The integrated process of claim 3 , wherein the Group I alkali metal is potassium.
15. The integrated process of claim 4 , wherein the Group I alkali metal is potassium.
16. The integrated process of claim 7 , wherein the Group I alkali metal is potassium.
17. The integrated process of claim 8 , wherein the Group I alkali metal is potassium.
18. The integrated process of claim 9 , wherein the Group I alkali metal is potassium.
19. The integrated process of claim 10 , wherein the Group I alkali metal is potassium.
20. The integrated process of claim 11 , wherein the Group I alkali metal is potassium.