Iron oxide absorbent compositions
Embodiments provided herein are compositions directed to porous iron oxides, which are suitable for removing hydrogen sulfide and other sulfur-containing organic contaminants from hydrocarbon streams, and in which the iron oxide component of the composition contains both maghemite and hematite phases, with maghemite forming the greater portion of these phases. In some embodiments, magnetite, aluminum oxide, alumina silicate, and a binder comprised of an organic substance are homogenized, followed by calcining which burns away the organic and converts magnetite to a mix of maghemite and hematite.
1. A porous absorbent for removing contaminants from a fluid stream, comprising iron oxide existing as a mixture of maghemite and hematite; at least one inorganic binder; and at least one reinforcing agent, wherein the iron oxide comprises at least about 60% by weight of the absorbent, and wherein the iron oxide is about 60%-90% maghemite and hematite substantially comprises the balance of the iron oxide content.
2. The absorbent of claim 1 , wherein maghemite comprises about 80%-90% of the iron oxide content, and hematite substantially comprises the balance of the iron oxide content.
3. The absorbent of claim 1 , wherein the at least one inorganic binder is aluminum oxide.
4. The absorbent of claim 1 , wherein the at least one inorganic binder comprises about 5%-20% by weight of the absorbent.
5. The absorbent of claim 1 , wherein the reinforcing agent is an alumina silicate.
6. The absorbent of claim 5 , wherein the alumina silicate is perlite.
7. The absorbent of claim 6 , wherein the absorbent does not spontaneously ignite upon exposure to air at temperatures below about 50° C. after an exposure time of at least 5 minutes.
8. The absorbent of claim 1 , wherein the reinforcing agent comprises about 5%-20% by weight of the absorbent.
9. A method of preparing an absorbent for removing contaminants from a fluid stream, comprising:
mixing, to form a feed, an amount of iron oxide primarily in the form of magnetite with at least one inorganic binder; at least one organic binder; and at least one reinforcing agent;
compressing the feed;
separating the feed into units; and
calcining the units to cause the organic binder to burnout of the absorbent and to induce the iron oxide in the form of magnetite to undergo phase change to a combination of maghemite and hematite,
wherein the amount of iron oxide comprises at least about 60% by weight of the mixture, and
wherein after calcining the iron oxide is about 60%-90% maghemite and hematite substantially comprises the balance of the iron oxide content.
10. The method of claim 9 , wherein the feed is a homogenous mixture, and the amount of iron oxide in the feed is about 60% by weight.
11. The method of claim 10 , wherein the remainder of the feed comprises about 5%-20% by weight inorganic binder, about 5%-20% by weight reinforcing agent, and about 1%-5% by weight organic binder.
12. The method of claim 9 , wherein burnout of the organic binder results in the formation of macropores in the absorbent.
13. The method of claim 9 , wherein the at least one inorganic binder is aluminum oxide.
14. The method of claim 13 , wherein the reinforcing agent is perlite, and the absorbent does not spontaneously ignite upon exposure to air at temperatures below about 50° C. after an exposure time of at least 5 minutes.
15. The method of claim 9 , wherein the reinforcing agent is alumina silicate.