PRETREATMENT OF BIOLOGICAL FEEDSTOCKS FOR HYDROCONVERSION IN FIXED-BED REACTORS
A process for pretreating biological feedstocks for hydroconversion in a fixed-bed reactor. A feed stream having free fatty acids, fatty acid esters, or combinations thereof is contacted with a citric acid solution. The biological feedstock is separated from the aqueous solution to efficiently produce a pretreated biological feedstock substantially absent of metals and phosphorus.
1 . A process for pre-treating biological feedstocks for hydroconversion comprising the steps of:
(a) providing a biological feedstock stream containing free fatty acids, fatty acid esters, or combinations thereof;
(b) contacting the biological feedstock stream with an aqueous acid solution; and
(c) separating an aqueous phase to yield a pre-treated biological feedstock having an ash content less than about 100 wppm.
2 . The process of claim 1 wherein the biological feedstock comprises animal fat and yellow grease.
3 . The process of claim 1 further comprising the step of:
filtering the biological feed stock stream.
4 . The process of claim 1 wherein the acid is citric acid.
5 . The process of claim 4 wherein the concentration of the citric acid solution is at least 0.5 wt. %.
6 . The process of claim 1 wherein the acid is sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, acetic acid, or carbonic acid.
7 . The process of claim 1 further comprising the step of:
feeding the pre-treated biological feedstock to a hydroconversion unit.
8 . The process of claim 7 wherein the hydroconversion unit includes a fixed-bed reactor.
9 . The process of claim 8 wherein the fixed-bed reactor converts pre-treated biological feedstock to hydrocarbons.
10 . The process of claim 1 wherein the ash content of the biological feedstock is reduced by at least 90%.
11 . The process of claim 1 wherein the pretreated biological feedstock having an ash content less than about 80 wppm ash.
12 . The process of claim 1 wherein the pre-treated biological feedstock having an ash content less than about 50 wppm ash.
13 . The process of claim 1 wherein the total metals and phosphorus of the pretreated biological feedstock is less than about 40 wppm
14 . The process of claim 13 wherein the metals include calcium, iron, potassium, magnesium, and sodium.
15 . The process of claim 1 further comprising the steps of:
providing a plurality of contacting steps; and
providing a plurality of separating steps.